Impact of multiple-scale circulation interactions on the spring diurnal precipitation over Luzon

This study examines the spatiotemporal characteristics of diurnal precipitation over Luzon and the nearby oceans in boreal spring. The study focuses on exploring the impact of the interaction between large- and local-scale circulation changes on the modulation of diurnal precipitation. We analyze the satellite precipitation data obtained from the Tropical Rainfall Measuring Mission and Global Precipitation Measurement Mission during the spring (March-May) of 2001-2019. The results show that the spring diurnal precipitation over Luzon and the nearby oceans consists of a clear eastward propagation signal. The direction of this propagation is opposite to that of the prevailing low-level easterly wind in spring and differs from the well-known westward propagation direction of diurnal precipitation over Luzon in summer. Diagnoses of the possible maintenance mechanisms suggest that the eastward propagation diurnal precipitation can be attributed to the interaction between the topography and multiple-scale circulation changes, including the mountain-valley breeze, island-scale land-sea breeze (LSB), large-scale LSB-like circulation, and mid-to-upper-level prevailing wind fields. This finding highlights the importance of considering multiple-scale circulation changes in the modulation of spring diurnal precipitation over the East Asia-western North Pacific region.