During 1987, measurements were always made on the most recently expanded leaf of the selected plant. Measurements were made on a variety of forbs and grasses. During 1988, measurements were made on the most recently expanded leaf of the selected plant unless specified. Measurements were also made of older green, yellow and brown leaves on a plant. Measurements were usually made on grasses (i.e., Indian grass, Switch grass and Big bluestem). A few forbs were measured. The same leaf was sometimes measured throughout the day. During 1989, measurements were usually made on the most recently expanded leaf of the selected plant unless specified. Typically, leaves of the dominant grass species at a site were measured. At least two samples of each species were measured. Typically, during all collections (i.e., 1987 - 1989) an external light source with a restricted beam spot (slitted illuminator) was used to restrict the illumination spot on narrow grass leaves so that only leaf material was illuminated.
Measuring and Modeling Near-Surface Reflected and Emitted Radiation Fluxes at the FIFE Site.
Contact 1:
Cynthia J. Hays
Lincoln, NE
(402)472-6701
Contact 2:
Mark A. Mesarch
Lincoln, NE
(402)472-5904
AGME012@129.93.200.1
Contact 3:
Elizabeth A. Walter-Shea
Lincoln, NE
(402)472-1553
AGME012@129.93.200.1
The MMR leaf optical properties measurements were made by B.L. Blad, E.A. Walter-Shea, C.J. Hays, and M.A. Mesarch of the University of Nebraska. Their contribution of these data is particularly appreciated.
To measure reflectance and transmittance of leaf surfaces an integrating sphere is used. The integrating sphere collects all of the radiation reflected from or transmitted through a surface. In the LiCor 1800-12 integrating sphere the sample is held to the outside of the sphere, with a small section of the sample acting as part of the sphere wall. The interior of the sphere is coated with barium sulfate to make a uniform diffuse reflector. In this type of sphere the sensor does not directly observe the sample. The field of view of the sensor is on a section of the sphere wall.
To calculate reflectance a comparison of the wall illumination caused by a beam of radiation reflected by the sample material to that reflected from the reference material. The LiCor 1800-12 uses the same illumination source for both cases. The source is moved between ports to illuminate the sample and reference material. Under ideal conditions the sample reflectance Rs is given by:
Where Is is the output when the sample is illuminated and Ir is the reference output. In reality other factors must be considered. First, the reference material is not a perfect reflector, and second, not all of the incoming radiation beam hits the sample or reference, some radiation is scattered off of the sphere walls without hitting the target. Taking these factors into account the reflectance is given by: Where Rr is the reflectance of the reference material and Id is the radiation scattered without hitting the target. Id can be determined by illuminating the sample port with no sample in it such that no external radiation can enter. Thus the only radiation illuminating the sample wall will be internally scattered.Transmittance is calculated by comparing the wall illumination from radiation passed through the sample to the illumination caused by radiation that did not pass through the sample. For diffusive samples, the transmittance Ts is:
where Rr is the reflectance of the reference material, Is is the output when the sample is illuminated and Ir is the output when the reference material is illuminated.Leaf optical properties can be directly or indirectly related to leaf water content. Mild water stress decreases relative water content (RWC) (10-20%) and turgor slightly, which is accompanied by cell wall relaxation, resulting in decreases in cell dimension, cell surface, cell volume and intercellular space (Levitt and Ben Zaken 1975). Severe water stress can greatly decrease RWC (below 70-80%) and turgor, and result in cell collapse (Levitt and Ben Zaken 1975). Changes in intercellular arrangement may affect the radiative scattering within the leaf resulting in an alteration in overall leaf reflectance and transmittance.
The seven waveband radiometer (Nebraska Multiband Leaf Radiometer (NMLR)) produces an analog voltage response in 7 spectral bands. The nominal bandwidths of the 7 spectral bands 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 and 2.08-2.35 microns. The detector is a single silicon-lead sulfide detector. Wavebands 1 through 4 are monitored by the silicon side and wavebands 5 through 7 are monitored by the lead sulfide side of the detector. The filters for the NMLR are the same filters used for the seven visible and near infrared bands of the Modular Multiband Radiometer (MMR) (Markham 1987).
