Retrieval of upper tropospheric water vapor and upper tropospheric humidity from AMSU radiances A. Houshangpour, V. O. John, and S. A. Buehler Institute of Environmental Physics, University of Bremen, Bremen, Germany
Abstract. A regression method was developed to retrieve upper tropospheric
water vapor (UTWV in kg/m2) and upper tropospheric humidity
(UTH in % RH) from radiances measured by the Advanced Microwave
Sounding Unit (AMSU). In contrast to other UTH retrieval methods,
UTH is defined as the average relative humidity between 500 and
200hPa, not as a Jacobian weighted average, which has the
advantage that the UTH altitude does not depend on the atmospheric
conditions. The method uses AMSU channels 6-10, 18, and 19, and
should achieve an accuracy of 0.48 kg/m2 for UTWV and
6.3% RH for UTH, according to a test against an independent
synthetic data set. This performance was confirmed for northern
mid-latitudes by a comparison against radiosonde data from station
Lindenberg in Germany, which yielded errors of 0.23 kg/m2 for
UTWV and 6.1% RH for UTH.
Citation: Houshangpour, A., John, V. O., and Buehler, S. A.: Retrieval of upper tropospheric water vapor and upper tropospheric humidity from AMSU radiances, Atmos. Chem. Phys., 5, 2019-2028, doi:10.5194/acp-5-2019-2005, 2005.