Influence of internal gravity waves on meteorological fields and gas constituents near Moscow and Beijing

The influence of internal gravity waves on the spatial coherence and temporal variability of the atmospheric pressure, wind velocity, and gas constituents near Moscow and Beijing is studied in the mesoscale range of periods: from a few tens of seconds to several hours. The results of simultaneous measurements of variations in the atmospheric pressure (using a network of spaced microbarographs), wind velocity at different heights of the atmospheric boundary layer, and gas constituents are given for each city. The wave structures are filtered using a coherence analysis of the atmospheric pressure variations at different measurement sites. The dominant periods and the coherences, phase speeds, and horizontal scales of variations corresponding to these periods are estimated. The general mechanism of the influence of wave structures on meteorological fields and gas constituents is discussed, which is independent of the measurement site and the specificity of meteorological conditions.     

Analysis of time series of global mean values of thermodynamic and circulation parameters of the atmosphere and concentrations of ozone and water vapor

Models for global mean values of temperature; air, ozone, and water-vapor concentrations; and zonal and meridional winds at heights of 0–45 km are developed and constructed from data of the European ERA-40 and Era Interim databases over the period 1958–2007. An analysis of the time series consists of the decomposition of parameter values into harmonic, trend, and pulsation components. A comparative analysis of these models is performed, and a relationship between the global mean ozone concentration and solar activity is detected. A hypothesis about the physical mechanism for the relationship between the total ozone concentration (TOC) and solar activity is proposed.     

The Aleutian Low, storm tracks, and winter climate variability in the Bering Sea

Previous studies have found inconsistent results regarding how wintertime conditions in the Bering Sea relate to variations in the North Pacific climate system. This problem is addressed through analysis of data from the NCEP/NCAR Reanalysis for the period 1950–2003. Composite patterns of sea-level pressure, 500 hPa geopotential heights, storm tracks and surface air temperature are presented for four situations: periods of strong Aleutian Low, weak Aleutian Low, warm Bering Sea air temperatures, and cold Bering Sea air temperatures. Winter temperatures in the Bering Sea are only marginally related to the strength of the Aleutian Low, and are much more sensitive to the position of the Aleutian Low and to variations in storm tracks. In particular, relatively warm temperatures are associated with either an enhanced storm track off the coast of Siberia, and hence anomalous southerly low-level flow, or an enhanced storm track entering the eastern Bering Sea from the southeast. These latter storms do not systematically affect the mean meridional winds, but rather serve to transport mild air of maritime origin over the Bering Sea. The leading indices for the North Pacific, such as the NP and PNA, are more representative of the patterns of tropospheric circulation and storm track anomalies associated with the strength of the Aleutian Low than patterns associated with warm and cold wintertime conditions in the Bering Sea.     

Analysis of the weekly cycle in the atmosphere near Moscow

Using the spectral method and the method of grouping by days of week, we analyzed the weekly cycles by standard air sounding data obtained at the Dolgoprudny station near Moscow and by the results of measurements of NO₂ content in the stratosphere and the atmospheric boundary layer at the Zvenigorod Research Station of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, in 1990–2010. We revealed weekly cycles of the NO₂ content in the vertical column of the stratosphere, temperature, geopotential, meridional wind velocity in the troposphere and lower stratosphere, and the tropopause height in the warm half of the year (mid-April to mid-October). The weekly variations in temperature in the troposphere are positive in the first half of the week and negative in the second half, and the variations in temperature in the tropopause layer and in the lower stratosphere are opposite in sign to the tropospheric variations. The weekly cycle of the tropopause height is approximately in phase with the cycle of tropospheric temperature, and the weekly cycle of the NO₂ content in the stratospheric column is opposite in phase to the cycle of the tropopause height. Weekly variations were also observed in the total ozone content over Moscow. This finding was confirmed by calculations based on regression relationships between the vertical distribution of ozone and tropopause height. Conceptual mechanisms of weekly cycles were proposed.     

