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Canopy Photosynthesis Rates (FIFE)


The Canopy Photosynthesis Data Set data were collected from five sites within the FIFE study area during July 1, 1987 through October 12, 1987. The objectives of the study were to estimate canopy photosynthetic rates, respiration rates, and bulk stomatal resistance. Photosynthesis was measured by monitoring the net exchange of CO2 from the canopy to the atmosphere while the canopy is enclosed in a Plexiglas chamber equipped with a LI-COR CO2 gas analyzer. The rate of CO2 concentration change over intervals of 10 - 20 seconds is measured. This CO2 concentration rate of change is used along with other factors (e.g., the amount of canopy area enclosed, the volume of the enclosure, and temperature) to estimate the net photosynthesis rate. The stomatal resistance and conductance is calculated from the total leaf resistance (i.e., calculated via the transpiration rate along with the leaf and air temperatures) minus the boundary layer resistance. Stomatal resistance of selected species of the grass used to estimate the total canopy resistance were measured independently using a leaf diffusion porometer.

The results showed that estimated values of net CO2 flux varied between about 0.25 and 1.0 [mg][m^-2][sec^-1] during IFC-2 and IFC-3, and around zero during IFC-4. Resistances ranged from 80 [sec][m^-1] to 300 [sec] [m^-1] during IFC-2 and IFC-3, rising to very high values (greater than 1000 [sec][m^-1]) during IFC-4.

Table of Contents:

1. Data Set Overview:

Data Set Identification:

Canopy Photosynthesis Rates (FIFE)
(Canopy Photosynthesis).

Data Set Introduction:

The Canopy Photosynthesis Data Set data were collected from five sites within the FIFE study area during July 1, 1987 through October 12, 1987. The data set contains estimates of canopy photosynthetic rates, respiration rates, and bulk stomatal resistance.


The objectives were to estimate canopy photosynthetic rates, respiration rates, and bulk stomatal resistance using sealed Plexiglas chambers.

Summary of Parameters:

Vapor pressure, air temperature, surface temperature, incident photosynthetically active radiation, rate of photosynthesis, and total canopy resistance.


Measurements of photosynthetic respiration and bulk stomatal resistance of the plant canopy were made using a Plexiglas chamber equipped with a LI-COR CO2 gas analyzer. Measurements of incident Photosynthetically Active Radiation (PAR) were made throughout the day within and outside the chamber. These data were collected from sites 60 (2133-PSB), 16 (4439-PSB), 28 (6943-PSB), 36 (2655-PSB), and 44 (2043-PSB) during July 1, 1987 through October 12, 1987, which fell within FIFE IFCs 1-4. Three sites (2133-PSB, 4439-PSB and 2043-PSB) were located within the northwest quadrant of the FIFE study area. The other sites were distributed within the rest of the FIFE area.

The results showed that estimated values of net CO2 flux varied between about 0.25 and 1.0 [mg][m^-2][sec^-1] during IFC-2 and IFC-3, and around zero during IFC-4. Resistances ranged from 80 [sec][m^-1] to 300 [sec] [m^-1] during IFC-2 and IFC-3, rising to very high values (greater than 1000 [sec][m^-1]) during IFC-4. The FIFE Interim Report (Sellers et al., 1990) shows some results for individual sites.

Related Data Sets:

FIS Data Base Table Name:


2. Investigator(s):

Investigator(s) Name and Title:

Dr. G. Asrar
NASA Headquarters

Dr. P.J. Sellers
NASA Goddard Space Flight Center

Title of Investigation:

Canopy Photosynthesis and Resistance Chamber Measurements During FIFE.

Contact Information:

Contact 1:
Dr. P.J. Sellers
NASA Goddard Sp. Fl. Ctr.
Greenbelt, MD
(301) 286-7282

Contact 2:
Dr. G. Asrar
NASA Headquarters
Washington, DC
(202) 358-2559

Requested Form of Acknowledgment.

The Canopy Photosynthesis data were collected by G. Asrar of NASA Headquarters and P.J. Sellers of NASA Goddard Space Flight Center.

3. Theory of Measurements:

Photosynthesis is measured by monitoring the net exchange of CO2 from the canopy to the atmosphere while the canopy is enclosed in a chamber. The rate at which the CO2 concentration changes within the chamber over intervals of 10 - 20 seconds is measured. The net photosynthesis rate is then calculated using this rate of change and other factors, such as the amount of canopy area enclosed, the volume of the enclosure, and temperature (Farquhar et al., 1982).

