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NPP Multi-Biome: NPP and Driver Data for Ecosystem Model-data Intercomparison, R2
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Revision date: August 29, 2013

Summary:

This data set represents a refined set of global net primary productivity (NPP) estimates and model driver data that are the results of the Ecosystem Model-Data Intercomparison (EMDI) workshop review and outlier analyses undertaken to assess the accuracy of global model forecasts of terrestrial carbon cycling. EMDI builds upon the accomplishments of the original worldwide synthesis of NPP measurements and associated model driver data prepared by the Global Primary Production Data Initiative (GPPDI) (Olson et al., 2001; 2013). The EMDI review and analyses produced NPP, climate, NDVI, land cover, vegetation, and soil data for a sub-set of GPPDI data: 81 Class A sites, 933 Class B sites, and 3,855 Class C 0.5-degree cell grids. Class A sites represent well-documented study sites that have complete above- and below-ground NPP measurements. Class B sites represent more numerous extensive sites with less documentation and site-specific information available. Class C cells represent estimates of NPP for 0.5-degree grid cells for which inventory, modeling, or remote-sensing tools were used to scale up the point measurements.

The data files are in comma-separated-value (.csv) format:

This document and a companion file (Olson et al., 2001) describe the compilation of NPP estimates under the GPPDI and the EMDI review and outlier analyses that produced this refined set of NPP estimates and model driver data.

Revision Notes: This data set has been revised to correct previously reported NPP estimates for three OTTER Transect sites, USA, in the Class A NPP data file. Please see the Data Set Revisions section of this document for detailed information.

Additional Documentation:

The NPP data collection contains field measurements of biomass, estimated NPP, and climate data for terrestrial grassland, tropical forest, temperate forest, boreal forest, and tundra sites worldwide. Data were compiled from the published literature for intensively studied and well-documented individual field sites and from a number of previously compiled multi-site, multi-biome data sets of georeferenced NPP estimates. The principal compilation effort (Olson et al., 2001) was sponsored by the NASA Terrestrial Ecology Program. For more information, please visit the NPP web site at http://daac.ornl.gov/NPP/npp_home.html.

Data Citation:

Cite this data set as follows:

Olson, R.J., J.M.O. Scurlock, S.D. Prince, D.L. Zheng, and K.R. Johnson (eds.). 2013. NPP Multi-Biome: NPP and Driver Data for Ecosystem Model-Data Intercomparison, R2. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. doi:10.3334/ORNLDAAC/615

 

Table of Contents:

1. Data Set Overview:

Project: Net Primary Productivity (NPP)

Understanding global-scale ecosystem responses to changing environmental conditions is important both as a scientific question and as the basis for making policy decisions. The confidence in regional ecosystem models depends on how well the field data used to develop the models represent the region of interest, how well the environmental model driving variables (e.g., vegetation type, climate, and soils associated with a site used to parameterize ecosystem models) represent the region of interest, and how well regional model predictions agree with observed data for the region. To assess the accuracy of global model forecasts of terrestrial carbon cycling, two EMDI workshops were held (December 1999 and April 2001). The workshops included 11 biogeochemical, satellite-driven, detailed process, and dynamic vegetation global model types. The approach was to (1) run regional or global versions of the models for sites with NPP measurements (i.e., not fine-tuned for specific site conditions) that were assembled under the GPPDI process (Olson et al., 2001; 2012) and then (2) analyze the model-data differences.

Extensive worldwide NPP data were assembled under GPPDI along with model driver data, including vegetation, land cover, climate, and soils data, for use in the EMDI model-data intercomparison (Olson et al., 2013; Zheng et al., 2013). The NPP measurements were collected over a long time period by many investigators using a variety of methods. The minimum requirements for NPP data to be included were as follows:

• the use of one or more accepted methods to estimate above- or below-ground NPP;
• geographical location for the study site;
• definition of biome or vegetation type; and
• a citable reference to peer-reviewed publication, symposium, or workshop proceedings; book chapter; or technical memorandum.

The initial GPPDI data compilations are included in two ORNL DAAC mulit-biome NPP data sets: (1) NPP Multi-Biome: Global Primary Production Data Initiative Products, R2 (Olson et al., 2013), otherwise known as the GPPDI database; and (2) NPP Multi-Biome: Gridded Estimates for Selected Regions Worldwide, 1954-2001, R3 (Zheng et al., 2013), otherwise known as GPPDI-gridded. The GPPDI data were analyzed to extract a subset of NPP data suitable for the EMDI workshops. Model driver data (e.g., vegetation type, climate, and soils associated with a site used to parameterize ecosystem models) were compiled for the set of EMDI data and an extensive review of the combined NPP and driver data was conducted. The sequence of NPP activities culminating in the EMDI Workshops is summarized in Olson et al. (2001).

The results of the EMDI review and outlier analyses produced a refined set of NPP estimates and model driver data (i.e., this data set, known as the EMDI database). The EMDI process resulted in 81 Class A sites, 933 Class B sites, and 3,855 Class C 0.5-degree grid cells derived from the original GPPDI synthesis of NPP measurements and associated driver data. Class A sites represent well-documented study sites that have complete above- and below-ground NPP measurements. Class B sites represent more numerous “extensive” sites with less documentation and site-specific information available. Class C 0.5-degree grid cells represent estimates of NPP for which inventory, modeling, or remote-sensing tools were used to scale up the point measurements.

Comparing the NPP field measurements with an average NPP from the ensemble of model outputs provided a unique method to improve NPP data, model driver data, and model processes. Initial results showed general agreement between model predictions of NPP and field measurements of NPP but with obvious differences that indicated areas for potential data and model improvement.


2. Data Description:

The data files are in .csv and .zip format. There are 18 data files for Class A sites, 11 data files for Class B sites, and 9 data files for Class C grid cells.

Spatial Coverage

Site: Global

Site Boundaries: (All latitude and longitude given in decimal degrees)

Site (Region) Westernmost Longitude Easternmost Longitude Northernmost Latitude Southernmost Latitude Elevation (m)
Global -151.92 179.5 75.5 -49.75 17-3,114

Site Information

NPP estimates compiled under GPPDI (for 2,525 point sites and 5,164 0.5-degree grid cells) were reviewed and analyzed under the EMDI process to produce a refined set of NPP estimates and model driver data. The EMDI process resulted in 81 Class A sites, 933 Class B sites, and 3,855 Class C 0.5-degree grid cells derived from the original synthesis of NPP measurements and associated driver data. Class A sites represent well-documented study sites that have complete aboveground and below ground NPP measurements. Class B sites represent more numerous “extensive” sites with less documentation and site-specific information available. Class C cells represent estimates of NPP for 0.5-degree grid cells for which inventory, modeling, or remote-sensing tools were used to scale up the point measurements. 

Site (Region) Westernmost Longitude Easternmost Longitude Northernmost Latitude Southernmost Latitude Elevation (m)
Class A (81 sites) -148.25 152.45 66.37 -27.75 17 - 2,500
Class B (933 sites) -151.92 179.5 75.5 -43.17

20 - 3,114

(0 - 4,655)

Class C (3,855 0.5-degree grid cells) -122.25 152.75 63.75 -49.75 na

Notes: Reported elevations are given from the literature, along with elevations computed by TerrainBase Digital Elevation Model (DEM), where available, in parenthesis. na = not available.

Spatial Resolution

The NPP measurements are based on sampling of small field plots (m2 to 1 ha). Gridded NPP data are half-degree latitude-longitude grid cells. The spatial resolution of model driver data are given in Tables 1, 2, 10, 11, 14, and 17.

Temporal Coverage

The overall temporal coverage is from 1901 through 1999. The point and gridded NPP measurements cover the period from 1931 through 1996. This coverage does NOT include all years for all sites. EMDI Class A and B climate model driver data cover either 95 years (1901-1995), 30 years (1961-1990), or both. Class C gridded climate model drivers cover the period 1930-1995. NDVI model driver data are 3-year means based on data from 1986, 1989, and 1990. Land cover model driver data are derived from the UMD 1-km Global Land Cover product circa 1992-1993. Soils model driver data cover the period from January 1970 to August 1996.

Temporal Resolution

Each individual point or gridded NPP measurement provides an annual NPP estimate. All NPP estimates are based on plant dry matter accumulation, expressed as gC/m2/year (carbon content of dry matter weight). Climate model driver data are provided as monthly and/or annual means (temperature and precipitation), or percentages (cloud cover and sunshine).

Data File Information

I. EMDI CLASS A DATA

Table 1. EMDI Class A data files.

