Evaluation of different WRF microphysics schemes: a case study of landslide induced by heavy rainfall in Kulon Progo

Kulon Progo district in Yogyakarta, Indonesia experienced heavy rainfall starting from 26 November 2018 which triggered the landslide on 28 November 2018 in Samigaluh district. In this study, precipitation during this heavy rainfall event was simulated using the Weather Research and Forecasting (WRF) model in three domains with a resolution of 9-3-1 km for three days starting November 25, 2018. One of schemes in WRF model that should be configured is the microphysics scheme. Microphysics is the process of removing moisture from the air represented in a numerical model. Three microphysics schemes (Lin, Morrison and Thompson) were tested for sensitivities. The output precipitation from the model was compared to the observation stations and the closest weather radar data. The results showed that the model can simulate the spatial distribution of rainfall as observed by radar data on daily basis. The model output and in-situ data were consistent for the three stations (ARG Panjatan, ARG Waduk Sermo, and AWS Kulon Progo), except on the 27 November 2018. While the WRF model can generally capture the daily rainfall pattern, but the hourly pattern is less likely. Amongst three microphysics schemes, the Purdue Lin scheme produced a higher hourly rain rate and the Thompson scheme produced a lower rain rate over the region. In general, the model tends to overestimate the precipitation for all three schemes.