Stomatal conductance is measured by monitoring the humidity within an enclosed chamber, which normally rises as the leaves transpire. The increase in humidity is balanced by the flow of partially dried air returning to the chamber from the CO2 analyzer. The transpiration rate is calculated from the change in canopy chamber humidity with time (if any) and the flow rate of that portion of the total flow, which passes through the desiccant. The transpiration rate is then used with the leaf and air temperatures to calculate total leaf resistance, from which the boundary layer resistance is subtracted, yielding the stomatal resistance and conductance.

4. Equipment:

Sensor/Instrument Description:

An airtight Plexiglas chamber of dimensions 1.8 m high, 0.8 m long, and 0.8 m wide, was equipped with a LI-COR 6200 gas analyzer, a system console, and a sensor housing containing an infrared thermometer and quantum sensor. A frame fixed to the soil surface, which forms a seal with the chamber (box) when the latter is placed over it, was built around the plants whose canopy were to be measured. The chamber was placed on these frames thus sealing the internal air for sampling.

The complete system was capable of monitoring the canopy/ground surface temperature and air temperature, CO2 concentration, and water vapor concentration at a 1-second time resolution. Five frames were placed at sites 6 (2132-PSB), 16(4439-PSB), 28 (6943-PSB), 36 (2655-PSB) and 44 (2043-PSB).

A Quantum Sensor was used for measurement of incident PAR.

Collection Environment:




Source/Platform Mission Objectives:

The aim was to measure the canopy photosynthesis rates, respiration rates, and bulk stomatal resistance at the FIFE study area.

Key Variables:

Photosynthetically active radiation, photosynthesis rate, air and canopy surface temperature, vapor pressure, stomatal resistance.

Principles of Operation:

A portion of the plant canopy was enclosed in a fabricated chamber, which is attached to a LI-6200 gas exchange system. Gas is re-circulated between the canopy chamber and the LI-6200 console, which contains a computer to do all calculations from various sensors monitoring the operation of the system.

The chamber is placed over the plant canopy and the dry-air flow rate adjusted to maintain the chamber relative humidity at the value of the ambient air. A small amount of carbon dioxide is injected into the chamber so that the concentration does not drop significantly during this initial period. Logging on the LI-6200 is begun when the concentration of carbon dioxide is near the ambient value. As the leaves photosynthesize the carbon dioxide, and concentration in the chamber drops, it is possible to determine the canopy photosynthetic rate as a function of carbon dioxide concentration inside and outside the leaves.

After the carbon dioxide concentration in the chamber has dropped such that the canopy photosynthetic rate is about half of its initial rate, some carbon dioxide is injected into the chamber to raise the concentration to about 400 to 500 micromol per mol. Then the photosynthetic rate as a function of higher carbon dioxide concentrations is measured until the canopy photosynthetic rate returns to the original value. Matching of initial and final canopy photosynthetic rates and internal CO2 concentrations is a requirement for acceptable data because it provides some assurance that the canopy is functioning in a stable mode.

Sensor/Instrument Measurement Geometry:

The Plexiglas chamber (box) dimensions were 1.8 m x 0.8 m x 0.8 m.

Manufacturer of Sensor/Instrument:

Gas Analyzer and Quantum Sensor:
LI-Cor, Inc.
4421 Superior Street
P.O. Box 4425
Lincoln, NE 68504.

Plexiglas chamber was fabricated at:
University of Maryland
College Park, MD


The gas analyzer was factory calibrated over a range of temperatures by generating data that relates C02 concentration to voltage output of the analyzer and fitting the response with a third-order polynomial. Factory calibration is for 0-1500 ppm; higher ranges are possible through user calibration. Calibration accuracy is enhanced by the use of the National Bureau of Standard traceable standard gases in the factory linearization procedure.

During FIFE, calibration of the analyzer was done by adjusting the zero and span knobs located on the analyzer housing. The minimal zero and span drift of the analyzer requires few adjustments in the field. Temperature effects are automatically compensated for in the software. The zero was checked approximately once each hour using the zero reference gas, which was generated by using the soda lime scrubber within the analyzer. The span was set by flowing a known concentration of CO2 through the analyzer.

