The influence of cross-equatorial northerly surge in the western maritime continent

¹ Department Climatology, State College of Meteorology Climatology and Geophysics (STMKG), Jakarta, Indonesia
² Center for Climate Change Information, Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG), Jakarta, Indonesia
³ Disaster Prevention Research Institute, Kyoto University, Japan

^* Corresponding author: sayful.amri@stmkg.ac.id

Abstract

Cross Equatorial Northerly Surge (CENS) is a synoptic disturbance that occurs during the boreal winter in November-December-January-February-March (NDJFM). This phenomenon affects convective activity and rainfall on the Maritime Continent (MC). This study aims to determine the relationship and influence of CENS on cloudiness and rain in western Indonesia. The data used are Mean Top Net Long- Wave Radiation Flux (MTNLWRF) data, Global Satellite Mapping of Precipitation (GSMaP) rainfall, and ERA-5 reanalysis data. This study analyzes spatial correlation, low-level moisture transport (LLMT) and its divergence, spatial composite, and hovmoller of anomalies of MTNLWRF and GSMAP. These results show that the identification of CENS for 20 years (2003–2022) obtained 204 days of CENS events. The relationship between CENS, cloudiness, and rainfall is significant, with a correlation coefficient of 0.465 and -0.345. When CENS occurs, the North Coast region of West Java has a large moisture transport and convergence there. The range of moisture transport is from 240 kg/m/s to 300 kg/m/s. It increased convective clouds and rainfall in the region, which reached 534 mm/day on the north coast of West Java. The peak of increased rainfall due to CENS in the north-coastal of West Java occurs in the Early Morning around 03 Local Time.