This study examined the response of spectral reflectance characteristics (using an Exotech radiometer) to canopies that were manipulated using simulated grazing and fertilization of plots. The spectral reflectance data set supports the original hypothesis of a curvilinear relationship between productivity and grazing intensity. Reflectances for the four MSS bands and the standard error for each are reported. These data were collected at two locations within the northwest quadrant of the FIFE study area during the growing season of 1987.
Reflected radiation measurements were converted to radiances and reflectance factor. The reflectance factor is the ratio of the target reflected radiant flux to an ideal radiant flux reflected by an ideal Lambertian standard surface irradiated in exactly the same way as the target.
The spectral reflectance data set supports the original hypothesis of a curvilinear relationship between productivity and grazing intensity. Reflectances for the four MSS bands and the standard error for each are reported. These data were collected at two locations within the northwest quadrant of the FIFE study area during the growing season of 1987.
The objective of this study was to determine effects of simulated grazing on canopy optical properties (reflectance).
Surface reflectance for the 4 MSS bands.
This study examined the response of spectral reflectance characteristics (using an Exotech radiometer) to canopies that were manipulated using simulated grazing and fertilization of plots. The spectral reflectance data set supports the original hypothesis of a curvilinear relationship between productivity and grazing intensity. Reflectances for the four MSS bands and the standard error for each are reported. These data were collected at two locations within the northwest quadrant of the FIFE study area during the growing season of 1987.
MOW_EXOTECH_DATA.
Dr. Tim R. Seastedt
University of Colorado
The Influence of Grazing on Land Surface Climatological Variables.
Contact 1:
Dr. Clarence L. Turner
Kansas State Univ.
Manhattan, KS
(913) 532-7627
cturner@ksuvm.ksu.edu
Contact 2:
Dr. Tim R. Seastedt
INSTAAR
University of Colorado
Boulder, CO
(303) 492-3302
tims@culter.colorado.edu
The Exotech Surface Reflectances for the Mowing Experiment data were collected by T.R. Seastedt and C.L. Turner of Kansas State University.
Light radiation striking a vegetative canopy interacts with individual phyto-elements (leaves, stems, branches) and the underlying substrate. The interaction depends on light quality, radiative form (direct or diffuse), illumination incidence angle, vegetative component optical properties and canopy architecture. Radiation is reflected, transmitted or absorbed.
Mowing, grazing, and fertilization can affect the canopy architecture or optical properties of vegetation, thus changing the canopy reflectance.
Reflected radiation measurements were converted to radiances and reflectance factor. The reflectance factor is the ratio of the target reflected radiant flux to an ideal radiant flux reflected by an ideal Lambertian standard surface irradiated in exactly the same way as the target.
The Exotech four channel radiometer model 100BX produces analog voltage responses to scene radiance in 4 spectral bands. The 4 wavebands are approximately 0.5-0.6, 0.6-0.7, 0.7-0.8 and 0.8-1.1 um (Landsat MSS bands). The wavebands have silicon detectors. The Exotech's dimensions are 12.7 cm by 12.7 cm by 21.6 cm and weighs approximately 2.3 Kg. The Exotech was equipped with a 15 degree field-of-view.
Ground-based.
The Exotech was hand-held at shoulder height about 1 m above the ground, and directed toward the ground at an approximate nadir view.
The aim of the procedure was to measure reflectance.
Surface reflectance in 4 MSS bands.
The Exotech four channel radiometer model 100BX produces analog voltage responses to scene radiance in 4 spectral bands. The Exotech consists of the following: 1) four silicon photodiodes mounted in the filter wells of the housing behind four composite filters, 2) four high sensitivity DC amplifiers, and 3) detachable optics which determine the field-of-view. The DC amplifiers are low-noise, field effect transistor input, operational amplifiers. The amplifiers are gain-switchable via the gain switches on the rear panel of the instrument. For further information consult the Exotech model 100BX instruction manual.
The Exotech was hand-held at about 1 m above the soil surface with a 15 degree field-of-view and a spot size of approximately 0.22 m diameter at nadir.
Exotech Incorporated
1200 Quince Orchard Boulevard
Gaithersburg, Maryland 20878
(301) 948-3060
The instrument was calibrated with a barium sulfate panel.
Not available at this revision.