FILE NAME TEMPORAL COVERAGE FILE CONTENTS
EMDI_ClassA_Cover_UMD_81.csv 19920101-19931231 Proportion of each of the 14 UMD land cover types in a 9 x 9 patch of 1-km pixels around each of the 81 points and the associated land cover value for the centered 1-km pixel and the 0.5-degree pixel
EMDI_ClassA_NDVI_81.csv 3-year monthly averages based on 1986, 1989, and 1990 Monthly average NDVI from 8-km pixels within a 25-km radius of the EMDI point
EMDI_ClassA_NPP_81.csv 19310101-19960101 ANPP, BNPP, and TNPP data for each of the 81 Class A sites
EMDI_ClassA_PREC_1901-95.zip 19010101-19951231 Compressed (zip) file containing one .csv file for each of the 95 years in this series (95 *.csv files). Each file contains monthly precipitation amount for each of the 81 sites, derived from New et al. (2000b).
EMDI_ClassA_PREC_PIK_81.csv 19610101-19901231 Monthly and annual 30-year mean precipitation amount for each of the 81 sites, derived from Leemans and Cramer (1991)
EMDI_ClassA_Site_81.csv 19310101-19960101 Summary data for each of the 81 sites. Data include site ID, location, elevation, country, annual average, minimum, and maximum temperature, and annual precipitation amount.
EMDI_ClassA_Soil_IGBP_81.csv 19700101-19960801 Soil characteristics for each of the 81 sites derived from the from the IGBP-DIS Soils Database
EMDI_ClassA_Summary_81.csv 19310101-19960101 Summary data for each of the 81 sites. Data include site ID, location, elevation, soil texture, annual average, minimum, and maximum temperature, annual precipitation amount, annual percentage of sunlight for daylight hours, dominant land cover type based on a 1 km grid cell centered on the site, and dominant land cover type based on 0.5-degree grid cell centered on the site.
EMDI_ClassA_SUN_1901-95.zip 19010101-19951231 Compressed (zip) file containing one .csv file for each of the 95 years in this series (95 *.csv files). Each file contains monthly percentage of sunlight during daylight hours for each of the 81 sites, derived from New et al. (2000b).
EMDI_ClassA_SUN_PIK_81.csv 19610101-19901231 Monthly and annual 30-year mean percentage of sunlight during daylight hours for each of the 81 sites, derived from Leemans and Cramer (1991)
EMDI_ClassA_TAVE_1901-95.zip 19010101-19951231 Compressed (zip) file containing one .csv file for each of the 95 years in this series (95 *.csv files). Each file contains monthly mean temperature for each of the 81 sites, derived from New et al. (2000b).
EMDI_ClassA_TAVE_PIK_81.csv 19610101-19901231 Monthly and annual mean temperature for each of the 81 sites, derived from Leemans and Cramer (1991)
EMDI_ClassA_TMAX_1901-95.zip 19010101-19951231 Compressed (zip) file containing one .csv file for each of the 95 years in this series (95 *.csv files). Each file contains monthly maximum temperature for each of the 81 sites, derived from New et al. (2000b).
EMDI_ClassA_TMAX_PIK_81.csv 19610101-19901231 Monthly and annual maximum temperature for each of the 81 sites, derived from Leemans and Cramer (1991)
EMDI_ClassA_TMIN_1901-95.zip 19010101-19951231 Compressed (zip) file containing one .csv file for each of the 95 years in this series (95 *.csv files). Each file contains monthly minimum temperature for each of the 81 sites, derived from New et al. (2000b).
EMDI_ClassA_TMIN_PIK_81.csv 19610101-19901231 Monthly and annual minimum temperature for each of the 81 sites, derived from Leemans and Cramer (1991)
EMDI_ClassA_TRANGE_1901-95.zip 19010101-19951231 Compressed (zip) file containing one .csv file for each of the 95 years in this series (95 *.csv files). Each file contains actual monthly diurnal temperature for each of the 81 sites, derived from New et al. (2000b).
EMDI_ClassA_Veg_81.csv 19310101-19960101 Summary vegetation data for each of the 81 sites. Data include site ID, location, biome, vegetation type, dominant species, and management regime.

Table 2. Column headings, parameter definitions, and units of measure for Class A site summary information data files.

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassA_Site_81.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
ELEV_GIV Elevation as given for the site Meters
ELEV_DEM Elevation extracted from the global TerrainBase Digital Elevation Model (DEM) (5-min resolution)
COUNTRY Country where site is located Text
TAVE_ANN Annual average temperature, 1961-1990 degrees Celsius
TMIN_ANN Minimum annual temperature, 1961-1990
TMAX_ANN Maximum annual temperature, 1961-1990
PREC_ANN Annual total precipitation, 1961-1990 mm
EMDI_ClassA_Summary_81.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
ELEV Elevation as given for the site meters
SAND Sand content in top 30 cm % w/w
SILT Silt content in top 30 cm
CLAY Clay content in top 30 cm
TAVE Annual average temperature, 1961-1990 degrees Celsius
TMIN Minimum annual temperature, 1961-1990
TMAX Maximum annual temperature, 1961-1990
PREC Annual total precipitation, 1961-1990 mm
SUN Annual mean percentage of sunlight during daylight hours, 1961-1990 %
COVR1KM Dominant UMD land cover type based on a 1 km grid cell centered on the site Numerical code (0 through 13) defined in Table 4
COVR50KM Dominant UMD land cover type based on 0.5-degree  grid cell centered on the site.

Table 3. Column headings, parameter definitions, and units of measure for the Class A point NPP measurements (global sources).

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassA_NPP_81_R2.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
ELEV_GIV Elevation as given for the site Meters
ELEV_N Number of elevation measurements for this site Numeric
SOURCE Source of the NPP data name or code. Reference to person or organization that compiled the data or to another ORNL DAAC data set where the data came from. Text
BIOMENEW Biome type, standardized to EDMI classes (see Table 24)
BIOME2 Aggregated biome type (see Table 24)
TAVE_N Number of temperature measurements for this site Numeric
PREC_N Number of precipitation measurements for this site
TEMP_ANN Annual average temperature degrees Celsius
PREC_ANN Annual total precipitation mm
ANPP_N Number of published above-ground NPP measurements for this site Numeric
BNPP_N Number of published below-ground NPP measurements for this site
TNPP_N Number of published total NPP measurements for this site
MOD_N Number of NPP estimates from models for this site
FLAG_N Sum of all the flag values
ANPP_C Above-ground NPP gC/m2/y
BNPP_C Below-ground NPP
TNPP_C Total NPP
MODCA_AV Average ensemble value from up to 11 EMDI models
FLAGS Sum of all the flag values Numeric

Table 4. Column headings, parameter definitions, and units of measure for the Class A point UMD land cover classification (Hansen et al., 2000b).

FILE NAME COLUMN HEADING DEFINITION UNITS CODE FOR LAND USE CLASS
EMDI_ClassA_Cover_UMD_81.csv SITE_ID Site identification number based on unique lat/long Numerical  
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
WATER Water Numerical Code 0
NEEDLE_E Evergreen needleleaf forests 1
BROAD_E Evergreen broadleaf forests 2
NEEDLE_D Deciduous needleleaf forests 3
BROAD_D Deciduous broadleaf forests 4
MIXED Mixed forests 5
WOODLAND Woodlands 6
WOODGRSS Wooded grasslands/ shrubs 7
SHRUB_CL Closed bushlands or shrublands 8
SHRUB_OP Open shrublands 9
GRASS Grasses 10
CROP Croplands 11
BARE Bare ground 12
URBAN Urban and built-up 13
COVR1KM Dominant UMD land cover type based on a 1 km grid cell centered on the site Numerical Code 0 through 13 (defined above)
COVR50KM Dominant UMD land cover type based on 0.5-degree  grid cell centered on the site.

Table 5. Column headings, parameter definitions, and units of measure for the Class A point NDVI calculations (James and Kalluri, 1994).

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassA_NDVI_81.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
JAN ... DEC Monthly NDVI mean -- average of 1986, 1987, and 1990 Index (0-1)
JAN_N ... DEC_N Monthly NDVI standard deviation
JAN_STD ... DEC_STD NDVI number of years in mean (0-3)

Table 6. Column headings, parameter definitions, and units of measure for the Class A model drivers climate information, 95-year climate series (1901-1995) (New et al., 2000b).

