Surname: Shih
First Name: Shun-Peng
Status= studentno
Institution: National Central University
E-mail: spshih@jupiter.ss.ncu.edu.tw
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Title: 
A Study of 19.5 GHz Brightness Temperature over Taiwan Area
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Authors: 
Shun-Peng Shih 
Yen-Hsyang Chu
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Abstract: 
    Using a single-frequency ground-based microwave radiometer with steerable 
horn antenna at frequency 19.5 GHz, we measure sky radiometric temperature over
Taiwan area during the period from May 1997 to September 1999. Statistics 
indicates
that for more than 80% of the time in the absence of surface precipitation the
brightness temperature is above 27 K. Multi-zenith angle observations show that 
the
median brightness temperature increases with zenith angle from about 30 K at 
zenith 
to about 128 K at 80¢X off-zenith angle. The opacity t of atmosphere is also 
observed. 
We found that basically the dependence of opacity t(q) on zenith angle q follows 
perfectly 
the secant law, namely, t(q)=tosec(q) (to is zenith opacity), if the zenith 
angle is less 
than 70¢X.
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Discipline Category: Troposphere