The extreme phenomena from the end of June 2021 and the variations of the planetary boundary layer height, in Moldavia region

Abstract

<p>On June 30<sup>th</sup>, 2021, a low-pressure formed in the center of Europe, causing the advection of warm air and the infiltration of cold air from the rear sector of the low-pressure field. This resulted in the formation of a strong convergence line in the Moldavia region, which generated a multicellular system. We analyzed the forecast atmospheric sounding for this date at 12 UTC in various locations in Moldavia, using the European Centre for Medium-Range Weather Forecasts (ECMWF) to identify areas with high convective potential. The planetary boundary layer (PBL) was determined through the analysis of selected atmospheric sounding, and a well-mixed PBL was observed. As the air particle rises, it cools adiabatically, carrying moisture with it. However, slight variations in the height of PBL were noted at different locations, with the northern-central part of Moldavia experiencing more convection than the southern part, which was less affected by severe weather. The region of the atmosphere closest to the ground surface that is directly influenced by it in terms of turbulence, wind direction and speed, moisture, heat, and convective activity is known as PBL. Most of the water vapor and aerosols in the atmosphere are concentrated in this layer, where turbulent mixing occurs and atmospheric fronts and their associated phenomena are manifested. It is important to analyze the height of PBL and how it varies, as it does not have the same height everywhere and changes over time and space. In our work we determined the height of  PBL through the use of atmospheric sounding.</p> <p> </p> <p>Keywords: forecast, convection, PBL, atmospheric sounding</p>