Surface flux measurements were made at selected sites within the FIFE area. Each surface flux station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat. The data contained in the Eddy Correlation Surface Flux Observations (USGS) Data Set were collected from two sites located in the northwest and southwest quadrants on slight inclines in the FIFE study area. These data are available only during the four Intensive Field Campaigns, held during the growing season of 1987, May 25 - October 17. During this period there are 66 days of data.
Eddy Corr. Surface Flux: USGS (FIFE)
(Eddy Correlation Surface Flux Observations (USGS)).
The data contained in the Eddy Correlation Surface Flux Observations (USGS) Data Set were collected from two sites located in the northwest and southwest quadrants on slight inclines in the FIFE study area.
The combined aim of the surface flux group was to use a network of ground based observing systems to measure fluxes of heat, water vapor and radiation at a number of points within the FIFE study area.
Latent heat flux, net radiation, sensible heat flux, soil heat flux, incoming solar radiation, outgoing solar radiation, heat storage, soil temperature, Bowen ratio, wind speed and direction, air temperature, vapor pressure, and friction velocity.
Surface flux measurements were made at selected sites within the FIFE area. The major data collection effort was conducted in 1987 when 6 stationary sites were equipped with Eddy correlation instrumentation operated by several different groups. In 1989, Eddy correlation surface flux stations were installed at 3 locations within the FIFE study area. Each surface flux station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat.
The data described here were located from two sites in the FIFE study area. The sites were located in the northwest (site 22, SITEGRID_ID = 4609) and southwest (site 28, SITEGRID_ID = 6943) quadrants on slight inclines (3 deg and 7 deg), respectively. These data are available only during the four Intensive Field Campaigns, held during the growing season of 1987, May 25 - October 17. During this period there are 66 days of data.
SURFACE_FLUX_30MIN_DATA.
Dr. Harold L. Weaver
United States Geological Survey
FIFE observations of surface fluxes.
Contact 1:
Dr. Harold L. Weaver
HCR-88
Baker City, OR
Tel. (503) 893-6467
Contact 2:
David I. Stannard
U. S. Geological Survey-WRD
Denver, CO
Tel. (303) 236-4983
Please include reference to the following in any presentations or papers making use of these data:
Weaver, H.L. 1990. Temperature and humidity flux-variance relations determined by one-dimensional eddy correlation. Boundary-Layer Meteorol. 53: 77-91.
Eddy correlation is the most direct micrometeorological technique for measuring turbulent fluxes in the surface layer of the atmospheric boundary layer. It is direct in that it involves fewer assumptions than other methods. Some remaining assumptions are that sensors have fast response and the measurement site is horizontally homogeneous enough to avoid measurement problems associated with adjective fluxes and terrain-induced flow distortion.
The eddy-correlation computation of SENSIBLE_HEAT_FLUX is the product of the volumetric heat capacity of air and the covariance between vertical wind speed and air temperature. The covariance between vertical wind speed and air temperature is separately entered as W_T_MEAN. LATENT_HEAT_FLUX is calculated as the product of the latent heat of vaporization and the covariance between vertical wind speed and humidity. This covariance is also entered as W_E_MEAN.
Summary of Eddy Correlation System used by USGS:
All eddy correlation measurements used a single-axis Campbell sonic anemometer for vertical wind speed (w) and air temperature(T). Prior to August, 1987, Lyman-alpha hygrometers were used to measure humidity. Campbell Scientific Inc. made these and the KH-20 Krypton hygrometers that replaced them in August. Webb et al. (1980) adjustments have been applied.
Ground-based.
Ground: instruments supported by combinations of tripods and vertical and horizontal pipe supports. For heights above the ground, see the Field Notes Section.
Not available.
Not available.
Sonic Anemometer:
Absorption hygrometer:
Soil Heat Flux Transducer:
The eddy correlation data represents an area ranging from about 0.01 ha for very stable atmospheric conditions to about 1 ha for unstable and some neutral atmospheric conditions.
