Convective Permitting Simulations for Excessive Precipitation Event Under Pseudo-Global Warming in the Black Sea Region

Extreme weather events have been increasing as global temperatures rise. Semi-enclosed basins such as the Black Sea and the Mediterranean are particularly susceptible to extreme weather due to their unique topographic features and land-sea distribution. Extreme precipitation events on the north-facing slopes of the mountains in the Black Sea Region occur due to relatively cold air interacting with the warm sea and being orographically lifted over the mountains. On August 10-12 2021, a deadly flash flood occurred on the coast of the Black Sea in Northern Türkiye which resulted in excessive precipitation (200-450 mm) causing loss of lives of 97 people and leaving 228 injured. We investigated extreme weather event which occurred near the Black Sea along with future climate conditions using the Pseudo-Global Warming method. In order to analyze the event, we used a numerical weather prediction model (WRF) in convection-permitting 3 km horizontal resolution with a domain covering the Black Sea and surrounding area. The model simulations are driven by ECMWF Reanalysis 5th Generation (ERA5) data for initial and boundary conditions. To derive climate change signals, we used 25 CMIP6 Earth System Models and eliminating the rest of the models that have no ocean model component over the Black Sea. The signals are computed for three different future periods (2025–2049, 2050–2074, and 2075–2099) relative to the 1990–2014 historical period. Each climate change signal which represents different periods were added to ERA5 6-hourly data as ensemble means. In the first future period (2025-2049), sea surface temperature (SST) in August is projected to increase by 1.7 °C, and by the end of the period (2075-2099), SST is expected to rise by 5 °C over the Black Sea. Additionally, while near-surface air temperatures in August are projected to increase by 1.5 °C to 2.5 °C initially, they are expected to rise by approximately 5.5 °C to 8.5 °C in the final period over the simulation domain. Moreover, near-surface relative humidity over land in August is simulated to decrease by nearly 10% in the last quarter of the century. The findings of this study will contribute to our understanding of how extreme precipitation events develop under future climate conditions and provide insights of the physical and dynamic processes that could drive these events in a warmer world.