Tropical Tropospheric Ozone (TTO) data from Earth Probe (EP) Total Ozone Mapping Spectrometer (TOMS) for the period August 8-September 29, 2000, were processed and provided by the Atmospheric Chemistry and Dynamics Branch at NASA/GSFC for the SAFARI 2000 Dry Season Aircraft Campaign.
The TTO measurement is derived from TOMS total ozone (Thompson and Hudson, 1999; Thompson et al., 2001) using the modified-residual method to separate stratospheric ozone from tropospheric ozone. The tropospheric ozone column thickness is reported in Dobson Units (DU).
EP TOMS is currently the only NASA spacecraft in orbit specializing in ozone retrieval. EP TOMS was launched in 1996 into an orbit 500 km rather than the 950 km that was originally planned. The lower orbit of EP TOMS decreased the size of the footprint of each measurement, which increased the resolution and also increased the ability to make measurements over cloudless scenes. This orbit was chosen to improve the ability of the TOMS instrument to make measurements of UV-absorbing aerosols in the troposphere and enhance the capability of converting the TOMS aerosol measurements into geophysical quantities such as optical depth. Tropospheric aerosols play a major role in the Earth's climate. The capability to measure them from a TOMS instrument had recently been developed using data from Nimbus-7 and Meteor-3 TOMS. The Earth Probe satellite was boosted to 740 km in 1997 when the ADEOS satellite failed.
The TOMS Tropospheric Ozone data are 9-day averaged, gridded (1-degree by 2-degree) ASCII products. There is also a GIF image of each data file.
Cite this data set as follows:
McPeters, R., A. M. Thompson, and D. Larko. 2005. SAFARI 2000 TOMS Tropospheric Ozone Data, Southern Africa Subset, Dry 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/824.
Thompson, A. M. and R. D. Hudson. 1999. Tropical Tropospheric Ozone (TTO) maps from Nimbus-7 and Earth-Probe TOMS by the modified-residual method: Evaluation with sondes, ENSO signals and trends from Atlantic regional time series. J. Geophys. Res., 26: 961-26,975.
Thompson, A. M., J. C. Witte, R. D. Hudson, H. Guo, J. R. Herman, and M. Fujiwara. 2001. Tropical tropospheric ozone and biomass burning. Science, 291: 2128-2132.
The TOMS Tropospheric Ozone data files are an 9-day averaged, gridded ASCII product. There is also a GIF image of each data file. The data are on a fixed 1-degree latitude by 2-degree longitude grid.
Data Users Please Note:
In all data files, the first data value corresponds to a location centered at -25 S, -41 W.
In all data files, the last data value corresponds to a location centered at 0 N, 75 E.
Sample TOMS Tropospheric Ozone Data File
Additional information about the data format and parameters measured is found in the companion file: http://daac.ornl.gov/daacdata/safari2k/remote_sensing/TOMS_ozone/comp/TOMS_ozone_readme.pdf. Also see the TOMS Users Guide: http://daac.ornl.gov/daacdata/safari2k/remote_sensing/TOMS_ozone/comp/EARTHPROBE_USERGUIDE.pdf.
2005/7/19
2005/7/19
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