Sonic anemometer - hygrometer separation: 10 cm
Sonic anemometers:
Fine-wire thermocouple:
Lyman-alpha Hygrometer:
Krypton Hygrometer:
Soil heat transducer:
Soil thermocouples:
Pyranometer (outgoing shortwave radiation):
Pyranometer, silicon (incoming shortwave radiation):
Net radiometer:
Cup anemometer, #03001:
Not provided by Principal Investigator.
Not available at this revision.
Varies according to sensor. About every two years for net radiometers (shortwave), soil heat transducers, and open-path hygrometers. Less often for other classes of sensors.
The data were acquired with Campbell 21x data loggers and transferred to cassette tapes. A single computer program used 21x data as input to output the data files on disc. All quality controls and algorithms are formal and explicit in the processing programs, written in Pascal.
The standard deviation of air temperature was obtained from a fine-wire thermocouple on the sonic anemometer, and the standard deviation of vapor pressure was measured with a fast-response wet-bulb psychrometer. During IFC-3 and IFC-4, the standard deviations of vapor pressure were obtained from the Campbell Scientific KH-20 krypton hygrometer used in eddy-correlation measurements of vapor flux. During periods when the weather prevented eddy-correlation measurements, the standard deviations of vapor pressure and air temperature were obtained from the fast-response wet-bulb psychrometer. Friction velocity was calculated from wind measurement at a single height and an estimate of surface roughness (0.03 m).
Not available.
Site 22 (4609-ECW) had a Campbell Scientific eddy correlation system set up on a 3 degree slope with E exposure. The slope was approximately a plane surface. A gravel road about 70 m SW of the site probably affected flux measurement very little. There was a PAM station about 60 m S and 8 degrees W. During IFC-1 the measurement site was almost collocated with the PAM station, the latter being 10 m NE of the site. Site 22 was moved farther away from the road for IFCs 2, 3, and 4 to further reduce its effects on flux measurements.
All measurements were made normal to the 3 degree slope except for radio-meter measurements.
Instrument and vegetation heights:
Measurement Height (m) IFC-1 IFC-2 IFC-3 IFC-4 ______ ______ ______ ______ Net radiation 1.73 1.80 1.21 1.20 Wind*Temperature mean 2.03 2.00 1.92 1.90 Wind*Vapor pressure mean 2.03 2.00 1.92 1.90 Vapor pressure 2.74 2.10 2.74 2.90 Air temperature 2.74 2.10 2.74 2.90 Soil Temp depth 1 -0.025 -0.025 -0.025 -0.025 Soil Temp depth 2 -0.10 -0.10 -0.10 -0.10 Soil Temp depth 3 -0.50 -0.50 -0.50 -0.50 Soil heat flux -0.05 -0.05 -0.05 -0.05 Wind speed 2.33 2.30 2.41 2.40 Vegetation 0.35 0.40 0.40 0.40
Negative values indicate depth below ground.
Site 28 had a Campbell Scientific eddy correlation system set up on a 7 degree slope with E exposure. The slope was not a plane surface. A hill to the W with approx. 20 deg slope created a grade break about 30 m W of the site. Contours curved such that the slope N of the site had a more NE exposure and the slope S of the site had a SE exposure. Scattered trees from NE to SE of the site interfered with ideal fetch. All measurements were made normal to the 7 degree slope except for radiometer measurements. During IFC-2, there was a rotation of the eddy correlation system, which did not avoid problems with flux recovery; but daytime flux recovery was generally between 80% and 120% during this period. Since the net radiometer was level, rather than parallel to the slope, it tended to underestimate available energy normal to the slope in the morning and to overestimate available energy normal to the slope in the afternoon. When comparing fluxes of sensible heat and water vapor with those measured normal to the geopotential they should be multiplied by 1/cos (7 deg) or 1.0075. This small correction is left to the data uses to make.
During Aug. 5-12, 1987, all thermocouple measurements required some adjustment because a voltage offset in the data logger affected single-ended measurement of millivolt-range signals. The correction for this voltage offset was determined mainly at night from the non-zero values of pyranometers. Large daytime changes in the voltage offset could be closely estimated from changes in the soil temperature signal at 50 cm. Small daytime changes in the voltage offset went undetected, resulting in inaccuracies in the temperature measurements reported from Site 28 during this 8-day period.
