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1.
The physics of solar forcing of the climate and long term climate change is summarized, and the role of energetic charged particles (including cosmic rays) on cloud formation and their effect on climate is examined. It is considered that the cosmic ray-cloud cover hypothesis is not supported by presently available data and further investigations (during Forbush decreases and at other times) should be analyzed to further examine the hypothesis. Another player in climate is lightning through the production of NOx; this greenhouse gas, water vapour in the troposphere (and stratosphere) and carbon dioxide influence the global temperature through different processes. The enhancement of aerosol concentrations and their distribution in the troposphere also affect the climate and may result in enhanced lightning activity. Finally, the roles of atmospheric conductivity on the electrical activity of thunderstorms and lightning discharges in relation to climate are discussed.  相似文献   

2.
In order to determine typical sizes of ice-supersaturated regions (ISSRs) in the upper troposphere and lowermost stratosphere we set up the frequency distribution of path lengths flown by MOZAIC aircraft within ISSRs. The mean path length is about 150 km with a standard deviation of 250 km. We analyse the influence of a selection bias (viz. that large ISSRs are more often crossed by aircraft than small ones) on the obtained path length statistics and derive a mathematical equation that relates the path length distribution to the underlying size distribution of ISSRs, assuming that they have circular shape. We solve the equation (by trial and error) and test the result using numerical simulations. Surprisingly, we find that there may be many more very small ISSRs than apparent from the data such that the true mean diameter of the ISSRs may be of the order a few kilometres only. The relevance of the result is discussed and dedicated research flights to measure the true extension of ISSRs are recommended.  相似文献   

3.
The Stratospheric Regular Sounding project was planned to measure regularly the vertical profiles of several tracers like ozone, water vapor, NOx, ClOx and BrOx radicals, aerosol, pressure and temperature, at three latitudes, to discriminate between the transport and photochemical terms which control their distribution. As part of this project, the “Istituto di Fisica dell’Atmosfera” launched nine laser backscattersondes (LABS) on board stratospheric balloons to make observations of background aerosol and PSCs. LABS was launched with an optical particle counter operated by the University of Wyoming. Observations have been performed in the arctic, mid-latitudes and tropical regions in different seasons. Polar stratospheric clouds have been observed in areas inside and outside the polar vortex edge. A background aerosol was observed both in mid-latitudes and in arctic regions with a backscattering ratio of 1.2 at 692 nm. Very stratified aerosol layers, possibly transported into the lower stratosphere by deep convective systems, have been observed in the lower stratosphere between 20 and 29 km in the tropics in the Southern Hemisphere.  相似文献   

4.
A discussion is given of atmospheric reactions in the H2O–CH4–O2–O3–NO x system. In the lower troposphere such reactions may lead to significant production of ozone. Their role in the odd hydrogen balance, especially of the troposphere and lower stratosphere, is discussed. CH3OH may be an intermediate in the oxidation cycle of methane, especially in the cold stratosphere. Its photodissociation into H2 and CH2O may consequently provide an important source for stratospheric H2. Catalytic photochemical chains of reactions involving NO x and HO x may also lead to tropospheric destruction of ozone. Due to lack of knowledge it is not possible at present to evaluate the importance of the before-mentioned reactions.With the aid of model calculations it is indicated that stratospheric ozone is most sensitive to changes in the adopted lower boundary values of N2O and that an increase in water vapour concentrations in the lower stratosphere will indeed cause some increase in ozone as predicted.Fluctuations in the flux of solar radiation near 190 nm may cause significant variations in stratospheric ozone concentrations.  相似文献   

5.
The research on climate change in polar regions, especially on the role of polar in the global climate system, has gain unprecedented level of interest. It has been the key scientific issue of the International Polar Year program (IPY, 2007―2008). In this paper, we dealt with the debate upon the breakup time of the stratospheric polar vortex in boreal spring. An observational study of the relation between strato- spheric polar vortex breakup and the extra-tropical circulation was performed. The mean breakup date―when the winter westerly at the core of polar jet turns to summer easterly―is about April 10. The breakup time has large interannual variation with a time span of about 2 months. It also has a long-term trend with the 1990s and 2000s witnessing more and more late breakups of polar vortex. Composite of wind speed at the core of polar jet for the extremely early and late breakup years shows that late years have two periods of westerly weakening while early breakup years have only one. The first weakening in the late years happens in middle January with wind speed dropping sharply from more than 40 m s?1 to about 15 m s?1. This is accompanied with anomalous activities of planetary waves in both strato- sphere and troposphere; while the second weakening in the late breaking years is mainly the results of diabatic heating with very weak wave activities. In early breakup years, the transition from westerly to easterly is rapid with wind speed dropping from more than 30 m s?1 to less than ?10 m s?1 within a month. This evolution is associated with a strong bidirectional dynamical coupling of the stratosphere and troposphere. The circulation anomalies at low troposphere are also analyzed in the extremely early and late breakup years. It shows that there are significant differences between the two kinds of extreme years in the geopotential height and temperature composite analysis, indicating the dynamical cou- pling of stratosphere and troposphere with the evolution of stratospheric polar vortex.  相似文献   