The quantum sensor was factory calibrated.


LI-6200: Available from LI-COR, Inc.

Quantum sensor: Available from LI-COR, Inc.


LI-6200: Accuracy of photosynthetic rate 5-10%.

Accuracy of stomatal conductance 10-20%.

Frequency of Calibration:

LI-6200 was calibrated at the beginning of each run and periodically using known concentrations of CO2 and a dry-air feed.

Recalibration was not necessary for the quantum sensor.

Other Calibration Information:


5. Data Acquisition Methods:

The Plexiglas chamber (box) was placed over the fixed frame surrounding the plants, whose canopy were to be measured, for a few minutes at a time. Carbon dioxide and water vapor exchange between the plant canopy and the air inside the airtight Plexiglas chamber were measured with the LI-COR 6200 gas analysis system. The surface radiative temperature of the canopy and the air temperature inside the chamber were measured. A pair of LI-COR quantum sensors were used to measure the incident PAR flux density inside and outside the chamber. The chamber was momentarily removed between measurements to prevent heating of the substrate. A space blanket was placed over the chamber between readings. Stomatal resistance of selected species of the grass used to estimate the total canopy resistance were measured independently using a leaf diffusion porometer.

6. Observations:

Data Notes:

Not available.

Field Notes:


7. Data Description:

Spatial Characteristics:

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.

Spatial Coverage:

Measurements were made at the five sites listed below:

--------   ---   --------  -------  --------   ---------  ----  -----  ------
2043-PSB    44   4330003   713536   39 05 42   -96 31 51   415
2133-PSB    60   4329720   711521   39 05 34   -96 33 15   405             
2655-PSB    36   4328787   716070   39 05 00   -96 30 07   367     4    E
4439-PSB    16   4325215   712794   39 03 07   -96 32 28   445     2    N
6943-PSB    28   4320147   713500   39 00 22   -96 32 04   415

Spatial Coverage Map:

Not available.

Spatial Resolution:

The chamber covered an area of ground 1.8 m by 0.8 m.


Not available.

Grid Description:

Not available.

Temporal Characteristics:

Temporal Coverage:

Data were obtained from July 1, 1987 through October 12, 1987. A total of 25 days of usable data were obtained with the box during IFC-2, IFC-3, and IFC-4.

Temporal Coverage Map:

Not available.

Temporal Resolution:

During each month, data were collected at an average of 3 days apart. Each time a site was visited, a series of observations were taken at half-hourly intervals for 4 to 6 hours.

Data Characteristics:

The SQL definition for this table is found in the PHO_BOX.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 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).
VAPOR_PRESS The vapor pressure within the box. [millibars]
AIR_TEMP The air temperature within the box. [degrees Kelvin]
SURFACE_TEMP The surface temperature. [degrees Kelvin]
PAR_DOWN The downward (incoming) [microEinst] Photosynthetically Active [meter^-2] Radiation (PAR). [sec^-1]
PHOTOSYN_RATE The photosynthesis rate (CO2 [mg of CO2] assimilation rate). [meter^-2] [sec^-1]
RESISTANCE The total canopy resistance, the [sec] plants resistance to the transfer [meter^-1] of water.
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 data, in the format (DD-MMM-YY).


Missing values are indicated by a -999, -999.9 or -999.99.

** Valid levels

The primary certification codes are: EXM Example or Test data (not for release). PRE Preliminary (unchecked, use at your own risk). CPI Checked by Principal Investigator (reviewed for quality). CGR Checked by a group and reconciled (data comparisons and cross-checks).

The certification code modifiers are: PRE-NFP Preliminary - Not for publication, at the request of investigator. CPI-MRG PAMS data that are "merged" from two separate receiving stations to eliminate transmission errors. CPI-??? Investigator thinks data item may be questionable.

Sample Data Record:

-----------   ----------   ----------  --------   -----------   --------
2043-PBS         44        06-OCT-87     1529        4.90        292.90
2043-PBS         44        06-OCT-87     1558        4.46        293.47
2043-PBS         44        06-OCT-87     1636        4.37        295.40
2655-PBS         36        12-OCT-87     2115        7.29        305.93
------------   --------   -------------   -----------  ---------------------
293.92        947.0         .5940       1585.8300             CPI
295.63       1122.0       -4.2281       1122.1800             CPI
297.83       1197.0       -3.9848       1916.8200             CPI
300.51        698.0       -3.2340       2167.7700             CPI

8. Data Organization:

Data Granularity:

The Canopy Photosynthesis data were collected at an average of 3 days apart. Each time a site was visited, a series of observations were taken at half-hourly intervals for 4 to 6 hours.