The LI-COR LI-1800-12 Integrating Sphere is an instrument for collecting radiation that has been reflected from or transmitted through a sample material. An external light source with a restricted beam was usually used to restrict the illumination spot on the leaf. The lamp used in the external light source is a 6 Volt 10 Watt glass-halogen For a further description see the LI-COR Integrating Sphere Instruction Manual.
Ground-based.
The Nebraska Multiband Leaf Radiometer and LI-COR LI-1800-12 Integrating Sphere were mounted on a tripod.
To measure leaf reflectance and transmittance in situ.
Hemispherical reflectance and transmittance factors of individual leaves illuminated at near-normal incidence measured using a LI-COR LI-1800-12 Integrating Sphere and external light source attached to a seven-waveband leaf radiometer.
The Nebraska Multiband Leaf Radiometer is described in Mesarch et al., (1991).
The Li-COR LI-1800-12 Integrating Sphere is an external integrating sphere, which means that the sample is external to the sphere; when it is in place, a small part of the sample actually makes up part of the sphere wall. For further information see the LI-COR 1800-12 Integrating Sphere instruction manual.
The Nebraska Multiband Leaf Radiometer (NMLR) is mounted on a tripod and the LI-COR LI-1800-12 Integrating Sphere is mounted on top of the NMLR. The assembly can be inverted and held under the tripod to reach samples low to the ground. A modified external light source with a slitted beam (3.5 mm x 11 mm) was used to illuminate narrow leaf samples (such as grasses) and reference. In 1989, an external light source with an unrestricted beam was also used so that measurement procedures were comparable to the procedures of E.M. Middleton. See the SE-590 Leaf Level Spectral Observations from GSFC document.
Nebraska Multiband Leaf Radiometer (NMLR)
Barrett Robinson
Department of Electrical Engineering
Purdue University
West Lafayette, IN 47907
LI-COR LI-1800-12 Integrating Sphere
LI-COR, Inc.
Box 4425
Lincoln, Nebraska 68504
(402) 467-3576
1987, 1988 & 1989: Periodically the Nebraska Multiband Leaf Radiometer (NMLR) response was checked using a screen or neutral density filter of a known transmittance (Mesarch et al., 1991). No corrections were made to the NMLR response. The collimation of the LI-COR LI-1800-12 Integrating Sphere illuminator was checked periodically by making a stray light measurement (LI-COR 1983).
Reflectances and transmittances may not be as accurate for wavebands 5 - 7 as they are for wave bands 1 - 4 (the MBEs (see the Tolerance Section)) for the lead-sulfide wavebands are larger than those for silicon wavebands). This is especially true for waveband 7 when using the slitted illuminator due to combined effect of low light produced by the slitted illuminator and the lead-sulfide detector response to low light. Ambient temperature can alter the voltage response with the lead sulfide detector (as temperature decreases, the voltage decreases).
Calibrations performed in the Fall of 1989 (Mesarch et al., 1991) indicate that the calculated reflectance and transmittance values may be in error. MBEs for the unrestricted light source are: -0.17%, 0.05%, 0.03%, 0.23%, 0.88%, 0.72% and 3.25% for wavebands 1 through 7. MBEs for the restricted light source are: -0.31%, 0.05%, -0.06%, -0.05%, 1.87%, 1.02% and 4.59% for wavebands 1 through 7.
Not available at this revision.
A calibration procedure was developed in the Fall of 1989. The procedure is described by Mesarch et al., (1991). The FIFE data were not corrected and may be in error (as indicated by the mean square error) as follows: 0.09% (waveband 1), 0.02% (waveband 2), 0.05%(waveband 3), 0.2% (waveband 4), 1.3% (waveband 5), 0.5% (waveband 6), and 9.8% (waveband 7).
