Summer Diurnal Precipitation Over the Ocean and Land in Northwest Luzon, Philippines

Angelyn General and Olivia C Cabrera, Institute of Environmental Science and Meteorology, University of the Philippines, Quezon City, Philippines
Southwest Monsoon (SWM) with the enhancement of Tropical Cyclone (TC) brings heavy precipitation in the Philippines, particularly in Northwest Luzon. The purpose of this study is to analyze the characteristics of diurnal cycle precipitation activity generated by strong SWM or monsoon westerlies and TC contribution during the June-July-August (JJA) of 2017. Using precipitation dataset from synoptic station, Global Satellite Mapping of Precipitation (GSMaP), Tropical Rainfall Measuring Mission (TRMM) 3B42-V7 and Himawari-8 satellite data from Japan Meteorological Agency (JMA). Two dimensional - threshold (2D-THR) cloud classification algorithm were utilized to determine the Himawari convective and stratiform clouds development and propagation. TCs best track data from the Joint Typhoon Warning Center (JTWC) were used to examine the precipitation over ocean and land between TC days and non-TC days. Diurnal cycle of rainfall is seen clearly without the influence of TC. Convective rainfall starts to develop at afternoon around 1400 LST and ends at 2300 LST over land. While during night to morning (0200 LST to 0700 LST) over ocean. Stratiform or decayed convective clouds gives secondary rainfall at early morning over land and afternoon rainfall over ocean. The result shows that rainfall with TC enhanced rainfall both over ocean and land. However, TC contributes more rainfall over ocean than over land.