The Incoming Longwave Radiation Data from UNL Data Set was collected as part of a study of thermal radiant energy from vegetative canopies. These data were collected during the growing season of 1987 and 1989. The data measurements were made at 13 stations within 12 sitegrids scattered throughout the FIFE study area.
Values for incoming longwave radiation were calculated using the radiometer chopper or detector temperature as a measure of air temperature. When determining surface temperatures from infrared thermometer measurements of the surface, the surface emissivity and the reflected component must be taken into account. The reflected component is dependent on the surface emissivity and the incoming longwave radiation.
Longwave Radiation Data: UNL (FIFE).
(Incoming Longwave Radiation Data from UNL).
The Incoming Longwave Radiation Data from UNL Data Set was collected as part of a study of thermal radiant energy from vegetative canopies. These data were collected during the growing season of 1987 and 1989. Values for incoming longwave radiation were calculated using the radiometer chopper or detector temperature as a measure of air temperature.
The objective was to determine the incoming longwave radiation as part of a study of thermal radiant energy from vegetative canopies.
Average estimated incoming longwave data using equation of Deacon (1970). The time period averaged ranged from a few minutes to 30 minutes.
Values for incoming longwave radiation were calculated for each Barnes Model 12-1000 Modular Multiband Radiometer (MMR) data record using the radiometer chopper or detector temperature as a measure of air temperature in the Deacon equation. See the Surface Reflectance Measured with a Mast-borne MMR document for more information. The equation is valid for clear daytime conditions (Deacon 1970). These measurements were made at 13 stations within 12 sitegrids scattered throughout the FIFE study area. About half of these stations were located in the northwest quadrant of the study area within the Konza Prairie Natural Research Area. These data were collected during the growing season of 1987 and 1989.
Drs. Blaine L. Blad and Elizabeth A. Walter-Shea
University of Nebraska
Measuring and Modeling Near-Surface Reflected and Emitted Radiation Fluxes at the FIFE Site.
Cynthia J. Hays
Mark A. Mesarch
Elizabeth A. Walter-Shea
The Incoming Longwave Radiation Data from UNL data were collected under the direction of B.L. Blad and E.A. Walter-Shea at the University of Nebraska. The dedicated efforts of C.J. Hays and M.A. Mesarch in the collection and preparation of these data is particularly appreciated.
Thermal radiant energy (Rb) is composed of an emitted component (e * a * Ts**4) and a reflected component [(1 - e)ILW]:
When determining surface temperatures from infrared thermometer measurements of the surface, the surface emissivity and the reflected component must be taken into account. The reflected component is dependent on the surface emissivity and the incoming longwave radiation. A typical incoming longwave radiation value is 300 [W][m^-2] (Fuchs and Tanner 1966; Chen and Zhang 1989). The emissivity of vegetation foliage is of the order of 0.98. Assuming typical values of incoming longwave radiation and surface emissivity and an infrared thermometer measurement of a vegetative surface of 299.5 degrees K, the surface temperature would be 300 degrees K. Correcting the infrared thermometer measurement for surface emissivity alone would yield a temperature of the surface of 301 degrees K (Fuchs 1990).
The Barnes Model 12-1000 Modular Multiband Radiometers have been described in the literature (Robinson et al. 1979 and Robinson et al. 1981). The Barnes Modular Multiband Radiometer (MMR) produces analog voltage responses to scene radiance in 8 spectral bands, and to the instrument chopper and detector temperatures. The 8 wavebands are approximately 0.45-0.52, 0.52-0.60, 0.63-0.69, 0.76-0.90, 1.15-1.30, 1.55-1.75, 2.08-2.35, 10.4-12.5 um. Wavebands 1-4 have silicon detectors, wavebands 5-7 have lead sulfide detectors and waveband 8 has a Lithium Tantalum trioxide detector. The MMR's dimensions are 26.4 cm by 20.5 cm by 22.2 cm and weighs 6.4 kg.
Portable mast on the ground.
The objective was to determine incoming longwave radiation.
