Showing papers in "Russian Meteorology and Hydrology in 2018"
TL;DR: In this article, the authors studied the impact of the multiscale version of the global atmosphere model SL-AV on forecast quality and showed that the increase in accuracy of model climate characteristics has led to the reduction of forecast errors.
Abstract: Development of the multiscale version of the global atmosphere model SL-AV required many improvements in the dynamical core, replacement or refinement of parameterization algorithms and complex tuning of the model. These modifications were initially tested with the experiments on modern climate simulation and then incorporated into the model configuration for medium-range numerical weather prediction. The impact of these model improvements on forecast quality is studied in this paper. The increase in accuracy of model climate characteristics has led to the reduction of forecast errors. The comparison of quality for numerical forecasts starting from the initial data of Hydrometcenter of Russia and ECMWF is carried out. The effect of replacing the initial data turned out to be comparable to the effect of multi-year works on model development. This shows the importance and necessity of development and improvement of the Hydrometcenter of Russia data assimilation system.
18 citations
TL;DR: In this paper, a method for discriminating among different types of precipitation is presented, based on surface observations of precipitation, present and past weather, and the morphological types of clouds.
Abstract: A method for discriminating among different types of precipitation is presented. The method is based on surface observations of precipitation, present and past weather, and the morphological types of clouds. The climatology of showery, nonshowery, and drizzle precipitation in Northern Eurasia is studied using the data of 529 Russian weather stations for the period of 1966–2014. Showery precipitation dominates in Northern Eurasia. In general, showery precipitation has greater temporal (monthly and diurnal) and spatial variability than nonshowery precipitation. The majority of showers are registered in summer (the maximum is in July), whereas the high est total monthly nonshowery precipitation is observed in autumn (the maximum is in October). The daily intensity values of showery and nonshowery precipitation are generally close, the maximum intensity is recorded in July–August. For three-hour in tervals, the shower in tensity is by 1.1–1.5 times higher. The drawbacks of the presented methodology are discussed.
17 citations
TL;DR: In this paper, the contribution of radiative forcing of greenhouse gases (GHG) and Atlantic Multidecadal Oscillation (AMO) to the trends in global surface air temperature (GST) and surface temperature for different latitude bands are estimated.
Abstract: The contributions of radiative forcing of greenhouse gases (GHG) and Atlantic Multidecadal Oscillation (AMO) to the trends in global surface air temperature (GST) and surface air temperature for different latitude bands are estimated. Instrumental observational data obtained since the middle of the 19th century and three-component autoregressive models are used. Characteristics of influences of both factors on GST (Wiener–Granger causality) are obtained. The contribution of AMO over the length intervals of 15–30 years appears comparable in absolute value to the contribution of GHG and sometimes even exceeds it, while its contribution over 60-year and longer periods is insignificant. During the recent decades, GHG contribute stronger to the trends of GST and tropical surface air temperature, while their contribution to the trends in surface air temperature in the middle and high latitudes is smaller.
16 citations
TL;DR: In this paper, specific features of climate change in the Black Sea and on its northeastern coast for the period of 1982-2014 are investigated based on weather station data, ERA-Interim reanalysis, and satellite data on sea surface temperature.
Abstract: Specific features of climate change in the Black Sea and on its northeastern coast for the period of 1982-2014 are investigated based on weather station data, ERA-Interim reanalysis, and satellite data on sea surface temperature. The main trends in air temperature and precipitation are revealed from weather station data and are compared with reanalysis data. The spatial peculiarities of variations in air temperature, integrated water vapor, moisture flux divergence, CAPE, and vertical velocity are analyzed. It is shown that air temperature variations on the coast highly correlate with sea surface temperature. In general, surface air temperature in the region has risen, especially in summer. Despite the increase in integrated water vapor and CAPE, no statistically significant increase was revealed for the mean amount of precipitation, for its intensity and maximum values. This fact might be associated with the moisture flux divergence increase in the region due to the intensification of large-scale downdrafts.
16 citations
TL;DR: In this paper, an automatic weather station with the coupled set of soil sensors is described, which is used for measuring the profiles of soil temperature and surface soil moisture and for the synchronous measurements of air temperature and air humidity at the height of 1 and 2 m, wind speed and wind direction, amount of precipitation, and snow depth as well as of soil-water conductivity.