COMPRESSED FILE NAME UNCOMPRESSED FILE NAMES
(There is one file for each year, 1901-1995, with no missing years)
VARIABLE DEFINITION (COLUMN HEADING) UNITS
EMDI_ClassA_PREC_1901-95.zip pre.81_1901.csv through pre.81_1995.csv Precipitation Monthly total precipitation amount, 1901-1995 (JAN ... DEC) mm
EMDI_ClassA_TAVE_1901-95.zip tmp.81_1901.csv through tmp.81_1995.csv Average temperature Monthly mean temperature, 1901-1995 (JAN ... DEC) degrees Celsius
EMDI_ClassA_TMAX_1901-95.zip tmx.81_1901.csv through tmx.81_1995.csv Maximum temperature Maximum monthly temperature, 1901-1995 (JAN ... DEC)
EMDI_ClassA_TMIN_1901-95.zip tmn.81_1901.csv through tmn.81_1995.csv Minimum temperature Minimum monthly temperature, 1901-1995 (JAN ... DEC)
EMDI_ClassA_TRANGE_1901-95.zip dtr.81_1901.csv through dtr.81_1995.csv Actual diurnal temperature Actual monthly diurnal temperature range, 1901-1995 (JAN ... DEC)
EMDI_ClassA_SUN_1901-95.zip sun.81_1901.csv through sun.81_1995.csv Sunshine Monthly mean percentage of sunlight during daylight hours, 1901-1995 (JAN ... DEC) %

Table 7. Column headings, parameter definitions, and units of measure for the Class A model drivers climate information, 30-year climate series (1961-1990) (Leemans and Cramer, 1991, compiled by PIK).

FILE NAME VARIABLE DEFINITION (COLUMN HEADING) UNITS
EMDI_ClassA_PREC_PIK_81.csv Precipitation Annual and monthly total precipitation amount, 1961-1990 (ANN; JAN ... DEC) mm
EMDI_ClassA_TAVE_PIK_81.csv Average temperature Annual and monthly mean temperature, 1961-1990 (ANN; JAN ... DEC) degrees Celsius
EMDI_ClassA_TMAX_PIK_81.csv Maximum temperature Maximum annual and monthly temperature, 1961-1990 (ANN; JAN ... DEC)
EMDI_ClassA_TMIN_PIK_81.csv Minimum temperature Minimum annual and monthly temperature, 1961-1990 (ANN; JAN ... DEC)
EMDI_ClassA_SUN_PIK_81.csv Sunshine Annual and monthly mean percentage of sunlight during daylight hours, 1961-1990 (ANN; JAN ... DEC) %

Table 8. Column headings, parameter definitions, and units of measure for the Class A model drivers soil information (IGBP Soils Database).

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassA_Soil_IGBP_81.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
SAND Sand content in top 30 cm % w/w
SILT Silt content in top 30 cm
CLAY Clay content in top 30 cm
SOILN30 Soil nitrogen in top 30 cm kg/m2
SOILN20 Soil nitrogen in top 20 cm
SOILN100 Soil nitrogen in top 100 cm
SOILC30 Soil carbon in top 30 cm g/m2
SOILC20 Soil carbon in top 20 cm
SOILC100 Soil carbon in top 100 cm
PH Soil pH (water) in top 30 cm Units
BD Bulk density of top 30 cm g/cm
FC Field capacity (water holding capacity) in top 30 cm mm
WP Wilting point for top 30 cm
PAWC Profile available water capacity

Table 9. Column headings, parameter definitions, and units of measure for the Class A model drivers vegetation information (site-specific sources).

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassA_Veg_81.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
BIOME Biome type, standardized to EMDI classes (see Table 24) Text
VEG_TYPE Vegetation type as given, somewhat standardized
SPECIES Dominant species
MNGMT Site management, if known

II. EMDI CLASS B DATA

Table 10. EMDI Class B data files.

FILE NAME TEMPORAL COVERAGE FILE CONTENTS
EMDI_ClassB_Cover_UMD_933.csv 19920101-19931231 Proportion of each of the 14 UMD land cover types in a 9 x 9 patch of 1-km pixels around each of the 933 points and the associated land cover value for the centered1-km pixel and the 0.5-degree pixel
EMDI_ClassB_NDVI_933.csv 3-year monthly averages based on 1986, 1989, and 1990 Monthly average NDVI from 8-km pixels within a 25-km radius of the EMDI point
EMDI_ClassB_NPP_933_v2.csv 19310101-19960101 ANPP, BNPP, and TNPP data for each of the 933 Class B sites
EMDI_ClassB_PREC_933.csv 19610101-19901231 Monthly and annual 30-year mean precipitation amount for each of the 933 sites, derived from Leemans and Cramer (1991)
EMDI_ClassB_Site_933.csv 19310101-19960101 Summary data for each of the 933 sites. Data include site ID, location, elevation, country, biome, vegetation type, dominant species, sub-biome, reference, and year of publication.
EMDI_ClassB_Soil_IGBP_933.csv 19700101-19960801 Soil characteristics for each of the 933 sites derived from the from the IGBP-DIS Soils Database
EMDI_ClassB_Summary_933.csv 19310101-19960101 Summary data for each of the 933 sites. Data include site ID, location, elevation, soil texture, annual average, minimum, and maximum temperature, annual precipitation amount, annual percentage of sunlight for daylight hours, dominant land cover type based on a 1 km grid cell centered on the site, and dominant land cover type based on 0.5-degree  grid cell centered the on site.
EMDI_ClassB_SUN_933.csv 19610101-19901231 Monthly and annual 30-year mean percentage of sunlight during daylight hours for each of the 933 sites, derived from Leemans and Cramer (1991)
EMDI_ClassB_TAVE_933.csv 19610101-19901231 Monthly and annual 30-year mean temperature for each of the 933 sites, derived from Leemans and Cramer (1991)
EMDI_ClassB_TMAX_933.csv 19610101-19901231 Monthly and annual 30-year maximum temperature for each of the 933 sites, derived from Leemans and Cramer (1991)
EMDI_ClassB_TMIN_933.csv 19610101-19901231 Monthly and annual 30-year minimum temperature for each of the 933 sites, derived from Leemans and Cramer (1991)

Table 11. Column headings, parameter definitions, and units of measure for the Class B point UMD land cover classification (Hansen et al., 2000b).

ILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassB_Cover_UMD_933.csv SITE_ID Site identification number based on unique lat/long Numerical
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
COVR1KM Dominant UMD land cover type based on a 1 km grid cell centered on the site Numerical Code (0 through 13 defined in Table 4)
COVR50KM Dominant UMD land cover type based on 0.5-degree  grid cell centered on the site.
COVTYPES Dominant UMD land cover frequencies based on 0.5-degree  grid cell. This value equates to the number of unique land cover types (with a possible maximum of 14) in a 5 x 5 neighborhood patch of 0.5-degree cells around each site. It provides an indication of the homogeneity in land cover at the site.

Table 12. Column headings, parameter definitions, and units of measure for the Class B point NDVI calculations (James and Kalluri, 1994).

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassB_NDVI_933.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
JAN ... DEC Monthly NDVI mean -- average of 1986, 1987, and 1990 Index (0-1)
JAN_N ... DEC_N NDVI number of years in mean (0-3) Numeric
JAN_STD ... DEC_STD Monthly NDVI standard deviation Index (0-1)

Table 13. Column headings, parameter definitions, and units of measure for the Class B point NPP measurements.

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassB_NPP_933_v2.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
ELEV Elevation as given for the site Meters
ELEV_N Number of elevation measurements for this site Numeric
SOURCE Source of the NPP data name or code. Reference to person or organization that compiled the data or to another ORNL DAAC data set where the data came from. Text
BIOMENEW Biome type, standardized to EDMI classes (see Table 25)  
TAVE_N Number of temperature measurements for this site Numeric
PREC_N Number of precipitation measurements for this site
TAVE Annual average temperature degrees Celsius
PREC Annual total precipitation mm
ANPP_N Number of published above-ground NPP measurements for this site Numeric
BNPP_N Number of published below-ground NPP measurements for this site
TNPP_N Number of published total NPP measurements for this site
NPP_N Number of estimated total NPP measurements for this site (estimated from ANPP or BNPP if no TNPP)
MOD_N Number of NPP estimates from models for this site
AET_N Number of models providing Actual Evapotranspiration (AET) for this site
FLAG_N Sum of all the flag values
ANPP_C Above-ground NPP gC/m2/y
BNPP_C Below-ground NPP
TNPP_C Total NPP
MODCB_AV Average ensemble value from up to 11 EMDI models
AETCB_AV Average ensemble value for Actual Evapotranspiration from up to 5 EMDI models mm/y
FLAGS Sum of all the flag values Numeric
TAVE_MAX Maximum temperature for this site degrees Celsius
PREC_MAX Maximum precipitation for this site mm
ELEV_MAX Maximum elevation for this site meters
ANPP_MAX Above-ground NPP – maximum of several published estimates gC/m2/y
BNPP_MAX Below-ground NPP – maximum of several published estimates
TNPP_MAX Total NPP – maximum of several published estimates
NPP_MAX NPP_EST – maximum of several estimates from ANPP or BNPP if no TNPP
MOD_MAX Maximum model output of NPP
AET_MAX Maximum model output of AET mm/y
FLAG_MAX Maximum number of flags associated with a site Numeric
TAVE_MIN Minimum temperature for this site degrees Celsius
PREC_MIN Minimum precipitation for this site mm
ELEV_MIN Minimum elevation for this site meters
ANPP_MIN Above-ground NPP – minimum of several published estimates gC/m2/y
BNPP_MIN Below-ground NPP – minimum of several published estimates
TNPP_MIN Total NPP – minimum of several published estimates
NPP_MIN NPP_EST – minimum of several estimates from ANPP or BNPP if no TNPP
MOD_MIN Minimum model output of NPP
AET_MIN Minimum model output of AET mm/y
FLAG_MIN Minimum number of flags associated with a site Numeric

Table 14. Column headings, parameter definitions, and units of measure for Class B site summary information data files.