Diurnal variations in the intensity of tropical cyclones

We statistically study diurnal variations in the maximum wind velocity in tropical cyclones on the basis of vast experimental material. We have found notable oscillations in the acceleration of rotation velocity (rate of variations in the maximum wind velocity), which are most pronounced in the periods of intensification and decay of the cyclones. The diurnal variations can differ notably in phase in different geographical conditions.     

Spatio-Temporal Variability of the Phase of Total Ozone Quasi-Decennial Oscillations

The SBUV/SBUV2 (65° S–65° N) and Bodeker Scientific (90° S–90° N) satellite databases have been used for composite and cross-wavelet analyses of the spatio-temporal variability of phase relations between a 11-year cycle of solar activity (SA) and quasi-decennial oscillations (QDOs) of total ozone content (TOC). For globally average TOC values, the QDO maxima coincide in phase with the solar-activity maxima, and amplitude variations of TOC correlate with those of the 11-year solar cycle. According to the analysis of amplitude and phase of QDOs for the zonal average TOC fields, a QDO amplitude is about 6–7 Dobson Units (DU) in the high northern and southern latitudes, and it does not exceed 2–3 DU in the tropic regions. The latitudinal TOC variations are distinguished by a delay of the quasi-decennial oscillation phase in the southern latitudes in comparison with the northern latitudes. The TOC maxima phase coincides with the SA maxima phase in the tropic regions; the TOC variations go ahead of the SA variations, on average, in moderate and high latitudes of the Northern Hemisphere; the TOC variations are behind the SA variations in the Southern Hemisphere. The phase delay between TOC QDO maxima in the northern and southern latitudes appears to increase in the course of time, and the TOC quasi-decennial variations in the Arctic and Antarctic subpolar regions occur approximately in an antiphase over the last two decades.     

Effects of the equatorial quasi-biennial oscillation in the total ozone content over Russia

On the basis of ground-based measurements of total ozone content (TOC) over Russia and a number of neighboring states during 1973–2002, the amplitudes and phases of TOC variations caused by the quasi-biennial oscillation (QBO) of wind in the equatorial stratosphere are estimated for different regions and for the whole area. The seasonal dependence of the QBO effect in the TOC is analyzed. It is shown that the magnitude and even the sign of the effect depend on the relation between the equatorial QBO phase and the season. The regional empirical models of seasonally dependent QBO effects are constructed. It is found that the seasonal dependence of regional effects accounts for 4% (in the north of the area) to 20% (in the south) of the interannual variability of the TOC. The relation between the QBO effect and the 11-year cycle of solar activity is analyzed. Significant differences are revealed in the effects under the conditions of maximum and minimum solar activity. The QBO effects obtained from observations at Russian stations, satellite measurements with a TOMS instrument, and spectrometric observations of the TOC at western European stations are compared, and their satisfactory agreement is shown. An analysis of the results suggests that the QBO effects in the TOC over Russia are caused by several interacting factors and apparently reflect their regional properties.     

Seasonal features of quasi-biennial variations of NO<Subscript>2</Subscript> stratospheric content derived from ground-based measurements

Seasonal and latitudinal distributions of amplitudes of quasi-biennial variations in total NO₂ content (NO₂ TC), total ozone content (TOC), and stratospheric temperature are obtained. NO₂ TC data from ground-based spectrometric measurements within the Network for the Detection of Atmospheric Composition Change (NDACC), TOC data from satellite measurements, and stratospheric temperature data from ERA-Interim reanalysis are used for the analysis. The differences in the NO₂ TC diurnal cycles are identified between the westerly and easterly phases of the quasi-biennial oscillations (QBO) of equatorial stratospheric wind. The QBO effects in the NO₂ TC, TOC, and stratospheric temperature in the Northern (NH) and Southern (SH) hemispheres are most significant in the winter–spring periods, with essential differences between the NH and SH. The NO₂ TC in the Antarctic is less for the westerly phase of the QBO than that for the easterly phase, and the NO₂ TC quasi-biennial variations in the SH mid-latitudes are opposite of the variations in the Antarctic. In the NH, the winter values of the NO₂ TC are generally less during the westerly QBO phase than during the easterly phase, whereas in spring, on the contrary, the values for the westerly QBO phase exceed those for the easterly phase. Along with NO₂, the features of the quasi-biennial variations of TOC and stratospheric temperature are discussed. Possible mechanisms of the quasi-biennial variations of the analyzed parameters are considered for the different latitudinal zones.     

