The aim of the FIFE soil moisture transect work was to characterize spatial and temporal patterns of soil moisture along selected transects at the FIFE study area. Two levels of ground data were collected to support the passive microwave (PBMR) flights over the Konza experimental area. The water content measurements were collected using gravimetric methods.
Soil moisture measured along a transect is necessary to calibrate airborne moisture instruments or compare data obtained from them. Soil units in a landscape are inherently heterogeneous, which leads to variations in moisture content along an aircraft flight path on the ground. In order to reduce errors, values on the flight path were sampled at close intervals.
Soil Moisture Transect Data (FIFE).
This data set contains soil water content measurements collected using gravimetric methods. The data was collected along selected transects within the FIFE study area. There were two levels of ground data collection. The top level consisted of three transects of 13 to 17 samples each. Other transects were measured less frequently.
The aim of the FIFE soil moisture transect work was to characterize spatial and temporal patterns of soil moisture along selected transects at the FIFE study area, to help validate and calibrate remote sensing measurements of soil moisture, and to evaluate alternative methods of measuring soil moisture both from the air and on the ground.
Ground data were collected to support the passive microwave (PBMR) flights over the Konza experimental area. There were two levels of ground data collection. The top level consisted of three transects of 13 to 17 samples each that traversed watersheds 1D and 2D. These transects were also the flight lines for the low level PBMR flights (aircraft elevation approximately 300 m above ground surface). The three top level transects were sampled for each CMP-3 mission by taking gravimetric samples and soil impedance measurements at each pre-marked sampling site. Sample sites were marked by flags and the actual samples were taken from a circular area with a radius of about 5 m. Other transects were measured less frequently depending on the need to support specific instruments (radar or gamma) or scientists' needs.
Goddard Space Flight Center
Estimation of Soil Moisture and other Surface Parameters from Airborne and Satellite Visible, Infrared and Microwave Data.
Dr. E.T. Engman
NASA/Goddard Sp. Fl. Ctr.
Dr. S.G. Ungar
NASA/Goddard Sp. Fl. Ctr.
The Soil Moisture Transect data were collected for FIFE by E.T. Engman and his colleagues at the Goddard Space Flight Center, and Barc at USDA.
Soil moisture measured along a transect is necessary to calibrate airborne moisture instruments or compare data obtained from them. Soil units in a landscape are inherently heterogeneous, which leads to variations in moisture content along an aircraft flight path on the ground. In order to reduce errors that arise due to use of average values covering large areas, it is more prudent to use values on the flight path, sampled at closer intervals.
Water content measurements by gravimetric methods involve weighing the wet sample, drying the sample in an oven, and reweighing the sample to determine the amount of water removed. Water content is obtained by dividing the difference between wet and dry masses by the mass of the dry sample to obtain the ratio of the mass of water to the mass of dry soil. When multiplied by 100, this becomes the percentage of water in the sample on a dry-mass (or, as often expressed, on a dry-weight) basis.
Soils were sampled with an auger, sampling tube or other suitable device to take a soil sample. Samples were stored in soil containers with tight-fitting lids and/or tape, dried in an oven with means for controlling the temperature between 100 and 110 degrees Celsius. Samples were weighed with a balance.
The aim was to determine soil moisture and bulk density along established transects, in support of airborne soil moisture measurements.
Soil moisture, bulk density, dry weight, and wet weight.
Previously weighed soil samples are dried to a constant weight, usually at about 105 degrees Celcius, and then weighed again. The difference in dry and wet weight of soil is expressed as a percentage of the dry weight. The bulk density is determined after drying the sample to constant weight, and using the volume of the sample as taken in the field, to find the ratio of mass of dry solids to the bulk volume of the sample.
Soil samples were obtained with a 2 cm diameter coring tube or a 5 x 5 x 5 cm sample tool.
Assorted vendors for gravimetric moisture components.
The weighing balance did not require calibration.