Abstract: The atmosphere-soil measurement system being an automatic weather station with the coupled set of soil sensors is described. It is used for measuring the profiles of soil temperature and surface soil moisture and for the synchronous measurements of air temperature and air humidity at the height of 1 and 2 m, wind speed and wind direction, amount of precipitation, and snow depth as well as of soil-water conductivity. Special software combines all sensors of the system into a single environmental monitoring system. The example of using measurement data for assessing the spatiotemporal dynamics of climate parameters is provided for contrasting landscapes of the Repubiic of Buryatia (eastern Baikalia and southern Vitim Plateau).
14 citations
TL;DR: In this paper, the causes of extremely cold winters over the mid-latitude continents observed in the recent decades against the warming background are discussed, and several conceptions are outlined which explain potential reasons for occurrence of this phenomenon.
Abstract: Studies dealing with impact of the Arctic warming and related sea ice decline on the Northern Hemisphere atmospheric circulation are considered. The causes of occurrence of extremely cold winters over the mid-latitude continents observed in the recent decades against the warming background are discussed. Several conceptions are outlined which explain potential reasons for occurrence of this phenomenon. The paper discusses impacts of the Arctic sea ice loss on the large-scale atmospheric circulation, oscillations of planetary waves. It also discusses issues related to sea ice changes in the Barents and Kara seas and their link to the frequency of extremely cold winters observed in Eurasia and North America, the contribution of internal atmospheric variability to the increasing frequency of cold weather, and the role of the Atlantic Multidecadal Oscillation in the Arctic sea ice reduction.
13 citations
TL;DR: In this article, the authors investigated the desertification of the territory of Mongolia by the analysis of vegetation dynamics over the period from 1982 to 2016 and its interrelation with climatic, natural, and anthropogenic components.
Abstract: The possibility of applying remote sensing data to the identification and monitoring of desertification is demonstrated. The present study includes the investigation of desertification of the territory of Mongolia by the analysis of vegetation dynamics over the period from 1982 to 2016 and its interrelation with climatic, natural, and anthropogenic components. It is found that the main contribution to the vegetation degradation in Mongolia was made by precipitation decrease and air temperature rise. The indirect factors such as livestock, land cultivation, and wildfires increased the influence of climatic factors and gave impetus to the desertification in some arid and semiarid regions.
13 citations
TL;DR: The simulation of stratosphere-troposphere dynamic coupling is considered in five 50-year realizations of ensemble calculations with the 5th version of the INM-CM5 climate model developed in the Marchuk Institute of Numerical Mathematics of Russian Academy of Sciences as discussed by the authors.
Abstract: The simulation of stratosphere-troposphere dynamic coupling is considered in five 50-year realizations of ensemble calculations with the 5th version of the INM-CM5 climate model developed in the Marchuk Institute of Numerical Mathematics of Russian Academy of Sciences. The model also includes the ocean model and the improved vertical resolution in the upper stratosphere and lower mesosphere.
12 citations
TL;DR: In the first half of the 1930s A.N. Kolmogorov was developing analytical methods for the probability theory and presented the solution of the Fokker-Planck type equation as mentioned in this paper.
Abstract: In the first half of the 1930s A.N. Kolmogorov was developing analytical methods for the probability theory and presented the solution of the Fokker–Planck type equation. This solution contains scales for the distribution function moments of the mean squares for velocities and relative displacements of the analyzed objects and for the mixed moments of velocities and coordinates. The exclusion of time from these moments leads to the 2/3 law for the velocity structure function and to the Richardson–Obukhov law for the eddy diffusion. The analysis of the fetch laws for wind waves demonstrates that the Kolmogorov laws are manifested in the growth of wave amplitudes and in the form of elevation spectra. These laws also work in the statistics of the planetary surface relief, in the size distribution of the lithospheric plates, in the energy spectra of cosmic rays, and in other processes. In the equation deduced in 1934, probability distribution functions are derived only under the condition of homogeneity of these functions and thereby allow describing a broad range of phenomena and processes.
11 citations
TL;DR: In this paper, the most extreme surges over the period of instrumental observations in the Taganrog Bay since 1881, the surges occurred on March 24, 2013 and September 24, 2014.
Abstract: The simulation the most extreme surges over the period of instrumental observations in the Taganrog Bay since 1881, the surges occurred on March 24, 2013 and September 24, 2014. The objective of the simulation is to study surge formation features and to reveal requirements for the accuracy of simulating atmospheric and oceanic circulation in the Sea of Azov. For this purpose, the Institute of Numerical Mathematics Ocean Model (INMOM) with the spatial resolution of ~4 km and ~250 m was used. The atmospheric forcing over the Black Sea region was specified using ERA-Interim reanalysis data and WRF model data with the spatial resolution of 80 and 10 km, respectively. It is shown that the quality of simulation of extreme surges in the Sea of Azov is more dependent on the quality of the input atmospheric forcing than on the spatial resolution of the ocean circulation model. The usage of WRF data as atmospheric forcing allows the more accurate simulation of extreme surges. However, the simulation of the extreme surge of 2014 overestimates, and simulations for the 2013 surge underestimate the surge level. Evidently, as the used version of INMOM does not take into account the coastal zone flooding, the maximum surge value is overestimated.
10 citations
TL;DR: In this paper, the long-term variability of frequency of atmospheric blockings over Western Siberia in 1948-2015 based on the data of three reanalysis projects was studied, and the effect of Western Siberian blockings imposed on synoptic and climatic variability of meteorological parameters in Asia was studied.
Abstract: This paper studies the long-term variability of frequency of atmospheric blockings over Western Siberia in 1948–2015 based on the data of three reanalysis projects. We revealed a decreasing blocking frequency for eight of twelve months. However, since the estimated trends of blocking frequency are small comparing to the significant amplitude of interannual variations, we proposed to divide the entire studied period into several quasi-decadal intervals that differ both in the amplitude of interannual fluctuations of blocking frequency and in trends. The effect of Western Siberian blockings imposed on synoptic and climatic variability of meteorological parameters in Asia was studied. The study demonstrated that in summer teleconnection patterns in temperature and precipitation fields are of the close sign-alternating structure; this indirectly indicates that in Western Siberia the blocking is a part of a large-scale wave mechanism. Like the Ural blockings, the blockings occurring over Western Siberia affect meteorological characteristics within the East Asian monsoon area. In winter time they contribute to lower surface temperature and decreased precipitation in Southeast Asia. In summer during blocking events over Western Siberia, precipitation increases in the East Asian monsoon area.
TL;DR: In this article, the authors describe the experience of using digital models (of terrain, soil, and vegetation) for the underlying surface of the catchment for developing the spatial structure of the open-source SWAT (Soil and Water Assessment Tool) hydrological model.
Abstract: The research describes the experience of using digital models (of terrain, soil, and vegetation) for the underlying surface of the catchment for developing the spatial structure of the open-source SWAT (Soil and Water Assessment Tool) hydrological model. The hydrological regime for the Komarovka River basin (616 km2) is simulated with a daily resolution using the data of Primorskaya water balance station and the modern observation network of Primorye Administration for Hydrometeorology and Environmental Monitoring. It is found that the calculated and measured runoff hydrographs are generally in good agreement, and the model is suitable for describing the hydrological regime of mid-latitude rivers where rainfall floods prevail. The model well reproduces average water years, underestimates the peaks caused by intense rainfall of the typhoon origin and overestimates baseflow.
TL;DR: In this paper, the interannual variations in the characteristics of the seasonal cycle (annual and seasonal amplitudes, winter emission, dates of annual minimum and maximum, and phase) and in the growth rate of atmospheric carbon dioxide concentration over Central Siberia are analyzed for the period from May 2009 to January 2016.
Abstract: The interannual variations in the characteristics of the seasonal cycle (annual and seasonal amplitudes, winter emission, dates of annual minimum and maximum, and phase) and in the growth rate of atmospheric carbon dioxide concentration over Central Siberia are analyzed for the period from May 2009 to January 2016. The results are based on the continuous monitoring of CO2 concentration at the Zotino Tall Tower Observatory (ZOTTO, www.zottoproject.org). It is found that the seasonal amplitude of CO2 concentration in the atmo spheric surface layer over Western Siberia is 26.4 ± 0.8 μmol/mol (no long-term trend toward its increase was revealed), the annual mean growth rate of CO2 is 2.34 μmol/mol per year, its variations range from 1 to 4 μmol/mol per year.
TL;DR: In this paper, the results of calculations for four tornados registered in 2015 are presented, showing that if the values of the indices are above the thresholds, the localized intensive convective cell is formed in the model in the vicinity of the maximum values of indices and at the moment when these values are reached.
Abstract: Calculation of convective indices using the WRF model for the analysis and forecasting of tornado-risk situations involved the calculation of vertical velocity field. The results of calculations for four tornados registered in 2015 are presented. It is shown that if the values of the indices are above the thresholds, the localized intensive convective cell is formed in the model in the vicinity of the maximum values of the indices and at the moment when these values are reached. The possibility of using this result as an additional predictor of tornado occurrence is discussed. It confirms the conclusion on the possibility of prediction of tornado-risk situations with the lead time to three days and with the accuracy to several hours in time and to 200 km in space.
TL;DR: In this article, the SWAP (Soil Water-Atmosphere-Plants) model using meteorological data as inputs which were simulated with different general atmosphere-ocean circulation models in accordance with the RCP climate change scenarios.
Abstract: The possibility ofassessing changes in river runofftill 2100 for a number oflarge river basins of the world for a wide range of natural conditions is investigated The assessment is based on the SWAP (Soil Water–Atmosphere–Plants) model using meteorological data as inputs which were simulated with different general atmosphere–ocean circulation models in accordance with the RCP climate change scenarios The possible climatic changes in annual runoff for some rivers by the end of the 21st century are compared with the natural interannual variability of river runoff caused by weather noise
TL;DR: In this paper, the authors described the environmental conditions that favored the 2011 Blagoveshchensk tornado event and the tornado characteristics, which occurred in the frontal zone of the cyclone over the warm underlying surface.
Abstract: The paper present description of the environmental conditions that favored the tornado event in the city of Blagoveshchensk at about 19:00 local time on July 31, 2011 as well as the tornado characteristics. The tornado was formed near the center of the city, then crossed it and caused significant damage. The tornado is classified in EF2 category of the Enhanced Fujita-Pearson scale. Atmospheric conditions near Blagoveshchensk on July 31, 2011 were favorable for the tornado initiation which occurred in the frontal zone of the cyclone over the warm underlying surface. The analysis of meteorological conditions during the tornado event are presented. A numerical study of the tornado was conducted to clarify its characteristics and environmental conditions during the event.
TL;DR: In this article, the first empirical orthogonal function of intraannual evolution of temperature averaged along the circle of latitude in the 0-60km layer is calculated using the data of the 500-year preindustrial experiment with the climate model of the Institute of Numerical Mathematics of Russian Academy of Sciences (INM RAS).
Abstract: The first empirical orthogonal function (EOF) of intraannual evolution of temperature averaged along the circle of latitude in the 0-60-km layer is calcul ated using the data of the 500-year preindustrial experiment with the climate model of the Institute of Numerical Mathematics of Russian Academy of Sciences (INM RAS). It is shown that the first EOF represents temperature anomalies which propagate downward from the upper stratosphere during December-April. Such anomalies are preceded by the anomaly of the meridional heat flux in the polar upper stratosphere in December. Using the ensemble of numerical experiments with the climate model, it was demonstrated that it is possible to predict the projection of temperature anomaly corresponding to the first EOF in December-April, to the first mode according to initial data for December 1.
TL;DR: In this paper, the authors analyzed long-term changes in peak spring runoff and daily minimum winter and summer-autumn runoff in the Volga River basin based on observational data from 94 gaging stations.
Abstract: Long-term changes in peak spring runoff and daily minimum winter and summer-autumn runoff in the Volga River basin are analyzed based on observational data from 94 gaging stations. It is revealed that climate changes in the basin during the period from the late 1970s till the middle of the 1980s led to the significant increase in minimum discharge, but maximum runoff changed ambiguously. The regions with the disturbed uniformity of the series of extreme values of river runoff are identified. Changes in the values of high runoff, above the 10% probability, and low runoff, below the 90% probability, are analyzed for current climate conditions. Under nonstationary conditions, it is recommended to assess the probability characteristics of extreme runoff with compound distribution curves or based on the Bayesian approach.
TL;DR: In this paper, changes in the runoff regime of Russian rivers and in the water inflow to reservoirs as a result of the climate warming observed in the country since the second half of the 1970s are considered.
Abstract: Changes are considered in the runoff regime of Russian rivers and in the water inflow to reservoirs as a result of the climate warming observed in the country since the second half of the 1970s Based on the analysis of long–term observational data on water inflow to 41 large reservoirs with the volume of 10 x 106 m3, it is shown that considerable changes in its intraannual distribution have occurred in the recent decades These changes are characterized, in particular, by the inflow increase during the cold season and by the runoff variability increasing in winter and summer–autumn seasons The growth of the number of severe hydrological events, especially of flash floods induced by rainfalls, has been registered in the recent decades Potential future changes in water inflow to reservoirs are considered in accordance with the scenarios of further climate warming It is justified that rules of using water resources of reservoirs should be corrected taking into account the observed changes in the river water inflow regime
TL;DR: In this article, a method is proposed for calculating the effective thermal conductivity of snow cover based on the data on snow surface temperature and soil temperature measured at weather stations, and quantitative estimates of the snow cover effect on soil temperature are presented.
Abstract: A method is proposed for calculating the effective thermal conductivity of snow cover based on the data on snow surface temperature and soil temperature measured at weather stations. The quantitative estimates of the snow cover effect on soil temperature are presented. The spatial differences in this effect are described. The results obtained significantly enhance the opportunities of applying simple models to forecast permafrost conditions under the climate change.
TL;DR: In this article, an attempt is made to identify the response of forest stands to recent climate change in the north of the European part of Russia using the series of Scots pine linear increments.
Abstract: An attempt is made to identify the response of forest stands to recent climate change in the north of the European part of Russia using the series of Scots pine linear increments. These series are a useful instrument for assessing the spatial variability of internode growth parameters during short (to 30 years) periods. Linear dendrochronological data allow separating climatogenic reactions of organisms from the interannual variability of increments. In other words, this method allows reducing the level of noise which masks the sought dependences.
TL;DR: In this paper, the results of complex investigation of clouds in India which were seeded with a glaciogenic reagent from the aircraft were presented by the comparison of radar characteristics of the seeded clouds with the characteristics of clouds within the radar field of view.
Abstract: The results are presented of complex investigation of clouds in India which were seeded with a glaciogenic reagent from the aircraft. The seeding effect was assessed by the comparison of radar characteristics of the seeded clouds with the characteristics of clouds within the radar field of view. The maximum reflectivity increase in the seeded clouds in comparison with clouds in the natural cycle, an increase in the precipitation flux and specific mass of precipitated hail are observed. The merging of seeded clouds was observed during the study. It is shown that this process affects cloud characteristics resulting in the significant (by several times) increase in the precipitation flux. The measurements of electric discharges registered by the lightning detection network demonstrated that there were no lightning strikes in the seeded clouds, although the calculations indicated an increase in the electric activity of the clouds.
TL;DR: In this article, the effects of these processes on the tropospheric circulation and weather conditions in the middle and high latitudes via the reflection of wave activity from the stratosphere are investigated.
Abstract: The dynamic coupling between the stratospheric and tropospheric processes is studied for the sudden stratospheric warming registered in January-February 2017. Also, the effects of these processes on the tropospheric circulation and weather conditions in the middle and high latitudes via the reflection of wave activity from the stratosphere are investigated.
TL;DR: In this article, the results of atmospheric electricity measurements are presented which were conducted at observation points of different types: at the urban point (Rostov-on-Don), at the point near the Sea of Azov (Taganrog and Primorka), and at the high-mountain point (Cheget Peak) near Elbrus.
Abstract: The results of atmospheric electricity measurements are presented which were conducted at observation points of different types: at the urban point (Rostov-on-Don), at the point near the Sea of Azov (Taganrog and Primorka), and at the high-mountain point (Cheget Peak) near Elbrus. The patterns of spatiotemporal variations in electrical conductivity (concentration of light ions) of the atmospheric surface layer are revealed for different conditions. The impact of natural radioactivity and aerosol pollution on the concentration of light ions is assessed for observation points near the Taganrog Bay (the Sea of Azov). The results of the comparative analysis of urban and high-mountain data of atmospheric electricity observations are presented.
TL;DR: In this paper, the estimates of nocturnal area fluxes for CO2, CH4, and CO presented for a suburb of Saint Petersburg (Peterhof) are obtained using the box model and continuous observations of concentration of these gases.
Abstract: Carbon dioxide, methane, and carbon monoxide are the carbon cycle gases, the data on their emissions are needed when monitoring air pollution and developing methods for reducing anthropogenic emissions to the atmosphere and for climate forecasting. The estimates of nocturnal area fluxes for CO2, CH4, and CO presented for a suburb of Saint Petersburg (Peterhof) are obtained using the box model and continuous observations of concentration of these gases. The mean values of CH4, CO2, and CO fluxes estimated for Peterhof for 2014–2015 are 44 ± 27, 6100 ± 4000, and 90 ± 100 t/(km2 year), respectively. The intensity of the CO area flux has pronounced seasonal variations characterized by the maximum of ~(160 ± 120) t/(km2 year) in November—February and by the minimum of ~(30 ± 20) t/(km2 year) in June-July. The analysis of the ratio of CO/CO2 fluxes identified the main types of anthropogenic sources typical of Peterhof: motor transport, natural gas combustion, and the use of wood stoves for the heating of private low-rise buildings (in the cold season).
TL;DR: The modern steppe zone of Eurasia is an active arena for the blowing of mineral matter out of the land surface and for its incorporation to the global process of exchange of matter and energy as mentioned in this paper.
Abstract: The modern steppe zone of Eurasia is an active arena for the blowing of mineral matter out of the land surface and for its incorporation to the global process of exchange of matter and energy. The ploughed soil of the steppe zone used in agriculture annually loses tens of tons of fine earth from each hectare. This reduces the natural fertility of lands and quickens the general degradation of steppe ecosystems. This occurs especially intensively during blocking processes, when a strong anticyclone sets in over southeastern Europe. In this case, the energy wind load on the soil surface increases by one or two orders of magnitude as compared to the normal, and its destruction becomes catastrophic. In the zone where airflows converge in the steppes of the Lower Volga, Caspian region, and Ciscaucasia, wind-blown mineral substances are transported in the storm zone for a distance of 2000 km and are accumulated on the land surface in Central and northwestern Europe.
TL;DR: In this article, the long-term values for the annual sum of active temperatures in the surface air layer and for total precipitation during the vegetation period (May-September) in Russia and neighboring countries for two time periods: 1951-1970 and 1991-2010.
Abstract: The long–term values are calculated for the annual sum ofactive temperatures in the surface air layer and for total precipitation during the vegetation period (May–September) in Russia and neighboring countries for two time periods: 1951–1970 and 1991–2010. The statistical procedures are used to demonstrate the reliability of differences in the values of these parameters for the analyzed time periods. The sum of active temperatures significantly increased almost on the whole territory of Russia except for some Arctic and Far East regions. The spatial variations in total precipitation during the vegetation period are obviously inhomogeneous.
TL;DR: In this article, a complex approach is considered to the estimation of emissions of carbon gases formed during wildfires in the middle taiga subzone in the Yenisei region of Siberia.
Abstract: A complex approach is considered to the estimation of emissions of carbon gases formed during wildfires in the middle taiga subzone in the Yenisei region of Siberia. Based on the large-scale Siberian wildfires in 2012, the relative contribution of emissions to the values of background concentration of carbon gases (CO2, CH4, CO) in the atmospheric boundary layer measured at the 300-m ZOTTO tall tower is assessed. The degree of ecosystem damage caused by wildfires is estimated depending on their intensity and combustion phase (flame or flameless). Emission factors are calculated for the major carbon gases in wildfire plumes which are the key component for assessing wildfire emissions to the atmosphere.
TL;DR: In this article, the most important specialized indicators of the thermal and moisture regimes which characterize climatic impacts on the economic development of the Russian Arctic in the 21st century are presented.
Abstract: The problem of increasing the informativeness of climate projections in the Russian Arctic in order to meet the current economy needs is considered. The detailed estimates are presented of changes for the most important specialized indicators of the thermal and moisture regimes which characterize climatic impacts on the economic development of the Russian Arctic in the 21st century. The calculations are based on the data of numerical experiments with the regional climate model which were conducted for the Arctic region in the framework of the international CORDEX project. The high resolution of the model (50 km) and the consideration of mesoscale factors helped to detect significant spatial differences in the estimates of changes in the analyzed parameters which should be taken into account when adapting to climate change at the regional level.
TL;DR: In this article, the authors used new oceanographic observations for studying the Kamchatka Current and the Alaskan Stream and its Aleutian eddies in 1990-2017.
Abstract: New oceanographic observations are used for studying the Kamchatka Current and the Alaskan Stream and its Aleutian eddies in 1990–2017. The Aleutian eddies are mesoscale anticyclonic eddies that are formed within the Alaskan Stream southward of the Aleutian Islands be tween 170° and 180° E and are moving to the southwest. The rapid freshening of the upper layer and the increase in tem-perature and salinity in the Kamchatka Current halocline are detected. In the upper layer of the Kamchatka Current, salinity decreased by 0.2 psu per 27 years. The most rapid variations in salinity and temperature have been observed in recent years. In the halocline (at the isopycnic of 26.75σθ) temperature rose by 1.4°C and salinity in creased by 0.15 psu. The maximum temperature of the warm intermediate layer in the Kamchatka Current exceeded 4°C for the first time. The most likely reason for the temperature and salinity increase in the halocline is the transport of warm and salt water by the Aleu-tian eddies.