INVESTIGATION OF THE INTERACTION BEHAVIOR OF AEROSOL-CLOUD- PRECIPITATION RATES IN STRATOCUMULUS AND SHALLOW CUMULUS CLOUDS USING THE KOREN-FEINGOLD (KF11) MODEL APPROACH

• Main Author: Sulistyowati, Rita
• Format: Dissertations
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/42126
• Institution: Institut Teknologi Bandung

An investigation on the effects of aerosol on precipitation in Stratocumulus (Sc) and Shallow Cumulus (Cu) cloud types has been conducted using the Koren-Feingold (2011) (KF11) model approach. The KF11 model, which consists of nonlinear equations with delay time, was solved by numerical computations using the finite difference method. In this study, the KF11 equations was applied using several pairs of potential cloud thickness (H0) and aerosol concentration (N0) values to calculate the precipitation values (R). The precipitation values at the output of the calculation result are classified into several categories, namely No Drizzle, Light Drizzle, Moderate Drizzle and Heavy Drizzle. The distribution of aerosol concentration and cloud thickness in various drizzle were then simulated to analyze the behavior of their interactions on Sc and Cu clouds. The clouds are classified with a thickness (200?H?500 m for Sc and H>500 m for Cu). The model calculation data were then compared to regional observational data from VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx). VOCALS-REx data were also analyzed using a k-means clustering. The results of the KF11 model calculations and observational data show that the behavior tends to be similar. Precipitation can not occur (No Drizzle condition) if H0 is too low. For low aerosol concentration ranges, precipitation begins when clouds are at least 200 m thick. A qualitative precipitation prediction scheme for Sc and Cu clouds was obtained by applying a combination of R = f [H0, N0]. Sc clouds typically produces low precipitation (Light Drizzle conditions) dominated by a combination of [moderate H0, high N0]. In contrast, Cu clouds generally produce Heavy Drizzle conditions that are dominated by a combination of [high H0, low N0]. The results of the study also show that precipitation tends to decrease with increasing aerosol in fixed thicknesses. The behavior of the change in precipitation rate is thought to be related to the value of the aerosol concentration threshold (Nth) as the value of the aerosol concentration when the precipitation rate begins to decrease, based on the model calculation results. The amount of precipitation reduction was quantitatively calculated using the Suseptibility Precipitation (S0) formulation. The study also revealed that Sc clouds were more sensitive to aerosol perturbations (susceptible) than Cu clouds. The S0 increases with increasing thickness of the cloud (H) on the Sc cloud, around 0.74-0.87. In Cu clouds, the value of S0 decreases with increasing cloud thickness. The decrease in the value of S0 in the Cu clouds would be related to the influence of the updraft velocity at the cloud base. The behavior of aerosol-cloud-precipitation interactions in Sc and Cu clouds were discussed in more detail in this dissertation.