Solar cycle changes to planetary wave propagation and their influence on the middle atmosphere circulation     

N. F. Arnold  T. R. Robinson 《Annales Geophysicae》1997,16(1):69-76

Recent observations suggest that there may be a causal relationship between solar activity and the strength of the winter Northern Hemisphere circulation in the stratosphere. A three-dimensional model of the atmosphere between 10–140 km was developed to assess the influence of solar minimum and solar maximum conditions on the propagation of planetary waves and the subsequent changes to the circulation of the stratosphere. Ultraviolet heating in the middle atmosphere was kept constant in order to emphasise the importance of non-linear dynamical coupling. A realistic thermo-sphere was achieved by relaxing the upper layers to the MSIS-90 empirical temperature model. In the summer hemisphere, strong radiative damping prevents significant dynamical coupling from taking place. Within the dynamically controlled winter hemisphere, small perturbations are reinforced over long periods of time, resulting in systematic changes to the stratospheric circulation. The winter vortex was significantly weakened during solar maximum and western phase of the quasi-biennial oscillation, in accordance with reported 30 mb geopotential height and total ozone measurements.  相似文献   

Climatology　and　Interannual　Variability　of　the　Southeast　Asian　Summer　Monsoon   总被引：82，自引：0，他引：82  

K.-M. Lau  Song Yang 《大气科学进展》1997,14(2):141-162

ＣｌｉｍａｔｏｌｏｇｙａｎｄＩｎｔｅｒａｎｎｕａｌＶａｒｉａｂｉｌｉｔｙｏｆｔｈｅＳｏｕｔｈｅａｓｔＡｓｉａｎＳｕｍｍｅｒＭｏｎｓｏｏｎＫ．－Ｍ．ＬａｕＬａｂｏｒａｔｏｒｙｆｏｒＡｔｍｏｓｐｈｅｒｅｓ，Ｃｏｄｅ９１３，ＮＡＳＡ－ＧｏｄｄａｒｄＳｐａｃ...  相似文献   

Vertical profile of polycyclic aromatic hydrocarbons in a sediment core from a reservoir in Osaka City   总被引：1，自引：0，他引：1  

Miho Ishitake  Hiroshi Moriwaki  Kenshi Katahira  Osamu Yamamoto  Kenshiro Tsuruho  Hideo Yamazaki  Shusaku Yoshikawa 《Environmental Geology》2007,52(1):123-129

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in a dated sediment core from a reservoir at Osaka City, Southwest Japan. The sediment core consisted of deposits collected over a period of almost 70 years whose PAH content would serve as a historical record of atmospheric environment at Osaka City. Total PAH concentrations varied from 4.2 to 26 mg kg⁻¹ dry wt, and peaked in the 1940s, reflecting the occurrence of a large fire due to air attacks during World War II. The results indicated that warfare had the largest impact on atmospheric environment in Osaka City. Total PAH concentrations decreased in the post-war period except for a small peak. In the 1950s, there was a downward trend from the 1970s to the present. These trends can be ascribed to the growth of industrial activities and the regulation of atmospheric pollutant emissions, respectively.  相似文献   

西北太平洋热带气旋和台风活动若干气候问题的研究   总被引：19，自引：0，他引：19  

陈光华  黄荣辉 《地球科学进展》2006,21(6):610-616

热带气旋和台风是严重的突发性自然灾害之一。近20年来，对热带气旋和台风活动的气候学研究成为台风领域的一个重要研究方向，并取得了显著的研究进展。通过对西北太平洋热带气旋和台风活动的季节、年际和年代际时间尺度变化的研究回顾，揭示了造成热带气旋和台风活动不同时间尺度变化的主要影响机制，其中包括低频振荡、季风槽和西传赤道波动、ENSO和QBO现象等，这些系统主要通过改变西北太平洋上空的环流，而影响到西北太平洋热带气旋活动以及登陆我国台风的不同时间尺度变化。还在西北太平洋海域热带气旋和台风活动的气候学研究进展和作者最新的研究成果的基础上，展望了该领域的研究前景，并提出当前此研究领域中一些亟需研究的科学问题，主要包括了季风槽区能量交换、不同海域动力过程、赤道波动演变，以及热带气旋的季节和更长时间尺度的预测。  相似文献   

Climatological Ertel’s potential-vorticity flux and mean meridional circulation in the extratropical troposphere – lower stratosphere     

