SENSITIVITY AND SEA SURFACE TEMPERATURE ANALYSES OF WRF MODEL FOR PREDICTING HEAVY RAINFALL EVENTS OBSERVED IN EASTERN BLACK SEA AND MEDITERRANEAN REGIONS OF TURKEY


Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Graduate School of Natural and Applied Sciences, Turkey

Approval Date: 2020

Thesis Language: English

Student: HEVES PİLATİN

Principal Supervisor (For Co-Supervisor Theses): İsmail Yücel

Co-Supervisor: Elçin Kentel Erdoğan

Abstract:

With this thesis it is aimed to enhance the prediction accuracy of the Weather Research and Forecasting (WRF) model on the extreme precipitation events of Mediterranean and Eastern Black Sea regions of Turkey. While the first part of sensitivity analysis was conducted for the physical parameters (microphysics, cumulus and PBL) and the initial boundary conditions, the second part has only focused on the impact of sea surface temperature (SST). After choosing 4 microphysics, 3 cumulus, 2 PBL and 2 input meteorological source s options, in total 96 scenarios have been tested through the first part of sensitivity analysis for each region. Among all of the schemes, generally for microphysics Eta / Ferrier (ES) scheme, for cumulus Grell Freitas (GFES) sheme and finally for PBL Mellor Yamada Janjic (MYJ) scheme performed better than the other options in Mediterranean event cases. However, for Eastern Black Sea region, Aeresol Aware Thomspon (AATS) and WRF Single Moment 6 (WSM6) as microphysics, Betts Miller Janjic (BMJ) and GFES as cumulus and MYJ as PBL scheme become prominent. Again, WRF model usually performs better by using the Global Forecasting System (GFS) meteorological input dataset in Mediterranean region whereas it produces more realistic forecasts for Eastern Black Sea, if it uses ERA5 Reanalysis (ERA5, ECMWF) meteorologic data. For SST analysis, three SST data sources were selected to use. Through detailed examination, the Medspiration and NCEP sources were found successful for the prediction of the Mediterranean event cases. In Eastern Black Sea region, the two satellite based sourced datasets (Medspiration and GHRSST) performed better than the other two.