Average estimated incoming longwave radiation [W][m^-2] using equation of Deacon (1970). The time period averaged ranged from a few minutes to 30 minutes.
Two thermistor circuits provide temperature information for the chopper area (chopper temperature) and instrument housing (detector temperature). The chopper temperature monitor circuitry utilizes a thermistor component providing linear voltage output as a function of temperature. The detector temperature monitor circuitry is adjusted to read thermistor resistance directly in volts. For more information see the Barnes Operation and Service Instruction Manual (Anonymous 1982b).
The Barnes Model 12-1000 Modular Multiband Radiometer was mounted 2.2 m (50 degree view zenith angle) to 3.4 m (0 degree view zenith angle) above the soil surface.
Barnes Engineering Company
30 Commerce Road
Stamford, Connecticut 07904
Pre-season and post-season calibrations were supplemented with daily stability checks using an Everest Model 100 calibration source. Calibration procedures and specifics can be found in Jackson et al. 1983 and Markham 1987.
The Barnes Model 12-1000 Modular Multiband Radiometer chopper temperature standard errors of estimates for the regression equations were always less then 0.1. The detector thermistor is a precision thermistor bead accurate to better than 0.1 degree C over a 0-70 degree temperature range (Anonymous 1982a).
In 1987 and 1989 pre-season and post-season calibrations were performed. In 1988 only a post-season calibration was performed.
Chopper temperature coefficients.
1987 (Markham 1987):
Serial Number (SN) 103 (chopper thermistor malfunctioned)
SN 111 AC = 0.16091 BC = 14.508
SN 128 AC = 0.1573 BC = 13.727
SN 108 (chopper thermistor malfunctioned)
1989 (Markham 1989):
SN 114 AC = 0.1296 BC = 14.42
The MMR was mounted on a pointable portable mast at a height of 3.4 m above the soil surface at a view zenith angle of 0 degree. The mast allowed the sensor to view the same surface area regardless of the view zenith angle. Seven to 8 view zenith angles ranging from 0 to 50 degrees were measured at each plot. During IFC-1 in 1987 only one replication was recorded at each view zenith angle, otherwise three replications were recorded. A reference panel measurement was taken at intervals of less then 30 minutes (Blad et al. 1990). See the Surface Reflectance Measured with a Mast-borne MMR document for further information.
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.
Measurements for this data set were made at the following locations:
SITEGRID STN NORTHING EASTING LATITUDE LONGITUDE ELEV -------- --- -------- ------- -------- --------- ---- 0847-MRN 29 4332344 714439 39 06 57 -96 31 11 418 1246-MRN 40 4331666 714212 39 06 35 -96 31 21 365 1445-MRN 42 4331160 714090 39 06 19 -96 31 27 400 1916-MRN 70 4330296 708263 39 05 56 -96 35 30 340 2123-MRN 5 4329866 709506 39 05 41 -96 34 39 405 2133-MRN 906 4329726 711604 39 05 34 -96 33 12 443 2437-MRN 966 4329150 712375 39 05 15 -96 32 41 3129-MRN 8 4327702 710711 39 04 30 -96 33 51 430 4268-MRN 32 4325626 718579 39 03 15 -96 28 27 445 4439-MRN 18 4325218 712792 39 03 07 -96 32 28 445 4439-MRN 916 4325193 712773 39 03 06 -96 32 28 443 6943-MRN 28 4320147 713500 39 00 22 -96 32 04 415 8739-MRN 26 4316699 712845 38 58 31 -96 32 35 442 SITEGRID SLOPE ASPECT -------- ----- ------ 0847-MRN 1246-MRN 1445-MRN 1916-MRN 2123-MRN 2133-MRN 1 TOP 2437-MRN 3129-MRN 4268-MRN 4439-MRN 4439-MRN 2 N 6943-MRN 8739-MRN
In 1987 measurement plots generally encircled the AMS station located at the site. In 1989 measurement plots were located northeast of the Wind Aligned Blob (WAB) site (Sellers et al. 1989). Topography files containing the northing and easting of the plots at each site, except for site 18 (SITEGRID=4439-MRN) in 1987 and site 966 (SITEGRID=2437-MRN) in 1989, are available in the GRABBAG section of FIFE CD-ROM Volume 1 in the UNL directory, in files UNL_PLOT.T87 and UNL_PLOT.T89. These files also include the slope, aspect, soil depth, species and vegetative height of the plots.