1987:
Leaves remained attached to plants during measurements. The most recently expanded leaf was always measured. A screen filter was measured periodically to check instrument response and to determine the appropriate data reduction method using electronic background (dark) measurements (Mesarch et al., 1991). Measurements were always made with an external light source with a restricted beam spot (slitted illuminator), to restrict the illumination spot on the leaf, so that only leaf material was illuminated.
The tripod was adjusted so that the leaf could be placed in the LI-COR LI-1800-12 Integrating Sphere sample port without disturbing the plant and to maintain the light source in the horizontal plane to reduce illuminator variation (LI-COR manual). The leaf was placed in the sample port with the adaxial side facing the inside of the sphere without disturbing the plant. Reference adaxial, reflected adaxial, and transmitted abaxial measurement were made. The leaf was removed and reinserted in the sample port so that the abaxial surface was placed toward the inside of the sphere. Transmitted adaxial, reflected abaxial and reference abaxial measurements were made to complete a set of leaf measurements. For more details on the LI-COR LI-1800-12 Integrating Sphere configuration for each measurement see Mesarch et al., (1991). After each measurement, a measurement of the electronic background signal (dark measurement) was made. The next leaf was selected and the above measurements were repeated.
1988:
Usually the most recently expanded leaf was measured, exceptions are: dead leaves, yellow leaves, and the second and fourth to the most recently expanded leaves. Leaves remained attached to the plant with the exception of the dead leaf samples. On June 29th at site 811 (SITEGRID_ID = 4438-BBN) the same leaves were measured throughout the day. On August 9th at site 811 (SITEGRID_ID = 4438-BBN) 3 leaves were measured on the same plant (most recently expanded leaf, second expanded leaf, and fourth expanded leaf). Unless otherwise noted the same procedure as in 1987 was followed.
1989:
Usually the most recently expanded leaf was measured from grasses of the site's dominant species. The leaves remained attached to the plant during the measurement. Generally, two samples of each species were measured during each measurement period. Occasionally, an external light source with an unrestricted beam spot was used with two leaves taped together to fill the sample port to replicate the measurement procedure of E.M. Middleton for comparison of measurement results. Unless otherwise noted the same procedure as in 1987 was followed.
Not available.
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.
Species were selected to be representative of the site.
Measurements were taken at representative areas scattered throughout the FIFE study area.
SITEGRID NORTHING EASTING LATITUDE LONGITUDE ELEV
-------- --------- -------- -------- ----------- -----
1246-BBN 4331625 714200 39 06 34 -96 31 22 410
2133-BBN 4329706 711577 39 05 34 -96 33 13 443
2139-BBN 4329843 712789 39 05 37 -96 32 23 385
2437-BBN 4329150 712375 39 05 15 -96 32 41
3414-BBN 4327286 707854 39 04 19 -96 35 51 410
4439-BBN 4325219 712795 39 03 07 -96 32 27 445
6943-BBN 4320147 713500 39 00 22 -96 32 04 415
8739-BBN 4316699 712845 38 58 31 -96 32 35 442
SITEGRID SLOPE ASPECT
-------- ----- ------
1246-BBN 12 S
2133-BBN 1 TOP
2139-BBN
2437-BBN
3414-BBN
4439-BBN 2 N
6943-BBN
8739-BBN 1 TOP
Not available.
The external light source with a restricted beam spot illumination size is 3.5 mm x 11 mm whereas the unrestricted external light source has an illumination spot with a diameter of 11.4 mm.
Not available.
Not available.
Measurements were made throughout a day. Measurements of one leaf required a minimum of 10 minutes.
On an individual day measurements were taken from 1200 to 2358 GMT. The overall time period of the measurements was June of 1987, and July and August of 1988 and 1989. Measurements were not made continuously.
Not available.
Measurements were made at varying intervals during the measurement periods. On a given day, the optimum time interval between leaf measurements was a few minutes.
The SQL definition for this table is found in the MMR_LEAF.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 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).
