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.     

Multidecadal climate variability in the subtropics/mid‐latitudes of the Southern Hemisphere oceans

Observations of multidecadal variability in sea surface temperature (SST), surface air temperature and winds over the Southern Hemisphere are presented and an ocean general circulation model applied towards investigating links between the SST variability and that of the overlying atmosphere. The results suggest that the dynamical effect of the wind stress anomalies is significant mainly in the neighbourhood of the western boundary currents and their outflows across the mid‐latitudes of each Southern Hemisphere basin (more so in the South Indian and South Atlantic than in the South Pacific Ocean) and in the equatorial upwelling zones. Over most of the subtropics to mid‐latitudes of the Southern Hemisphere oceans, changes in net surface heat flux (particularly in latent heat) appear to be more important for the SST variability than dynamical effects. Implications of these results for modelling and understanding low frequency climate variability in the Southern Hemisphere as well as possible links with mechanisms of decadal/interdecadal variability in the Northern Hemisphere are discussed.     

Numerical simulation of wave interactions during sudden stratospheric warming

Parameterizations of normal atmospheric modes (NAMs) and orographic gravity waves (OGWs) are implemented into the mechanistic general circulation model of the middle and upper atmosphere (MUA). Numerical experiments of sudden stratospheric warming (SSW) events are performed for climatological conditions typical for January and February using meteorological reanalysis data from the UK MET Office in the MUA model averaged over the years 1992–2011 with the easterly phase of quasi-biennial oscillation (QBO). The simulation shows that an increase in the OGW amplitudes occurs at altitudes higher than 30 km in the Northern Hemisphere after SSW. The OGW amplitudes have maximums at altitudes of about 50 km over the North American and European mountain systems before and during SSW, as well as over the Himalayas after SSW. At high latitudes of the Northern Hemisphere, significant (up to 50–70%) variations in the amplitudes of stationary planetary waves (SPWs) are observed during and after the SSW. Westward travelling NAMs have local amplitude maximums not only in the Northern Hemisphere, but also in the Southern Hemisphere, where there are waveguides for the propagation of these modes. Calculated variations of SPW and NAM amplitudes correspond to changes in the mean temperature and wind fields, as well as the Eliassen-Palm flux and atmospheric refractive index for the planetary waves, during SSW. Including OGW thermal and dynamical effects leads to an increase in amplitude (by 30–70%) of almost all SPWs before and during SSW and to a decrease (up to 20–100%) after the SSW at middle and high latitudes of the Northern Hemisphere.     

南印度洋副热带偶极子型海温异常与全球环流和我国降水变化的关系

用1951~2001年观测资料,研究了南印度洋副热带偶极子型(IOSD)海温异常对全球500hPa环流和我国降水的影响.结果表明,冬季IOSD激发出极显著的南北半球环绕太平洋的波列结构(CP),其年际变化周期是2.0和6.5 a,与赤道中东太平洋海温也有密切联系.北半球冬季异常峰值后的第二年春季欧亚中高纬度地区500 hPa环流出现显著的EUP型低频流型持续异常,同时中太平洋和北美地区出现CPNP流型和澳大利亚南部的南半球中高纬地区呈现极显著的西南太平洋遥相关型(SWP).当冬季赤道南印度洋副热带呈极显著的西负东正海温距平分布时,后期春季欧亚中高纬地区负EUP型遥相关波列持续偏强,导致东亚大槽明显偏弱,长江以北地区(特别是黄河中上游地区)多雨.反之,春季东亚大槽加强且稳定,我国东部地区大范围少雨.它反映了南印度洋地区海气系统相互作用与东亚热带内外环流低频变化的联系.因此,上一年冬季南印度洋副热带偶极子型(IOSD)海温异常强度是预测春季华北地区旱涝变化的重要因子之一.     

Relationship between transitional variation of summer sea surface temperature in the northwestern Pacific and ocean events during the 1960s

INTRODUCTIONIt has been pointed out in recent years by Yan et al. (1990 a, b) through analyses of timeand space variations in the different elements in the summer of the Northern Hemisphere during1951 ~ 1980 that climate jump generally occurred in the summer of the Northern Hemisphere during the 1960s, in which geopotential height on 500 hPa in the Northern Hemisphere, the nearsurface air temperature and the SST of the northwestern Pacific appeared in the early of the1960's (Fig. 1).T…     

全球越赤道气流基本特征

本文主要利用1973～1989年逐月全球热带200hPa及850hPa层经、纬向格点风及1980年以来1000,850,700,500,200,100,50hPa各层经纬向格点风,确定了热带对流层高、低(200,850hPa)层具有气候意义的越赤道气流通道,并分析了各越赤道气流通道强度的时、空变化特征。指出东半球比西半球越赤道气流强且稳定,季节变化也较明显。文章还指出,低层东半球向夏半球输送,高层夏半球向冬半球输送,且高、低层各相应通道强度变化趋势基本一致。高层与低层相比较,低层通道强且稳定,季节变化规律也较明显。文章还讨论了越赤道气流与大气环流系统的密切关系,指出各通道强度的年际变化是南、北两半球大尺度海-气相互作用的重要组成部分,是全球大气环流异常变化的重要信息。     

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.     