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassB_Site_933.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
ELEV_GIV Elevation as given for the site Meters
ELEV_DEM Elevation extracted from the global TerrainBase Digital Elevation Model (DEM) (5-min resolution)
ELEV_G_N Number of elevation measurements given for this site Numeric
ELEV_D_N Number of elevation measurements extracted from the global TerrainBase Digital Elevation Model (DEM) (5-min resolution)
SITE_OLD Reference to site ID in another ORNL DAAC data set. N/A = not applicable. Numeric or Text
SOURCE Source of the NPP data name or code. Reference to person or organization that compiled the data or to another ORNL DAAC data set where the data came from. Text
COUNTRY Country where site is located
BIOMENEW Biome type, standardized to EDMI classes (see Table 25)
VEG_TYPE Vegetation type as given, somewhat standardized
SPECIES Dominant species
SUBBIOME Sub Biome, e.g., conifer, deciduous
REFERENC Published reference
YEAR_REF Year of reference YYYY
EMDI_ClassB_Summary_933.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
ELEV_GIV Elevation as given for the site Meters
ELEV_DEM Elevation extracted from the global TerrainBase Digital Elevation Model (DEM) (5-min resolution)
SAND Sand content in top 30 cm % w/w
SILT Silt content in top 30 cm
CLAY Clay content in top 30 cm
TAVE Annual average temperature, 1961-1990 degrees Celsius
TMIN Minimum annual temperature, 1961-1990
TMAX Maximum annual temperature, 1961-1990
PREC Annual total precipitation, 1961-1990 mm
SUN Annual mean percentage of sunlight for daylight hours, 1961-1990 %
COVR1KM Dominant UMD land cover type based on a 1 km grid cell centered on the site Numerical code (0 through 13) defined in Table 4
COVR50KM Dominant UMD land cover type based on 0.5-degree  grid cell centered on the site.
COVTYPES Dominant UMD land cover frequencies based on 0.5-degree  grid cell. This value equates to the number of unique land cover types (with a possible maximum of 14) in a 5 x 5 neighborhood patch of 0.5-degree cells around each site. It provides an indication of the homogeneity in land cover at the site.
SITE_NO Unique site number Numeric

Table 15. Column headings, parameter definitions, and units of measure for the Class B model drivers climate information, 30-year climate series (1961-1990) (Leemans and Cramer, 1991, compiled by PIK).

FILE NAME VARIABLE DEFINITION (COLUMN HEADING) UNITS
EMDI_ClassB_PREC_933.csv Precipitation Annual and monthly total precipitation amount, 1961-1990 (ANN; JAN ... DEC) mm
EMDI_ClassB_TAVE_933.csv Average temperature Annual and monthly mean temperature, 1961-1990 (ANN; JAN ... DEC) degrees Celsius
EMDI_ClassB_TMAX_933.csv Maximum temperature Maximum annual and monthly temperature, 1961-1990 (ANN; JAN ... DEC)
EMDI_ClassB_TMIN_933.csv Minimum temperature Minimum annual and monthly temperature, 1961-1990 (ANN; JAN ... DEC)
EMDI_ClassB_SUN_933.csv Sunshine Annual and monthly mean percentage of sunlight during daylight hours, 1961-1990 (ANN; JAN ... DEC) %

Table 16. Column headings, parameter definitions, and units of measure for the Class B model drivers soil information (IGBP Soils Database).

FILE NAME COLUMN HEADING DEFINITION UNITS
EMDI_ClassB_Soil_IGBP_933.csv SITE_ID Site identification number based on unique lat/long Numeric
LAT_DD Latitude of NPP site (point) Decimal degrees
LONG_DD Longitude of NPP site (point)
SAND Sand content in top 30 cm % w/w
SILT Silt content in top 30 cm
CLAY Clay content in top 30 cm
SOILN30 Soil nitrogen in top 30 cm kg/m2
SOILN20 Soil nitrogen in top 20 cm
SOILN100 Soil nitrogen in top 100 cm
SOILC30 Soil carbon in top 30 cm g/m2
SOILC20 Soil carbon in top 20 cm
SOILC100 Soil carbon in top 100 cm
PH Soil pH (water) in top 30 cm Units
BD Bulk density of top 30 cm g/cm
FC Field capacity (water holding capacity) in top 30 cm mm
WP Wilting point for top 30 cm
PAWC Profile available water capacity

III. EMDI CLASS C DATA

Table 17. EMDI Class C data files.

FILE NAME TEMPORAL COVERAGE FILE CONTENTS
EMDI_ClassC_CLOUDS_1901-95.csv 19010101-19951231 One .csv file (48.5 MB) of monthly and annual mean cloud cover (%) for each year in the 95-year series for 3,855 0.5-degree grid cells based on New et al. (1999, 2000b)
EMDI_ClassC_Drivers.csv 19010101-19960101 Model driver data for 3,855 0.5-degree grid cells derived from global sources. Model drivers include cell ID; location; elevation; annual precipitation amount, average temperature, NDVI, and maximum/minimum temperatures; monthly average and maximum/minimum temperatures; monthly average and maximum/minimum precipitation amount; monthly NDVI; monthly and annual actual temperature range; predominant land cover class; soil texture (%); and biome classification.
EMDI_ClassC_IGBP_soils.csv 19700101-19960801 Soil characteristics for 3,855 0.5-degree grid cells derived from the IGBP-DIS Soils Database
EMDI_ClassC_NPP.csv 19310101-19960101 ANPP and TNPP estimates for 3,855 0.5-degree grid cells (global sources)
EMDI_ClassC_PREC_1901-95.csv 19010101-19951231 One .csv file (48.5 MB) of monthly and annual precipitation amount for the 95-year series for 3,855 0.5-degree grid cells based on New et al. (1999, 2000b)
EMDI_ClassC_TAVE_1901-95.csv 19010101-19951231 One .csv file (48.5 MB) of monthly and annual average temperature for the 95-year series for 3,855 0.5-degree grid cells based on New et al. (1999, 2000b)
EMDI_ClassC_TMAX_1930-95.csv 19300101-19951231 One .csv file (48.5 MB) of monthly and annual maximum temperature for the 82-year series for 3,855 0.5-degree grid cells based on New et al. (1999, 2000b)
EMDI_ClassC_TMIN_1930-95.csv 19300101-19951231 One .csv file (48.5 MB) of monthly and annual minimum temperature for the 82-year series for 3,855 0.5-degree grid cells based on New et al. (1999, 2000b)
EMDI_ClassC_TRANGE_1930-95.csv 19300101-19951231 One .csv file (48.5 MB) of monthly and annual actual temperature range for the 82-year series for 3,855 0.5-degree grid cells based on New et al. (1999, 2000b)

Table 18. Column headings, parameter definitions, and units of measure for the Class C 0.5-degree grid cell NPP measurements (global sources).

FILE NAME VARIABLE DEFINITION UNITS
EMDI_ClassC_NPP.csv Lat Latitude of 0.5-degree  cell centroid Decimal degrees
Lon Longitude of 0.5-degree  cell centroid
ID Cell identification number based on unique lat/long Numeric
GROUP Model group assignment for testing data Numeric (1 or 2)
ANPP Above-ground net primary productivity gC/m2/y
ANPP_N Number of records for ANPP Numeric
TNPP Total net primary productivity gC/m2/y
TNPP_N Number of records for TNPP Numeric
BIOME2 Biome type, standardized to 14 EMDI classes (See Table 24) Text

Table 19. Column headings, parameter definitions, and units of measure for the Class C 0.5- degree grid cell summary model drivers.