6.
Emissions from aircraft engines include carbon dioxide, water vapour, nitrogen oxides, sulphur components and various other gases and particles. Such emissions from high-flying global civil subsonic air traffic may cause anthropogenic climate changes by an increase of ozone and cloudiness in the upper troposphere, and by an enhanced greenhouse effect. The absolute emissions by air traffic are small (a few percent of the total) compared to surface emissions. However, the greenhouse effect of emitted water and of nitrogen oxides at cruise altitude is potentially large compared to that of the same emissions near the earth’s surface because of relatively large residence times at flight altitudes, low background concentrations, low temperature, and large radiative efficiency. Model computations indicate that emission of nitrogen oxides has doubled the background concentration in the upper troposphere between 40○N and 60○N. Models also indicate that this causes an increase of ozone by about 5-20%. Regionally, the observed annual mean change in cloudiness is 0.4%. It is estimated that the resultant greenhouse effect of changes in ozone and thin cirrus cloud cover causes a climatic surface temperature change of 0.01-0.1 K. These temperature changes are small compared to the natural variability. Recent research indicates that the emissions at cruise altitude may increase the amount of stratospheric aerosols and polar stratospheric clouds and thereby have an impact on the atmospheric environment. Air traffic is increasing about 5-6% per year, fuel consumption by about 3%, hence the effects of the related emissions are expected to grow. This paper surveys the state of knowledge and describes several results from recent and ongoing research.  相似文献   

7.
本文通过分析1957~2002年平流层爆发性增温(SSW)的环流特征,研究平流层爆发性增温可能对我国天气气候的影响.平流层爆发性增温发生后平流层高纬地区有异常的环流变化,但是这种变化并不仅局限于平流层内部,其产生的环流异常能够向下传播,并对对流层的天气和气候产生影响.研究发现,平流层出现强爆发性增温后,平流层异常温度场和位势高度场在中、高纬度形成AO型振荡并向下传播,使得对流层低层西伯利亚高压增强、阿留申低压加深,500 hPa东亚大槽加深且偏西,导致东亚冬季风增强,我国北部大部分地区气温偏低.而在爆发性增温前,强行星波扰动使得东亚大槽加深,西伯利亚高压和阿留申低压同时增强,也可能导致东亚冬季风偏强.El Nio可能激发出强行星波,有利于强SSW事件的发生.通过上述的两个过程可能造成东亚冬季风的加强,这将会对"El Nio事件通过对流层过程而引起东亚冬季风减弱"的结论有一定影响. 因此,ENSO事件影响东亚冬季风及中国的天气气候存在不止一种途径,具体影响情况应该是几种途径的综合结果.  相似文献   

8.
Radar measurements at Aberystwyth (52.4°N, 4.1°W) of winds at tropospheric and lower stratospheric heights are shown for 12–13 March 1994 in a region of highly curved flow, downstream of the jet maximum. The perturbations of horizontal velocity have comparable amplitudes in the troposphere and lower stratosphere with downward and upward phase propagation, respectively, in these two height regions. The sense of rotation with increasing height in hodographs of horizontal perturbation velocity derived for hourly intervals show downwards propagation of energy in the troposphere and upward propagation in the lower stratosphere with vertical wavelengths of 1.7 to 2.3 km. The results indicate inertia-gravity waves propagating in a direction similar to that of the jet stream but at smaller velocities. Some of the features observed contrast with those of previous observations of inertia-gravity waves propagating transverse to the jet stream. The interpretation of the hodographs to derive wave parameters has taken account of the vertical shear of the background wind transverse to the direction of wave propagation.  相似文献   

9.
Quasi-biennial oscillation (QBO) is a predominant phenomenon in the tropical stratosphere and troposphere. The possible interactions between the stratospheric QBO and tropospheric biennial oscillation (TBO) over the Indian monsoon region as well as the equatorial region is investigated using the zonal wind data of 23 vertical levels (1000–1 hpa) from 1960–2002. The structure of lower stratosphere and troposphere are entirely different over the equator and India. In biennial scales, both the stratosphere and troposphere over the Indian region are closely related and winter season QBO is a good predictor of Indian summer monsoon rainfall.  相似文献   

10.
Zonal mean data and amplitudes and phases of planetary zonal waves were derived from daily hemispheric maps for tropospheric and stratospheric levels, for the four winters 1975–76 to 1978–79. Important year-to-year fluctuation in zonal means and wave activity are described, most notable of which are the changes from 1975–76 to 1976–77. Comparison of the relative strengths of the stratospheric and tropospheric jet streams shows a strong negative correlation (–0.8) between monthly mean zonal stratospheric winds (at 10 mb, 65°N) and zonal tropospheric winds (at 200 mb, 32.5°N, in the jet core) and a positive correlation (+0.7) between the stratospheric 10 mb winds and the tropospheric 200 mb winds at 65°N. Parameters correlated were the departures from the climatological mean zonal winds. The structure of correlation between wave amplitudes in the same wave number (1, 2) at different altitudes and between wave numbers 1 and 2 is investigated. We find a high correlation (+0.93) between wave 1 in the stratosphere (10 mb height) and wave 2 (height) in the troposphere at 65°N; but only a weak correlation (+0.2) between wave 1 amplitudes in the stratosphere and troposphere. These results suggest the possible importance of wave-wave interactions in processes linking the stratosphere and troposphere. The wave correlations presented here are based on comparisons of monthly means of daily amplitudes; the correlation structure in individual wave developments may differ, in view of the likelihood of altitudinal lags in wave amplification.  相似文献   

11.
毕云 《地球物理学报》2011,54(10):2468-2476
北极地区(60°N～90°N)平流层纬向风和气压场有明显的季节变化,不同高度层季节变化的时间有差异.北极平流层从冬至夏,季节转换从上向下推进,从夏至冬,季节转换从下向上推进.以20 hPa为例,平均而言,4月上旬以前,北极被极涡控制;4月中旬北极地区高压的势力开始超过低压,5月上旬,北极高压正式建立;7月份达到最强,8...  相似文献   

12.
Air traffic is a source of trace gases in the upper troposphere and lower stratosphere. Contrails readily form from water vapor exhausts under favorable meteorological conditions. Since contrails are ice crystal clouds like natural cirrus clouds, they bear a greenhouse potential which has to be investigated. The IFU has built a scanning lidar system employing a pulsed Nd:YAG laser as the emitter and a 52-cm diameter telescope as the receiver. Signals are processed in several channels to investigate depolarization and wavelength dependencies of the light backscattered from ice crystals. These investigations are aimed at the formation and life cycles of contrails, their optical properties, and their climatological consequences in areas of dense air traffic. The experimental lidar setup is described and a sample measurement is shown.  相似文献   

13.
选用每天12∶00UTC时次的逐日ERA-Interim再分析资料,根据transformed Eulerian-mean(TEM)方程通过积分剩余速度珔v*,研究了1979—2011年间Brewer-Dobson(BD)环流的时空演变规律.并将其与downward control(DC)原理研究的结果进行比较,同时还探讨了平流层温度与BD环流之间的相互联系.结果表明,由TEM方程通过积分剩余速度珔v*估算的BD环流与利用DC原理估算的环流相比较,在热带地区的形势更加明显.环流在热带对流层中上层上升至平流层中下层,最高可达1hPa等压面附近.然后在热带外向极向下运动,最后在中高纬度下沉回到对流层.BD环流的上升中心及质量通量均随季节的变化产生变动,环流在冬半球的形势显著地强于夏半球.在春季和秋季期间,环流呈现出南北两半球的对称形势.从全球尺度物质输送的角度来看,在过去的33a间平流层BD环流的长期变化趋势是减弱的,且在平流层中下层减弱是明显的.环流的减弱趋势与纬向平均温度的长期变化趋势相匹配.  相似文献   

