Vol 43, No 1 (2018)

The monthly and seasonal anomalies of temperature and precipitation over the Arctic are considered depending on the global and regional patterns of atmospheric circulation. Ñlimate indices are used to identify patterns. The composite analysis allowed identifying the geographic regions where the influence of atmospheric circulation modes on temperature and precipitation is statistically significant. The contingency of atmospheric circulation patterns in the Northern Hemisphere was statistically estimated. Special attention is paid to the case studies where the extreme episodes of circulation indices are associated with the significant anomalies of air temperature and precipitation. The potential is demonstrated of the numerical simulation of extreme episodes on monthly and seasonal timescales with the global semi-Lagrangian model SL-AV developed in the Institute of Numerical Mathematics jointly with the Hydrometcenter of Russia.

The development of the bora in case of strong southeastern wind in the area of Novaya Zemlya in the winter-spring of 2016 is simulated using the WRF-ARW numerical atmosphere circulation model with high spatial resolution. The features of wind speed and air temperature fields are considered which define the formation of the intensive near-surface flow, the bora, over the lee western slope of the mountain range. It is demonstrated that the bora development leads to the air temperature rise over the eastern part of the Barents Sea, to the increased surface heat fluxes, and to the formation of the cloudless zone over the sea westward of Novaya Zemlya. It was found that the main reason for the bora development is the high stability of the atmospheric boundary layer over the Kara Sea. It is shown that in case of western wind the Novaya Zemlya archipelago does not exert considerable influence on the air exchange in the Kara Sea area.

The optimized (all iterative procedures are excluded) local one-dimensional thermody-namic model of the formation and melting of ice is proposed. The numerical computation of ice cover evolution in the Kerch Strait under the influence of thermodynamic factors for the period of 5 months is carried out for the real conditions of winter of 2011/12. Thec results agree well with the available obser-vational data on the timing of ice formation and on ice thickness in the southern part of the Sea of Azov and in the Taman Bay. In combination with the full three-dimensional hydrodynamic model and taking into account diurnal variations in external factors, the model simulates the spatial distribution of ice cover formation.

This study creates a database on incoming solar radiation using artificial neural networks (ANN) and information on altitude, air temperature and pressure, water vapor pressure, dry air density, water vapor density, and mixing ratio obtained at five weather stations in Turkey. The coefficients of correlation of the calculation results for three regimes of air density with observational data for the training sample (2000–2001) are 99.24%, 99.82%, and 96.67%; for the testing sample (2002), 95.97%, 82.32%, and 95.11%. These values indicate that the usage of artificial neural networks and data of at-mosphere parameters is a correct and effective method for estimation of solar radiation and creation solar databases.

The potential of Doppler weather radars in estimating the speed and direction of airflows within the area of coverage is investigated. It is demonstrated that the usage of one radar does notre-trieve the field of these parame ters but makes possible the solution of partial problems. Different ways of solution are considered. The method based on multiposition radiolocation is proposed as the most promising one.