One method of estimating the longwave radiative heating of the atmosphere is to
combine satellite observations of emitted radiances with those computed from synoptic
temperature and humidity profiles. Modeled and observed radiances are brought into
agreement by altering cloud properties or even by adjusting the temperature and water
vapor profiles.
Here this strategy is examined in an exploratory study using global meteorological
data sets and a radiative transfer model typical of those found in general circulation
models. Calculated radiances are compared to those observed by the Earth Radiation
Budget Satellite (ERBS). Input for the model is obtained from the National Meteorological
Center (NMC) in the form of vertical profiles of temperature and relative
humidity. The comparisons are limited to clear sky as deduced by ERBE algorithms,
and additional filtering which requires homogeneous surface type for a 3 x 3 array
of ERBS scanner fields of view. Observations are obtained from 60° N to 60° S that
lie within 30 minutes of the NMC analysis time. Following the work of Ramanathan
and Downey (1986), comparisons are separated into climatologically distinct groups as
well as by satellite viewing angle. This separation is an attempt to distinguish between
biases in the radiation model and those in the NMC data set. Results are presented for
the months of July 1985, and January 1986.
A comparison of the present radiation model's output with that obtained from a
Geophysical Fluid Dynamics Laboratory (GFDL) model shows a bias of nearly 3% in
the present model for a standard mid-latitude summer profile.
Global results show a negative bias in the modeled values for nearly all scenes,
except for nighttime desert. The nighttime desert bias may be a result of a skin-air
temperature difference not resolved by the NMC analyses. The overall negative bias
may be a result of an overestimation of water vapor for regions with low relative
humidity. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28726 |
| Date | 11 July 1990 |
| Creators | Stone, Kenneth A. |
| Contributors | Coakley, James A. Jr |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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