Climatic variability of transport in the upper layer of the Antarctic Circumpolar Current from hydrological and satellite data

Based on the satellite altimetry dataset of sea level anomalies, the climatic hydrological database World Ocean Atlas-2009, ocean reanalysis ECMWF ORA-S3, and wind velocity components from NCEP/NCAR reanalysis, the interannual variability of Antarctic Circumpolar Current (ACC) transport in the ocean upper layer is investigated for the period 1959–2008, and estimations of correlative connections between ACC transport and wind velocity components are performed. It has been revealed that the maximum (by absolute value) linear trends of ACC transport over the last 50 years are observed in the date-line region, in the Western and Eastern Atlantic and the western part of the Indian Ocean. The greatest increase in wind velocity for this period for the zonal component is observed in Drake Passage, at Greenwich meridian, in the Indian Ocean near 90° E, and in the date-line region; for the meridional component, it is in the Western and Eastern Pacific, in Drake Passage, and to the south of Africa. It has been shown that the basic energy-carrying frequencies of interannual variability of ACC transport and wind velocity components, as well as their correlative connections, correspond to the periods of basic large-scale modes of atmospheric circulation: multidecadal and interdecadal oscillations, Antarctic Circumpolar Wave, Southern Annual Mode, and Southern Oscillation. A significant influence of the wind field on the interannual variability of ACC transport is observed in the Western Pacific (140° E–160° W) and Eastern Pacific; Drake Passage and Western Atlantic (90°–30° W); in the Eastern Atlantic and Western Indian Ocean (10°–70° E). It has been shown in the Pacific Ocean that the ACC transport responds to changes of the meridional wind more promptly than to changes of the zonal wind.     

Studying internal gravity waves generated by atmospheric fronts over the Moscow region

Internal gravity wave (IGW) data obtained during the passage of atmospheric fronts over the Moscow region in June–July 2015 is analyzed. IGWs were recorded using a group of four microbarographs (developed at the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences) located at distances of 7 to 54 km between them. Regularities of variations in IGW parameters (spatial coherence, characteristic scales, propagation direction, horizontal propagation velocity, and amplitudes) before, during, and after the passage of an atmospheric front over the observation network, when the observation network finds itself inside the cyclone and outside the front, are studied. The results may be useful in studying the relationships between IGW effects in different physical fields at different atmospheric heights. It is shown that, within periods exceeding 30 min, IGWs are coherent between observation points horizontally spaced at distances of about 60 km (coherence coefficient is 0.6–0.9). It is also shown that there is coherence between wave fluctuations in atmospheric pressure and fluctuations in horizontal wind velocity within the height range 60–200 m. A joint analysis of both atmospheric pressure and horizontal wind fluctuations has revealed the presence of characteristic dominant periods, within which cross coherences between fluctuations in atmospheric pressure and wind velocity have local maxima. These periods are within approximate ranges of 20–29, 37–47, 62–72, and 100–110 min. The corresponding (to these dominant periods) phase propagation velocities of IGWs lie within an interval of 15–25 m/s, and the horizontal wavelengths vary from 52 to 99 km within periods of 35 to 110 min, respectively.     