FILE NAME VARIABLE DEFINITION UNITS
EMDI_ClassC_Drivers.csv LAT_DD Latitude of 0.5-degree cell centroid Decimal degrees
LONG_DD Longitude of 0.5-degree cell centroid
ID Cell identification number based on unique lat/long Numeric
ELE Elevation of 0.5-degree cell centroid based on 1 km Global Land One-km Base Elevation (GLOBE) Meters
ELE_STD Standard deviation of elevation in a 0.5-degree cell based on 1-km data
ANU_PPT Annual mean total precipitation in millimeters, 1961–1990 mm
ANU_AVGT Annual mean air temperature (ºC), 1961–1990 degrees Celsius
ANU_MAXT Annual maximum temperature (ºC), 1961–1990
ANU_MINT Annual minimum temperature (ºC), 1961–1990
ANU_NDVI Annual mean NDVI, August 1981-July 1994 Index (0-1)
JAN_AVGT .. DEC_AVGT Monthly mean air temperature (ºC), 1961–1990 degrees Celsius
JAN_MAXT .. DEC_MAXT Monthly maximum temperature (ºC), 1961–1990
JAN_MINT .. DEC_MINT Monthly minimum temperature (ºC), 1961–1990
JAN_AVGP .. DEC_AVGP Monthly mean total precipitation in millimeters, 1961–1990 mm
JAN_MAXP .. DEC_MAXP Monthly maximum total precipitation in millimeters, 1961–1990
JAN_MINP .. DEC_MINP Monthly minimum total precipitation in millimeters, 1961–1990
JAN_NDVI .. DEC_NDVI Monthly mean NDVI, August 1981-July 1994 Index
JAN_DTRT .. DEC_DTRT Monthly actual diurnal temperature range degrees Celsius
ANN_DTRT Annual actual diurnal temperature range
LANDCOVE Dominant UMD land cover type for 0.5-degree grid cell (Hansen et al., 2000b) Numerical code (0 through 13) defined in Table 4
SAND Percentages of soil composition in sand %
SILT Percentages of soil composition in silt
CLAY Percentages of soil composition in clay
BIOME2 Biome types (see Table 26) Text

Table 20. Column headings, parameter definitions, and units of measure for the Class C 0.5-degree grid cell model drivers climate information (New et al., 1999; 2000b, compiled by PIK).

 FILE NAME VARIABLE DEFINITION UNITS
EMDI_ClassC_CLOUDS_1901-95.csv CLDS Annual and monthly average cloud cover, 1901-1995 (ann_clds; jan_clds .. dec_clds) %
EMDI_ClassC_PREC_1901-95.csv PREC Annual and monthly total precipitation amount, 1901-1995 (ann_prec; jan_prec .. dec_prec) mm
EMDI_ClassC_TAVE_1901-95.csv TAVE Annual and monthly mean temperature, 1901-1995 (ann_tave; jan_tave .. dec_tave) degrees Celsius
EMDI_ClassC_TMAX_1930-95.csv TMAX Maximum annual and monthly temperature, 1930-1995 (ann_tmax; jan_tmax .. dec_tmax)
EMDI_ClassC_TMIN_1930-95.csv TMIN Minimum annual and monthly temperature, 1930-1995 (ann_tmin; jan_tmin .. dec_tmin)
EMDI_ClassC_TRANGE_1930-95.csv DTR Actual annual and monthly diurnal temperature range, 1930-1995 (ann_dtr; jan_dtr .. dec_dtr)

Table 21. Column headings, parameter definitions, and units of measure for the Class C 0.5-degree grid cell model drivers soil information (IGBP Soils Database).

FILE NAME VARIABLE DEFINITION UNITS
EMDI_ClassC_IGBP_soils.csv LAT_DD Latitude of 0.5-degree cell centroid Decimal degrees
LONG_DD Longitude of 0.5-degree cell centroid
Source IGBP Soils 0.5-degree unless otherwise stated Text
BIOME2 Biome types (see Table 26) Text
GROUP Model group assignment for testing data Numeric (1 or 2)
Sand Sand content in top 30 cm % w/w
Silt Silt content in top 30 cm
Clay Clay content in top 30 cm
WiltPont Wilting point for top 30 cm mm
Fieldcap Field capacity (water holding capacity) in top 30 cm
PAWC Profile available water capacity
SoilC Soil carbon in top 30 cm g/m2
SoilC20 Soil carbon in top 20 cm
SoilC100 Soil carbon in top 100 cm
TotN2 Soil nitrogen in top 30 cm kg/m2
TotN220 Soil nitrogen in top 20 cm
TotN2100 Soil nitrogen in top 100 cm
PHH20 Soil pH (water) in top 30 cm Units
Bulkdens Bulk density of top 30 cm g/cm

 

3. Data Application and Derivation:

The EMDI initiative was launched to assess the accuracy of global model forecasts of terrestrial carbon cycling, NPP in particular. The questions of interest were how well NPP field data used to develop the model forecasts represent the region of interest, how well the environmental model driving variables (e.g., vegetation type, climate, and soils associated with a site used to parameterize ecosystem models) represent the region of interest, and how well regional model predictions agree with observed data for the region. Under EMDI, extensive worldwide NPP data and model driver data, including vegetation, climate, and soils data, compiled under GPPDI (Olson et al, 2012) were reviewed and analyzed. Data that passed EMDI scrutiny were used to perform a model intercomparison exercise involving 11 regional and global ecosystem models (Table 23). Model-data differences were analyzed.

Comparing the NPP field measurements with an average NPP from the ensemble of model outputs provided a unique method to improve NPP data, model driver data, and model processes. Initial results showed general agreement between model predictions of NPP and field measurements of NPP but with obvious differences that indicated areas for potential data and model improvement.

 

4. Quality Assessment:

The ORNL DAAC collection of NPP data has undergone several levels of review or filtering. The activities associated with the GPPDI provided a literature review and data compilation that resulted in selecting Class A and B sites and Class C grid cells. The EMDI activity provided another level of review for all the data by examining relationships between NPP estimates and associated environmental controlling variables, such as temperature and precipitation. As a result of the EMDI review, flags were assigned to each NPP estimate and the EMDI investigators selected a subset of data for the model-data intercomparison based on the flags.

The data were reviewed at the EMDI I Workshop and a strategy was developed for additional “outlier analysis” to flag those NPP measurements that, in combination with their driver data and the NPP ensemble model values, appeared to be unrepresentative or represented conditions that the global ecosystem models did not consider (e.g., wetlands). The EMDI exercise also assigned consistent biome classes to all sites, standardized latitude and longitude to two decimal places, and assigned unique identifiers for locations (SITE_ID) and individual measurements (MEAS_ID) within classes for linking with model driver data and validation data.

The specific issues that were addressed include:

Olson et al. (2001) provide a detailed discussion of data quality issues, outlier analysis, and solutions used to compile the EMDI database.

Sources of Error

Approximately 50% of Class B measurement sites lacked a site-specific record of elevation. TerrainBase Digital Elevation Model (DEM), which has a 5-minute resolution (approximately 10 km at the equator), was used to generate elevation when missing. Because of the limited precision of both the site coordinates and the DEM algorithm, the latitude/longitude/elevation values may contain significant errors. Approximately 5% of the elevations based on the DEM had significantly negative elevations (>100 m below sea level), a likely indicator of compounded errors.

5. Data Acquisition Materials and Methods:

Extensive worldwide NPP data were assembled from the published literature, regression analysis, remote-sensing, and model simulations under GPPDI along with model driver data, including vegetation, climate, and soils data. Data contributors who compiled these data are listed in Table 22. EMDI was undertaken to review and subset the GPPDI data based on data quality analysis and criteria, perform an intercomparison of 11 regional or global versions of ecosystem models (Table 23) using the subsets, and analyze the model-field data differences. The sequence of EMDI activities that culminated in the preparation of the EMDI database is summarized in Olson et al. (2001).

Table 22. EMDI Data Contributors.

Data Contributor Institution, Country
NPP Jonathan Scurlock, Dick Olson, Keri Johnson Oak Ridge National Laboratory, USA
Steve Prince, Daolan Zheng University of Maryland, USA
Bill Parton, Steve Del Grossa Colorado State University, USA
Tom Gower, Drew Feldkirchner University of Wisconsin-Madison, USA
Jian Ni University of Beijing, China
Larry Tieszen USGS EROS Data Center, USA
Jennifer Jenkins USDA Forest Service, USA
Elevation Rob Braswell University of New Hampshire, USA
Soil properties Dick Olson, Keri Johnson Oak Ridge National Laboratory, USA
Land cover Steve Prince, Robb Wright University of Maryland, USA
Monthly NDVI Rob Braswell University of New Hampshire, USA
Atmospheric CO2 Bob Cushman ORNL Carbon Dioxide Information and Analysis Center, USA
30-year average monthly climate Wolfgang Cramer, Stephen Sitch Potsdam Institute for Climate Impact Research, Germany
Actual monthly climates

Table 23. EMDI Modeling Groups.