A general description of data granularity as it applies to the IMS appears in the EOSDIS Glossary.

Data Format:

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.

9. Data Manipulations:


Derivation Techniques and Algorithms:

Sellers et al. (1990) used the following mass conservation equation (Eq. 1) and canopy/surface resistance equation (Eq. 2) to produce a set of net CO2 flux and surface resistance estimates.

CO2 assimilation rate:

A = (-12.031/Ta) * (Vb/Ab) [P * (dC/dt) + (C/P) * (de/dt)] (Eq. 1)

A = assimilation rate, [mmol][m^-2][s^-1]
C = CO2 conc., [ppm]
Ta = air temperature, [degrees K]
e = vapor pressure, [mb]
Vb = box volume, [m^3]
Ab = ground surface area, [m^2]
P = atmospheric pressure, [mb]
t = time

Equation (1) can be solved in two ways:
(i) Derivative: A line fit is made to the time-series of CO2 data. This yields dC/dt and hence A.
(ii) Integrative: Both sides of (Eq. 1) are integrated with time so that the start and end values of C and e are used to get an average estimate of A. This can be done over different portions of the time series of data.

Canopy/surface resistance (rc):

dqa/dt = (rho*Cp) / (lamda*gamma) [(es(Ts)-e) / (rb+rc)] Ab/Vb (Eq. 2)

qa = mixing ration inside box, [kg][kg^-1]
rho = density, [kg][m^-3]
cp = specific heat of air, [J][kg^-1][K^-1]
gamma = psychrometric constant, 0.66 [mb][K^-1]
lamda = latent heat of vaporization, [J][kg^-1]
es(Ts) = saturated vapor pressure at surface temperature (Ts), [mb]
rb = aerodynamic resistance between foliage and air in box, [sec][m^-1]
rc = canopy/surface resistance, [sec m^-1]
t = time

In (Eq. 1), the solution of C(t) is essentially linear. In (Eq. 2), the increase in water vapor suppresses further evapotranspiration so qa(t) is exponential. The calculation of the combined term ( rb + rc ) is then given by three methods.

(i) Derivative: Exponential fits to the time-series of qa, Ts and e. Derivatives of the fits are used to solve (Eq. 2).
(ii) Line fit: The time-constants for qa(t) involve terms from the right-hand side of (Eq. 2).
(iii) Integrative: Both sides of (Eq. 2) are integrated numerically with time. Aerodynamic resistance between foliage and air in box and canopy/surface resistance are assumed constant over this period.

Data Processing Sequence:

Processing Steps:

Photosynthesis rates and canopy resistance were computed by:

  1. Determining CO2 assimilation rate.
  2. Determining canopy/surface resistance.
  3. Storing these data in a data base.

Processing Changes:



Special Corrections/Adjustments:


Calculated Variables:

Graphs and Plots:


10. Errors:

Sources of Error:

Errors could result from calibration drift of the LI-COR 6200 gas analyzer, dust on chamber surface during measurements, or a gas leak of the box.

Quality Assessment:

Data Validation by Source:

Data were validated by intercomparison with Surface flux data and other Surface Radiance Biology data sets.

Confidence Level/Accuracy Judgment:

Data showed expected trends, but quantitative accuracy is uncertain.

Measurement Error for Parameters:

No quantitative assessment was made.

Other errors mentioned in the Sources of Error Section were not assessed.

Additional Quality Assessments:

FIS staff applied a general Quality Assessment (QA) procedure to these 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 discrepancies, which were identified, are reported as problems in the Known Problems with the Data Section.

Data Verification by Data Center:

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.

11. Notes:

Limitations of the Data:

Not available.

Known Problems with the Data:

discrepancies or errors have been found in these data:
  1. On August 10, 1987, two very high values (greater than 368 degrees K) for SURFACE_TEMP were reported at sitegrid 2043-PSB.
  2. On July 24, 1987, at sitegrid 4439-PSB, the PHOTSYN_RATE and PAR_DOWN have lower than anticipated values. For PAR_DOWN there are six values between -2 and 2, and for PHOTOSYN_RATE there are six values less than zero.
  3. The RESISTANCE data also have suspicious values on October 6, 1987 sitegrid 2043-PSB, and October 12, 1987 at 2655-PSB. On October 6, 1987 there were 9 values greater than 1500 and on the twelfth there were 13 values greater than 1500.

