Environmental Engineering Reference
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Fig. 15.3 Equatorial passing times of the DMSP satellites and other microwave sensor platforms.
Solid lines represent ascending nodes, and dotted lines (for F8 and WindSat) represent descending
nodes (From http://www.ssmi.com/support/crossing_times.html )
Figure 15.3 shows the mean equatorial passing time of the DMSP satellites,
together with other spaceborne microwave radiometers - the wind sensing
scatterometers QuikScat and WindSat and the Advanced Microwave Scanning
Radiometer onboard NASA's EOS Aqua satellite (AMSR-E). These sensors are
designed to have local satellite overpass times around early morning and evening
(6 a.m. and 6 p.m.). However, there are substantial drifts in the orbital parameters
during the satellite life.
Two types of products, 2.5
2.5 monthly and 5
5 monthly products, are
5 products are produced by first computing the histograms for
the morning (a.m.) and afternoon (p.m.) satellite passes separately, and the monthly
mean is an average of the a.m. and p.m. rain rates. The 2.5 product is derived from
combining all a.m. and p.m. satellite passes to form a monthly histogram, before
computing the monthly average. The original monthly time series were processed
using SSM/I version 4 (V4) T b data provided by Remote Sensing Systems (RSS)
(website: http://www.ssmi.com/ ).
A trend in the T 0 data was found in the version 4 products which may be related
to differences in the orbital parameters of satellites (Chokngamwong and Chiu
2006 ). Trends in other oceanic water cycle products, in particular, surface latent
heat fluxes, were also noted for satellite products that are mostly based on SSM/I
(Chiu et al. 2008 ). Further analyses of the trends in the latent heat fluxes show that
the trend in the NASA Goddard Satellite-based Sea Surface Turbulent Fluxes
(GSSTF) product is associated with an increase in the wind speed and an increase
in the sea-air humidity difference. These trends can be traced back to the brightness
temperature data of the SSM/I (Chiu et al. 2012 ; Chap. 11 , this topic).
available. The 5
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