Model Modelers Institution, Country
AVIM Jinjun Ji Institute of Atmospheric Physics, China
BGC Peter Thornton University of Montana, USA
CARAIB Bernard Nemry University of Liege, Belgium
CENTURY Bill Parton Colorado State University, USA
GLO-PEM Steve Prince, Daolan Zheng University of Maryland, USA
GTEC Mac Post, Tony King Oak Ridge National Laboratory, USA
IBIS Chris Kucharik, Jon Foley University of Wisconsin, USA
LPJ Stephen Sitch, Ben Smith Potsdam Institute for Climate Impact Research, Germany
PNET John Aber University of New Hampshire, USA
STOMATE Pierre Friedlingston, Laurent Kergoat CNRS, France
VECODE Victor Brovkin Potsdam Institute for Climate Impact Research, Germany

Model Driver Data

Model driver data (e.g., vegetation type, climate, and soils associated with a site used to parameterize ecosystem models) were compiled from global databases specifically for the EMDI workshops. The information is consistent for all sites but may represent a value for a 5-km or 5-minute grid cell within which a Class A or B site is located, thus the data may not necessarily reflect the conditions at the specific site of the NPP measurement. The same sources of driver data were used for the Class A and B data sets and an initial subset of Class C data; however, the driver data for the full set of Class C cells for EMDI II was taken from different sources than for EMDI I. See Olson et al. (2001) for details.

Elevation

For Class A and B sites, the site elevation from the published literature was used when available. However, approximately 25% of Class A and 50% of Class B measurement sites lacked a site-specific record of elevation. TerrainBase Digital Elevation Model (DEM), which has a 5-minute resolution (approximately 10 km at the equator), was used to generate elevation where missing. Because of the limited precision of both the site coordinates and the DEM algorithm, the latitude/longitude/elevation values may contain significant errors. Approximately 5% of the elevations based on the DEM had significantly negative elevations (>100 m below sea level), a likely indicator of compounded errors.

Elevations for Class C cells were based on an alternative 1-km DEM derived from the Global Land One-km Base Elevation (GLOBE) Project, a quality-controlled global DEM developed by the U.S. National Geophysical Data Center for International Geosphere-Biosphere Programme, Data and Information System (IGBP-DIS). Aggregation of the GLOBE DEM 1-km elevations to 0.5-degree cells resulted in only 0.2% of cells with significantly negative elevations. The GLOBE database was not available in 1999 when the Class A and B sites were assigned elevations.

Site and Grid Cell Biome Classification

Twenty-one (21) biome classes were defined to represent the NPP data and needs of the models. Sites were assigned to a biome based on initial biome class, sub-biome, species, vegetation type, and elevation. The 21 biome types were grouped into aggregated biome types based on similarity and the number of Class A and B sites to ensure there was enough data within each aggregated biome to conduct outlier detection. All of the biomes are represented in the GPPDI database. Heavily managed sites or sites typically not addressed by regional models, including crop, pasture, plantation, and wetland biome types, were assigned to a single “Managed” type and were excluded from the EMDI exercises.

Table 24. Biome Categories for EMDI Class A Sites.

Biome Type (BIOMENEW) Aggregated Biome Type (BIOME2) Number of Sites
Class A
Crops Managed N/A
Pasture
Plantation
Wetland
Deciduous broad-leaf forest/boreal DBL-DNL forest/boreal 8
Deciduous needle-leaf forest/boreal
Deciduous broad-leaf forest/temperate DBL forest/ temperate  
Deciduous broad-leaf forest/tropical DBL forest/tropical 3
Desert Desert 0
Evergreen broad-leaf forest/temperate EBL forest/ temperate 0
Evergreen broad-leaf forest/tropical EBL forest/tropical 17
Evergreen needle-leaf forest/boreal ENL forest/boreal 15
Evergreen needle-leaf forest/temperate ENL forest/temperate 6
Grassland/C3 Grassland 31
Grassland/C4 temperate
Grassland/C4 tropical
Mediterranean Mediterranean 0
Mixed forest Mixed forest
Savanna/temperate Savanna
Savanna/tropical Savanna
Tundra Tundra
Total Records   81

Notes: N/A = Not applicable because biome category was excluded from EMDI.

Table 25. Biome Categories for EMDI Class B Sites.

Biome Type Aggregated Biome Type (BIOMENEW) Number of Sites
Class B
Crops Managed N/A
Pasture
Plantation
Wetland
Deciduous broad-leaf forest/boreal DBL forest/boreal 26
Deciduous needle-leaf forest/boreal DNL forest/boreal 28
Deciduous broad-leaf forest/temperate DBL forest/temperate 198
Deciduous broad-leaf forest/tropical DBL forest/tropical 12
Desert Desert 16
Evergreen broad-leaf forest/temperate EBL forest/temperate 209
Evergreen broad-leaf forest/tropical EBL forest/tropical 96
Evergreen needle-leaf forest/boreal ENL forest/boreal 74
Evergreen needle-leaf forest/temperate ENL forest/temperate 136
Grassland Grassland/C3 36
Grassland/C4 temperate 16
Grassland/C4 tropical 21
Mediterranean Mediterranean 9
Mixed forest Mixed forest 39
Savanna Savanna/temperate 1
Savanna/tropical 6
Tundra Tundra 10
Total Records   933

Notes: N/A = Not applicable because biome category was excluded from EMDI.

Biome type for Class C cells was based on information obtained from or reported by each individual study. If the biome was not available (e.g., in Senegal), an aggregated type based on the Hansen et al. (2000b) 1-km product was used. The biomes are listed in Table 26 along with the scheme that was used to consolidate the biomes into types consistent with the Class A and B aggregated biome types.

Table 26. Biome Categories for EMDI Class C Sites.

Biome Type Aggregated Biome Type (BIOME2) Number of Sites
Class C
Arid shrubland Shrubland 576
Closed shrubland
Open shrubland
Boreal forest forest/boreal 70
Boreal conifer-dominated ENL forest/ boreal 82
Deciduous forest DBL forest/ tropical 16
Evergreen forest EBL forest/ tropical 1,195
Grass Grassland 1,300
Grassland
Savanna Savanna 69
Subtropical forest forest/ tropical 10
Temperate forest forest/ temperate 312
Wooded grassland Wooded grassland 92
Woodland Forest 2
Xeric forest Forrest/xeric 131
Total Records   3,855

Land Cover

Land cover was extracted from the University of Maryland's 1-km Global Land Cover product (Hansen et al., 2000b). Because of the limited spatial resolution of the database around coastlines (and especially islands), approximately 5% of the study sites were assigned a cover type of 0 (water). The land cover codes and respective land cover classes are shown in Table 4, with the abbreviations used in the data files.

Climate

Long-term monthly climate averages (1931–1960) from the PIK database (Leemans and Cramer, 1991) and a 95-year monthly climate time series (1900–1995) based on the University of East Anglia climate database (New et al., 2000b; see also New et al. 1999 and 2000a) were used to compile climate data for Class A and B sites. The 95-year series was generated for the Class A sites only, while the 30-year means were generated for all of the Class A and B sites. Latitude, longitude, and elevation were used for interpolation; therefore, estimated climate depends on the accuracy of the site location. The approximate minimum and maximum temperatures were calculated from the average temperature by subtracting or adding one-half the diurnal temperature range. The annual mean was calculated as the mean of the 12 monthly means, while the annual minimum was calculated as the minimum of the 12 monthly minimums (not the mean minimum) and the annual maximum was calculated as the maximum of the 12 monthly maximums. The climate surfaces cover all of the land area north of 60° S and the nearby oceans. Some sites on isolated islands and in Antarctica do not have climate data. For Class C cells, climate variables are calculated by Daolan Zheng based on the data set of New et al. (1999, 2000a, b) for the period 1961–1990 and on the long-term monthly averages (1931–1960) from the PIK database (Leemans and Cramer, 1991) to keep the consistency with EMDI I climate data. Transient monthly climate for the 1901–1995 were extracted from New et al. (2000b) for the Class C cells, although the diurnal temperature range was only available for the years 1930–1995 so that minimum and maximum temperatures were limited to those years.

Soils

Soils data for EMDI sites were extracted from the IGBP Soils Database. The means of 14 distinct EMDI soil characteristics were calculated. Soils data were extracted at a 5-minute resolution for Class A and B sites and at a 0.5-degree resolution for Class C cell. See Olson et al. (2001) for details.

NDVI

NDVI data were extracted from the Pathfinder AVHRR [Advanced Very High Resolution Radiometer] Land (PAL) data set (James and Kalluri, 1994). PAL data are available as 10-day composites for August 1981 to August 1994 in global 8-km Goode's Homolosine (equal area) projection. Three-year monthly averages were calculated for Class A and B sites based on 1986, 1987, and 1990. A 13-year average was calculated for Class C grid cells.