Soil samples of the top 5 cm of soil were taken using the special sampling tool, carving a sample with a putty knife, or taking several cores with a 2 cm diameter coring tube. The total sample (approximately 100-150 grams) was put in a tin sample can and sealed with plastic tape. Each sample can was identified by the sample site ID code. The cans were returned to the laboratory, and the cans were opened and weighed to obtain the wet weight. Open cans were placed in ovens at 105 degrees Celsius for a minimum of 24 hours for drying, then they were weighed again to obtain the dry weight.
Bulk density is determined by excavating a quantity of soil, drying and weighing it, and determining the volume of the excavation. The volume was determined by inserting a rubber-balloon into the excavation and filling it with water until the excavation was just full. The volume of the excavated soil sample is equal to the volume of the fluid dispensed from a graduated cylinder.
Soil samples were collected from the following transects:
Approximate coordinates: 39 04' 53" N, 96 33' 42" W
39 04' 53" N, 96 33' 17" W
Transect 883 is numbered from West to East; Sample sites are approximately 50 m apart.
Approximate coordinates: 39 04' 43" N, 96 33' 50" W
39 04' 43" N, 96 33' 14" W.
Transect 884 is numbered from west to east; sample sites are approximately 50 m apart.
Approximate coordinates: 39 04' 36" N, 96 33' 20" W
39 04' 36" N, 96 33' 56" W.
Transect 885 in numbered from east to west; sample sites are approximately 50 m apart.
Approximate coordinates: 39 04' 34" N, 96 33' 56" W
39 04' 34" N, 96 33' 21" W
Transect 886 is numbered from west to east; sample sites are approximately 50 m apart.
Between IFC-1 and IFC-2, transect 885 was moved approximately 65 m south, so that the transect 886 was in line with the southern-most dead tree of the six trees (second tree from the south of the total of six trees) along the channel in 2D. The transect 885 used in IFC-1 was in line with the northern-most of the six trees. The new transect is numbered 886 and the sample sites run from west to east (as do 883 and 884). Each sample site is spaced about 50 to 55 m from the previous site. Site 885-1 is located about 10 m east of the fire road on the western boundary of watershed 1D, sample number 2164.
Approximate coordinates: 39 03'07 N, 96 32'35 W
39 03'07 N, 96 34'00 W.
Transect 881 is numbered from east to west; sample sites are approximately 50 m apart.
Transect 881 was chosen to monitor the privately owned, burned cover, to provide a calibration line for the NOAA gamma instrument, and to provide a relatively level ground data track for the Kansas radar mounted on the NASA helicopter. The 18 sites on transect 881 were located about 50 m apart, starting about 50 m west of Shashi Verma's EC/S, PAM6 site (site-grid = 4439). The sample sites were not flagged so subsequent samples taken on different days were not necessarily within 5 m of the previous samples.
Transect 884 extended:
Approximate coordinates: 39 04'43" N, 96 34'05" W
39 04'43" N, 96 34'45" W.
Transect 884 extended is a western extension of transect 884 into the unburned area of watershed N1B. Sample sites are approximately 50 m apart.
Transect 884 extended was chosen to monitor soil moisture in an unburned area that had been sampled in 1985 to provide comparable data. The sample sites (7 sites numbered 2871 through 2421) started about 50 m west of the fire road and extended at about 50 m intervals down a rough and steep hill. The sample sites were flagged.
Approximate coordinates: 39 04'30" N, 96 36'00" W
39 04'30" N, 96 36'30" W.
Transect 882 consisted of 6 unflagged sample sites approximately 50 m apart starting 50 m west of the fire road and crossing the northern arm of watershed 4B. Sample sites progressed East to West.
Locations of 1985 transects (station numbers 851 through 855) are included in the Miscellaneous Geographic Reference data on FIFE CD-ROM Volume 5.
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.
