Multiple satellite-observed long-term changes in the summer diurnal precipitation over Luzon and its adjacent seas during 2000–2019

Long-term satellite precipitation products (SPPs) provide insight into how precipitation has changed in the past. As the changes observed from various SPPs may differ, research is needed to clarify related uncertainties using multiple SPPs. This study aims to explore long-term changes in the summer (June to August) diurnal precipitation over Luzon and its adjacent seas using multiple SPPs from 2000 − 2019, and to determine the possible atmospheric thermodynamic causes of such changes using the latest atmospheric reanalysis data. The four SPPs include the TRMM 3B42, the IMERG Final Run, the PERSIANN-CDR, and the PERSIANN-CCS-CDR. Our results show that all four SPPs depicted a common diurnal precipitation signal formed over the coastal region of western Luzon propagating westward to the adjacent South China Sea (SCS). This feature had been enhanced from 2000–2009 (Period1) to 2010–2019 (Period2). By contrast, there was uncertainty for central to eastern Luzon, where most SPPs with the exception of PERSIANN-CCS-CDR, captured a decline in diurnal precipitation from Period1 to Period2. These long-term changes in diurnal precipitation, which were suggested by the majority of SPPs, were further attributed to a strengthening (weakening) of local diurnal heating and related wind convergence over the SCS (Luzon), coupled with an intensification of regional prevailing winds. These findings highlight how the formation of precipitation over Luzon and SCS has changed under a changing climate.