Study of Convective Initiation Over Kototabang

The mechanism of atmospheric convection remains inadequately comprehended despite its essential role in facilitating the transfer of energy and momentum within the atmosphere. Consequently, modeling this convection process is challenging in climate studies, as there are currently no methods or criteria that precisely pinpoint the timing and location of convection (the convective initiation). Research has been conducted to study atmospheric convection in the equatorial area at the site of the Equatorial Atmosphere Radar (EAR), Kototabang Station, West Sumatra, Indonesia. Observational data from the EAR, Boundary Layer Radar (BLR), Sound Detection and Ranging (SODAR), Microwave Radiometer, and Optical Rain Gauge (ORG) were utilized to determine the convective signature in the diurnal cycle. Moreover, the convective parameters such as Lifting Condensation Level (LCL), Level of Free Convection (LFC), Convective Inhibition Energy (CINH), and Convective Available Potential Energy (CAPE) were calculated from radiosonde data obtained from a campaign in April 2004 and November 2005. Statistical analysis in the form of mean (indicating probability) has been conducted to investigate the diurnal cycle of convection and possible convective triggering mechanisms. The results indicated that the CINH might play a significant role in convective initiation as the probability of convection and a rapidly increasing rainfall when CINH reached the minimum. The CINH became very small when the rising LCL merged with the descending LFC, meaning that there is no longer a barrier to convection. Hence, the CINH was reduced by both the rising of the LCL and the lowering of the LFC. The presence of CAPE might be necessary in providing the potential energy (buoyancy/instability) required for the convective process. These results could be helpful for consideration in formulating convective trigger criteria in developing a convective parameterization scheme.