The tropics is a very important region in terms of earth’s radiation budget
because the net radiative heating is largest in the tropics and that surplus energy is
redistributed by the circulations of oceans and atmospheres. Moreover, a large number
of clouds are formed by deep convection and convergence of water vapor. Thus, it is
very important to understand the radiative energy balance of the tropics and the effect of
clouds on the radiation field.
For mixed-phase clouds, error analyses pertaining to the inference of effective
particle sizes and optical thicknesses are performed. Errors are calculated with respect to
the assumption of a cloud containing solely liquid or ice phase particles. The analyses
suggest that the effective particle size inferred for a mixed-phase cloud can be
underestimated (or overestimated) if a pure liquid phase (or pure ice phase) is assumed
for the cloud, whereas the corresponding cloud optical thickness can be overestimated
(or underestimated). The analyses of optical depth and fraction of occurrence for thin cirrus clouds
showed that about 40% of pixels flagged as clear-sky contain detectible thin cirrus
clouds. The regions of high occurrence and large optical depth located around deep
convection showed seasonal variations. The thin cirrus clouds occur more frequently
with larger optical depth in the northern (southern) hemisphere during spring and
summer (autumn and winter). The net cloud radiative forcing by thin cirrus clouds is
positive at the top of atmosphere and is negative at the bottom of atmosphere.
The difference in OLR between measurement and model is 4.2 Wm-2 for
September 2005. The difference is smaller in moist regions and larger in drier regions.
OLR increases with increasing surface temperatures up to 300 K but decreases at surface
temperatures larger than 300 K due to the strong absorption of increased water vapor. In
summary, if the surface temperature is lower than the threshold of convection (300 K),
temperature is a dominant factor in OLR and if the surface temperature is larger than 300
K, OLR is strongly influenced by water vapor.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1897 |
| Date | 02 June 2009 |
| Creators | Lee, Joonsuk |
| Contributors | Dessler, Andrew E., Yang, Ping |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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