This project uses data from a modern ground-based instrument for acoustic sounding of the ABL (SCINTEC Flat Array Sodar MFAS) with vertical range of about 1000 m. This instrument was set up at Ahtopol Experimental Polygon of NIMH-BAS in July 2008 under a bilateral scientific collaboration between NIMH and the Production Research Establishment Typhoon of the Russian State Committee for Hydrology and Meteorology (ROSHYDROMET). This Doppler sounding system provides data for wind speed and turbulence parameters with high temporal (every 10 minutes a running 20-min average value is calculated) and special (data at every 10 m starting from 30 m above ground and reaching a different height between 400 and 800 m depending on atmospheric conditions), thus characterizing the processes within the coastal ABL and allowing to collect unique information and new knowledge on the vertical structure and evolution of the coastal ABL. The new type of information provided by the sodar allows the realization of a number of theoretical and practical studies, such as studies of the local circulation – sea breeze, coastal area climate, assessments of wind energy potential, weather forecast improvement, etc.

Flat Array middle range instrument (MFAS) sodar: frequency range 1650 – 2750 Hz; 9 emission/reception angles (0°, ± 9.3°, ± 15.6°, ± 22.1°, ± 29°); maximum 100 vertical layers; range between 150 – 1000 m, vertical resolution of 10 m; accuracy of horizontal wind speed 0.1 – 0.3 ms-1; range of horizontal wind speed ± 50 ms-1; accuracy of vertical wind speed 0.03 – 0.1ms-1; range of vertical wind speed ± 10 ms-1; accuracy of wind direction 2 – 3 degrees.

Meteorological Observatory (MO) Ahtopol is located in the south-eastern part of the Bulgarian Black Sea coast region at about 2 km southeast of the town of Ahtopol. The Observatory falls into the Black Sea coastal Strandzha climate region, which is a part of the Black Sea climatic sub-region of the Continental-Mediterranean climatic zone in Bulgaria. MO Ahtopol is situated primarily on a flat grassland at about 400 m inland and 30 m height above sea level. The coastline is stretching out from NW to SE with a steep about 10m high cost.