The Exotech regression equations for radiance gains and offsets yield standard errors of estimates as follows:
Waveband # Radiance Gains Offset
SEE* SEE*
---------- -------------- ------------
1 1 E-5 4.2 E-4
2 2 E-5 11.9 E-4
3 3 E-5 19.0 E-4
4 4 E-5 36.2 E-4
* SEE = Standard Error of Estimate
Not available at this revision.
None.
The Exotech was directed at the plots of interest with approximate nadir view. Many of the plots used were the same as in the Root Biomass, and the Mowing Experiment Biophysical Measurements on FIFE CD-ROM Volume 1.
In these experiments the intensity and frequency of grazing, burning and fertilization of the prairie were examined. Details of these experiments are outlined in the Mowing Experiment Biophysical Measurements and the Vegetation Biomass Production and Consumption at Selected Sites data sets on FIFE CD-ROM Volume 1.
Not available.
None.
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.
All view zenith angles were measured with respect to gravity not in relation to the slope of the plot.
Below is a list of the FIFE sites for which Exotech data exists:
SITEGRID_ID STATION_ID NORTHING EASTING LATITUDE
----------- ---------- --------- ------- ------------
1916-MOW 150 4330296 708270 39 05 56
2139-MOW 152 4329843 712789 39 05 37
LONGITUDE ELEVATION COLOCATED
----------- ---------- ---------
-96 35 30 340 2,70,902
-96 32 23 385 31
Not available.
The footprint (surface area viewed by the Exotech) had a diameter of 0.22 m which was held at approximate nadir view during all measurements reported here. The plot size was approximately 0.1 square m.
Not available.
Not available.
The overall time period of data acquisition was from May 30, 1987 through October 13, 1987 during the four FIFE IFCs in 1987.
Not available.
Four to 16 measurements were made in a day. Collection times were during daylight hours and ranged from 1332 to 2124 GMT.
The SQL definition for this table is found in the MOW_EXO.TDF file located on FIFE CD-ROM Volume 1.
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 east (EE) cell number in a 100 x 100 array of 200 meter 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 was [GMT] taken in GMT. The format is (HHMM).
MOW_DATE The date of most recent mowing treatment.
MOW_HEIGHT If this record is from the mowing [cm] height experiment, this column contains the mowed height of the vegetation in cm, otherwise this column is null.
MOW_FREQ If this record is from the mowing frequency experiment, the value is the number of times the site was mowed up to the day of observation, otherwise this column is null.
FERTILIZER If this record is from the brome sites of the mowing height experiment, this column tells if the site was fertilized, F for fertilized, N for no fertilizer, otherwise this column is null.
NUM_OBS The number of observations used in the averages.
BAND1_MSS_AVG_REFL The average reflectance from the Multi-Spectral Sensor (MSS) in band 1 (0.5-0.6 microns).
BAND2_MSS_AVG_REFL The average reflectance from the Multi-Spectral Sensor (MSS) in band 2 (0.6-0.7 microns).
BAND3_MSS_AVG_REFL The average reflectance from the Multi-Spectral Sensor (MSS) in band 3 (0.7-0.8 microns).
BAND4_MSS_AVG_REFL The average reflectance from the Multi-Spectral Sensor (MSS) in band 4 (0.8-1.1 microns).
BAND1_MSS_ST_ERR The standard error of the mean of the reflectances from the Multi-Spectral Sensor (MSS) in band 1.
BAND2_MSS_ST_ERR The standard error of the mean of the reflectances from the Multi-Spectral Sensor (MSS) in band 2.
BAND3_MSS_ST_ERR The standard error of the mean of the reflectances from the Multi-Spectral Sensor (MSS) in band 3.
BAND4_MSS_ST_ERR The standard error of the mean of the reflectances from the Multi-Spectral Sensor (MSS) in band 4.
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).
Footnotes:
A value of -9 means no data were collected.