Statistics of Wind and Waves off Tsuyazaki, Fukuoka, in the Eastern Tsushima Strait

The variability of the sea surface wind and wind waves in the coastal area of the Eastern Tsushima Strait was investigated based on the hourly data from 1990 to 1997 obtained at a station 2 km off Tsuyazaki, Fukuoka. The annual mean wind speed was 4.84 m s⁻¹, with strong northwesterly monsoon in winter and weak southwesterly wind in summer. Significant wave heights and wave periods showed similar sinusoidal seasonal cycles around their annual means of 0.608 m and 4.77 s, respectively. The seasonal variability relative to the annual mean is maximum for wave heights, medium for wind speeds, and minimum for wave periods. Significant wave heights off Tsuyazaki turned out to be bounded by a criterion, which is proportional to the square of the significant wave period corresponding to a constant steepness, irrespective of the season or the wind speed. For terms shorter than a month, the significant wave height and the wave period were found to have the same spectral form as the inshore wind velocity: white for frequencies less than 0.2 day⁻¹ and proportional to the frequency to the −5/3 power for higher frequencies, where the latter corresponds to the inertial subrange of turbulence. The spectral levels of wave heights and wave periods in that inertial range were also correlated with those of the inshore wind velocity, though the scatter was large. This revised version was published online in August 2006 with corrections to the Cover Date.     

基于Copula函数的海岸增水高度与相应风速的遭遇概率分析

简要论述了Copula理论与几种常用的二维Archimedean Copula函数的性质和适用性。以粤东汕头海域妈屿历年最高增水高度与相应风速的遭遇为研究实例,在分别采用3个三参数的概率分布模式:广义极值分布(GEV)、Weibull分布(WBL)和皮尔逊Ⅲ型(P-Ⅲ)分布对两个边缘分布(年最高增水高度与相应风速)拟合优度检验基础上构建了两变量联合概率分布模型。主要结果如下:(1) 年最大增水高度与相应风速的边缘分布分别服从Weibull分布和P-Ⅲ型分布;(2) 拟合优度检验指标表明二者的最优连接函数为Archimedean Copula类的Gumbel-Hougaard Copula;(3) 重现期介于2~200 a之间的边缘分布与同频率的联合分布的重现水平相对差值大约介于6.7%~22.2%之间;(4) 特定风速设计频率条件下,随年最大增水设计频率的减小,二者的遭遇概率也随之迅速减小;反之,特定增水设计频率随风速条件频率的减小,二者的遭遇概率随之明显增大。     

Long-term variability of oceanic frontal zones associated with large-scale atmospheric forcing

Global satellite sea surface temperature (SST) measurements and NCEP/NCAR reanalysis wind data for the period of 1982–2009 have been used to study the relationship between long-term variability of oceanic frontal zones (OFZ) and large-scale atmospheric forcing. Statistically significant positive correlations between the maximum magnitude of the meridional gradient of zonally averaged SST and meridional shear of zonal wind (which is an estimate of the Ekman convergence intensity) were found for all subpolar and subtropical OFZ of the World Ocean. Variability of the latitudinal position of OFZ cores may be associated with Ekman advection variability due to zonal wind variations. Strengthening of zonal wind results in a shift of subpolar OFZ cores to the south/north in the Northern/Southern hemispheres.     

Temporal Variability of Total Ozone in the Asian Region Inferred from Ground-Based and Satellite Measurement Data

This paper reports investigation data on the temporal variability of total ozone content (TOC) in the Central Asian and Tibet Plateau mountain regions obtained by conventional methods, as well as by spectral, cross-wavelet, and composite analyses. The data of ground-based observation stations located at Huang He, Kunming, and Lake Issyk-Kul, along with the satellite data obtained at SBUV/SBUV2 (SBUV merged total and profile ozone data, Version 8.6) for 1980–2013 and OMI (Ozone Monitoring Instrument) and TOU (Total Ozone Unit) for 2009–2013 have been used. The average relative deviation from the SBUV/SBUV2 data is less than 1% in Kunming and Issyk-Kul for the period of 1980–2013, while the Huang He Station is characterized by an excess of the satellite data over the ground-based information at an average deviation of 2%. According to the Fourier analysis results, the distribution of amplitudes and the periods of TOC oscillations within a range of over 14 months is similar for all series analyzed. Meanwhile, according to the cross-wavelet and composite analyses results, the phase relationships between the series may considerably differ, especially in the periods of 5–7 years. The phase of quasi-decennial oscillations in the Kunming Station is close to the 11-year oscillations of the solar cycle, while in the Huang He and Issyk-Kul stations the TOC variations go ahead of the solar cycle.     

