P1.97
Deep convection defined by split window
Toshiro Inoue, MRI, Tsukuba, Ibaraki, Japan
We can classify optically thin cirrus clouds using the split window (11 and 12 micron). The brightness temperature difference between the split window (BTD=TBB11-TBB12) indicates larger value because of the differential absorption for ice. Using this characteristics of the split window, we can see the evolution of deep convection by computing the percentage of cirrus clouds within deep convection (say clouds colder than 253K). We study the percentage of deep convection over the eastern tropical Pacific (180-90W, 30S-30N) using hourly GOES images during one year of 2001. The life stage of deep convection can be defined by using the percentage of cirrus cloud within the deep convection. Using The coincide observation of PR/TRMM shows the dominance of convective rain for the deep convection with anvil percentage smaller than 10%.
Further IRIS effect was studied using the cirrus cloud percentage, SST and Total water vapor from TMI/TRMM. We can see the IRIS effect when we use the data over 30S-30N data, however, no evidence of IRIS when we use the data over 20S-20N.
Thus, the split window is very effective to study the ice cloud. We stress here the importance of calibration of split window. Current GOES data generally shows noisy spots for colder TBB. However, no noisy characteristics for MSG split window. The improvement of calibration for the split window is essential for the study of cirrus cloud which is generally colder TBB.
Supplementary URL: http://grns1.mri-jma.go.jp
Poster Session 1, Fifth GOES Users' Confererence Poster Session
Wednesday, 23 January 2008, 2:30 PM-4:00 PM, Exhibit Hall B
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