Juying X. Warner,
John C. Gille,
David P. Edwards,
Dan C. Ziskin,
Mark W. Smith,
Paul L. Bailey,
and Laurie Rokke
J. X. Warner, J. C. Gille, D. P. Edwards, D. C. Ziskin, M. W. Smith, and P. L. Bailey are with the Atmospheric Chemistry Division, National Center for Atmospheric Research, P.O. Box 3000, Boulder, Colorado 80307-3000. USA
L. Rokke is with the Office of Data Assimilation, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771. USA
Juying X. Warner, John C. Gille, David P. Edwards, Dan C. Ziskin, Mark W. Smith, Paul L. Bailey, and Laurie Rokke, "Cloud detection and clearing for the Earth Observing System Terra satellite Measurements of Pollution in the Troposphere (MOPITT) experiment," Appl. Opt. 40, 1269-1284 (2001)
The Measurements of Pollution in the Troposphere (MOPITT)
instrument, which was launched aboard the Earth Observing System
(EOS) Terra spacecraft on 18 December 1999, is designed to measure
tropospheric CO and CH4 by use of a nadir-viewing
geometry. The measurements are taken at 4.7 µm in the
thermal emission and absorption for the CO mixing ratio profile
retrieval and at 2.3 and 2.2 µm in the reflected solar region
for the total CO column amount and CH4 column amount
retrieval, respectively. To achieve the required measurement
accuracy, it is critical to identify and remove cloud contamination in
the radiometric signals. We describe an algorithm to detect cloudy
pixels, to reconstruct clear column radiance for pixels with partial
cloud covers, and to estimate equivalent cloud top height for overcast
conditions to allow CO profile retrievals above clouds. The MOPITT
channel radiances, as well as the first-guess calculations, are
simulated with a fast forward model with input atmospheric profiles
from ancillary data sets. The precision of the retrieved CO
profiles and total column amounts in cloudy atmospheres is within the
expected ±10% range. Validations of the cloud-detecting
thresholds with the moderate-resolution imaging spectroradiometer
airborne simulator data and MOPITT airborne test radiometer
measurements were performed. The validation results showed that the
MOPITT cloud detection thresholds work well for scenes covered with
more than 5–10% cloud cover if the uncertainties in the model input
profiles are less than 2 K for temperature, 10% for water vapor, and
5% for CO and CH4.
Jianguo Niu, Merritt N. Deeter, John C. Gille, David P. Edwards, Daniel C. Ziskin, Gene L. Francis, Alan J. Hills, and Mark W. Smith Appl. Opt. 43(24) 4685-4696 (2004)
Cathy Clerbaux, Juliette Hadji-Lazaro, Sébastien Payan, Claude Camy-Peyret, Jinxue Wang, David P. Edwards, and Ming Luo Appl. Opt. 41(33) 7068-7078 (2002)
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