Transect data were gathered mostly from watershed 1D in the northwest quadrant of the FIFE study area (a diagram of watershed 1D is on FIFE CD-ROM Volume 5 in the Miscellaneous GIS Raster Images data grouping). The stations and sitegrids for the starting point for each of the soil moisture transects are shown below:
SITEGRID STN NORTHING EASTING LATITUDE LONGITUDE -------- --- -------- ------- -------- --------- 2829-SMT 855 4328480 710850 39 04 55 -96 33 45 2840-FTR 883 4328485 712935 39 04 53 -96 32 18 2940-FTR 884 4328177 712943 39 04 43 -96 32 18 3040-FTR 885 4327961 712949 39 04 36 -96 32 18 3126-SMT 853 4327790 710280 39 04 33 -96 34 09 3140-FTR 886 4327899 712951 39 04 34 -96 32 18 3140-FTR 882 4327776 712954 39 04 30 -96 32 18 3228-SMT 852 4327700 710640 39 04 30 -96 33 54 3229-SMT 851 4327700 710700 39 04 30 -96 33 52 4440-FTR 881 4325217 713023 39 03 07 -96 32 18
These were point data, collected approximately 50 m apart along transect lines. FIS staff converted site numbers to estimates of distance from the road (U.S. Rt. 177) in meters. The distance estimate is probably +/-20 m at most, see the Data Acquisition Methods Section.
Prior to FIFE 1987 IFC, data were collected from June 13 through July 11, 1985. Soil samples were collected from late spring through the fall of 1987, during the Intensive Field Campaigns (IFC) of approximately 2 weeks each. Specifically, 1987 data were collected from May 28 through October 15, 1987.
Maximum of one set (one transect) of measurements per day during the IFCs.
The SQL definition for this table is found in the SM_TRAN.TDF file located on FIFE CD-ROM Volume 1.
Parameter/Variable Description Range Units Source
SITEGRID_ID This is a FIS grid location code. FIS Site grid codes (SSEE-III) give the south (SS) and 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 three-digit FIFE site min = 851, FIS identification number for the site max = 886 where the data were collected.
OBS_DATE The date on which the observation min = 13-JUN-85, GSFC was made. max = 15-OCT-87
OBS_TIME The time of day that the data min = 608, [GMT] GSFC were collected, given as the max = 2157, midpoint of 30-minute average. missing = -999
SAMPLE_NUM The sample number, an min = 0, GSFC approximation of the distance max = 5885 along the transect in meters.
SAMPLE_DEPTH The depth of the sample. min = 5, [cm] SCALE max = 5 MEASURE
SOIL_TEMP The temperature of the soil at min = 10, [degrees THERMOMETER the sample depth. max = 38, Celsius] missing = -99.9
WET_WEIGHT The weight of the soil sample min = 37.29, [grams] WEIGHING before drying. max = 196.65, BALANCE missing = -9.99
DRY_WEIGHT The weight of the soil sample min = 26.37, [grams] WEIGHING after drying. max = 168.4, BALANCE missing = -9.99
BULK_DENSITY The bulk density of the soil. min = .53, [grams] FIXED RING max = 1.29, [cm^-3] missing = -9.99
GRAVMTRC_SOIL_MOISTURE The gravimetric soil moisture. min = 4.4, [percent] SOIL CORE max = 63.68, missing = -9.99
VOLUMTRC_SOIL_MOISTURE The volumetric soil moisture. min = 4, [percent] SOIL CORE max = 72.6, missing = -9.99
FIFE_DATA_CRTFCN_CODE ** The FIFE Certification Code for CPI = checked FIS the data, in the following format: by principal CPI (Certified by PI), CPI-??? investigator, (CPI - questionable data). CPI-UPS=checked by principal investigator and updated position of sample
LAST_REVISION_DATE data, in the format (DD-MMM-YY). max = 11-MAY-90
** Decode the FIFE_DATA_CRTFCN_CODE field as follows:
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.