** Decode the FIFE_DATA_CRTFCN_CODE field as follows:
The primary certification codes are:
The certification code modifiers are:
SITEGRID_ID STATION_ID OBS_DATE OBS_TIME MOW_DATE MOW_HEIGHT MOW_FREQ
----------- ---------- --------- -------- --------- ---------- --------
1916-MOW 150 31-MAY-87 1958 29-MAY-87
1916-MOW 150 31-MAY-87 1959 29-MAY-87
1916-MOW 150 31-MAY-87 1959 29-MAY-87 5
1916-MOW 150 31-MAY-87 2000 29-MAY-87 5
FERTILIZER NUM_OBS BAND1_MSS_AVG_REFL BAND2_MSS_AVG_REFL BAND3_MSS_AVG_REFL
---------- ------- ------------------ ------------------ ------------------
N 3 .0514 .0454 .2034
F 3 .0440 .0327 .2792
N 3 .0652 .0665 .1752
F 3 .0572 .0551 .1859
BAND4_MSS_AVG_REFL BAND1_MSS_ST_ERR BAND2_MSS_ST_ERR BAND3_MSS_ST_ERR
------------------ ---------------- ---------------- ----------------
.2749 .0010 .0034 .0070
.4336 .0011 .0011 .0098
.2417 .0014 .0040 .0114
.2684 .0043 .0045 .0089
BAND4_MSS_ST_ERR FIFE_DATA_CRTFCN_CODE LAST_REVISION_DATE
---------------- --------------------- ------------------
.0114 CPI 09-JUL-90
.0150 CPI 09-JUL-90
.0175 CPI 09-JUL-90
.0079 CPI 09-JUL-90
Four to 16 measurements were made in a day. The surface area viewed by the Exotech had a diameter of 0.22 m. The plot size was approximately 0.1 square m.
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.
Conversion of voltage to radiance:
Ls(t,j),Lp(t1,j) or Lp(t2,j) = [V(t,j) - O(j)]/G(j) [1]
where
V(t,j) = waveband response at time t (volts)
j = wave band 1-4
G(j) = waveband gain [Volts][W^-1][m^-2][sr^-1][um^-1]
O(j) = waveband offset [Volts]
Ls(t,j), Lp(t1,j) or Lp(t2,j) = waveband spectral radiance for
surface or reference panel at time t, t1, or t2[W][m^-2][sr^-1][um^-1]
Conversion of radiance to reflectance:
RF(t,j) = Ls(t,j)/ (Lp(t,j)/RFp(t,j)) [2]
where
Ls(t,j) = waveband surface radiance at time t [W][m^-2][sr^-1][um^-1]
RF(t,j) = waveband surface reflectance factor at time t (%)
RFp(t,j) = waveband reflectance factor for the reference panel at time t (%)
Lp(t,j) = band reference panel reflectance at time t.
Not available at this revision.
Not applicable.
Not applicable.
None.
No information on data validation was provided by the investigator.
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 precision of the instrument and errors that were discussed in previous sections.
No quantitative assessment was made, see the 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 data sets 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 data set. 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.
None reported at the time of this revision.
Before using reflectance factors the incoming radiation from the AMS station at a nearby site should be checked for possible cloud-induced error in reflectance factors.
None.
This data set can be used to study the effects of grazing on canopy optical properties (reflectance).
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.
The Exotech Surface Reflectances for the Mowing Experiment data are available on FIFE CD-ROM Volume 1. The CD-ROM filename is as follows:
\DATA\BIOLOGY\MOW_EXO\GRIDxxxx\ydddgrid.MEX
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 .MEX for this data set.
Instruction manual: four channel radiometer Model 100BX. Exotech Incorporated. Gaithersburg, Maryland (1985).
Bauer, M.E., B.F. Robinson, C. Daughtry, and L.L. Biehl. 1981. Field Measurement Workshop. Oct. 14-16. Laboratory for application of Remote Sensing. Purdue University. Lafayette, Indiana.
Irons, J.R., R.A. Weismiller, and G.W. Peterson. 1989. Soil reflectance In G. Asrar (ed.). Theory and Applications of Optical Remote Sensing. John Wiley & Sons. New York. p.66-106.
Walter-Shea, E.A., J.M. Norman, and B.L. Blad. 1989. Bi-directional reflectance and transmittance in corn and soybean. Remote Sensing of Environment. 29:161-174.
Walter-Shea, E.A. and L.L. Biehl. 1990. Measuring vegetation spectral properties. Remote Sensing Review. 5:179-205.
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 4, 1994 (citation revised on October 14, 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.
Seastedt, T. R. 1994. Mowing Experiment Exotech 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. 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).