OBS_TIME The time that the observation was [GMT] taken in GMT. The format is (HHMM).
PLOT_NUM The plot number at the site where the data were collected.
SPECIES_NAME The common name of the plant being measured.
LTER_SPECIES_CODE The LTER species code (see VEG_SPECIES_REF) for the species of the leaf measured.
OBS_TYPE Type of measurement: RT, reflectance from leaf top; TT, transmittance through leaf top,; RB, reflectance from leaf bottom; TB, transmittance through leaf bottom.
BAND1_REFL The percent reflectance or [percent] transmittance of the leaf in MMR band 1, 0.45-0.52 um.
BAND2_REFL The percent reflectance or [percent] transmittance of the leaf in MMR band 2, 0.52-0.60 um.
BAND3_REFL The percent reflectance or [percent] transmittance of the leaf in MMR band 3, 0.63-0.69 um.
BAND4_REFL The percent reflectance or [percent] transmittance of the leaf in MMR band 4, 0.76-0.90 um.
BAND5_REFL The percent reflectance or [percent] transmittance of the leaf in MMR band 5, 1.15-1.30 um.
BAND6_REFL The percent reflectance or [percent] transmittance of the leaf in MMR band 6, 1.55-1.75 um.
BAND7_REFL The percent reflectance or [percent] transmittance of the leaf in MMR band 7, 2.08-2.35 um.
COMMENTS Any comments about the data.
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).
Footnote:
Valid levels
The primary certification codes are:
The certification code modifiers are:
SITEGRID_ID STATION_ID OBS_DATE OBS_TIME PLOT_NUM SPECIES_NAME
----------- ---------- ---------- -------- -------- -------------
4439-BBN 916 04-AUG-89 1444 BIG BLUESTEM
4439-BBN 916 04-AUG-89 1444 BIG BLUESTEM
4439-BBN 916 04-AUG-89 1444 BIG BLUESTEM
4439-BBN 916 04-AUG-89 1444 BIG BLUESTEM
LTER_SPECIES_CODE OBS_TYPE BAND1_REFL BAND2_REFL BAND3_REFL BAND4_REFL
----------------- -------- ---------- ---------- ---------- ----------
2 RT 10.02 17.50 8.78 42.96
2 TT 6.31 18.24 6.78 51.75
2 RB 9.91 17.44 8.48 42.98
2 TB 6.07 17.82 6.26 51.45
BAND5_REFL BAND6_REFL BAND7_REFL COMMENTS
---------- ---------- ---------- --------------------------
40.59 30.16 21.03 HEALTHY PLANT MATERIAL
54.17 46.10 34.63 HEALTHY PLANT MATERIAL
41.41 31.72 22.36 HEALTHY PLANT MATERIAL
54.20 46.67 35.31 HEALTHY PLANT MATERIAL
FIFE_DATA_CRTFCN_CODE LAST_REVISION_DATE
--------------------- ------------------
CPI 13-FEB-90
CPI 13-FEB-90
CPI 13-FEB-90
CPI 13-FEB-90
Measurements were taken at representative areas scattered throughout the FIFE study area. Measurements were made at varying intervals during the 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 Sectionand described in detail in the TDF file. These fields are in the same order as in the chart.
LEAF REFLECTANCE CALCULATION:
Equation 1:
where: LEAF TRANSMITTANCE CALCULATION:Equation 2:
where:A screen filter was measured periodically to determine the appropriate data reduction calculation using the electronic background (dark) measurements. The dark measurements are always subtracted for wavebands 1 - 4 (silicon detector); for wavebands 5 - 7 (lead-sulfide detector), the dark measurements are either ignored, added or subtracted. The dark measurements are usually subtracted. For details see Mesarch et al., (1991).
The stray light measurements were made only during calibrations (see the Calibration Section).
Equation 1 is used to calculate the hemispherical reflectance for the adaxial and abaxial leaf surfaces. Equation 2 is used to calculate the hemispherical transmittance of the adaxial and abaxial leaf surfaces.