Forecasting the western Pacific subtropical high index during typhoon activity using a hybrid deep learning model

Seasonal location and intensity changes in the western Pacific subtropical high(WPSH) are important factors dominating the synoptic weather and the distribution and magnitude of precipitation in the rain belt over East Asia. Therefore, this article delves into the forecast of the western Pacific subtropical high index during typhoon activity by adopting a hybrid deep learning model. Firstly, the predictors, which are the inputs of the model, are analysed based on three characteristics: the first...     

Interhemispheric distinctions between the polar vortex positions in the winter stratosphere and mesosphere from measurements with a SABER instrument aboard the TIMED satellite

Distinctions between the longitudinal structures of circulation in the stratosphere and mesosphere/lower thermosphere of the Northern and Southern hemispheres are investigated on the basis of the temperature and geopotential distributions obtained with a SABER instrument (TIMED satellite) in the months of February and August in 2002–2005. The positions of the winter cyclone and polar vortex at stratospheric and mesospheric heights in 2002–2005 are compared to the climatic data over 1978–1998. At stratospheric heights, the mean position of the polar vortex’s center over several years changed insignificantly during the specified years (several degrees in latitude and longitude) in both the Southern and Northern hemispheres. At mesosphere/lower thermosphere heights, the polar vortex occupies the same position in the Southern Hemisphere each year during 2002–2005, and this position agrees with the estimates for 1996–1997. Parameters of stationary planetary waves with the zonal wave number 1 (SPW1) in the fields of temperature, geopotential, and wind are calculated from data on the temperature and geopotential. The height profiles of SPW1 amplitudes and phases calculated from the SABER instrument data for August in the Southern Hemisphere are in good agreement with the profiles of amplitudes and phases obtained from the direct wind measurements with HRDI and WINDII instruments. A strong interannual variability of SPW1 parameters is observed in the Northern Hemisphere. The calculation of the Eliassen-Palm flux and its divergence has shown that SPW1 penetrates into the mesosphere mainly from the stratosphere and slows down the zonal mean flux. However, in the Southern Hemisphere, there is a regular additional SPW1 source with the center at a height of about 65 km and a latitude of 55°S. Such a SPW1 source is, on average, absent in the Northern Hemisphere during 2002–2005; however, in some years (for example, in February 2004), its existence is possible.     

Height-season structure of the available potential energy and kinetic energy in the lower and middle atmosphere

The distributions of kinetic energy (KE) and available potential energy (APE) in the lower and middle atmosphere of the Northern and Southern hemispheres over the period 1992–2003 are investigated. Annual mean values of the amplitude and phase of annual and semiannual oscillations in the zonal and eddy forms of KE and APE are calculated in the height range 0–55 km (1000–0.316 hPa) for the 21st layer. A clearly pronounced annual cycle of the zonal and eddy components of KE and APE with maxima in the winter season are observed in the troposphere of both hemispheres. In the lower stratosphere, the annual-cycle maximum is shifted toward the summer season because of the meridional gradient of the zonal mean temperature. In the stratosphere of both hemispheres, along with annual oscillations, semiannual oscillations are present in all forms of energy. The intensity of these oscillations for the zonal KE and APE at the upper-stratosphere heights is comparable to the intensity of annual oscillations. A local structure of the energy regime of the upper mesosphere-lower thermosphere is investigated against the background of the global energy regime from the data of meteor sounding in Kazan. It is shown that, for both the global and regional regimes, specific features of the phase profiles of energy characteristics can be explained by the presence of barriers during the propagation of wave disturbances along the vertical.     

