Patterns of PBL hight during 1989-2019 over Romania, Moldavia Region using ERA5 data and correlation with NAO index.

The evolution of the Planetary Boundary Layer Height (PBLH) is a very important meteorological parameter because most of the population carries out their socio-economic activities inside this layer and because it has a significant impact on weather events and air quality. This parameter is influenced by energy and mass exchanges between the land surface and the atmosphere. In our study, hourly PBLH data were used over a period of 30 years (1989-2018), for the warm season (May, June, July, August and September). The data we used comes from the ECMWF (European Centre for Medium-Range Weather Forecasts) database, ERA5. By means of Open GrADS (The Grid Analysis and Display System), the PBLH deviations were graphically represented and interpreted. On the other hand, the NAO (The North Atlantic Oscillation) has influences over the climate variability and weather worldwide. It is well known that NAO exhibits considerable variability throughout a season and during a year, as well, and prolonged periods (for a few months) of both positive and negative phases of the pattern are ordinary. Both the PBLH variations and the NAO index can have an impact on the weather and climate conditions. In this study we will present the patterns of PBLH during 1989-2019 and correlations between the NAO index and the variability of the monthly summer PBLH in Moldavia Region, Romania.