Data from the LAI-2000 instrument were processed to determine the leaf area index (LAI) at the EOS Validation Core Site in Kataba Local Forest, approximately 20 km south of Mongu, Zambia. Measurements began in 2000 and continued into 2002, with measurements collected about every month throughout the growing season to examine the phenology of LAI for the site.
The LAI-2000 measures the intensity of blue light in five upward-looking concentric conical rings. Measurements are made under the forest canopy and compared with open-sky measurements to determine transmittance for each of the five viewing angles. The sensor head was placed at ground level while the sensors measured light levels in conical scans. Effective leaf area was calculated from the transmittance in the different view angles based on the assumption of a random distribution of leaves (Welles and Norman, 1991).
The LAI-2000 was carried along three parallel transects, each 750 m long and spaced 250 m apart. Each transect was divided into 25 m segments, and measurements were collected at the endpoints of each segment. Data from all transects were combined to provide site-average LAI for each sampling date.
The length and spacing of the transects were chosen to sample an area large enough to be representative of a 1-km MODIS pixel. Ground observations of LAI from this study compared with MODIS LAI products were found to be in close agreement.
The data are stored in an ASCII text file, in comma-separated-value (csv) format, with column headers.
Cite this data set as follows:
Privette, J. L., M. M. Mukelabai, and K. F. Huemmrich. 2005. SAFARI 2000 Leaf Area Measurements at the Mongu Tower Site, Zambia, 2000-2002. Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/781.
Privette, J. L., R. B. Myneni, Y. Knyazikhin, M. Mukufute, G. Roberts, Y. Tian, Y. Wang, and S. G. Leblanc. 2002. Early spatial and temporal validation of MODIS LAI product in Africa. Remote Sensing of Environment, 83(1-2): 232-243.
Welles, J. M. and J. M. Norman. 1991. Instrument for indirect measurement of canopy architecture. Agronomy Journal, 83(5): 818-825.
The data are stored in an ASCII text file, in comma-separated-value (csv) format, with column headers.
| Column Name | Definition | Units/Format |
|---|---|---|
| Date | The observation date | DD/MM/YY |
| START TIME | The starting time of data collection | HH:MM GMT |
| END TIME | The ending time of data collection | HH:MM GMT |
| NUM PTS | The number of data values collected | numeric |
| LAI | The average LAI | m2/m2 |
| Notes | Further information about the data | ASCII |
Sample Records
Date,Start Time,End time,num points,LAI,Notes 10/09/00,4:33:47,6:02:30,93,0.78, 10/18/00,4:36:33,5:59:06,93,0.77, 10/31/00,,,,,Data not processed 11/16/00,,,,,Data not processed |
Only data collected under good open sky conditions at both the beginning and end of data collection and covering two or three transects were processed.
Additional information about the Mongu study site, data collection and processing, measurement theory, LAI-2000 instrumentation, and data limitations or problems is found in the companion file: http://daac.ornl.gov/daacdata/safari2k/field_campaign/mongu_lai-2000/comp/mongu_lai-2000_readme.pdf.
2004/12/28
2004/12/28
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