Spatial and temporal structure of Tropical Pacific interannual variability in 20th century coupled simulations

Tropical Pacific interannual variability is examined in nine state-of-the-art coupled climate models, and compared with observations and ocean analyses data sets, the primary focus being on the spatial structure and spectral characteristics of El Niño-Southern Oscillation (ENSO). The spatial patterns of interannual sea surface temperature (SST) anomalies from the coupled models are characterized by maximum variations displaced from the coast of South America, and generally extending too far west with respect to observations. Thermocline variability is characterized by dominant modes that are qualitatively similar in all the models, and consistent with the “recharge oscillator” paradigm for ENSO. The meridional scale of the thermocline depth anomalies is generally narrower than observed, a result that can be related to the pattern of zonal wind stress perturbations in the central-western equatorial Pacific. The wind stress response to eastern equatorial Pacific SST anomalies in the models is narrower and displaced further west than observed. The meridional scale of the wind stress can affect the amount of warm water involved in the recharge/discharge of the equatorial thermocline, while the longitudinal location of the wind stress anomalies can influence the advection of the mean zonal temperature gradient by the anomalous zonal currents, a process that may favor the growth and longer duration of ENSO events when the wind stress perturbations are displaced eastwards. Thus, both discrepancies of the wind stress anomaly patterns in the coupled models with respect to observations (narrow meridional extent, and westward displacement along the equator) may be responsible for the ENSO timescale being shorter in the models than in observations. The examination of the leading advective processes in the SST tendency equation indicates that vertical advection of temperature anomalies tends to favor ENSO growth in all the CGCMs, but at a smaller rate than in observations. In some models it can also promote a phase transition. Longer periods tend to be associated with thermocline and advective feedbacks that are in phase with the SST anomalies, while advective tendencies that lead the SST anomalies by a quarter cycle favor ENSO transitions, thus leading to a shorter period.     

Meridional mass and energy fluxes in the vicinity of the Arctic border

The air exchange between the Arctic and midlatitude regions is one of the processes forming the climate of the whole Northern Hemisphere. Analysis of the wind regime in the vicinity of the Arctic border (70° N) at the boundary between the 20th and 21st (1997–2004) centuries showed significant changes in the conditions of a meridional air transport between the Arctic and midlatitude regions as compared to the previous years (1960–1990). In this study, the wind fluxes of mass and heat (internal) and kinetic energies are estimated without consideration for turbulent and convective processes. The importance of spatial, seasonal, and interannual variations in wind velocity and air temperature in the formation of these fluxes is analyzed. It is shown that, during the period 1997–2004, an advective transport of energy from the northern latitudes occurred in the lower 6-km tropospheric layer at 70° N latitude over almost a whole year. Only in spring (April) did the wind fluxes bring heat energy from the south. The total amount of both heat and kinetic energies transported from the Arctic region in this way during a year is comparable to the mean amount of these energies contained in the whole atmosphere over the area bounded by 70° N latitude. The current spatial and temporal distributions of wind velocity and meridional mass and energy fluxes, which are presented in this study, may serve as additional information for interpreting data obtained from different on-site measurements in Arctic regions.     

Sudden stratospheric warmings: statistical characteristics and influence on NO<Subscript>2</Subscript> and O<Subscript>3</Subscript> total contents

Statistical characteristics of major and minor sudden stratospheric warmings (SSWs) in the Northern Hemisphere (NH) for 1958–2015 are analyzed using data of NCEP-NCAR, ERA 40, and ERA-Interim reanalyses. Dependencies of the number of major SSWs with the displacement of the circumpolar stratospheric vortex and the number of minor SSWs on the phase of the quasi-biennial oscillation (QBO) of the equatorial stratospheric wind and on the level of solar activity (SA) in the 11-year solar cycle have been revealed. Major SSWs accompanied by a displacement of the polar vortex occur more often at a high level of SA and at the easterly phase of the QBO in the 50–40 hPa layer, while minor SSWs occur more often at a low SA level and at the westerly phase of the QBO. An analysis of spatiotemporal dynamics of the stratospheric polar vortex at major SSWs is performed. The most probable directions of vortex displacement caused by SSWs have been revealed. Influences of the major SSWs on the total contents of NO₂ and ozone, as well as on stratosphere temperature, are analyzed.