Response of the atmospheric circulation in non-tropical regions of the Northern Hemisphere to processes taking place in the tropical region

The paper concentrates on the response of the atmospheric circulation non-tropical regions of the Northern Hemisphere to considerable sea surface temperature anomalies regularly occurring in the equatorial Pacific Ocean, related to the El Niño event. It has been established that during El Niño, zonal western circulation and meridional southern circulation tend to decay (being ?2.6% and ?5.4% respectively), while meridional northern circulation intensifies (+8.0%). The paper examines regional peculiarities of the non-tropical atmospheric response to the processes taking in the tropics. It is shown that atmospheric circulation reconstruction is most essential in the Siberian (10.4%) and Pacific (10.2%) sections and is minimal (4.3%) in the Atlantic region. These peculiarities of the regional atmospheric circulation reconstruction may be taken into account to predict short-term climatic variations in the Northern Hemisphere.     

全球海域风能资源在不同季节的等级区划

在资源危机愈演愈烈的时代背景下,积极开发利用可再生能源将会对缓解能源危机、环境危机做出有益贡献,同时也必将成为“21世纪海上丝绸之路”建设的新亮点。利用来自欧洲中期天气预报中心（ECMWF）的ERA-Interim风场资料,本文制作了全球海域风能资源的年等级区划、季节等级区划。结果表明：从多年平均状态来看,全球海上风能资源的潜力巨大,南北半球西风带海域的风能等级为7级（最优等级）;中低纬大部分海域也比较乐观,多在4级以上;北冰洋的风能资源为4级,比传统估值乐观。北半球西风带7级风能资源的范围具有较大的季节性差异：1月最广,4月和10月次之,7月最小;南半球西风带的季节性差异则相对较小：7月相对最大,其余月份略小于7月。7月,阿拉伯海和孟加拉湾的风能资源都属于7级,明显比其余代表月丰富。4月和10月,北印度洋的风能资源整体贫乏,大部分区域为1级（最贫乏）。     

基于SODA资料的太平洋及我国周边海域温差能资源时空特征分析

基于简单海洋数据同化数据集的逐月再分析海温资料,对1971年1月至2010年12月共40年的太平洋及我国周边海域温差能资源的时空特征进行统计分析,得到以下主要结论:（1）温差季节变化特征明显,北半球的20℃等温差线从冬季到夏季可由20°N扩展到40°N,而南半球的温差受季节变化相对较小;温差能有效开采区域集中在30°S~40°N范围内,但纬向分布不均;可近似将气候态平均的20℃等温差线作为全年可开采区域的边界;（2）太平洋绝大部分海域的温差能等价深度呈逐年上升趋势,最大可达近2 m/a;温差能的变异系数具有明显季节变化特征但总体维持在较低水平,有效开采区域之内的变异系数在各季节均低于0.1;（3）我国温差能资源在南海及台湾以东海域最为丰富,其温差维持较高水平,能量密度总体呈逐年上升趋势,能量的稳定性较好且可实现全年有效开采,其最佳利用时间为5-7月,最差利用时间为2-3月;（4）太平洋温差能储量在TW量级,且以2.83 GW/a的趋势递增。     

Estimating the global flux of methane into the atmosphere and its seasonal variations

A new method of estimating the global fluxes of methane into the Earth’s atmosphere is proposed. This method allows one to take into account the whole spectrum of methane sources irrespectively of their location and calculate seasonal variations in methane fluxes. The results of numerical calculations of the amount of methane emitted into the atmosphere on the basis of this method are supported by data obtained from field measurements. In the Northern Hemisphere (NH), during fall, maximum concentrations of CH₄ are due to methane sources in the arctic region which have not been taken into account before. For the condition of balance between the emission and sink of methane to be fulfilled, the total capacity of its sources amounts to no less than ～530 Tg/year for the NH and ～470 Tg/year for the Southern Hemisphere (SH). The results of our calculations and an analysis of the behavior of the concentration and mass of methane in the Earth’s hemispheres show that the global flux of methane from the surfaces of the lithosphere and ocean into the atmosphere may amount to more than ～1000 Tg/year.     

