The Bowen Ratio Surface Flux Observations (UNL) Data Set contains surface flux and micrometeorolgical measurements collected at one location located in a flat area of uniform surface vegetation approximately in the center of the FIFE study area. The data collection effort was during the four Intensive Field Campaigns in the spring, summer, and fall of 1987 (May 28 - Oct 17).
The Bowen ratio system that collected these data was designed to retrieve all major components of the surface energy budget along with a large set of measured and derived parameters describing the dynamical, thermodynamical, hydrological, and radiative properties of the ground surface and atmosphere surface layer.
Bowen Ratio Surface Flux: UNL (FIFE)
(Bowen Ratio Surface Flux Observations (UNL)).
The Bowen Ratio Surface Flux Observations (UNL) Data Set contains surface flux and micrometeorolgical measurements collected at one location located in a flat area of uniform surface vegetation approximately in the center of 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. The specific objectives were to:
Latent heat flux, net radiation, sensible heat flux, soil heat flux, soil temperature, Bowen ratio, wind speed, air temperature, vapor pressure.
Surface flux measurements were made at selected sites within the FIFE area. The major data collection effort was conducted in 1987 when 16 stationary sites were equipped with Bowen ratio equipment that was operated by several different groups. In 1988 and 1989, surface flux stations were installed at 12 and 19 sites, respectively. Surface flux stations were capable of measuring the fluxes of net radiation, sensible heat and latent heat. The Bowen ratio stations measured the soil heat flux as well.
The surface flux and micrometeorolgical measurements available in the data set described here were collected at one location within the FIFE study area during the four Intensive Field Campaigns in the spring, summer, and fall of 1987 (May 28-Oct 17). During this period there are 56 days of data. This site was located in a flat area of uniform surface vegetation approximately in the center of the FIFE study area.
The Bowen ratio system that collected these data was designed to retrieve all major components of the surface energy budget along with a large set of measured and derived parameters describing the dynamical, thermodynamical, hydrological, and radiative properties of the ground surface and atmosphere surface layer.
SURFACE_FLUX_30MIN_DATA.
Dr. Shashi B. Verma
Dept. of Agricultural Meteorology, University of Nebraska
Measurement and analysis of latent and sensible heat flux by Bowen ratio and aerodynamic characteristics of vegetation at the FIFE study area.
Contact 1:
Dr. Shashi B. Verma
University of Nebraska
Lincoln, NE
(402) 472-3679/6702
The Bowen Ratio Surface Flux Observation (UNL) were collected by Dr. Shashi B. Verma and his colleagues at the University of Nebraska-Lincoln. Their contribution of these data are particularly appreciated.
The components of the energy balance were determined with the Bowen Ratio Energy Balance (BREB) method. The Bowen ratio, B {a ratio of sensible heat, H and latent heat, E} is given by:
Where: where symbols are defined as:Substituting (1) in the energy balance equation (2) yields equation (3). Q is net radiation and G is soil heat flux density.
In this system surface-air interface is considered as a closed system. Any energy flux coming in is considered positive and going out is negative.
For more information on the instrumentation used to collect these data, see Gay and Greenberg 1985.
Ground-based.
The Bowen ratio sensors were mounted on a scaffold at 2.25 m above the ground.
To measure fluxes of sensible and latent heat using the Bowen ratio, energy balance technique.
Latent heat flux, net radiation, sensible heat flux, soil heat flux, soil temperature, Bowen ratio, wind velocity, air temperature, vapor pressure.
Net radiation was measured with net radiometers at 2m above the ground. Seven heat flow transducers were installed at a depth of 50 mm. Platinum resistance thermometers were used to measure an average soil temperature from the surface to a depth of 50 mm. Soil heat fluxes were corrected for differences in thermal conductivity among calibration medium, transducer and soil following a method described by Philip (1961). Surface soil heat flux was estimated by employing a combination method (Kimball et al. 1976). Mean air temperature and humidity were measured with an aspirated ceramic wick psychrometer at 2.25 m above ground. To reduce the effects of instrument bias they were mounted on a 1 m arm that interchanged their positions every 5 minutes (Hartman and Gay 1981). Fritschen and Gay 1979 and Fritschen and Simpson 1989 also provide details on the principles guiding the operation of the Bowen ratio instrumentation.
Net radiation was measured with net radiometers at 2 m above the ground. Seven heat flow transducers were installed at a depth of 50 mm. Psychrometers were mounted at 2.25 m above the ground.