Instrument and vegetation heights:
Measurement Height (m) IFC-1 IFC-2 IFC-3 IFC-4 ------ ------ ------ ----------------- Oct 3-9 Oct 10-27 Net radiation 0.90 1.15 1.11 0.93 0.93 Wind*Temperature mean 1.35 1.65 1.59 1.80 1.08 Wind*Vapor pressure mean 1.35 1.65 1.59 1.80 1.08 Vapor pressure 1.88 2.00 2.02 2.20 1.39 Air temperature 2.74 2.10 2.02 2.20 1.39 Soil Temp depth 1 -0.025 -0.025 -0.025 -0.025 -0.025 Soil Temp depth 2 -0.10 -0.10 -0.10 -0.10 -0.10 Soil Temp depth 3 -0.50 -0.50 -0.50 -0.50 -0.50 Soil heat flux -0.05 -0.05 -0.05 -0.05 -0.05 Wind speed 1 .70 2.00 2.10 2.30 1.59 Vegetation 0.30 0.35 0.35 0.30
Negative values indicate depth below ground.
The FIFE study area, with areal extent of 15 km by 15 km, is located south of the Tuttle Reservoir and Kansas River, and about 10 km from Manhattan, Kansas, USA. The northwest corner of the area has UTM coordinates of 4,334,000 Northing and 705,000 Easting in UTM Zone 14.
These data were obtained at the following locations within the FIFE study area.
SITEGRID STN LATITUDE LONGITUDE EASTING NORTHING ELEV SLOPE ASPECT (FT) (DEG) -------- ---- -------- --------- ------- -------- ---- ----- ------ 4609-ECW 22 39 03 02 -96 36 41 706705 4324890 390 3 EAST 6943-ECW 28 39 00 22 -96 32 04 713500 4320147 415 7 EAST
Station 22 (4609-ECW) was located in the Northwest quadrant of the FIFE study area along the southern boundary of this quadrant, and station 28 (6943-ECW) was located in the southwest quadrant along the eastern boundary of this quadrant. Station 22 was located on a 3 degree slope with an eastern exposure. Station 28 was located on a 7 degree slope with an eastern exposure.
Not available.
These are point data. However, the eddy correlation data represents an area ranging from about 0.01 ha for very stable atmospheric conditions to about 1 ha for unstable and some neutral atmospheric conditions.
Not available.
Not available.
Surface flux data were collected at sitegrids 4609 and 6943 from May 25, 1987 to October 17, 1987. During this period there are 66 days of data. Data are available only during the four IFC's in 1987, May 25 - June 7, June 24 - July 12, August 5 - 22, and October 3 - 17.
Not available.
Data are reported at 30 minute intervals and are available daily during the four IFC's.
The SQL definition for this table is found in the SF_30MIN.TDF file found on the CD-ROM Volume 1. The following chart lists only those variables that are contained in the data set described in this document.
Parameter/Variable Name
Parameter/Variable Description Range Units Source
SITEGRID_ID This is a FIS grid location code. Site grid codes (SSEE-III) give the south (SS) and the east (EE) cell number in a 100x100 array of 200 m square cells. The last 3 characters (III) are an instrument identifier.
STATION_ID The station ID designating the location of the observations.
OBS_DATE The date of the observations, in the format (DD-mmm-YY).
OBS_TIME The time that the observation [GMT] was taken, in GMT. The format is HHMM.
LATENT_HEAT_FLUX The latent heat flux, the flux [Watts] of the energy due to the [meter^-2] evaporation of water.
NET_RADTN The net radiation, including both [Watts] downward and upward energy. [meter^-2]
SENSIBLE_HEAT_FLUX The sensible heat flux, the flux [Watts] of the energy due to temperature [meter^-2] differences.
SOIL_HEAT_FLUX The surface soil heat flux, the [Watts] flux of energy into the soil. [meter^-2]
SOLAR_RADTN_DOWN The downward (incoming) solar [Watts] radiation. [meter^-2]
SOLAR_RADTN_UP The upward (outgoing) solar [Watts] radiation. [meter^-2]
SOIL_HEAT_FLUX_0_TO_5CM The soil heat flux recorded [Watts] somewhere between 0 and 5 cm in [meter^-2] depth. This is an average from 0 to 5 cm.
