The data presented here include the aerosol optical thickness (AOT) and column water vapor measurements taken at sites along the Kalahari Transect using a Microtops sunphotometer. Data were collected every 30 minutes at 4 sites that were visited during the SAFARI 2000 Kalahari Wet Season Campaign between March 3, 2000, and March 18, 2000. AOT values are provided at 340-, 440-, 675-, 870-, and 936-nm wavelengths. An estimate of the Angstrom Coefficient is also provided to allow the estimation of AOT at other wavelengths. The purpose of this data collection was primarily to document the conditions at each site and to aid in the correction of remote-sensing data, to validate Earth Observation System (EOS) products such as MODIS and MISR aerosol products, and to model canopy productivity.
Cite this data set as follows:
Privette, J. L., M. Mukelabai, and C. Pietras. 2004. SAFARI 2000 AOT & Column Water Vapor at Kalahari Transect Sites, Wet Season 2000. 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/719.
Dowty, P., P. Frost, D. Lesolle, G. Midgly, M. Mukelabai, L. Otter, J. Privette, J. Ramontsho, R. Scholes, S. Ringrose, and Y. Wang. 2000. Summary of the SAFARI 2000 wet season field campaign along the Kalahari Transect. EOS Earth Observer, 12(3): 29-34. [http://eospso.gsfc.nasa.gov/eos_observ/5_6_00/5_6_00.pdf].
Otter, L. B., R. J. Scholes, P. Dowty, J. L. Privette, K. Caylor, S. Ringrose, M. Mukelabai, P. Frost, O. Totolo, and E. M. Veenendaal. 2002. The SAFARI 2000 wet season campaigns. S. African J. Sci., 98(3/4): 131-137.
Privette, J. L., R. B. Myneni, Y. Knyazikhin, M. Mukelabai, Y. Tian, Y. Wang, G. Roberts, and S. Leblanc. 2002. Early spatial and temporal validation of MODIS LAI in the Southern Africa Kalahari, Remote Sens. Environ., 83: 232-243.
Privette, J. L., Y. Tian, G. Roberts, R. J. Scholes, Y. Wang, K. Caylor, and M. Mukelabai. 2004. Structural characterization and relationships in Kalahari woodlands and savannas. Global Ch. Biol., 10(3): 281-291, March 2004.
Scholes, R. J., P. R. Dowty, K. Caylor, P. G. H. Frost, D. A. B. Parsons, J. Ramontsho, and H. H. Shugart. 2002. Trends in savanna structure and composition on an aridity gradient in the Kalahari. Journal of Vegetation Science 13(3): 419-428.
This data set contains the aerosol optical depth and column water vapor measurements made at Kalahari Transect sites in Botswana. The data are organized into two files corresponding to the two instruments used. In many cases, the instruments were used nearly simultaneously at the same point for redundancy. The sites visited were Pandamatenga, Maun (Okavango Delta), Okwa River Crossing, and Tshane. AOT measurements were made every half hour during cloud-free periods of the campaign at the following wavelengths: 340, 440, 675, 870, and 936 nm. An estimate of the Angstrom Coefficient (alpha) is also provided to allow estimation of AOT at other wavelengths. The associated time of day and geographic locations are also provided.
The data files contain numerical and character fields of varying length separated by commas. The metadata are in the file header, followed by the data arranged one row per measurement. The columns in each rows are as follows.
|Column Name||Column Description||Units/Format|
|year||Year of data collection||yyyy|
|month||Month of data collection||mm|
|day||Day of data collection||dd|
|hour||Hour of data measurement (UTC)||hh|
|minute||Minute of data measurement (UTC)||mn|
|second||Second of data measurement (UTC)||ss|
|Lat||Latitude location of data measurement||degrees|
|Lon||Longitude location of data measurement||degrees|
|AOT340||Aerosol optical thickness, 340 nm wavelength||dimensionless|
|AOT440||Aerosol optical thickness, 440 nm wavelength||dimensionless|
|AOT675||Aerosol optical thickness, 675 nm wavelength||dimensionless|
|AOT870||Aerosol optical thickness, 870 nm wavelength||dimensionless|
|AOT936||Aerosol optical thickness, 936 nm wavelength||dimensionless|
|WV||Columnar Water Vapor||cm|
Additional information about the data format, theory of measurements, instrument specifications, and parameters measured is found in the companion file: http://daac.ornl.gov/daacdata/safari2k/atmospheric/kalahari_aot_h2o_vapor/comp/ kalahari_aot_h2o_vapor_readme.pdf.