DATE2022-05-15 16:26:35
TITLERecent anticyclonic activity changes in the Black Sea–Mediterranean region
AUTHORSOlga Sukhonos (1) ,Elena Voskresenskaya (1) ,Michael Bardin (2)
  1. 1) Institute Of Natural And Technical Sysytems, Sevastopol (Russia) ,2) Yu. A. Izrael Institute Of Global Climate And Ecology, Moscow (Russia)
ABSTRACTThe climate features of the Black Sea-Mediterranean region (BSMR) are mainly caused by the unique geographic conditions. The region includes three continents, interior seas, surrounding mountains. The mountain groups influence strongly on the frequency of baric objects, as well as their trajectories, the deformation of the thermobaric fields when cyclones or anticyclones pass over a mountain range, and reduce their movement speed and block lower anticyclones. Now, the numerous publications on the long-term changes of anticyclonic activity cover the entire Northern hemisphere or separate regions but not specifically in the BSMR. The associated conclusions do not completely show the changes of anticyclone parameters including frequency, height, and area in the BSMR in the second half of the 20th century. That is why, the main aim of present study is to analyze the climatology and trends of the anticyclones parameters in the BSMR in 1951-2017. The data on 1000 hPa geopotential height between 20 and 80° N in 1951–2017 were extracted from the NCEP/NCAR Reanalysis 1. The method by Bardin described in detail in (Bardin, 1995, 2007, 2019) was used to identify anticyclones and calculate their parameters. Anticyclones’ parameters (frequency, height, area) were calculated within the following three BSMR subregions: the Black Sea region (40 – 50° N, 27,5 – 45° E), the Western Mediterranean region (35 – 47,5° N, 6° W – 17,5° E), the Eastern Mediterranean region (30 – 40° N, 17,5 – 37,5° E). These subregions are different by the physical and geographic features of region. The climatology of anticyclones’ parameters includes the assessment of their averages, root mean square deviations (RMS) and seasonality, as well as linear trends. The linear trend coefficients were calculated using the least-squares method. The statistical significance of linear trends was assessed using Student's t-test. In BSMR, the highest frequency and height of anticyclones in the second half of the 20th century were revealed in the Black Sea region, and the lowest height and area of anticyclones were found in the eastern Mediterranean region. At the same time it was found RMS maximum of the anticyclone height and area in the Western Mediterranean, while RMS minimum was shown in the anticyclone frequency there. Significant trends of anticyclone parameters in the BSMR for analyzed period were identified. In winter, the anticyclone frequency was increased in the Black Sea and the Western Mediterranean regions. In spring, the anticyclone frequency in the Eastern Mediterranean was decreased. In summer it was note the anticyclone frequency decrease in the Black Sea region and in the Eastern and Western Mediterranean, while anticyclone area is increasd in Western Mediterranean. In autumn, anticyclone height decreases in the Black Sea region and anticyclone frequency decreases in the Western and Eastern Mediterranean. This includes the anticyclone frequency in the Black Sea region, as well as the anticyclone frequency and height in the Eastern Mediterranean. Thus, obtained results provides the knowledge on the recent climatology and trends of the anticyclone parameters in the BSMR in 1951-2017.