HEAT_STORAGE The heat storage in the top [Watts] soil layer. [meter^-2]
SOIL_TEMP_0_TO_25MM The soil temperature recorded [degrees somewhere between 0 and 25 mm Celsius] in depth. Recorded at 25 mm.
SOIL_TEMP_5_TO_10CM The soil temperature recorded [degrees somewhere between 5 and 10 cm in Celsius] depth. Recorded at 10 cm.
SOIL_TEMP_20_TO_50CM The soil temperature recorded [degrees somewhere between 20 and 50 cm Celsius] in depth. Recorded at 50 cm.
BOWEN_RATIO The Bowen Ratio, the ratio of the SENSIBLE_HEAT_FLUX to the LATENT_HEAT_FLUX.
WIND_SPEED The average wind speed in this [meters] 30 minutes. [sec^-1]
WIND_DIR The average wind direction in [degrees this 30 minutes. from North]
WIND_SPEED_VERT_SDEV The standard deviation for the [meters] vertical wind speed. [sec^-1]
AIR_TEMP_MEAN The mean air temperature in [degrees this 30 minutes. Celsius]
AIR_TEMP_MEAN_SDEV The standard deviation for [degrees the mean air temperature. Celsius]
VAPOR_PRESS_MEAN The mean vapor pressure in [kiloPascals] this 30 minutes.
VAPOR_PRESS_SDEV The standard deviation for [kiloPascals] the vapor pressure.
FRICTION_VELOC The friction velocity. [meters] [sec^-1]
W_T_MEAN The mean of AIR_TEMP_MEAN [Watts] x WIND_VELOC_VERT_MEAN in [meter^-2] this 30 minutes.
W_E_MEAN The mean of VAPOR_PRESS_MEAN [Watts] x WIND_VELOC_VERT_MEAN in this [meter^-2] 30 minutes.
FIFE_DATA_CRTFCN_CODE The FIFE Certification Code for * the data, in the format: CGR (Certified by Group), CPI (Certified by PI), CPI-??? (CPI - questionable data).
LAST_REVISION_DATE the data, in the format (DD-MMM-YY).
Footnotes:
* Valid levels
The primary certification codes are:
EXM Example or Test data (not for release) PRE Preliminary (unchecked, use at your own risk) CPI Checked by Principal Investigator (reviewed for quality) CGR Checked by a group and reconciled (data comparisons and cross checks)
The certification code modifiers are:
PRE-NFP Preliminary - Not for publication, at the request of investigator. CPI-MRG PAMS data which is "merged" from two separate receiving stations to eliminate transmission errors. CPI-??? Investigator thinks data item may be questionable.
** There are several missing value indicators in each column. The values may be positive or negative 9.9, 9.99, 99.99, 999, 999.99, 9999 or 99999.99
The following sample record contains all the fields in the surface flux record but only those fields that were described here (i.e., reported by H.L. Weaver) contain data.