14.
利用现有大气本底站的大气CO2浓度观测信息,综合考虑不同经济区划与土地覆盖类型对应的CO2浓度差异及其季节变化规律,构建模式区域内以月为单位的网格化大气CO2浓度非均匀动态分布数据模型.由此数据模型驱动RegCM4-CLM3.5区域气候模式运行,对东亚区2000年3月—2009年2月之间的气候变化特征进行了模拟,进而对大气CO2浓度非均匀动态分布可能引起的区域气候效应进行了初步研究.结果表明:目前气候模式中CO2浓度的常态均匀分布假设可能将温室效应夸大了10%左右.对大气CO2浓度非均匀动态分布影响气温变化的可能机制进行研究表明:CO2的自身效应(改变大气透射率)并不是导致Exp2试验温度降低的主要原因.大气CO2浓度的变化影响了大气与植物胞间CO2分压差,陆地植被通过改变气孔阻力适应这种变化,气孔阻力的变化直接影响到植物与大气间水分的交换,这种作用一方面通过蒸发冷却改变环境温度,另一方面,蒸发水分改变了近地面层湿度,进而水汽扩散到空中影响低云的分布.冬季,植物处于非生长季,对大气CO2浓度变化响应微弱,湿度和低云变化不明显;夏季,植物生长旺盛,由CO2生理学强迫激发的云反馈效应强烈,其效果是使中低云趋于增加,进而减弱了到达对流层低层的太阳短波辐射,造成温室效应减弱.  相似文献   

15.
青藏高原为亚洲季风区的典型代表区域,研究其水汽进入平流层的过程和机理对认识全球气候和大气环境变化具有一定的现实意义. 本文基于中尺度气象模式(WRF)的模拟输出结果(2006年8月20日至8月26)驱动拉格朗日大气输送模式FLEXPART,通过追踪并解析气块的三维轨迹以及温度、湿度等相关物理量的相关变化特征,初步分析了夏季青藏高原地区近地层-对流层-平流层的水汽输送特征. 研究结果表明,源于高原地区近地层的水汽在进入平流层的过程中受南亚高压影响下的大尺度环流和中小尺度对流的共同影响.首先,在对流抬升作用下,气块在短时间内(24 h)可抬升到9~12 km的高度,然后在南亚高压闭合环流影响下,相当部分气块在反气旋的东南侧穿越对流层顶进入平流层中,并继续向低纬热带平流层输送,进而参与全球对流层-平流层的水汽循环过程. 在对流抬升高度上气块位置位于高原的西北侧,然而气块拉格朗日温度最小值主要分布于高原南侧,两个位置上气块的平均位温差值可达15~35 K,这种显著的温度差异将导致气块进入平流层时"脱水". 比较而言,夏季青藏高原地区近地层水汽进入平流层的多寡主要和大尺度汽流的垂直输送有关,而深对流的作用相对较弱.  相似文献   

16.
利用北半球40°N～50°N纬度带上HALOE实验测量的O3和H2O廓线资料,根据示踪成分O3和H2O空间分布的化学寿命以及输运特征时间常数等性质,在等熵坐标中构建了对流层顶附近及最低平流层300～390 K等熵面间,O3/H2O混合关系的结构形态和季节特征.结果表明: (1) 在对流层顶转换层的320～380 K等熵面间O3混合比廓线的斜率具有空间转折"突变",而H2O混合比廓线的斜率则出现空间渐变转折.在对流层顶附近O3和H2O的源分别是平流层与对流层,使O3混合比和H2O混合比在320～380 K等熵面的两侧显现出截然不同的垂直分布梯度.(2) 在对流层顶附近O3/H2O达到最小二乘意义上的最佳拟合时,两者参考关系的对流层支与平流层支呈现出非规则"L"结构形态的季节与季节内变化,其中对流层支的斜率为负,而平流层支的斜率可随季节出现正负变化.同时,由"L"形态的转角处可确定随季节变化的化学对流层顶(chemopause)特征.(3) 由O3/H2O混合关系反映出对流层不同区域空气携带的物质成分分别与平流层空气混合而形成混合层,而且可使混合层的混合线不恒定.混合层的表现在2003年、2005年1月和2003年4月的混合程度相当,混合的等熵厚度大约是30 K,即在320～350 K等熵面间.2005年11月的混合高度有所增高,进入平流层的H2O混合比要比2003年和2005年1月的小,混合的等熵厚度大约为30 K,在330～360 K等熵面间.不同季节混合的等熵厚度变化较小,但高度可随季节而变化.O3/H2O混合关系的平流层支随季节的变化很明显,1月最低平流层空气脱水是引起平流层支季节变化的重要原因.  相似文献   

