HR: 0830h
AN: A21C-0989    [PDF]
TI: Detection of cirrus and determination of cloud top pressure by HIRDLS
AU: * Lee, H
EM: halee@ucar.edu
AF: National Center for Atmospheric Research, 3450 Mitchelle Lane, Boulder, CO 80301 United States
AU: Lambert, A
EM: alambert@ucar.edu
AF: National Center for Atmospheric Research, 3450 Mitchelle Lane, Boulder, CO 80301 United States
AU: Massie, S
EM: massie@ucar.edu
AF: National Center for Atmospheric Research, 3450 Mitchelle Lane, Boulder, CO 80301 United States
AU: Khosravi, R
EM: rashid@ucar.edu
AF: National Center for Atmospheric Research, 3450 Mitchelle Lane, Boulder, CO 80301 United States
AU: Gille, J
EM: gille@ucar.edu
AF: National Center for Atmospheric Research, 3450 Mitchelle Lane, Boulder, CO 80301 United States
AU: Ewen, G
EM: gewen@atm.ox.ac.uk
AF: Atmospheric, Oceanic and Planetary Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU United Kingdom
AU: Grainger, R G
EM: grainger@atm.ox.ac.uk
AF: Atmospheric, Oceanic and Planetary Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU United Kingdom
AB: The infrared limb sounding measurements by the High Resolution Dynamics Limb Sounder (HIRDLS) allow detection of cirrus in the upper troposphere and near the tropopause. The HIRDLS detectors are in a focal plane arrangement of 7 rows by 3 columns. The detector size is 10 km horizontal by 1 km vertical and the horizontal across-track spacing between the three columns is 17 km and 8 km. Cloud detection is performed using the best selection from the 7 available detectors for each column. The characteristics of cirrus contaminated radiances detected by the HIRDLS channels have been analyzed by simulating radiances with varying cloud parameters. More than half a million radiance profiles with various combinations of cloud top pressure, thickness, effective radius, and number density were simulated for a wide latitude range. Several kinds of cloud detection methods are tested using the simulated radiances. Statisitical results from the simulated radiance analyses are used to improve cloud profile retrievals. The possibility of opaque cloud top temperature retrieval is investigated. The simulated radiances for the HIRDLS radiometer channels are compared with spectrally integrated observations of cirrus by ENVISAT/MIPAS.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0340 Middle atmosphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting