Diurnal variation of cloud derived from GOES-9 multi-IR-channel data

Diurnal variation of cloud is studied using the multi IR channel data of GOES-9. The split window can classify optically thin cirrus cloud, cumulonimbus cloud and low-level stratocumulus cloud. Further we can classify very deep convective cloud with the use of negative value of the brightness temperature difference between 11 and 6.7 um. We studied the diurnal variation of these cloud type for the month of February and August in 1996 over the area of 40N-40S 170E-70W. It is reported that the local time of the peak of cloud amount delayed with the colder to warmer TBB threshold from early in the morning to late afternoon over the ocean. This time delay for the peak cloud amount for the different TBB threshold can be explained with the consideration of cloud type. The deep convective cloud shows early morning peak and thin cirrus cloud shows late afternoon peak. The stratocumulus cloud show midnight peak of cloud amount over the ocean. Over the land area of south mexico shows late afternoon peak of deep convective cloud amount.