These were point data. The IFOV of the MMR varied with the view zenith angle as the mast was adjusted from 0 to 50 degrees.
Data were collected during two periods: June 3 through October 13, 1987 and June 15 through August 11, 1989. During these periods 28 days of data were collected in 1987 and 12 days of data in 1989.
The measurement time ranged from 1346 to 2220 GMT. Measurements were not continuously made over this range but were in discrete measurement periods.
The estimated longwave data were averaged over a time period between reference panel measurements that ranged from a few to 30 minutes.
The SQL definition for this table is found in the LONG_RAD.TDF file located on FIFE CD-ROM Volume 1.
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 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).
START_TIME The starting time of the [GMT] observations in the format (HHMM) in GMT.
END_TIME The ending time of the [GMT] observations in the format (HHMM) in GMT.
LONGWAVE_RADTN_DOWN The average downward (incoming) [Watts] longwave radiation for the time [meter^-2] period.
FIFE_DATA_CRTFCN_CODE * The FIFE Certification Code for the data, in the following format: CPI (Certified by PI), CPI-??? (CPI - questionable data).
LAST_REVISION_DATE The last revision date for the data, in the format (DD-mmm-YY).
Decode the FIFE_DATA_CRTFCN_CODE field as follows:
The primary certification codes are:
The certification code modifiers are:
SITEGRID STATION_ID OBS_DATE START_TIME END_TIME LONGWAVE_RADTN_DOWN -------- ---------- --------- ---------- ---------- ------------------- 1246-MRL 40 03-JUN-87 2019 2034 364.8 3129-MRL 8 04-JUN-87 1351 1403 341.7 4439-MRL 18 05-JUN-87 1700 1701 374.1 4268-MRL 32 05-JUN-87 2105 2116 386.8 8739-MRL 26 06-JUN-87 1719 1735 377.3 FIFE_DATA_CRTFCN_CODE LAST_REVISION_DATE --------------------- ------------------ CPI 10-MAR-89 CPI 10-MAR-89 CPI 10-MAR-89 CPI 10-MAR-89 CPI 10-MAR-89
The data set contains point data collected during two periods: June 3 through October 13, 1987 and June 15 through August 11, 1989. During these periods 28 days of data were collected in 1987 and 12 days of data in 1989. The data measurements were made at 13 stations within 12 sitegrids scattered throughout the FIFE study area. Measurements were not made continuously but were in discrete measurement periods.
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 begins with five header records. Header records contain the following information:
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.
Average estimated incoming longwave data was calculated using the equation of Deacon (1970).
or, (see the Processing Steps Section for an explanation)
Air temperatures were calculated for each Barnes Model 12-1000 Modular multiband Radiometer (MMR) data record using equation 1 or 2. Equation 1 is preferred but if the chopper thermistor was not functioning then Equation 2 was used. Values for incoming longwave radiation were calculated for each air temperature using Equation 3. This equation is valid for clear daytime conditions (Deacon 1970). The incoming longwave radiation values were averaged over the time period between reference panel measurements.
Air temperature estimated from the Barnes Model 12-1000 Modular Multiband Radiometer chopper or detector thermistor response.
Comparisons of the estimated incoming longwave radiation were made with data from the AMS of a nearby site.
On days with variable cloud conditions the data should be used with caution. The AMS incoming solar radiation data at the site or nearby site should be consulted. On clear days the measurements fall within the errors that were discussed in previous sections.
Comparisons of the estimated incoming longwave with measured pyrgeometer incoming longwave (AMS data) show mean bias errors of 29.74, 25.49 and 10.52 [W][m^-2] for 1987, 1988, and 1989 respectively.