Soil Heat Transducers:
Pyranometer:
Net radiometers:
Quantum sensor:
Psychrometer:
Cup anemometer:
Data logging system:
Not supplied by Principal Investigator.
Not provided by Principal Investigator.
Resistance thermometer devices were calibrated before and after the field experiment.
Cup anemometers were calibrated in a wind tunnel before the field experiment.
Pyranometer: supplied by the manufacturer.
The data were collected by an automated procedure using sensors described in the Sensor/Instrument Description Section. Sampling, recording, and near real-time processing of the data were done with a microcomputer.
Not available.
Fluxes toward the surface are positive and fluxes away from the surface are negative. * -999.00 = No data available
Lower levels of TA1 and EA1 in 1987 were variable as indicated below (in 1989 the lower level was 1.5 m above ground throughout the measurement periods):
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 collected at the following location within the FIFE study area:
SITEGRID STN_ID LATITUDE LONGITUDE EASTING NORTHING ELEVATION -------- ------ -------- --------- ------- -------- --------- 4439-BRV 18 39 03 07 -96 32 28 712792 4325218 445
Not available.
The footprint of the surface sampled is approximately 100 - 200 m upwind of the sensor, depending on the atmospheric stability, wind speed and direction. A thorough discussion of spatial resolution of flux measurement can be found in Leclerc and Thurtell 1990, and Schuepp et al. 1990.
Not available.
Not available.
These flux data were collected during the following periods:
There are 56 days of data during these periods.
Not available.
The data values are 30 minute averages. Measurements are daily during each of the time periods listed above. There are no measurements between these periods.
The SQL definition for this data table is found in the SF_30MIN.TDF file located on FIFE 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 100 x 100 array of 200m 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]
PAR_DOWN The downward (incoming) photo- [Watts] synthetically active radiation (PAR). [meter^-2]
SOIL_TEMP_0_TO_25MM The soil temperature recorded [degrees somewhere between 0 and 25 mm in Celsius] depth. This is an average value from 0 to 5 cm, same as in the column SOIL_TEMP_25MM_TO_5CM.
SOIL_TEMP_25MM_TO_5CM The soil temperature recorded [degrees somewhere between 25 mm and 5 cm Celsius] in depth. This is an average value from 0 to 5 cm, same as in the column SOIL_TEMP_0_TO_25MM.
WIND_SPEED The average wind speed in this 30 [meters] minutes. [sec^-1]
AIR_TEMP_MEAN The mean air temperature in this [degrees 30 minutes. Celsius]
VAPOR_PRESS_MEAN The mean vapor pressure in this [kiloPascals] 30 minutes.
FRICTION_VELOC The friction velocity. [meters] [sec^-1]
CO2_FLUX The carbon dioxide flux. [mg] [meter^-2] [sec^-1]
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 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 that 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 are described here (i.e., reported by S.B. Verma) contain data.
SITEGRID_ID STATION_ID OBS_DATE OBS_TIME LATENT_HEAT_FLUX ----------- ---------- --------- ---------- ---------------- 4439-BRV 18 17-AUG-87 1215 -9999 4439-BRV 18 17-AUG-87 1245 -102.85 4439-BRV 18 17-AUG-87 1315 -128.73 4439-BRV 18 17-AUG-87 1345 -147.46 NET_RADTN SENSIBLE_HEAT_FLUX SOIL_HEAT_FLUX DIFFUSE_SOLAR_RADTN_DOWN --------- ------------------ -------------- ------------------------ 12.91 -9999 -9999 50.66 30.85 21.33 115.19 2.57 10.97 180.17 -32.44 -.27 SOLAR_RADTN_DOWN SOLAR_RADTN_UP SOLAR_RADTN_NET SOLAR_RADTN_DOWN_SDEV ---------------- -------------- --------------- --------------------- 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 -------------- ----------------------- ------------------------ SOIL_HEAT_FLUX_10_TO_20CM HEAT_STORAGE SOIL_WATER_POTNTL_0_TO_5CM ------------------------- ------------ -------------------------- 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 ------------------- --------------------- ------------------- 22.05 22.05 22.11 22.11 22.27 22.27 22.5 22.5 SOIL_TEMP_10_TO_20CM SOIL_TEMP_20_TO_50CM RAINFALL BOWEN_RATIO -------------------- -------------------- ---------- ----------- -.35 -.3 -.02 .22 WIND_SPEED WIND_DIR WIND_SPEED_MIN WIND_SPEED_MAX WIND_SPEED_SDEV ---------- ---------- -------------- -------------- --------------- 1.08 1.78 1.97 1.65 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 ------------------- -------------------- ------------ ------------- 23.25 21.82 23.35 25.5 AIR_TEMP_OTHER AIR_TEMP_MEAN AIR_TEMP_MEAN_SDEV AIR_TEMP_OTHER_SDEV -------------- ------------- ------------------ ------------------- DELTA_TEMP WET_BULB_TEMP_LOW WET_BULB_TEMP_HIGH VAPOR_PRESS_LOW ---------- ----------------- ------------------ --------------- 2.41 1.77 1.84 1.91 VAPOR_PRESS_HIGH VAPOR_PRESS_MEAN VAPOR_PRESS_SDEV REL_HUMID_LOW ---------------- ---------------- ---------------- ------------- REL_HUMID_HIGH REL_HUMID_SDEV SURF_AIR_PRESS FRICTION_VELOC -------------- -------------- -------------- -------------- W_T_MEAN W_E_MEAN CO2_CONTENT OZONE_CONTENT CO2_CONTENT_SDEV ---------- ---------- ----------- ------------- ---------------- OZONE_CONTENT_SDEV CO2_FLUX OZONE_FLUX FIFE_DATA_CRTFCN_CODE ------------------ ---------- ---------- --------------------- CPI CPI CPI CPI LAST_REVISION_DATE ------------------ 11-JAN-90 11-JAN-90 11-JAN-90 11-JAN-90
The data values are 30 minute averages from measurements made daily during the time periods listed in the Temporal Coverage Section.
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.
The theory described in the Theory of Measurements Section was used to derive the algorithm used to compute the fluxes reported in this data set. See Verma 1990 for details.
None.
Soil heat flux was corrected for differences in thermal conductivity among calibration medium, transducer and soil following a method described by Philip 1961. Surface soil heat flux was estimated by employing a combination method (Kimball et al. 1976).
Not available.
None.
No information provided by the Principal Investigator.
It was recognized early in the study that standardization's of "constant" (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.
The Hydrological Sciences Branch at NASA Goddard Space Flight Center was given the responsibility to compare flux data from all flux stations. This served two purposes: 1) as a data quality check, and 2) a preliminary analysis of site differences.
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.
See the Confidence Level/Accuracy Judgment Section.
Several of the key surface flux parameters have undergone extensive intercomparisons and examination for spikes in the data. These data have also been checked for an imbalance in the energy equation. Details of these analyses are described in the Surface Flux Baseline 1992 document on FIFE CD-ROM Volume 1.
FIS staff applied a general QA procedure to some of the fields in this data set to identify inconsistencies and problems for potential users. As a general procedure, the FIS QA consisted of examining the maximum, minimum, average, and standard deviation for numerical field. Inconsistencies and problems found in the QA check are described in the Known Problems with the Data Section.
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.
Different missing values are used within each column. They can be positive or negative 9.9, 9.99, 99.99, 999.99, 9999, or 99999.99.
Nighttime flux data are noisy, especially when the Bowen ratio approaches -1. These data should be used with caution.
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
None.
None.
This data set can be used to estimate the aerodynamic characteristics (e.g., roughness, zero plane displacement, and the drag coefficient) of the prairie vegetation at various stages of growth and to develop functional relationships between these parameters and vegetation height.
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.
The Bowen Ratio Surface Flux Observations (UNL) data are available on FIFE CD-ROM Volume 1. The CD-ROM filename is as follows:
\DATA\SUR_FLUX\30_MIN\GRIDxxxx\YyyMmm\ydddgrid.BRV or \DATA\SUR_FLUX\30_MIN\GRIDxxxx\Yyyyy\ydddgrid.BRV
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 .BRV for this data set.
Baldocchi, D.D., B.B. Hicks, and T.P. Meyers. 1988. Measuring biosphere-atmosphere exchanges of biologically related gases with micrometeorological methods. Ecology. 69:1331-1340.
Field, R.T., L.J. Fritschen, E.T. Kanemasu, E.A. Smith, J.B. Stewart, S.B. Verma and W.P. Kustas. 1992. Calibration, comparison and correction of net radiometer instruments used during FIFE. J. Geophys. Res. 97(D17):18,681-18,695.
Fritschen, L.J., and J.R. Simpson. 1989. Surface energy and radiation balance systems: General description and improvements. J. Appl. Meteorol. 28:680-689.
Fritschen, L.J. and L.W. Gay. 1979. Environmental instrumentation, Springer-Verlag, New York, p. 216.