On the essential differences between the large-scale variations of the surface temperature over the oceans and continents

The characteristic features of the surface temperature variability in the Northern Hemisphere are studied on the secular time scale. The trends of the temperature anomalies over the continents and oceans were found to be opposite. The present global warming is concluded to be caused by the large-scale redistribution of heat in climatic system, indicating a compensative character of the variations observed. The dynamics of the longitudinal and latitudinal gradients of the surface temperature anomalies were analyzed. It was found that the dynamics of these gradients and the changes in the climate phases on the scales of the Northern Hemisphere are correlated. The present state of the climatic system is discussed, and it is concluded that a change in the climatic scenario in the nearest future is possible.     

Interhemispheric distinctions in wind-regime parameters in the polar mesosphere-lower thermosphere

The wind circulations in the mesosphere-lower thermosphere at polar latitudes of the Northern and Southern hemispheres are compared on the basis of long-term monthly-mean data on the prevailing zonal and meridional winds and on the parameters of diurnal and semidiurnal migrating tides obtained from the international network of radar stations. Comparison of the seasonal cycles and vertical profiles of the prevailing winds and tide parameters points to the existence of significant distinctions between the hemispheres. These distinctions are most clearly pronounced, first, in the prevailing meridional winds (for example, the annual mean winds in the polar regions have opposite directions in different hemispheres) and, second, the annual cycles of semidiurnal-tide amplitudes, as well as the character of changes in the tide phase with height, are fundamentally different for the Northern and Southern hemispheres. Along with these, significant distinctions are revealed in the prevailing zonal winds and in the diurnal-tide parameters.     

Latitudinal dependence of variations in stratospheric NO<Subscript>2</Subscript> content

Diurnal and annual variations in the NO₂ total content (TC), the effect of its decrease owing to the products of the eruption of Mt. Pinatubo, its variations during an 11-year cycle of solar activity, and its linear trends are analyzed on the basis of data obtained from the ground-based spectrometric measurements of the NO₂ TC in stratospheric vertical columns over the stations of the Network for the Detection of Atmospheric Composition Change. Latitudinal dependence of the indicated variations and trends is revealed. The annual estimates of the linear trends of the NO₂ TC are found to be mostly positive for the middle and low latitudes of the Southern Hemisphere and negative for the middle and low latitudes of the Northern Hemisphere. The maximum values of the positive and negative trends amount to ～10% per ten years. In the high and polar latitudes of both hemispheres, the annual trend estimates are statistically insignificant. Seasonal estimates of the trends may differ from their annual estimates. The trends and solar-activity effect in the NO₂ TC, which were estimated by using the two-dimensional model SOCRATES, as well as the analytical estimates of a zonal mean trend of the NO₂ TC, on the whole, significantly differ from the estimates obtained from the measurements.     

Non-sea-salt sulfate in the marine boundary layer and its possible impact on chloride depletion

1Introduction Sulfurisoneofthemostimportantelements whosebiogeochemicalcyclesarepivotaltotheatmo- sphericenvironmentandtotheclimaticchanges.The predominant,stablechemicalspeciesofsulfurinthe atmosphereissulfuricacidorsulfatewhichunderor- dinaryconditionsexistsmainlyinsmallaerosolparti- cles(Chinetal.,1996;Kerminenetal.,2000;Restadet al.,1998).Sulfuricacidorsulfate-dominatedaerosols areubiquitousintheloweratmosphere.Inthemarine boundarylayer(MBL),non-sea-saltsulfuricacidorsulfate(nss-SO42-)…     

On the transport of small river run off by an alongshore baroclinic sea current

A numerical simulation has been undertaken to study the process of the transport of small river runoff by alongshore baroclinic sea currents. The study is based on the implementation of the Princeton Ocean Model (POM) under the conditions of a circular stratified basin whose surface is exposed to a transient tangential wind stress to form an alongshore baroclinic current. A baroclinic current of the downwelling type (in the Northern Hemisphere directed to the left to a sea-viewing observer) was shown to provide the carrying out of the river discharge from estuary’s vicinity more effectively than that of the upwelling type (in the Northern Hemisphere directed to the right to a sea-viewing observer).     

Can the mean structure of the tropical pycnocline affect ENSO period in coupled climate models?