The cloud mask that accompanies the PAL 10-day composites was applied, using the most conservative approach of masking all pixels that are flagged as “cloudy” or “mixed.” The NDVI data were recomposited to one month in order to minimize the effects of variable atmospheric conditions and viewing geometry.

To extract the time series, the EMDI latitude-longitude coordinates were converted into Goode's X-Y coordinates, then all of the 8-km NDVI pixels within a 25-km radius of the EMDI point were averaged (excluding cloudy and quality control-flagged pixels). Ice- and snow-covered land is generally identified as cloudy by the cloud retrieval algorithm so only vegetated/potentially vegetated pixels are included in the average. Persistent clouds and snow cover will often result in having no pixels associated with the site for some number of months. These missing data are assigned a value of -999. To represent site patterns for modeling, 3-year monthly averages were calculated for Class A and B sites based on 1986, 1987, and 1990. These are the only years that do not contain an instrument change over or a major pulse of volcanic aerosols. Coincidentally, the 3 years are fairly anomalous with respect to global climate: 1986 and 1987 were ENSO years and 1990 was the warmest year in the AVHRR record.

A 13-year average NDVI was provided for EMDI II Class C cells based on an analysis of the relationships between 3-year and 13-year NDVI values. The results of that analysis are briefly summarized in Appendix B of Olson et al. (2001).

Model Ensemble

The investigators reviewed the literature-derived, observed NPP data extensively prior to EMDI by looking at scatter plots and data outside of reasonable limits. The EMDI Workshop provided the initial model results to compare with the observed NPP data. An ensemble NPP value was calculated for each site as the average of the 11 Class A models (AVIM, BGC, CARAIB, CENTURY, GLO-PEM, GTEC, IBIS, LPJ, PNET, STOMATE, and VECODE) (Table 23) and 8 Class B models (AVIM, CARAIB, CENTURY, GLO-PEM, IBIS, PnET, STOMATE, and VECODE). An ensemble NPP value was calculated for each Class C cell as the average of the 4 models including AVIM, IBIS, PnET, and VECODE. If the model ensemble NPP value was based on less than 3 model outputs for Class A or B sites, or less than 2 outputs for Class C cells, then the model average for that site or cell was dropped. In addition, an ensemble AET (actual evapotranspiration) value was calculated based on the average of AET provided by five of the models for Class A (CARAIB, CENTURY, IBIS, PNET, GTEC), four of the models for Class B (CARAIB, CENTURY, IBIS, PNET), and two of the models for Class C (IBIS, PNET). If the model ensemble AET value was based on less than 3 model outputs for Class A or B sites or less than 2 for Class C cells, then the AET average for that site or cell was dropped.

Outlier Analysis

The investigators used the power of the statistical-empirical analysis to look for inconsistencies in NPP values for individual sites within the patterns formed by homogeneous groups (i.e., biomes). Often these inconsistencies were not apparent in a review of the literature associated with a specific study. The overall approach used at the EMDI 1 Workshop included seven tests to set outlier flags. These analyses are described in Olson et al. (2001).

NPP Measurement Data -- The Results of the EMDI Review Process

The measurements of NPP were categorized as either Class A, representing intensively studied or well-documented study sites; Class B, representing more numerous “extensive” sites with less documentation and site-specific information available, or Class C, representing regional collections of 0.5-degree latitude-longitude grid cells.

The resulting EMDI Class A NPP data set contains 81 NPP data records.

Most of the NPP estimates provided in the literature were in units (g) of dry biomass (organic matter) per square meter per year. These values were converted to carbon units (e.g., gC/m2/y) using a mass fraction of 0.5 for woody components and 0.45 for grass and foliage components (Raich et al., 1991). If investigators were unable to determine whether the biomass was predominantly wood or foliage, a ratio of 0.475 g C per 1 g biomass was used.

For those sites lacking a value for total net primary productivity (TNPP), TNPP (NPP_EST) was estimated from ANPP or BNPP by calculating biome-specific ratios from sites that had both ANPP and BNPP measurements. These ratios were calculated based on the biome classification reviewed at the EMDI I workshop and using data with outliers excluded. The ratios of ANPP to BNPP differ by biome. Based on the EMDI analysis, a ratio of 0.5 BNPP:TNPP for grasslands, deserts, and tundra and a ratio of 0.22 BNPP:TNPP for forests was used (see Appendix C in Olson et al., 2001).

Missing components to provide estimates of TNPP were calculated as described above for Class B sites. In addition, a variety of methods were used to derive the 0.5-degree  grid-cell estimates. Table 27 and Olson et al. (2001) summarize methods used by each study. Principal methods used for estimation of 0.5-degree  cell NPP data include

• stratification of grid cells and area weighting of field NPP observations in each stratum;
• aggregation of finer scale (plot or stand level) spatial inventory data;
• local modeling of NPP using key environmental variables, for which maps are available; and
• direct correlation of ground measurements with remotely sensed vegetation indices.

See Olson et al. (2001) and data sources for details.

Table 27. Sources and information about EMDI Class C grid cell NPP.

Cell ID range Location NPP estimation method 0.5-degree cell scaling method Source
1000s Great Plains, USA Rangeland inventory Aggregated to 0.5-degree cells based on 1-km cells derived from soil maps Tieszen et al. (1997)
2000s Yellowstone, USA Measurements of DBH increment (540 plots) within uniform stands Multiple regression – cover type, topography, soils for each stand type Hansen et al. (2000a)
3000s N/A N/A N/A N/A
4000s Australia Measurements of grassland biomass increment GRASP pasture production model based on rainfall Day et al. (1997)
5000s Minnesota, USA Forest inventory (2,711 plots) Mean of plots for given forest type, then areal weighted Goetz and Prince (1996)
6000s Mid-Atlantic and Maine, USA Forest inventory (2,640 plots) Weighted mean of plots in cells Jenkins et al. (2001)
7000s Russia, SE and NE USA Forest inventory Mean of stands for different type (in Russia) or means of counties (in U.S.A.), areal weighted or resampled Gower et al. (2001); Krankina et al. (2001)
8000s Great Plains, USA Rangeland inventory Means by Major Land Resource Areas (MLRA) associated with 0.5-degree  cells within MLRAs Sala et al. (1988)
9000s Mid-West, USA Crop inventory and growth model Means by county extrapolated to 0.5-degree Prince et al. (2001)
10000s Pacific Northwest, USA Literature giving estimates by stand age Association of NPP with high resolution map of stand age Turner et al. (2000)
11000-12000s Great Plains, USA. Rangeland inventory Empirical relationship with precipitation used Gill et al. (2002)
13000s Eastern forests, USA Forest inventory by county Association of 0.5-degree  cells within counties Brown et al. (1999)
14000-17000s Australia Literature Least-squares statistical model based on climate, soils, and vegetation Barrett (2002)
18000s Finland and Sweden 5-year set of forest measurements (660 plots) with allometric equations Calibrated TM/AVHRR imagery with field data, aggregate to 0.5-degree  cells Zheng et al. (2003; 2004)
19000s Senegal 11-year set of measurements for major cover types Calibrated AVHRR Model with field data Diallo et al. (1991)
20000-21000s South America Calibrated model based on literature values TEM model simulations for 0.5-degree  cells Raich et al. (1991)
22000s China Forest inventory (>1,000 plots) Mean NPP for 33 forest classes, extrapolated to region at 6-km, aggregated to 0.5-degree  cells Jiang et al. (1999)

Notes: N/A = Not applicable because not included.

 

6. Data Access:

This data is available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Data Archive Center:

Contact for Data Center Access Information:
E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952

7. References:

Barrett, D. J. 2002. Steady state turnover time of carbon in the Australian terrestrial biosphere. Global Biogeochemical Cycles 16(4): 1108-1030.

Brown, S.L., P.E. Schroeder, and J.S. Kern. 1999. Spatial distribution of biomass in forests of the eastern USA. Forest Ecology and Management 123: 81-90.

Diallo, O., A. Diouf, N.P. Hanan, A. Naliaye, and Y. Prevost. 1991. AVHRR monitoring of savanna primary production in Senegal, West Africa: 1987-1988. Int. J. Remote Sens. 12: 1259–279.

Day, K.A., M.R. McCaskill, and G.M. McKeon. 1997. A review of pasture production data in Queensland. In K. A. Day, G. M. McKeon, and J. O. Carter (eds.), Evaluating the Risks of Pasture and Land Degradation in Native Pastures in Queensland. Final report for Rural Industries Research and Development Corporation Project DAQ-124A, February.

