Statistical analysis of organized cloud clusters on western North Pacific and their warm core structure

As early stage Dvorak analysis (EDA), Meteorological Satellite Center of Japanese Meteorological Agency has routinely watched organized cloud clusters on western North Pacific with the possibility to develop into tropical storms (OCC), which are defined in terms of Tsuchiya (2001), and logged their locations and T-numbers from 2001.

In this study, using the results of EDA, OCC developed into tropical storms (DOCC) and OCC not developed into tropical storms (NOCC) were statistically analyzed, and their frequency and geographical locations of genesis, their duration, and so on were investigated. For example, in 2004, it was found that the numbers of genesis of all OCC and DOCC are most on August, and convection and organization of clouds were active in this month. And in 2004, 55 % of all OCC and 59 % of DOCC were included between 5 degrees N and 20 degrees N latitude, and 125 degrees E and 160 degrees E longitude which is called as the primary genesis region in Zehr (1992).

Some case studies of OCC in this region on August 2004 were done with data obtained from Advanced Microwave Sounding Unit. As a result, it was discovered that DOCC has warm core structure with the temperature anomaly of 2-3 K within 2 days after their genesis. On the other hand, NOCC in this study has no clear warm core structure.