FIS staff applied a general Quality Assessment (QA) procedure to the data 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 each numerical field in the data table. An attempt was made to find an explanation for unexpected high or low values, values outside of the normal physical range for a variable, or standard deviations that appeared inconsistent with the mean. In some cases, histog-rams were examined to determine whether outliers were consistent with the shape of the data distribution.
The discrepancies, which were identified, are reported as problems 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.
Before using this data the incoming radiation from the AMS station at the site or nearby site should be checked for possible cloud-induced errors.
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
ORNL Distributed Active Archive Center
Oak Ridge National Laboratory
Telephone: (865) 241-3952
FAX: (865) 574-4665
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 Incoming Longwave Radiation Data from UNL are available on FIFE CD-ROM Volume 1. The CD-ROM file name is as follows:
Where yyyy are the four digits of the century and year (e.g., Y1987 = 1987). 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: yyyygrid.sfx, where grid is the four-number code for the location within the FIFE site grid, and yyyy are the four digits of the century and year (e.g., 1987, 1989). The filename extension (.sfx), identifies the data set content for the file (see the Data Characteristics Section) and is equal to .LWR for this data set.
Anonymous. 1982a. Barnes Engineering, Calibration and data book: Multispectral 8-channel radiometer. Barnes Engineering Company. Stamford. CN.
Anonymous. 1982b. Barnes Engineering, Operation and service instructions: Multispectral 8-channel radiometer. Barnes Engineering Company. Stamford, CN.
Blad, B.L., E.A. Walter Shea, P.J. Starks, R.C. Vining, C.J. Hays, and M.A. Mesarch. 1990. Measuring and modeling near-surface reflected and emitted radiation flux at the FIFE site. AgMet Progress Report 90-1. Department of Agricultural Meteorology. University of Nebraska-Lincoln. Lincoln, Nebraska. 68583-0728.
Chen, J-M. and R-H Zhang. 1989. Studies on the measurements of crop emissivity and sky temperature. Agricultural and Forest Meteorology. 49: 23-34.
Deacon, E.L. 1970. The derivation of Swinbank's long-wave radiation formula. Quarterly Journal of the Royal Meteorological Society. 96:313-319.
Fuchs, M. and C.B. Tanner. 1966. Infrared thermometry of vegetation. Agronomy Journal. 58:597-601.
Fuchs, M. 1990. Instrumentation of studying vegetation canopies for remote sensing in optical and thermal infrared regions - canopy thermal infrared observations. Remote Sensing Reviews. 5 (1): 323-333.
Jackson, R.D., D.A. Dusek, and E.E. Ezra. 1983. Calibration of the thermal channel on four Barnes model 12-1000 multi-modular radiometers. United States Water Conservation Laboratory. Report 12. Phoenix, Arizona.
Markham, B.L. 1987. Memo on review of Phoenix calibration of MMR Channel 8. GSFC/NASA, Greenbelt, MD 20771 Markham B.L. 1989. MMR Calibration data for FIFE 89 and related studies. GSFC/NASA, Greenbelt, MD 20771.
Robinson, B.F., M.E. Bauer, D.P. DeWitt, L.F. Silva and V.C. Vanderbilt. 1979. Multiband radiometer for field research. Measurements of Optical Radiation, Proceedings of the Society of Photo-Optical Instrumentation Engineers. 196:27-32.
Robinson, B.F., R.E. Buckley and J.A. Burgess. 1981. Performance evaluation and calibration of a modular multiband radiometer for remote sensing research. Proceedings of the Society of Photo-Optical Engineers. 208:146-157.
Sellers, P.J. and F.G. Hall. 1989. FIFE-89 Experiment Plan. GSFC/NASA. Greenbelt, MD 20771.
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.
May 11, 1994i (citation revised on October 16, 2002).
Warning: This document has not been checked for technical or editorial accuracy by the FIFE Information Scientist. There may be inconsistencies with other documents, technical or editorial errors that were inadvertently introduced when the document was compiled or references to preliminary data that were not included on the final CD-ROM.
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.
July 23, 1996.
Blad, B. L., and E. A. Walter-Shea. 1994. Longwave Radiation Data: 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. 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).