Gill, R.A., R.H. Kelly, W.J. Parton, K.A. Day, R.B. Jackson, J.A. Morgan, J.M O. Scurlock, L.L. Tieszen, J. Vande Castle, D.S. Ojima, and X.S. Zhang. 2002. Using simple environmental variables to estimate below ground productivity in grasslands. Global Ecology and Biogeography. 11(1): 79-86.

Global Soil Data Task Group. 2000. Global Gridded Surfaces of Selected Soil Characteristics (IGBP-DIS). [Global Gridded Surfaces of Selected Soil Characteristics (International Geosphere-Biosphere Programme - Data and Information System)]. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/569

GLOBE Task Team and others (eds.). 1999. The Global Land One-kilometer Base Elevation (GLOBE) Digital Elevation Model, Version 1.0. National Oceanic and Atmospheric Administration, National Geophysical Data Center, Boulder, Colorado, U.S.A.

Goetz, S.J., and S.D. Price. 1996. Remote sensing of net primary production in boreal forest stands. Agric. For. Meteorol. 78.

Gower, S.T., O. Krankina, R.J. Olson, M. Apps, S. Linder, and C. Wang. 2001. Net primary production and carbon allocation patterns of boreal forest ecosystems. Ecological Applications. 11: 1395-1411.

Hansen, A.J., J.J. Rotella, M.P.V. Kraska, and D. Brown. 2000a. Spatial patterns of primary productivity in the Greater Yellowstone ecosystem. Landscape Ecol. 15: 505-22.

Hansen, M. C., R. S. Defries, J. R. G. Townshend, and R. Sohlberg. 2000b. Global land cover classification at 1 km spatial resolution using a classification tree approach. Int. J. Remote Sens. 21:1331-364.

James, M.E., and S.N.V. Kalluri. 1994. The Pathfinder AHRR land data set. An improved coarse resolution data set for terrestrial monitoring. Int. J. Remote Sens. 15: 3347-364.

Jenkins, J.C., R.A. Birdsey, and Y. Pan. 2001. Biomass and NPP estimation for the mid-Atlantic region (USA) using forest inventory data. Ecol. Appl. 11(4): 1174-193.

Jiang, H., M.J. Apps, Y. Zhang, C. Peng, and P.M. Woodard. 1999. Modelling the spatial pattern of net primary productivity in Chinese forests. Ecol. Modell. 122: 275-88.

Krankina, O.N., S. Brown, J.C. Jenkins, D. Kicklighter, M.J. Apps, and R.J. Olson. 2001. Use of forest inventory data for estimating NPP. Ecological Applications (manuscript).

Leemans, R., and W. Cramer. 1991. The IIASA database for mean monthly values of temperature, precipitation, and cloudiness of a global terrestrial grid. International Institute for Applied Systems Analysis. RR91-18.

National Geophysical Data Center. 1995. TerrainBase, Global 5-Minute Ocean Depth and Land Elevation. NGDC, Boulder, Colorado, U.S.A.

New, M.G., M. Hulme, and P.D. Jones. 2000b. Global Mean Monthly Climatology, 1901–1995. Available online at [http://daac.ornl.gov/] from the ORNL Distributed Active Archive Center, Oak Ridge National Laboratory.

New, M.G., M. Hulme, and P.D. Jones. 1999. Representing 20th century space-time climate variability. I: Development of a 1961-1990 mean monthly terrestrial climatology. J. Climate 12: 829–56.

New, M.G., M. Hulme, and P.D. Jones. 2000a. Representing 20th century space-time climate variability. II: Development of 1901-1996 monthly grids of terrestrial surface climate. J. Climate 13: 2217-238.

Olson, R. J., K.R. Johnson, D.L. Zheng, and J.M.O. Scurlock. 2001. Global and Regional Ecosystem Modeling: Databases of Model Drivers and Validation Measurements. ORNL Technical Memorandum TM-2001/196. Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A.

Olson, R.J., J.M.O. Scurlock, S.D. Prince, D.L. Zheng, and K.R. Johnson (eds.). 2013. NPP Multi-Biome: Global Primary Production Data Initiative Products, R2. Data set. Available on-line [http://daac.ornl.gov] from the Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. doi:10.3334/ORNLDAAC/617

Prince, S.D. 1991. Satellite remote sensing of primary production: comparison of results for Sahelian grasslands 1981-1988. International Journal of Remote Sensing 12: 1301-1311.

Prince, S.D., J. Haskett, M. Steininger, H. Strand, and R. Wright. 2001. Net primary production of U.S. midwest croplands from agricultural harvest yield data. Ecol. Appl. 11(4): 1194-1205.

Raich, J.W., E.B. Rastetter, J.M. Mellillo, D.W. Kicklighter, P.A. Steudler, and B J. Petterson. 1991. Potential net primary productivity in South America: Application of a global model. Ecol. Appl. 1: 399-429.

Sala, O.E., W.J. Parton, L.A. Joyce, and W K. Lauenroth. 1988. Primary production of the central grassland region of the United States. Ecology 69: 40-5.

Tempel P., N.H. Batjes, and V.W.P. van Engelen. 1996. IGBP-DIS Data Set for Pedotransfer Function Development. International Soil Reference and Information Centre (ISRIC), World Soil Information (World Data Center for Soils), Wageningen, The Netherlands.

Tieszen, L.L., B.C. Reed, and D.D. Dejong. 1997. NDVI, C3 and C4 production, and distributions in Great Plains grassland land cover classes. Ecol. Appl. 7: 59-78.

Turner, D.P., W.B. Cohen, and R.E. Kennedy. 2000. Alternative spatial resolutions and estimations of carbon flux over a managed forest landscape in Western Oregon. Landscape Ecol. 15: 441-52.

Zheng, D., S. Prince, and Wright, R. 2003. Terrestrial net primary production estimates for 0.5 grid cells from field observations—a contribution to global biogeochemical modeling. Global Change Biology, 9: 46-64.

Zheng, D.L., S.D. Prince, and T. Hame. 2004. Estimating net primary production of boreal forests in Finland and Sweden from field data and remote sensing. Journal of Vegetation Science 15 (2): 161-170.

Zheng, D.L., S.D. Prince, and R. Wright. 2013. NPP Multi-Biome: Gridded Estimates for Selected Regions Worldwide, 1954-2001, R[evision]3. Data set. Available on-line [http://daac.ornl.gov] from the Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. doi:10.3334/ORNLDAAC/614

Zobler, L. 1986. A world soil file for global climate modelling. NASA Technical Memorandum TM-87802.

Additional Sources of Information:

Please see Olson et al. (2001) for additional data sources and references.

8. Data Set Revisions:

Revision Summary:

The EMDI data file for Class A sites [EMDI_ClassA_NPP_81_R1.csv ] has been revised to correct previously reported net primary production (NPP) values for three OTTER USA transect sites.

Data File Changes:

The EMDI data file for Class A sites [EMDI_ClassA_NPP_81_R1.csv] has been revised to correct previously reported above-ground, below-ground, and total NPP values for Waring's Woods and Scio (unfertilized) and above-ground and total NPP values for Juniper/Sisters OTTER transect sites to agree with values reported in Runyon et al. (1994). EMDI data for these OTTER sites in EMDI_ClassA_NPP_81_R2.csv are now correct.

In the table below, Uncorrected refers to file EMDI_ClassA_NPP_81_R1.csv, and Corrected refers to file EMDI_ClassA_NPP_81_R2.csv

 

Site Identification Parameter Field Uncorrected Corrected
GPPDI Class A 94 (ott Waring's Woods) ANPP (gC/m2/yr) 556 551
BNPP (gC/m2/yr) 219 181
TNPP (gC/m2/yr) 774 732
GPPDI Class A 95 (ott Scio, unfertilized) ANPP (gC/m2/yr) 551 831
BNPP (gC/m2/yr) 181 238
TNPP (gC/m2/yr) 732 1,069
GPPDI Class A 91 (ott Juniper/Sisters) ANPP (gC/m2/yr) 67 57
TNPP (gC/m2/yr) 152 143


Data User Action: If you downloaded this data set from the ORNL DAAC on-line archive before August 29, 2013, you should download it again from the ORNL DAAC.

Revision History:

Revision 1

Olson, R.J., J.M.O. Scurlock, S.D. Prince, D.L. Zheng, and K.R. Johnson (eds.). NPP Multi-Biome: NPP and Driver Data for Ecosystem Model-Data Intercomparison, R1. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.

Original

Olson, R. J., J. M. O. Scurlock, S. D. Prince, D. L. Zheng, and K. R. Johnson (eds.). 2001. NPP Multi-Biome: NPP and Driver Data for Ecosystem Model-Data Intercomparison. Data set. Available on-line [http://daac.ornl.gov] from the Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.