It is probable that this device underestimates C02 assimilation rates by underestimating gas concentration.

The dust, which accumulated on the chamber surfaces, may have reduced PAR levels, slightly.

Usage Guidance:

These data can be compared with the Leaf Photosynthesis data and with the surface flux measurements.

Any Other Relevant Information about the Study:

The major variables among the five sites selected for detailed study were soil type, management practices (burned, unburned, grazed, and ungrazed grassland), and topography. The dominant grass species were Andropogon gerardii, Andropogon scoparius, and Sorghastrum nutans.

12. Application of the Data Set:

Not available.

13. Future Modifications and Plans:

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.

14. Software:

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.

15. Data Access:

Contact Information:

ORNL DAAC User Services
Oak Ridge National Laboratory

Telephone: (865) 241-3952
FAX: (865) 574-4665


Data Center Identification:

ORNL Distributed Active Archive Center
Oak Ridge National Laboratory

Telephone: (865) 241-3952
FAX: (865) 574-4665


Procedures for Obtaining Data:

Users may place requests by telephone, electronic mail, or FAX. Data is also available via the World Wide Web at

Data Center Status/Plans:

FIFE data are available from the ORNL DAAC. Please contact the ORNL DAAC User Services Office for the most current information about these data.

16. Output Products and Availability:

The Canopy Photosynthesis data are available on FIFE CD-ROM Volume 1. The CD-ROM filename 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 .PSB for this data set.

17. References:

Satellite/Instrument/Data Processing Documentation.

Farquhar, G.D., and T.D. Sharkey. 1982. Stomatal conductance and photosynthesis. Ann. Rev. Plant Physiol. 33:317-345.

Journal Articles and Study Reports.

Asrar, G., M. Fuchs, E.T. Kanemasu, and J.L. Hatfield. 1984. Estimating absorbed photosynthetic radiation and leaf area index from spectral reflectance in wheat. Agron. J. 76:300-306.

Polley, H.W., J.M. Norman, T.J. Arkebauer, W.A. Walter-Shea, D.H. Greegor and B. Bramer. 1992. Leaf gas exchange of Andorpogon gerardii Vitman. Panicum virgatum L. and Sorghastrum nutans (L) NASH in a tallgrass prairie. J. Geophys. Res. 97:18,837-18,844.

Sellers, P.J. 1985. Canopy reflectance, photosynthesis and transpiration. Int. J. Remote Sens. 6:1335-1372.

Sellers, P.J. 1985. Canopy reflectance, photosynthesis and transpiration. II. The role of biophysics in the linearity of their interdependence. Remote Sens. Environ. 21:143-183.

Sellers P.J., F.G. Hall, D.E. Strebel, R.D. Kelly, S.B. Verma, B.L. Markham, B.L. Blad, D.S. Schimel, J.R. Wang, and E.T. Kanemasu. 1990. FIFE Interim Report. NASA Internal Document. No. 623. NASA Goddard Space Flight Center. Greenbelt, Maryland.

Archive/DBMS Usage Documentation.

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.

18. Glossary of Terms:

A general glossary for the DAAC is located at Glossary.

19. List of Acronyms:

CCT Computer Compatible Tape CD-ROM Compact Disk-Read Only Memory DAAC Distributed Active Archive Center EOSDIS Earth Observing System Data and Information System FIFE First ISLSCP Field Experiment FIS FIFE Information System ISLSCP International Satellite Land Surface Climatology Project LTER Long Term Ecological Research ORNL Oak Ridge National Laboratory PAR Photosynthetically Active Radiation URL Uniform Resource Locator UTM Universal Transverse Mercator

A general list of acronyms for the DAAC is available at

20. Document Information:

April 25, 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.

Document Review Date:

September 4, 1996.

Document ID:



Cite this data set as follows:

Asrar, G., and P. J. Sellers. 1994. Canopy Photosynthesis Rates (FIFE). Data set . Available on-line [] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/27. 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

Document Curator:

DAAC Staff

Document URL: