Russian Hydrometeorological Research Center
Russian Hydrometeorological Research Center
Alekseeva A.A.,Russian Hydrometeorological Research Center
Russian Meteorology and Hydrology | Year: 2017
In contrast to the common opinion, hurricane winds in extratropical cyclones are a quite frequent phenomenon followed by huge damage, especially in densely populated areas. This phenomenon has been poorly studied and is hardly predictable so far. The features of hurricane winds in extratropical cyclones, and the similarity and difference in their structure as compared to those in tropical cyclones are revealed. © 2017, Allerton Press, Inc.
Tsyrulnikov M.,Russian Hydrometeorological Research Center |
Rakitko A.,Russian Hydrometeorological Research Center
Physica D: Nonlinear Phenomena | Year: 2017
A new ensemble filter that allows for the uncertainty in the prior distribution is proposed and tested. The filter relies on the conditional Gaussian distribution of the state given the model-error and predictability-error covariance matrices. The latter are treated as random matrices and updated in a hierarchical Bayes scheme along with the state. The (hyper)prior distribution of the covariance matrices is assumed to be inverse Wishart. The new Hierarchical Bayes Ensemble Filter (HBEF) assimilates ensemble members as generalized observations and allows ordinary observations to influence the covariances. The actual probability distribution of the ensemble members is allowed to be different from the true one. An approximation that leads to a practicable analysis algorithm is proposed. The new filter is studied in numerical experiments with a doubly stochastic one-variable model of “truth”. The model permits the assessment of the variance of the truth and the true filtering error variance at each time instance. The HBEF is shown to outperform the EnKF and the HEnKF by Myrseth and Omre (2010) in a wide range of filtering regimes in terms of performance of its primary and secondary filters. © 2016 Elsevier B.V.
Konovalov I.B.,University Paris Est Creteil |
Beekmann M.,University Paris Est Creteil |
Kuznetsova I.N.,Russian Hydrometeorological Research Center |
Yurova A.,Russian Hydrometeorological Research Center |
Zvyagintsev A.M.,Central Aerological Laboratory
Atmospheric Chemistry and Physics | Year: 2011
Numerous wildfires provoked by an unprecedented intensive heat wave caused continuous episodes of extreme air pollution in several Russian cities and densely populated regions, including the Moscow region. This paper analyzes the evolution of the surface concentrations of CO, PM10 and ozone over the Moscow region during the 2010 heat wave by integrating available ground based and satellite measurements with results of a mesoscale model. The CHIMERE chemistry transport model is used and modified to include the wildfire emissions of primary pollutants and the shielding effect of smoke aerosols on photolysis. The wildfire emissions are derived from satellite measurements of the fire radiative power and are optimized by assimilating data of ground measurements of carbon monoxide (CO) and particulate matter (PM10) into the model. It is demonstrated that the optimized simulations reproduce independent observations, which were withheld during the optimisation procedure, quite adequately (specifically, the correlation coefficient of daily time series of CO and PM10 exceeds 0.8) and that inclusion of the fire emissions into the model significantly improves its performance. The model results show that wildfires are the principal factor causing the observed air pollution episode associated with the extremely high levels of daily mean CO and PM10 concentrations (up to 10 mg m-3 and 700 μg m-3 in the averages over available monitoring sites, respectively), although accumulation of anthropogenic pollution was also favoured by a stagnant meteorological situation. Indeed, ozone concentrations were simulated to be episodically very large (>400 μg m-3) even when fire emissions were omitted in the model. It was found that fire emissions increased ozone production by providing precursors for ozone formation (mainly VOC), but also inhibited the photochemistry by absorbing and scattering solar radiation. In contrast, diagnostic model runs indicate that ozone concentrations could reach very high values even without fire emissions which provide "fuel" for ozone formation, but, at the same time, inhibit it as a result of absorption and scattering of solar radiation by smoke aerosols. A comparison of MOPITT CO measurements and corresponding simulations indicates that the observed episodes of extreme air pollution in Moscow were only a part of a very strong perturbation of the atmospheric composition, caused by wildfires, over European Russia. It is estimated that 2010 fires in this region emitted ∼10 Tg CO, thus more than 85% of the total annual anthropogenic CO emissions. About 30% of total CO fire emissions in European Russia are identified as emissions from peat fires. © 2011 Author(s).
Bulygina O.N.,Russian Hydrometeorological Research Center |
Groisman P.Y.,U.S. National Center for Atmospheric Research |
Razuvaev V.N.,Russian Hydrometeorological Research Center |
Korshunova N.N.,Russian Hydrometeorological Research Center
Environmental Research Letters | Year: 2011
Current snow state descriptions and estimates of major snow characteristics (snow cover duration, maximum winter snow depth, snow water equivalent) up to 2010 have been recorded from 958 meteorological stations in Russia. Apart from the description of long-term averages of snow characteristics, the estimates of their change that are averaged over quasi-homogeneous climatic regions are derived and regional differences in the change of snow characteristics are studied. In recent decades, the Russian territory has experienced an increase in snow depth, both winter average and maximum snow depths, against the background of global temperature rise and sea ice reduction in the northern hemisphere. The first generalized regional characteristics of maximum snow water equivalent in the winter season have been obtained. According to field observations, an increase in water supply has been revealed in the north of the East European Plain, in the western part by 4.5% (10yr)- 1 and in the eastern part by 6%(10yr)- 1. This characteristic also increases by ∼ 6%(10yr)- 1 in the southern forest zone of Western Siberia and in the Far East. Snow water equivalent in central Eastern Siberia increases by 3.4% (10yr)- 1. From snow course observations in the forest, a tendency for a decrease in water supply (-6.4%(10yr)- 1 is only found in the southwest of the East European Plain. Snow cover characteristics, being a product of several climate-forming factors that simultaneously affected them, change nonlinearly and different characteristics may and often do change differently with time. Therefore, one cannot assume that having information about the trend of one of the snow characteristics implies knowledge of the trend sign of others. In particular, whilst during the past four decades over the Russian Federation most snow cover characteristics - including the most important of them responsible for water supply - have increased, the only quantity that is reliably monitored from space (snow cover extent) has decreased, but in the last two decades this decrease has ceased. These tendencies are opposite to those observed in Canada and Alaska. © 2011 IOP Publishing Ltd.
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.
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.
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.
He M.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute |
Yang B.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute |
Datsenko N.M.,Russian Hydrometeorological Research Center
Climate Dynamics | Year: 2014
The recent unprecedented warming found in different regions has aroused much attention in the past years. How temperature has really changed on the Tibetan Plateau (TP) remains unknown since very limited high-resolution temperature series can be found over this region, where large areas of snow and ice exist. Herein, we develop two Juniperus tibetica Kom. tree-ring width chronologies from different elevations. We found that the two tree-ring series only share high-frequency variability. Correlation, response function and partial correlation analysis indicate that prior year annual (January-December) minimum temperature is most responsible for the higher belt juniper radial growth, while more or less precipitation signal is contained by the tree-ring width chronology at the lower belt and is thus excluded from further analysis. The tree growth-climate model accounted for 40 % of the total variance in actual temperature during the common period 1957-2010. The detected temperature signal is further robustly verified by other results. Consequently, a six century long annual minimum temperature history was firstly recovered for the Yushu region, central TP. Interestingly, the rapid warming trend during the past five decades is identified as a significant cold phase in the context of the past 600 years. The recovered temperature series reflects low-frequency variability consistent with other temperature reconstructions over the whole TP region. Furthermore, the present recovered temperature series is associated with the Asian monsoon strength on decadal to multidecadal scales over the past 600 years. © 2013 Springer-Verlag Berlin Heidelberg.
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.
Gorin V.E.,Russian Hydrometeorological Research Center |
Tsyrulnikov M.D.,Russian Hydrometeorological Research Center
Monthly Weather Review | Year: 2011
Advanced Microwave Sounding Unit A (AMSU-A) observation-error covariances are objectively estimated by comparing satellite radiances with radiosonde data. Channels 6-8 are examined as being weakly dependent on the surface and on the stratosphere above the radiosonde top level. Significant horizontal, interchannel, temporal, and intersatellite correlations are found. Besides, cross correlations between satellite and forecast (background) errors (largely disregarded in practical data assimilation) proved to be far from zero. The directional isotropy hypothesis is found to be valid for satellite error correlations. Dependencies on the scan position, the season, and the satellite are also checked. Bootstrap simulations demonstrate that the estimated covariances are statistically significant. The estimated correlations are shown to be caused by the satellite errors in question and not by other (nonsatellite) factors. © 2011 American Meteorological Society.