Changes in Breeze Warmest Summers for the Romanian Black Sea Coast in Climate Scenarios for the Time Horizon 2050

The study aims to analyze and compare the mean sea level pressure field to show the changes in the breeze regime in the coastal area of Romania in the current climate and the one projected in climate scenarios. The mechanism and variability of the breeze cell (intensity, location, frequency, persistence) are analyzed and compared for extreme conditions of warmest summers (July) during the two climatic intervals: 1971- 2000 respectively for the RCP4.5 2021-2050 scenario. The high-resolution climate is simulated using the RegCMv4.5 regional climate model at 5 km resolution, coupled with the global EC-Earth model. These dynamical downscaling methods were performed for the first time for Romania in ANM (Meteo Romania) during the AZURE-Microsoft project (2018), aiming to refine the scale of the global climate scenarios to allow process analysis. The mechanism of changes is analyzed with the interaction between regional-scale conditions and large-scale dynamic factors. The results indicate changes in the frequency of intense events and the spatial development of the breeze cell, with a time-mean intensification of both sea and land breezes and, a greater spatial advance in the area mainly during the day. Large scale-dynamics changes in interaction with the breeze circulation lead to an anticyclonic rotation under a warmer climate of the coupled circulation that induces a shift to the South-West of the cell, with a possible impact on the location of the associated precipitation. Regarding timing, a time-delay in the sea breeze occurrence (smaller pressure gradients persist longer due to warmer sea surface temperature), together with enhanced cell intensity, later on, makes the event appear as a more abrupt or extreme one. The results of the study provide potentially important input for further analysis of projected impacts of the breeze circulation on the regional climate.