Not applicable.
Not applicable.
None.
Errors can result if the leaf sample has a thickness which does not permit proper sealing around the sample holder (this can be a problem especially in the mid-vein area.) Light entering from the loose seal can enter the sphere causing erroneous values. If the light source is not maintained in a horizontal position, the light output can vary, leading to errors.
Comparisons have been made between our measurements and those by E.M. Middleton. See the SE-590 Leaf Level Spectral Observations from GSFC document.
Calibrations performed in the Fall of 1989 (Mesarch et al., 1991) indicate that the calculated reflectance and transmittance values may be in error. Mean Bias Errors (MBEs) for the unrestricted light source are: -0.17%, 0.05%, 0.03%, 0.23%, 0.88%, 0.72% and 3.25% for wavebands 1 through 7. MBEs for the restricted light source are: -0.31%, -0.05%, -0.06%, -0.05%, 1.87%, 1.02%, 4.59% for wavebands 1 through 7.
Not available.
FIS staff applied a general 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. Inconsistencies and problems found in the QA check are described is 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.
As of the revision data of this document, the following discrepancies or errors in the data have been reported:
Reflectances and transmittances may not be as accurate for wavebands 5-7 as they are for wave bands 1-4 (the MBEs (see the Tolerance Section) for the lead-sulfide wavebands are larger than those for silicon wavebands). This is especially true for waveband 7 when using the slitted illuminator due to combined effect of low light produced by the slitted illuminator and the lead-sulfide detector response to low light. Ambient temperature can alter the voltage response with the lead sulfide detector (as temperature decreases, the voltage decreases).
Pregnant women and people with bad backs can have a difficult time working with short plants.
This data set can be used to gain a better understanding of how optical properties contribute to canopy reflectance and absorption of radiation.
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.
Leaf Optical Properties from UNL data are available on FIFE CD-ROM Volume 1. The CD-ROM file name is as follows:
DATA\SUR_REFL\MMR_LEAF\GRIDxxxx\Yyyyy\ydddgrid.MRL
Where xxxx is the four digit code for the location within the FIFE study area, 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: ydddgrid.sfx, where grid is the four-number code for the location within the FIFE sitegrid, 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 .MRL for this data set.
Barnes Engineering. 1982. Calibration and data book: Multispectral 8- channel radiometer. Barnes Engineering Company. Stamford, CT.
LI-COR LI-1800-12 Integrating Sphere instruction manual. Pub. No. 8305-0034. LI-COR, inc. Lincoln, NE. (1983).
Markham, B.L. 1987. Memo on review of Phoenix calibration of MMR Channel 8. GSFC/NASA, Greenbelt, MD 20771.
Markham, B.L. 1987. FIFE MMR Calibration Report. 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. 196:8-15.
Robinson, B.F., and L.L. Biehl. 1979. Calibration procedures for measurement of reflectance factor in remote sensing field research. Measurements of Optical Radiation. Proceedings of the Society of Photo-Optical Instrumentation Engineers. 196:16-26.
Mesarch, M. A., E.A. Walter-Shea, B.F. Robinson, J.M. Norman and C.J. Hays. 1991. Performance evaluation and operation of a field-portable radiometer for individual leaf optical measurements. AgMet Progress Report 91-2. Department of Agricultural Meteorology. University of Nebraska-Lincoln. Lincoln, Nebraska. 68583-0728.
Levitt, J. and R. Ben Zaken. 1975. Effects of small water stresses on cell turgor and intercellular space. Physiol. Plant. 34, 273-279.
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 26, 1994 (citation revised on October 16, 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.
August 13, 1996.
ORNL-FIFE_MMR_LEAF.
Blad, B. L., and E. A. Walter-Shea. 1994. MMR Leaf Optical Properties 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).
http://daac.ornl.gov/FIFE/Datasets/Surface_Radiation/MMR_Leaf_Data.html