The Effects of the Cross Equatorial Northerly Surge (CENS) on Atmospheric Convection and Convergence Over Jakarta and the Surrounding Area

The effect of the Cross Equatorial Northerly Surge (CENS) on the diurnal cycle of convection and moisture convergence over Jakarta and the surrounding area has been investigated. The data used in this study was the CENS indices, the Convective Available Potential Energy (CAPE), the Convective Inhibition Energy (CINH), the Vertically Integrated Moisture Fraction Convergence (VIMFC), and dew point temperature and rainfall from the fifth generation of the European Center for Medium-Range Weather Forecasting (ECMWF) Atmospheric Reanalysis (ERA5) during 2014. The data was depicted in a graph against the diurnal as well as the seasonal cycle, thus illustrating the multi-scale variability. The results showed a very strong influence of the CENS phenomena on the diurnal cycle of the CAPE, the CINH, the VIMFC, and rainfall in Jakarta and the surrounding area, over both the land and the sea areas. We found that in general, the CENS tended to suppress convection, but enhances moisture convergence. The important results of this study were that the increase of rainfall that occurred during active CENS was not actually caused by the increase of convection, but rather due to the increase in moisture convergence.