Environmental Engineering Reference
In-Depth Information
Fig. 15.8
Seasonal average (
middle panels
) and annual rain frequency (
bottom panel
). The zonal
annual and seasonal average rain frequency appears in the
top panel
coded and recorded. Analyses of meteorological observations in ICOADS show
zonal bands of high rain frequency near the equator and at latitudes of 50-60
latitudes in both hemispheres (Petty
1995
). This zonal pattern is consistent with the
pattern derived from the limited GTS and marine observations (Dai
2001
). Most
satellite algorithms were able to correctly estimate the high rain frequency near the
equator (Petty
1997
) and for the Atlantic from TRMM precipitation radar data
(Short
2003
). However, the high rain frequency at the high latitudes is usually
underestimated (Petty
1997
). Ellis et al. (
2009
) compare rain frequency derived
from the CloudSat radar for the period 2006-2007 and found that the CloudSat rain
frequency is quite consistent with that derived from ICOADS data. While the zonal
patterns are similar, the magnitudes are quite different. This is attributed to the
different fields of view of the observations. The CloudSat radar has a resolution of
about 1 km whereas that for the TRMM radar is 4-5 km. The FOV of the SSM/I
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