SITEGRID_ID STATION_ID OBS_DATE OBS_TIME SAMPLE_NUM SAMPLE_DEPTH SOIL_TEMP ----------- ---------- --------- -------- ---------- ------------ --------- 4440-FTR 881 30-JUN-87 1935 408 5 22.00 4440-FTR 881 30-JUN-87 1938 450 5 21.00 4440-FTR 881 30-JUN-87 1942 508 5 21.00 4440-FTR 881 30-JUN-87 1945 558 5 21.00 WET_WEIGHT DRY_WEIGHT BULK_DENSITY GRAVMTRC_SOIL_MOISTURE ---------- ---------- ------------ ---------------------- 122.280 97.610 .9000 41.900 117.750 95.950 .9000 38.100 126.140 104.830 .9000 32.200 102.140 83.100 .9000 42.900 VOLUMTRC_SOIL_MOISTURE FIFE_DATA_CRTFCN_CODE LAST_REVISION_DATE ---------------------- --------------------- ------------------ 37.700 CPI 11-MAY-90 34.300 CPI 11-MAY-90 29.000 CPI 11-MAY-90 38.600 CPI 11-MAY-90
These were point data, collected approximately 50 m apart along transect lines. Soil samples were collected from May 28 through the October 15, 1987, during the Intensive Field Campaigns (IFC) of approximately 2 weeks each.
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: Record 1 Name of this file, its table name, number of records in this file, path and name of the document that describes the data in this file, and name of principal investigator for these data. 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_ID)). 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.
Percent soil moisture on a weight basis was calculated according to the following formula:
Percent soil moisture on a volume basis was calculated according to the following formula:
Calculate the bulk density according to:
Dry soil wt. (grams) Bulk density = --------------------- (Volume 1 - Volume 2)
Minor errors could arise in water content measurements depending on the technique used to avoid absorption of water from the air during cooling and prior to weighing. Also, the time necessary to reach constant weight will depend upon the type of oven used (e.g., convection type forced draft), the size or depth of the sample, the nature of the soil, and if the oven is over-loaded. Major errors could result from mistakenly spilling soil samples.
Water content values for stony or gravely soils can be misleading. Large rocks can occupy appreciable volume in a soil sample and contribute appreciably to the mass without a commensurate contribution to the porosity or water capacity of the soil.
Consistency checks (spatial and temporal) were made by the Principal Investigator and no unusual values were found.
The Principal Investigator is confident that the transect data were good.
No quantitative assessment was made, see Confidence Level/Accuracy Judgment Section.
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, histograms were examined to determine whether outliers were consistent with the shape of the data distribution.
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.
This data set can be used in conjunction with other soil moisture data to validate the soil moisture values predicted by the airborne remote sensing instruments during FIFE (i.e., Peck Airborne Gamma Ray Soil Moisture and FIFE Level-3 Pushbroom Microwave Radiometer (PBMR) Soil Moisture Imagery).
This data set can be used in conjunction with other soil moisture data to validate the soil moisture values predicted by the airborne remote sensing instruments during FIFE.
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 Soil Moisture Transect data are available on FIFE CD-ROM Volume 1. The CD-ROM file name is as follows:
Where xxxx is the four digit code for the location within the FIFE site grid. 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 (e.g., 061 = sixty-first day in the year). The filename extension (.sfx), identifies the data set content for the file (see the Data Characteristics Section) and is equal to .SMT for this data set.
Gardner, W.H. 1986. Water content. pp.635-662. In: A. Klute (ed.) Methods of Soil Analysis. Part 1. Physical and mineralogical methods. 2nd ed. Agronomy Monogr. 9. ASA and SSSA. Madison, WI.
Carroll, T.R. 1981. Airborne soil moisture measurement using natural terrestrial gamma radiation. Soil Science. 132:358-366.
