Cloud-resolving modeling and evaluation of microphysical schemes for flash flood-producing convection over the Black Sea

Abstract
In the present study, the convective event over the Black Sea area in September 2018 is analyzed using the Weather Research and Forecasting (WRF) model configured with a fully convective-resolving setup. We test the WRF sensitivity to the choice of sea surface temperature (SST) dataset and microphysics scheme. The simulation is verified using weather radar measurements and ground observations. Both the choice of the microphysical scheme and SST dataset have a significant impact on the dynamic properties of the maritime convective system and associated rainfall. The best results are achieved with the WDM6 microphysical scheme and a more detailed and slightly warmer (compared to the default OSTIA SST) G1SST dataset. The optimally configured WRF simulations add value to coarser driving operational analysis, with more accurate amount and pattern of rainfall and the earlier arrival of the convective system, which is in better agreement with radar and weather station measurements. The vertical structure of the reflectivity profiles in the WDM6 scheme that simulates 15–20% larger rainwater loading compared to other schemes agrees best with the observed data. Other schemes reproduce excessive reflectivity above the freezing level. Enhanced rainfall estimates and faster convective system propagation in the G1SST WDM6 simulations are linked to stronger cold pools caused by enhanced evaporation due to the higher rainwater content and droplet number concentrations. Stronger cold pools result in the 15–20% enhancement of latent and sensible heat fluxes, reflecting the strong sensitivity of ocean–atmosphere heat and moisture exchange to the choice of microphysics scheme and SST dataset.

Citation
Anisimov, A., Efimov, V., Lvova, M., Mostamandy, S., & Stenchikov, G. (2023). Cloud-resolving modeling and evaluation of microphysical schemes for flash flood-producing convection over the Black Sea. Journal of Hydrometeorology. https://doi.org/10.1175/jhm-d-22-0060.1

Acknowledgements
The study was funded by RFBR and Sevastopol municipality under research project No. 20 45 920017 “Quantitative estimates of precipitation in Southwestern Crimea and Sevastopol based on numerical modeling and radar observations” and the state research project No. 0555-2021-0002 “Fundamental studies of the interaction processes in the ocean-atmosphere system conditioning the regional spatial-temporal variability of the natural environment and climate”. Computer resources from the King Abdullah University for Science and Technology (KAUST) were used during the preparation of the paper. We kindly thank Anton Garmashov from Marine Hydrophysical Institute, Sevastopol, for providing the data from the Katsiveli platform observations.

Publisher
American Meteorological Society

Journal
Journal of Hydrometeorology

DOI
10.1175/jhm-d-22-0060.1

Additional Links
https://journals.ametsoc.org/view/journals/hydr/aop/JHM-D-22-0060.1/JHM-D-22-0060.1.xml

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