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Chernokulsky A.V.,Russian Academy of Sciences | Bulygina O.N.,Russian Hydrometeorological Research Center | Mokhov I.I.,Russian Academy of Sciences
Environmental Research Letters | Year: 2011

Changes of total and low cloud fraction and the occurrence of different cloud types over Russia were assessed. The analysis was based on visual observations from more than 1600 meteorological stations. Differences between the 2001-10 and 1991-2000 year ranges were evaluated. In general, cloud fraction has tended to increase during recent years. A major increase of total cloud fraction and a decrease of the number of days without clouds are revealed in spring and autumn mostly due to an increase of the occurrence of convective and non-precipitating stratiform clouds. In contrast, the occurrence of nimbostratus clouds has tended to decrease. In general, the ratio between the occurrence of cumulonimbus and nimbostratus clouds has increased for the period 2001-10 relative to 1991-2000. Over particular regions, a decrease of total cloud fraction and an increase of the number of days without clouds are noted. © 2011 IOP Publishing Ltd. Source

Ivanova A.R.,Russian Hydrometeorological Research Center
Russian Meteorology and Hydrology | Year: 2016

A review of the papers dealing with various aspects of stratosphere-troposphere exchange (STE) is presented. The development of STE concepts is described and quantitative estimates of STE obtained by different authors are given. Typical time scales and geographic features of STE are described. Special attention is given to the specific features of STE at extratropical latitudes where active vertical air transport is observed in both directions. The air ascent through the tropopause occurs there in the zones of warm conveyor belts, and the air descent takes place in the zones of stratospheric intrusions. Exchange processes in the key region including the upper troposphere and the lowermost stratosphere are described. The mechanisms of large-scale stratospheric intrusions in the systems of tropopause folds or cut-off lows are presented as well as the mechanisms of the mixing of the stratospheric air with the tropospheric one. Specific features of deep stratospheric intrusions are discussed which are based on the analysis of such indicators of stratospheric air as high concentrations of ozone and stratospheric radionuclide 7Be. Some aspects of stratosphere-troposphere energy exchange are considered. © 2016, Allerton Press, Inc. Source

Kuznetsova I.N.,Russian Hydrometeorological Research Center
Izvestiya - Atmospheric and Ocean Physics | Year: 2012

Relations between short-term variations in the concentrations of aerosol (PM 10) and carbon monoxide (CO) and meteorological characteristics are considered for the episodes of severe atmospheric pollution in the region of Moscow in the summer of 2010. The assumption is made and substantiated that the observed (in late June) severe aerosol pollution of the atmosphere over Moscow was caused by air masses arrived from soil-drought regions of southern Russia. In August, during the episodes of advection of forest-fire products, the maximum surface concentrations of pollutants were observed in Moscow mainly at 11:00-12:00 under a convective burst into the atmospheric boundary layer and at night in the presence of local wind-velocity maxima or low-level jet streams within the inversion layer. On the basis of results from an analysis of these air-pollution episodes before and after fires, it is concluded that the shearing instability of wind velocity favors the surface-air purification under ordinary conditions and an increase in the surface concentrations of pollutants during their advection (long-range transport, natural-fire plumes, etc.). It is shown that the pollution of the air basin over the megapolis with biomass-combustion products in 2010 led to an increase in the thermal stability of the atmospheric surface layer and in the duration of radiation inversions, as well as to an attenuation of the processes of purification in the urban heat island. © 2012 Pleiades Publishing, Ltd. Source

Pokhil A.E.,Russian Hydrometeorological Research Center
Russian Meteorology and Hydrology | Year: 2012

Studied is the evolution of the family of tropical cyclones in the Pacific Ocean in 2009. Analyzed is an unusual behavior of real simultaneously existing tropical cyclones (TCs). Investigated is a mechanism of the interaction between a pair of tropical cyclones of various intensities. Considered are the cases of triple interaction between a pair of TCs and the polar front, as well as the transformation and regeneration of TCs due to their entry to the cold front area. The dynamics of groups of real tropical cyclones is compared with the behavior of ideal cyclonic vortices in the experiments with the numerical model. Proposed are the variants of explaining the disappearance and formation of vortices, as well as of loops, zigzags, and sharp turns during their movement. © 2012 Allerton Press, Inc. Source

Kryjov V.N.,Russian Hydrometeorological Research Center
International Journal of Climatology | Year: 2015

Investigation into atmospheric processes preceding winters of different Arctic Oscillation index (AOI) polarity, based on empirical data analysis, has revealed highly statistically significant relationships between the wintertime AOI and preceding October circulation. The wintertime AOI strongly covaries with an October circulation anomaly barotropically spanning the depth of the troposphere over the Taymyr Peninsula (Taymyr circulation anomaly, TCA), with the anticyclonic (cyclonic) TCA preceding winters of the negative (positive) AOI polarity. The October TCA affects the wintertime AOI polarity mainly via its impact on air temperature over the Arctic and North-East Asia. Anticyclonic (cyclonic) TCA leads to the positive (negative) temperature anomaly over the Arctic and a corresponding increase (decrease) of geopotential heights, and to the negative (positive) temperature anomaly over North-East Asia and so to enhancement (weakening) of the climatological trough associated with long planetary waves and corresponding enhancement (weakening) of the upward wave activity flux. To characterize temporal variability of the TCA, a Taymyr circulation index (TCI) is suggested. Correlation coefficient between the (inverted) wintertime AOI and the October TCI is 0.58 for the 1958-2012 period, with correlations being stable in time. The anticyclonic (cyclonic) TCA is associated with smaller (larger) number of cyclones coming to the region of the eastern Barents Sea-Taymyr Peninsula-Laptev Sea. Statistical relationships between the October TCA, wintertime AOI and September/October sea surface temperature in the northern Barents Sea are shown. © 2014 Royal Meteorological Society. Source

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