The dynamical link between mean state biases and dominant timescales of interannual variability is examined using the output from two state-of-the-art coupled model simulations, results from an ocean-only simulation forced with observed surface fields, and various observational data sets. The focus of this study is the relative role of the mean upper ocean density structure vs. anomalous wind forcing in controlling the spectral characteristics of tropical Pacific interannual variability. It is shown that an extensive South Pacific Convergence Zone (SPCZ) creates a potential vorticity (PV) barrier in the Southern Hemisphere similar to the one associated with the Intertropical Convergence Zone (ITCZ) in the Northern Hemisphere in both climate models. The PV barrier in the Southern Hemisphere strongly constrains the mean equatorward flow in the ocean model pycnocline, creating a “choke point” for the mean flow around 10°S. It is then examined whether the PV barrier can also limit the anomalous flow associated with mass recharge/discharge to/from the equatorial thermocline at interannual timescales. If the anomalous flow were impeded by the mean PV structure the meridional extent of the area involved in the mass recharge/discharge process would be narrower, leading to a shorter adjustment (and ENSO) timescale. Comparison of the two climate models, both of which have similarly erroneous PV structures in the southern tropical Pacific, but different interannual timescales, shows that the meridional extent of the anomalous meridional transport is primarily controlled by the latitudinal location of the wind stress curl anomalies, while the mean state bias in the Southern Hemisphere does not seem to have any significant influence.     

Properties and changes in empirical orthogonal components of temperature fields in Northern Eurasia in the 20th century

Using data from 55 meteorological stations in the Northern Hemisphere for the 20th century as a whole and separately for 1901–1950 and 1951–2000, the norms and empirical orthogonal components (EOCs) of the fields of the annual mean surface air temperature were calculated. These fields were found to have two components: smooth and nonsmooth. The field of differences between the temperature norms of the first and second halves of the 20th century was found to be projected almost completely on the very first component of fixed sign; i.e., the current climate trend of the Northern Hemisphere is spatially homogeneous. No substantial changes were found in the transition from the first half to the second half of the 20th century, either in the form of components or in the spectrum of eigenvalues, with the only exception being a small growth (in magnitude) in part of the eigenvalues corresponding to the nonsmooth component. This can be explained by the progressing urbanization of northern Eurasia. All coefficients of the temperature-field expansion by natural components are distributed normally, and their temporal correlation functions for smooth components of fields have a form characteristic of processes with long-term memory. The latter manifests itself particularly in the motions of the two main waves of the smooth component and reflects two stages of the current climate warming.     

The atmospheric distribution of lead over a number of marine regions

A data base of 111 filter-collected marine atmospheric particulates is used to describe the distribution of lead over the North and South Atlantic, the Mediterranean Sea, the Red Sea, the Gulf of Aden and the northern and central Arabian Sea. The distribution of atmospheric Pb is assessed in terms of enrichment factor diagrams, and it is shown that over the marine regions studied in both the Northern and Southern Hemispheres the distribution of Pb in the atmosphere is controlled by the mixing of a background component, or components, with crustal material within certain concentration limits. For the Northern Hemisphere samples used in the investigation there is a reasonably well-defined Pb concentration minimum of ～ 0.6 ng m^?3 of air; however, this will be severely decreased in more remote Northern Hemisphere marine regions. Geometric average Pb atmospheric concentrations vary from one marine region to another, ranging from ～ 0.98 ng m^?3 of air for the South Atlantic westerlies to ～ 15 ng m^?3 of air in the North Atlantic westerlies; although the latter reduces to ～ 7 ng m^?3 of air when ‘polluted’ samples are excluded. Lead sea-surface deposition fluxes are calculated on the basis of two deposition velocities (0.25 and 1 cm s^?1), the largest flux (220 ng Pb cm^?2 yr^?1) being found for the westerlies over the eastern margins of the North Atlantic. The distribution of lead over the North Atlantic is assessed in terms of the global lead budget and it is estimated that a maximum of ～ 24% of the total ‘natural’ lead injected annually into the World atmosphere, and ～ 3.5% of the anthropogenic lead injected annually into the Northern Hemisphere atmosphere, are deposited over the North Atlantic sea surface.     

On the reliability of millennial reconstructions of variations in surface air temperature in the Northern Hemisphere

The reliability of the recently published reconstructions of the surface air temperature variability in the Northern Hemisphere over the past 2000 yr is discussed. For this purpose, the power spectra of the two best known reconstructions (Mann et al.[10–12] and Moberg et al. [13]) are calculated and compared to the spectra of the 150-yr temperature series based on instrumental observations and simulated 1000-yr series. It is found that the Mann et al. reconstruction drastically underestimates low-frequency temperature variations, whereas the Moberg et al. reconstruction reproduces them much better, although with a certain underestimation rather than overestimation, as Mann et al. have recently argued.