Carroll, T.R., and E.L. Peck. 1988. Airborne time-series measurements of soil moisture using terrestrial gamma radiation. Proc. Am. Congr. Sur. Map. and Am. Soc. for Photogram. & Rem. Sens. St. Louis, MO.
Engman, E.T., W. Kustas, T.J. Schmugge, and J.R. Wang. 1987. Relationship among the remotely sensed soil moisture, streamflow, and evapotranspiration. AGU Fall Meeting. San Francisco.
Engman, E.T., G. Angus, and W. Kustas. 1989. Relationships between the hydrologic balance of a small watershed and remotely sensed soil moisture. Remote Sensing and Large Scale Processes. IAHS Publ. No. 186. Proc. IAHS. 3rd Int. Asso. Baltimore, MD.
Engman, E.T., J.R. Wang. 1989. Remotely Sensed Soil Moisture Input to a Hydrologic Model. Proc. IGARSS. 89. 12th Canadian Symposium or Remote Sensing July 10-14. Vancouver, Canada. 4:2150-2153.
Engman, E.T., W.P. Kustas, J.R. Wang. 1990. Remotely Sensed Soil Moisture Input to a Hydrological Model for Simulating the Water Balance of a Small Basin. Regionalization in Hydrology. 2:4-16. M.A. Beran, M. Brilly, A. Becker and O. Bonacci (Eds.).
Gogineni, S. 1990. Radar measurements of soil moisture over the Konza prairie. AMS Symposium on the First ISLSCP Field Expt. Anaheim, CA.
Peck, E.L., T.R. Carroll, and D.M. Lipinski. 1990. Airborne gamma radiation soil moisture measurements over short flight lines. AMS Symposium on the First ISLSCP Field Expt. Anaheim, CA.
Savabi, M.R., E.T. Engman, W.P. Kustas, and W.J. Rawls. 1989. Evaluation of Wepp Water Balance Model for Watershed 1D in the Konza Prairie, Kansas. 19th Conference Agricultural and Forest Meteorology and 9th Conference Biometeorology and Aerdrology. AMS. Charleston, SC. pp.147-150.
Schmugge,T.J. 1978. Remote sensing of surface soil moisture. J. Appl. Meteorol. 17:1547-1557.
Schmugge, T.J., J.M. Meneely, A. Rango, and R. Neff. 1977. Satellite microwave observations of soil moisture variations. Bull. of Water Resources. 13:265.
Schmugge, T.J., T.J. Jackson, and H.L. McKim. 1980. Survey of methods of soil moisture determination. Water Resources Res. 16(16):961-979.
Wang, J.R., J.C. Shiue, E.T. Engman, and T.J. Schmugge. 1988. The soil moisture variations of two small watersheds in Konza prairie as estimated from the L-band radiometric measurements. Geophys. Res. Lett. (in review).
Wang, J.R., and J.C. Shieu. 1989. Remote sensing of soil moisture variations with PBMR. AGU EOS. 70(issue 15). No. 347.
Wang, J.R., T.J. Schmugge, J.C. Shiue, E.T. Engman. 1989. Mapping Surface Soil Moisture with L-Band Radiometric Measurements. Remote Sens. Environ. 27:305-312.
Wang, J.R., J.C. Shiue, T.J. Schmugge, E.T. Engman. 1989. Results of PBMR Flights During the Four Intensive Field Campaigns of FIFE. Microwave Radiomet. Remote Sens. Appl. 29-38 P. Pampaloni (Ed.)
Wetzel, P.J., and J.T. Chang. 1987. Concerning the relationship between evapotranspiration and soil moisture. J. Clim. Appl. Meteor.
The Collected Data of the First ISLSCP Field Experiment is archived at the EOS Distributed Active Archive Center (DAAC) at Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee (see Data Center Identification). 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 6, 1994 (citation revised on October 15, 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.
February 18, 1996.
Wang, J. 1994. Soil Moisture Transect Data (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/113. 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).