Sensitivity Analysis of Microphysics and Cumulus Parameterization Schemes: Numerical Simulation of Cloudbursts Over Uttarakhand Using WRF Modelling System

Abstract

Cloudbursts are powerful precipitation events that cause flash floods and landslides over a 20 km2 area. Three cloudburst events on July 16, 17, and 19 in three Uttarakhand locations are examined in this study. The Weather Research and Forecasting (WRF) model was used to simulate three cloudburst occurrences at a timestep of 18s on a nested domain of 9 km and 3 km resolutions from 1° by 1° spatial resolution NCEP-FNL data. IMDAA and NGFS data were compared. In the three studied scenarios, all simulations forecast 100 mm rainfall and considerable vertical velocity. Maximum rainfall and vertical velocity are somewhat shifted in two situations. Based on GPM-IMERG rainfall observations, each configuration was evaluated using deterministic and categorical metrics. For each timestep's 5 cm rainfall threshold, Equitable Threat Score and False Threat Score were calculated. The analysis indicated that the third configuration had the most skill.

Sensitivity of the Planetary Boundary Layer and Cloud Microphysics schemes to the drivers of dispersion and transportation of aerosols

“…These aerosols when interact with the clouds, they result in an increased number density of cloud droplets (Masrour and Rezazadeh, 2023) and sometimes in riming due to formation of super cooled liquids (Tao et al 2017). This in turn affects the amount of latent heat released or absorbed which can impact the stability and mixing processes within the boundary layer (Devan et al 2024;Zhang et al 2021;Shen et al 2022) and hence impacting the PBL structure and height (Skamarock et al 2019). Therefore, the microphysics scheme impacting the heat and moisture fluxes results in a feedback to simulate PBLH using the PBL scheme.…”