SITEGRID_ID STATION_ID OBS_DATE OBS_TIME LATENT_HEAT_FLUX ----------- ---------- --------- --------- ---------------- 4609-ECW 22 17-AUG-87 1215 -11 4609-ECW 22 17-AUG-87 1245 -38 4609-ECW 22 17-AUG-87 1315 -92 4609-ECW 22 17-AUG-87 1345 -129 NET_RADTN SENSIBLE_HEAT_FLUX SOIL_HEAT_FLUX DIFFUSE_SOLAR_RADTN_DOWN --------- ------------------ -------------- ------------------------ -24 2 46 28 -3 28 96 -16 11 168 -35 -5 SOLAR_RADTN_DOWN SOLAR_RADTN_UP SOLAR_RADTN_NET SOLAR_RADTN_DOWN_SDEV ---------------- -------------- --------------- --------------------- 999 999 999 999 999 999 999 999 SOLAR_RADTN_UP_SDEV PAR_DOWN PAR_UP SURF_ALBEDO ------------------- ---------- ---------- ----------- LONGWAVE_RADTN_DOWN LONGWAVE_RADTN_UP LONGWAVE_RADTN_NET ------------------- ----------------- ------------------ BB_TEMP_LONGWAVE_DOWN BB_TEMP_LONGWAVE_UP TOTAL_RADTN_DOWN --------------------- ------------------- ---------------- TOTAL_RADTN_UP SOIL_HEAT_FLUX_0_TO_5CM SOIL_HEAT_FLUX_5_TO_10CM -------------- ----------------------- ------------------------ 41 33 23 13 SOIL_HEAT_FLUX_10_TO_20CM HEAT_STORAGE SOIL_WATER_POTNTL_0_TO_5CM ------------------------- ------------ -------------------------- 4 -5 -12 -17 SOIL_WATER_POTNTL_5_TO_20CM SURF_RADIANT_TEMP SURF_RADIANT_TEMP_SDEV --------------------------- ----------------- ---------------------- SOIL_TEMP_0_TO_25MM SOIL_TEMP_25MM_TO_5CM SOIL_TEMP_5_TO_10CM ------------------- --------------------- ------------------- 21.83 22.97 21.92 22.84 22.14 22.76 22.45 22.76 SOIL_TEMP_10_TO_20CM SOIL_TEMP_20_TO_50CM RAINFALL BOWEN_RATIO -------------------- -------------------- ---------- ----------- 23.59 -9.99 23.56 -9.99 23.53 -9.99 23.47 .27 WIND_SPEED WIND_DIR WIND_SPEED_MIN WIND_SPEED_MAX WIND_SPEED_SDEV ---------- ---------- -------------- -------------- --------------- 1.2 47 1.32 91 1.14 45 .7 1 WIND_DIR_SDEV TIME_WIND_SPEED_MIN TIME_WIND_SPEED_MAX ------------- ------------------- ------------------- TIME_WIND_DIR_MIN TIME_WIND_DIR_MAX WIND_SPEED_HOR_MEAN ----------------- ----------------- ------------------- WIND_SPEED_LAT_MEAN WIND_SPEED_VERT_MEAN WIND_SPEED_HOR_SDEV ------------------- -------------------- ------------------- WIND_SPEED_LAT_SDEV WIND_SPEED_VERT_SDEV AIR_TEMP_LOW AIR_TEMP_HIGH ------------------- -------------------- ------------ ------------- .09 .11 .15 .15 AIR_TEMP_OTHER AIR_TEMP_MEAN AIR_TEMP_MEAN_SDEV AIR_TEMP_OTHER_SDEV -------------- ------------- ------------------ ------------------- 18.69 .26 20.43 .2 21.78 .24 23.9 .37 DELTA_TEMP WET_BULB_TEMP_LOW WET_BULB_TEMP_HIGH VAPOR_PRESS_LOW ---------- ----------------- ------------------ --------------- VAPOR_PRESS_HIGH VAPOR_PRESS_MEAN VAPOR_PRESS_SDEV REL_HUMID_LOW ---------------- ---------------- ---------------- ------------- 1.58 .029 1.68 .058 1.77 .076 1.69 .08 REL_HUMID_HIGH REL_HUMID_SDEV SURF_AIR_PRESS FRICTION_VELOC -------------- -------------- -------------- -------------- .11 .14 .13 .1 W_T_MEAN W_E_MEAN CO2_CONTENT OZONE_CONTENT CO2_CONTENT_SDEV ---------- ---------- ----------- ------------- ---------------- -.002 .0006 .003 .0021 .014 .0051 .024 .0056 OZONE_CONTENT_SDEV CO2_FLUX OZONE_FLUX FIFE_DATA_CRTFCN_CODE ------------------ ---------- ---------- --------------------- CPI CPI CPI CPI LAST_REVISION_DATE ------------------ 29-AUG-88 29-AUG-88 29-AUG-88 29-AUG-88
These are point data. However, the eddy correlation data represents an area ranging from about 0.01 ha for very stable atmospheric conditions to about 1 ha for unstable and some neutral atmospheric conditions. Data are reported at 30-minute intervals and are available daily during the four IFC's.