J. Bartels  D. Peters  G. Schmitz 《Annales Geophysicae》1998,16(2):250-265

We investigated to what extent the isentropic, non-geostrophic formulation of zonally averaged circulation derived for stratospheric conditions is applicable to climatological transport in the extratropical troposphere and lower stratosphere. The study is based on 10 years of daily data of ECMWF analysis and on the ECHAM3 climate model of the German Climate Computing Centre. The main result is a scalar isentropic mixing coefficient, K_yy, and a mean meridional transport circulation consistently derived from the same data base. For both data sources, isentropic mean meridional circulation is derived from horizontal mass flow rate for 4 representative months. Alternatively, a mean meridional circulation is calculated from total diabatic heating rates of the ECHAM3 model. It is shown that only the latter is in good agreement with the ECMWF mean meridional circulation. Isentropic analysis also comprises the seasonal cycle of the climatological meridional gradient and flux of Ertels potential vorticity (PV). Application of Tungs flux-gradient relation yields that for all seasons K_yy is positive in height-latitude regions where statistical significance is reached. Large K_yy values, marking regions of more efficient mixing, have been found in the subtropical vertical band of weak westerly wind and in mid-latitudes in regions of upward-propagating baroclinic wave activity in the middle and upper troposphere. Based on the ECMWF data and results of baroclinic-wave behaviour, strong indications are presented that positive zonally averaged PV flux polewards of the jet core in the NH is strengthened by stationary waves and nonlinear effects. Reduced eddy transport is apparent in winter and spring slightly below the subtropical tropopause jet. The seasonal cycle of K_yy from ECHAM3 data is to a great extent in agreement with the result based on ECMWF analysis. In the model, reduced interannual variability enlarges the height-latitude range where sign of K_yy is significant.  相似文献   

中国旅游气候学研究综述   总被引：9，自引：0，他引：9  

吴普  席建超  葛全胜 《地理科学进展》2010,29(2):131-137

随着全球气候变化的加剧和旅游业的快速发展,气候变化对旅游业的影响逐渐为各界所重视,旅游气候学也因此成为旅游和气候学界研究的热点。文章从文献总量、结构,研究阶段划分,研究内容和方法4个方面回顾我国旅游气候学的研究进展。对我国旅游气候学研究的综述表明：目前,我国旅游气候学研究尚处在初级阶段,方法体系还没建立;旅游气候学研究也没得到旅游学界充分认可,研究领域“留白”较多。未来旅游界要更加充分认识气候变化对旅游业的影响,更多地投入到该领域研究中来;加强旅游气候学理论研究,不断拓宽研究的领域、视角,深入研究旅游者对气候变化的响应;厘清气候变化对旅游业的影响,提出旅游业对气候变化的适应与对策,不断丰富、完善旅游气候学研究。  相似文献   

我国五百年干湿期、冷暖期的划分     

唐佑民  朱燕军  柳又春 《成都信息工程学院学报》1989,(1)

本文依据五百年旱涝,温度等级资料,用最优分割法进行了早涝的干湿期划分和冷暖期划分,并对此进行了统计分析。  相似文献   

Simulated Climatology of Atmospheric Ducts Over the Persian Gulf   总被引：4，自引：0，他引：4  

M. Zhu  B. W. Atkinson 《Boundary-Layer Meteorology》2005,115(3):433-452

A simulated climatology of ducts in the Persian Gulf area was produced with the MM3 atmospheric model. From November to January ducts were sporadic, land and surface based, shallow and weak. From February to October ducts of all types occurred. In the duct season, spatial and temporal variations were related to the land/sea distribution and to day and night. Over land at night, widespread, shallow, weak surface ducts occurred well away from the sea; within about 100 km of the south-western coast in the late evening, ducts were S-shaped. Over land in daytime, the dry, convective boundary layer prevented duct formation. Over the Gulf in the season, duct coverage was complete throughout night and day. A spatial sequence of shallow, weak surface ducts, deeper, stronger S-shaped ducts and deep, strong elevated ducts lay from north-west to south-east over the Gulf. This sequence was related to the growth of a marine internal boundary layer (MIBL) and the effects of land- and sea-breeze circulations. Subsidence in the sea-breeze circulation reduced magnitudes of depth and strength and created gradients in a direction normal to the main growth axis of the MIBL. Ducts growing in the MIBL were tilted upward from west to east. The combined effect gave relatively weak surface ducts in the north-west and strong elevated ducts in the south-east. Duct depth and strength increased as the season progressed, owing to increased wind speed within, and increased depth of, the MIBL.  相似文献