17.
本文利用2006年6月至2014年6月COSMIC掩星观测的水汽廓线,分析了对流层/下平流层（TLS）比湿信号对ENSO的响应.在数据处理中,将COSMIC掩星水汽廓线计算得到的全球比湿数据内插为1000~30 hPa区间水平分辨率为5°×5°的三维格网,在各等压面上求取各格网点去除年/月际信号后的比湿月异常值.然后在对比湿月异常时间序列低通滤波的基础上,进行经验正交分解（EOF）得到比湿主成分,并对该主成分信号进行二项式平滑;接下来将平滑后的主成分信号与反映ENSO活动的ONI指数进行相关处理,得到各等压面主成分信号相对于ONI指数的相关系数及对应的时间延迟.论文分析了包括Niño-3.4的5个代表性区域的TLS比湿异常主成分信号,结果表明：在各区域,采用本文先低通滤波再EOF分解的处理方法获得的TLS比湿异常主成分信号与ONI指数均有很强相关性,对流层相关系数绝对值达0.8以上,低平流层高于0.7,在300~200 hPa的上对流层达到峰值;各等压面上比湿异常主成分信号相对于ONI指数的时间延迟不尽相同,在对流层中比湿异常主成分信号普遍滞后于ONI指数1~6个月;在各区域,比湿异常主成分与ONI指数相关系数绝对值达到最大的等压面都接近250 hPa,最大相关系数绝对值均达到0.9以上.进一步对全球250 hPa等压面比湿异常主成分与ONI指数相关性的分析表明：两者强相关的区域主要集中在热带;在这些强相关区域,比湿异常主成分相对于ONI主要表现为滞后,且相关系数越大,相应的时间延迟越短.  相似文献   

18.
We compare the equilibrium climate responses of a quasi-dynamical energy balance model to radiative forcing by equivalent changes in CO2, solar total irradiance (Stot) and solar UV (SUV). The response is largest in the SUV case, in which the imposed UV radiative forcing is preferentially absorbed in the layer above 250 mb, in contrast to the weak response from global-columnar radiative loading by increases in CO2 or Stot. The hypersensitive response of the climate system to solar UV forcing is caused by strongly coupled feedback involving vertical static stability, tropical thick cirrus ice clouds and stratospheric ozone. This mechanism offers a plausible explanation of the apparent hypersensitivity of climate to solar forcing, as suggested by analyses of recent climatic records. The model hypersensitivity strongly depends on climate parameters, especially cloud radiative properties, but is effective for arguably realistic values of these parameters. The proposed solar forcing mechanism should be further confirmed using other models (e.g., general circulation models) that may better capture radiative and dynamical couplings of the troposphere and stratosphere.  相似文献   

19.
副热带急流对中国南部地区对流层中上层臭氧浓度的影响程度及地理范围目前还研究较少,且缺乏综合使用常规气象资料及卫星资料来判识对流层中上层臭氧浓度增高的方法.本文利用NCEP再分析与最终分析资料、日本GMS-5地球静止卫星水汽云图资料,以2001年3月27~29日中国南部的临安、昆明、香港臭氧探测个例为基础,结合1996年3月29日香港与2001年4月13日临安对流层中上层高浓度臭氧分布个例对副热带急流对中国南部对流层中上层臭氧浓度的影响进行了详细分析,提出根据气象要素场判识春季中国南部对流层中上层臭氧浓度增高的充分条件为根据卫星水汽图像上的暗区、高空急流入口区的左侧辐合区、高空锋区、对流层中上层≥1 PVU的向下伸展的舌状高位涡区来综合判断.本文的分析结果表明,本文个例中对流层中上层高浓度臭氧来自平流层;香港对流层中上层低浓度臭氧来自热带海洋地区.不仅臭氧垂直廓线的多个极小与极大值表明臭氧垂直分布的多尺度变化特征,而且对流层中上层PV分布以及卫星水汽图像分析也表明大气中的多尺度运动对臭氧垂直分布特征有显著影响.本文的结果表明与副热带高空急流相联系的平流层空气侵入不仅发生在中国大陆的较高纬度地区,较低纬度的昆明与香港地区也有平流层空气侵入导致对流层中上层臭氧浓度升高.  相似文献   

20.
Nicolet  M.  Peetermans  W. 《Pure and Applied Geophysics》1973,106(1):1400-1416
The vertical distribution of the methane concentration in the stratosphere is related to its dissociation by two simultaneous daytime reactions with excited oxygen atoms O(1D) and with OH radicals and depends on the stratospheric eddy diffusion coefficient.Dissociation of CH4 in the lower stratosphere leads to the production of CO molecules while in the upper stratosphere thepphotodissociation of CO2 molecules is an additional process to the CO production.In the upper stratosphere (40±10 km) there is an equilibrium between the formation and destruction processes of carbon monoxide which leads to a minimum of its mixing ratio. There is an increase of the CO mixing ratio in the troposphere and mesosphere compared with that of the stratosphere.The vertical distribution of the CO mixing ratio is closely related to the eddy diffusion coefficient in the whole stratosphere but the absolute values of the hydroxyl radical concentration also determine the values of the CO mixing ratio.  相似文献   

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