A general description of data granularity as it applies to the IMS appears in the EOSDIS Glossary.
The CD-ROM file format consists of numerical and character fields of varying length separated by commas. The character fields are enclosed with a single apostrophe. There are no spaces between the fields. Each file begin with five header records. Header records contain the following information:
Record 1 Name of this file, its table name, number of records in this file, and principal investigator name.
Record 2 Path and filename of the previous data set, and path and filename of the next data set. (Path and filenames for files that contain another set of data taken at the same site on the same day.)
Record 3 Path and filename of the previous site, and path and filename of the next site. (Path and filenames for files of the same data set taken on the same day for the previous and next sites, sequentially numbered by SITEGRID.)
Record 4 Path and filename of the previous date, and path and filename of the next date. (Path and filenames for files of the same data set taken at the same site for the previous and next date.)
Record 5 Column names for the data within the file, delimited by commas.
Record 6 Data records begin.
Each field represents one of the attributes listed in the chart in the Data Characteristics Section and described in detail in the TDF file. These fields are in the same order as in the chart.
Pascal code from data processing program
SATURATED VAPOR PRESSURE: es
function es(T:real):real; {saturated vapor pressure in kPa}
var es_mb:real; {mb units}
begin
end;SLOPE OF SATURATED VAPOR PRESSURE: s
function s(T:real):real; {slope of saturated vapor pressure in kPa/K}
var s_mb:real; {mb/K units}
begin
endAIR DENSITY, Rho ( kg/m^3 )
Where:
HEAT CAPACITY OF AIR AT CONSTANT PRESSURE ( J/kg )
Where:STANDARD DEVIATION OF VAPOR PRESSURE (kPa) FROM STANDARD DEVIATION OF VAPOR DENSITY ( g/m^3 )
STANDARD DEVIATION OF VAPOR PRESSURE (kPa) FROM STANDARD DEVIATION OF VAPOR DENSITY ( g/m^3 )
Average 1 second samples from single net radiometer.
Average 1 second samples from three plates.
Average 10 minute samples from three Delta-T/delta-t measurements.
Sensible heat flux/Latent heat flux [dimensionless]
None.
SENSIBLE HEAT FLUX, H
Where:LATENT HEAT FLUX, L
Where:FRICTION VELOCITY, ustar { m/s }
WATER VAPOR FLUX CORRECTION FOR AIR DENSITY CHANGES AT SURFACE (Webb et al., 1980)
Where:None.
During Aug. 5-12, 1987, all thermocouple measurements at Site 28 (sitegrid 6943-ECW) required some adjustment because a voltage offset in the data logger affected single-ended measurement of millivolt-range signals. The correction for this voltage offset was determined mainly at night from the non-zero values of pyranometers. Large daytime changes in the voltage offset could be closely estimated from changes in the soil temperature signal at 50 cm. Small daytime changes in the voltage offset went undetected, resulting in inaccuracies in the temperature measurements reported from Site 28 during this 8-day period. The data so affected are: SOIL_TEMP_0_TO_25MM, SOIL_TEMP_5_TO_10CM, SOIL_TEMP_20_TO_50CM, AIR_TEMP_MEAN, and VAPOR_PRESS_MEAN.
It was recognized early in the study that standardization of "constants" (e.g., physical constants of the air, psychrometric constant, etc.), methods of computation, integration and reporting time, etc. were necessary. These were agreed upon in planning sessions. Preliminary data sets were compared among stations and instruments from different manufacturers for estimating net radiation, soil heat flux, water vapor density, temperature, solar radiation, and wind speed, it was necessary to have confidence that differences in observations were due to site differences and not due to instrumentation.
Spot checks of raw data was scanned in data-logger memory and hand recorded in field notes several times each day during field work with only occasional exceptions. Data values were qualitatively assessed for accuracy against previous data from site and from other USGS surface flux sites.
The following are the best estimates of accuracy for a single flux estimate:
None of these estimates addresses the variability of flux estimates from site-to-site.
