ATMOSPHERE DYNAMICS OF EXTREME RAINFALL AND THE PRELIMINARY EVALUATION OF WEATHER MODIFICATION STATIC SYSTEM IN DKI-JAKARTA
Promotor: Prof. Dr. Bayong Tjasyono H. K.
Co-Promotor: Prof Dr. The Houw Liong
Co-Promotor: Dr. Tri Wahyu Hadi
DKI-Jakarta is a part of Java Island which geographically lies between the Java Sea and the Indian Ocean. This geographical location leads to the forming of convective cloud which will result to the formation of heavy rain (shower). Jakarta area and its surroundings are hit by floods every year due to torrential rain. Among them, the worst cases are the flood that hits on 2002 and 2007, where the floods natural disaster swept over approximately 70% of Jakarta area.
One approach to solve the floods problem is to understand fundamentally the factors that cause floods, through precursor analysis of extreme rainfall and application of its corresponding technology. The understanding about atmosphere dynamics pattern in DKI-Jakarta is required, because the process causes changes in the fluctuation pattern of the rainfall. The study of cloud dynamics analysis will explain the occurrence of extreme rainfall which causes floods. The weather modification technology of Ground Based Generator (GBG) model adjustment is expected decreasing the extreme rainfall intensity.
The result of atmosphere dynamics analysis on extreme rainfall phenomena in DKI Jakarta region for the flood case periods on 2002 and 2007 shows the existence of an equal pattern of i.e. cold surge and strong vortex. As the local effect influence analysis, these two factors caused the updraft which results to the growth of deep convective cloud. The analysis of Madden-Julian Oscillation (MJO) and anomaly of Multivariate ENSO Index (MEI) indicates non dominant factor compared to the influence of Indian Ocean Dipole (IOD) to flood phenomena. The cloud pattern characteristic in the case of Jakarta floods from calculation of convective index either from outgoing Longwave Radiation (OLR) and Infra Red channel 1 (IR 1) temperature data in DKI Jakarta shows the growth of convective cloud is localized around Jakarta. As the two factors global analysis i.e. the sun activity and cosmic ray flux become the dominant factor of extreme rainfall in DKI Jakarta. This is based on the correlation between the years of flood occurrence, reanalysis of maximum rainfall in Jakarta to sunspot index and interrelationship variability between to cosmic ray flux with cloud cover.
The simulation of cloud dynamics in DKI-JAKARTA on 2007 was based on the Weather Research and Forecast (WRF) model with Final Analysis (FNL) data which takes global data as model input. The validation of extreme rainfall simulation with spatial rainfall data from BMKG (The Agency of Meteorology, Climatology and Geophysics) resulted to the correlation coefficient of 0.7. The cloud simulation analysis indicated the growth of deep convective cloud in extreme rainfall. The simulation of wind vector and the vertical temperature change from WRF model output applied to Ground Based Generator (GBG) model input. The result shows that movement vector of seeding material concentration to the based of cloud is 12.6 g/m3. As the validation of above result concentration calculation of seeding material with WRF model where obtained the minimum concentration is 150 g/m3 for the cloud to start growing.
Key Word: Flood, cloud dynamics, WRF model and weather modification.