Background

The challenge

The development of society requires from meteorology increasingly accurate forecasts in time and place, increasingly accurate data on past events, increasingly early warnings of dangerous and extreme weather events, increasingly reliable results of climate models for planning the future of the Planet, and absorption of its renewable energy resources. All these goals are achieved through the improvement of the models, which is determined by the progress in describing the physical and chemical processes in the atmosphere and, in particular, in the most difficult to understand part of it – the Atmospheric Boundary Layer (ABL) and especially in the conditions of a non-homogeneous surface. Тhe physical characteristics of the surface affect the exchange of energy with the adjacent layer of the ABL and the abrupt change in it (such as field-city, sea-land, field-forest, etc.) leads to complexity in atmospheric processes due to transformation of the air masses (AM) to the physical characteristics of the new surface. Such type atmospheric processes in coastal areas, influenced by the complex terrain and in addition by the existence of periodical local circulations are very difficult to be described because of the resulting complex layering of the coastal ABL. Consequently, the mesoscale numerical modeling of atmospheric processes is complicated too as most of the ABL parametrizations are developed for flat homogeneous terrain, and for coastal areas additional validation with high-resolution remote sensing observations is needed.

Тhe potential of modern technology

On the other hand, the industrial improvement of different kinds of ground-based remote sensing (GBRS) instruments for estimations of quantities of meteorological parameters in the ABL is a prerequisite and a method for realizing more accurate spatial, qualitative, and quantitative assessments of the state of lower layers of the atmosphere at a given moment and acquiring a real picture of the ongoing processes in it. High-resolution temporal and special information about an object or meteorological phenomenon is acquired without making physical contact with the site and allows data to be collected for hazardous or inaccessible areas by remote sensing which makes such type of technology indispensable, reliable, and unique for a number of innovative research approaches in studies of the basic meteorological parameters and turbulence within the ABL. During the last decade, the improvement of the data quality for model validation and data assimilation through the advancement of remote sensing technologies has initialized international collaborations such as COST ES0702 EG-CLIMET, COST 720 COST, COST ES1303 TOPROF, COST CA16202 InDust, and COST CA18235 PROBE. The research and collaboration within all these actions are of great importance for the weather forecast improvements and increasing of the quality of all meteorological products in service of society through the integration of a number of GBRS devices within a uniform European network for observations with developed standardization of the use of GBRS data.

Оpportunity

The operational mode of modern GBRS methods are not developed in Bulgaria but for an eight-year period (August 2008 – October 2016) in the region of the town of Ahtopol remote sensing data from acoustic sounding of the atmosphere is available and can be used both for acquiring a realistic picture of the complex vertical structure of the coastal ABL and for evaluation of mesometeorological models performance. The main goal of that post-doctoral study is to use these high spatial and temporal resolution GBRS data obtained with Dopler sodar to study the evolution of the vertical structure of the coastal ABL in Bulgaria and to evaluate the performance of Weather Research and Forecasting (WRF) numerical mesometeorological model to simulate that vertical structure under different weather conditions. For the purpose of this study, a statistical approach will be applied to the sodar data and will be analyzed for estimation of some typical regimes of the lower part of the coastal atmospheric circulation and for selected periods with sufficient data availability in time and space the WRF simulation will be used to evaluate the performance of the mesometeorological numerical modeling to reproduce the parameters of the wind field (wind speed, wind direction, and wind vector components). Statistical metrics as correlation coefficient of Pearson, changes in height and time for the values of 5 pairs of measured and modelled parameters as for non-linear parameters (a circular scale of wind direction), circular statistics will be used