No quantitative assessment was made, see the Confidence Level/Accuracy Judgment Section.
Other errors mentioned in the Sources of Error Section above were not quantified.
Graphical ("strip chart") display of selected data and data combinations for all the periods submitted to this database.
The data scanned for reasonable diurnal behavior were:
SOIL_HEAT_FLUX NET_RADTN LATENT_HEAT_FLUX SENSIBLE_HEAT_FLUX SOIL_TEMP_0_TO_25MM SOIL_TEMP_5_TO_10CM AIR_TEMP_MEAN VAPOR_PRESS_MEAN
Meaningful data combinations that helped ferret out bad data were used. One of these "evaporativity", E is calculated:
Another data combination was "surface resistance", Rc, from the Penman-Montieth combination equation (Montieth, 1973):
where:When time series graphs of the data or E or Rc appeared unreasonable, the offending data items were identified and corrected or replaced by either interpolation or by substitution from backup data measurements. If neither of these was possible, the null value was submitted instead of the data values.
Several of the key surface flux parameters have undergone extensive intercomparison and examination for spikes in the data. Details of these analyses are described in the Surface Flux Baseline 1992 document on FIFE CD-ROM Volume 1.
The data verification performed by the ORNL DAAC deals with the quality of the data format, media, and readability. The ORNL DAAC does not make an assessment of the quality of the data itself except during the course of performing other QA procedures as described below.
The FIFE data were transferred to the ORNL DAAC via CD-ROM. These CD-ROMs are distributed by the ORNL DAAC unmodified as a set or in individual volumes, as requested. In addition, the DAAC has incorporated each of the 98 FIFE tabular datasets from the CD-ROMs into its online data holdings. Incorporation of these data involved the following steps:
Each distinct type of data (i.e. "data set" on the CD-ROM), is accompanied by a documentation file (i.e., .doc file) and a data format/structure definition file (i.e., .tdf file). The data format files on the CD-ROM are Oracle SQL commands (e.g., "create table") that can be used to set up a relational database table structure. This file provides column/variable names, character/numeric type, length, and format, and labels/comments. These SQL commands were converted to SAS code and were used to create SAS data sets and subsequently to input data files directly from the CD-ROM into a SAS dataset. During this process, file names and directory paths were captured and metadata was extracted to the extent possible electronically. No files were found to be corrupted or unreadable during the conversion process.
Additional Quality Assurance procedures were performed as follows:
As errors are discovered in the online tabular data by investigators, users, or DAAC staff, corrections are made in cooperation with the principal investigators. These corrections are then distributed to users. CD-ROM data are corrected when re-mastering occurs for replenishment of CD-ROM stock.
Not available.
Several different missing values are used within each column. They can be positive or negative 9.9, 9.99, 99.99, 9999 or 99999.99.
The missing value indicators in the following fields may have been inadvertently converted to 1000. Use these data with caution.
Name Name
------------------------ ---------------------
DIFFUSE_SOLAR_RADTN_DOWN TOTAL_RADTN_DOWN
SOLAR_RADTN_DOWN TOTAL_RADTN_UP
SOLAR_RADTN_UP HEAT_STORAGE
SOLAR_RADTN_NET RAINFALL
SOLAR_RADTN_DOWN_SDEV WIND_DIR_MIN
SOLAR_RADTN_UP_SDEV WIND_DIR_MAX
LONGWAVE_RADTN_DOWN CO2_CONTENT
LONGWAVE_RADTN_UP O3_CONTENT
LONGWAVE_RADTN_NET CO2_STDEV
BB_TEMP_LONGWAVE_DOWN O3_STDEV
BB_TEMP_LONGWAVE_UP
Caution should be exercised when using flux data for several hours surrounding dawn and dusk since these are periods of unsteady conditions. In addition, nighttime data should be closely scrutinized.
None.
Not available.
The FIFE field campaigns were held in 1987 and 1989 and there are no plans for new data collection. Field work continues near the FIFE site at the Long-Term Ecological Research (LTER) Network Konza research site (i.e., LTER continues to monitor the site). The FIFE investigators are continuing to analyze and model the data from the field campaigns to produce new data products.
Software to access the data set is available on the all volumes of the FIFE CD-ROM set. For a detailed description of the available software see the Software Description Document.
ORNL DAAC User Services
Oak Ridge National Laboratory
Telephone: (865) 241-3952
FAX: (865) 574-4665
Email: ornldaac@ornl.gov
ORNL Distributed Active Archive Center
Oak Ridge National Laboratory
USA
Telephone: (865) 241-3952
FAX: (865) 574-4665
Email: ornldaac@ornl.gov
Users may place requests by telephone, electronic mail, or FAX. Data is also available via the World Wide Web at http://daac.ornl.gov.
FIFE data are available from the ORNL DAAC. Please contact the ORNL DAAC User Services Office for the most current information about these data.
Eddy Correlation Surface Flux Observations (USGS) data are available on FIFE CD-ROM Volume 1. The CD-ROM filename is as follows:
\DATA\SUR_FLUX\30_MIN\GRIDxxxx\YyyMmm\ydddgrid.ECW or \DATA\SUR_FLUX\30_MIN\GRIDxxxx\Yyyyy\ydddgrid.ECW
Where xxxx is the four digit code for the location within the FIFE site grid, yy is the last two digits of the year (e.g., Y87 = 1987), yyyy is the four digits of the century and year (e.g., Y1987 = 1987), mm is the month of the year (e.g., M12 = December), and ddd is the day of the year, (e.g., 061 = sixty-first day in the year). Note: capital letters indicate fixed values that appear on the CD-ROM exactly as shown here, lower case indicates characters (values) that change for each path and file.
The format used for the filenames is: ydddgrid.sfx, where grid is the four-number code for the location within the FIFE site grid, y is the last digit of the year (e.g., 7 = 1987, and 9 = 1989), and ddd is the day of the year. The filename extension (.sfx), identifies the data set content for the file (see the Data Characteristics Section) and is equal to .ECW for this data set.
Montieth, J.L. 1973. Principles of Environmental Physics. Edward Arnold, London. 241 pp.
Tanner, B.D., and J.P. Greene. 1989. Measurement of sensible heat and water vapor fluxes using eddy correlation methods. Campbell Scientific, Inc. Logan, Utah. Final report prepared for U.S. Army Proving Grounds. Dugway, Utah.
Webb, E.K., G.I. Pearman, and R. Leuning. 1980. Correction of flux measurements for density effects due to heat and water vapor transfer. Quart. J. Royal Meteorol. Soc. 106: 85-100.
Baldocchi, D.D., B.B. Hicks, and T.P. Meyers. 1988. Measuring biosphere-atmosphere exchanges of biologically related gases with micro- meteorological methods. Ecology 69:1331-1340.
Businger, J.A. 1986. Evaluation of the accuracy with which dry deposition can be measured with current micrometeorological techniques. J. Clim. and Appl. Meteorol. 25:1100-1124.
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Contact the EOS Distributed Active Archive Center (DAAC) at Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee (see the Data Center Identification Section). Documentation about using the archive and/or online access to the data at the ORNL DAAC is not available at this revision.
A general glossary for the DAAC is located at Glossary.
A general list of acronyms for the DAAC is available at Acronyms.
April 28, 1994 (citation revised on October 15, 2002).
This document has been reviewed by the FIFE Information Scientist to eliminate technical and editorial inaccuracies. Previous versions of this document have been reviewed by the Principal Investigator, the person who transmitted the data to FIS, a FIS staff member, or a FIFE scientist generally familiar with the data. It is believed that the document accurately describes the data as collected and as archived on the FIFE CD-ROM series.
October 28, 1996.
ORNL-FIFE_SF30_ECW.
Weaver, H. L. 1994. Eddy Corr[elation]. Surface Flux: USGS (FIFE). Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/34. Also published in D. E. Strebel, D. R. Landis, K. F. Huemmrich, and B. W. Meeson (eds.), Collected Data of the First ISLSCP Field Experiment, Vol. 1: Surface Observations and Non-Image Data Sets. CD-ROM. National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, Maryland, U.S.A. (available from http://www.daac.ornl.gov).