Gay, L.W. and R.J. Greenberg. 1985. The AEET battery-powered Bowen ratio system. Proc. 17th Conf. Agric. and Forest Meteorol. pp. 181-182. Am. Meteor. Soc., Boston, MA.
Hartman, R.K. and L.W. Gay. 1981. Improvements in the design and the calibration of temperature measurement systems. Proceedings the 15th Conference on Agricultural and Forest Meteorology. 210 pp.
Kimball. B.A., R.D. Jackson, F.S. Nakayama, S.B. Idso, and R.J. Reginato. 1976. Soil heat flux determination: temperature gradient method with computed thermal conductivities. Soil Sci. Soc. Am. J. 40:25-28.
Leclerc, M.Y. and G.W. Thurtell. 1990. Footprint prediction of scalar fluxes using a Markovian analysis. Boundary-Layer Meteorol. 52:247-258.
Philip, J.R. 1961. The theory of heat flux meters. J. Geophys. Res. 66:571-579.
Schuepp, P.H., M.Y. Leclerc, J.I. MacPherson, and R.L. Desjardins, 1990. Footprint prediction of scalar fluxes from analytical solutions of the diffusion equation. Boundary-Layer Meteorol. 50:355-373.
Tanner, C.B. 1960. Energy balance approach to evapotranspiration from crops. Soil Sci. Soc. Amer. Proc. 24:1-9.
Fritschen, L.J., P. Qian, E.T. Kanemasu, D. Nie, E.A. Smith, J.B. Stewart, S.B. Verma and M.L. Wesely. 1992. Comparison of Surface flux measurement systems used in FIFE 1989. J. Geophys. Res. 97(D17):18,697-18,713.
Kim, J. and S.B. Verma. 1990a. Components of surface energy balance in a temperate grassland ecosystem. Boundary-Layer Meteorol. 51:401-417.
Kim, J. and S.B. Verma. 1990b. Carbon dioxide exchange in a temperate, grassland ecosystem. Boundary-Layer Meteorol. 52:135-149.
Kim, J. and S.B. Verma. 1991a. Modeling canopy stomatal conductance in a temperate grassland ecosystem. Agric. & Forest Meteorol. 55:149-166.
Kim, J. and S.B. Verma. 1991b. Modeling canopy photosynthesis: scaling up from a leaf to canopy in a temperate grassland ecosystem. Agric. & Forest Meteorol. 57:187-208.
Kim, J., S.B. Verma, and R.J. Clement. 1992. Carbon dioxide budget in a temperate grassland ecosystem. J. Geophys. Res. 97:6,057-6,063.
Moncrieff, J.B., S.B. Verma and D.R. Cook. 1992. Intercomparison of eddy correlation carbon dioxide sensors during FIFE-1989. J. Geophys. Res. 97(D17):18,725-18,730.
Nie, D., E.T. Kanemasu, L.J. Fritschen, H.L. Weaver, E.A. Smith, S.B. Verma, R.T. Field, W.P. Kustas, and J.B. Stewart. 1992. An intercomparison of surface energy flux measurement systems used during FIFE 1987. J. Geophys. Res. 97(D17):18,715-18,724.
Norman, J.M., R. Garcia, and S.B. Verma. 1992. Soil surface CO2 fluxes and the carbon budget of a grassland. J. Geophys. Res. 97(D17):18,845-18,853.
Smith, E.A., A.Y. Hsu, W.L. Crosson, R.T. Field, L.J., Fritschen, R.J. Gurney, E.T. Kanemasu, W.P. Kustas, D. Nie, W.J. Shuttleworth, J.B.Stewart, S.B. Verma, H.L. Weaver, and M.L. Wesely. 1992. Area-averaged surface fluxes and their time-space variability over the FIFE experimental domain. J. Geophys. Res. 97(D17):18,599-18,622.
Stewart, J.B. and S.B. Verma. 1992. Comparison of surface fluxes and conductance at two contrasting sites within the FIFE area. J.Geophys. Res. 97(D17):18,623-18,628.
Verma, S.B. 1990. Micrometeorological methods for measuring surface fluxes of mass and energy. Remote Sensing Reviews. 5:99-115.
Verma, S.B., J. Kim, and R.J. Clement. 1992. Momentum, water vapor and carbon dioxide exchange at a centrally located prairie site during FIFE. J. Geopys. Res. 97(D17):18,629-18,639.
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 22, 1996.
ORNL-FIFE_SF30_BRV.
Verma, S. B. 1994. Bowen Ratio Surface Flux: UNL (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/23. 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).