"Variability of moisture in the upper troposphere as inferred from
TOVS satellite observations and ECMWF model analyses,"
E. P. Salathe, Jr. and D. Chesters, J. Climate,
8, 1995.
Abstract
Large-scale variability of moisture in the upper troposphere is
examined using a nd TOVS satellite observations and ECMWF model
analyses from 1989 in the latitud e band from 40N to 40S. To compare
these dissimilar datasets, upwelling radianc es were computed for the
6 to 7 micron water vapor band from the ECMWF tempera ture and
moisture analyses, and these computed radiances were compared to the
co rresponding TOVS satellite observations. The ECMWF-based radiances
reproduce th e general locations and seasonal cycle of the
TOVS-observed moisture features, p articularly after an improved
convective parameterization scheme was adopted by ECMWF in May 1989.
However, the ECMWF analysis scheme still results in much mil der
lateral moisture gradients and seasonal contrasts than indicated by
the TOVS observations. Seasonally, the upper troposphere in each hemisphere
dries in wi nter and moistens in summer, but there are regions in each
hemisphere that run c ounter to this seasonal trend, apparently
depending on continental- and monsoon- scale dynamics. Dynamically,
the TOVS-observed regions of significant subtropic al dryness are
correlated with persistent subsidence indicated by ECMWF 300m b
vertical velocity analyses. The TOVS radiance observations indicate
large var iations in space and time of the upper tropospheric moisture
field, which are no t fully captured by the ECMWF analyses.
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