1998年青藏高原臭氧低值中心异常及其背景环流场的分析

采用TOMS和SAGE II臭氧卫星观测资料,对1998年青藏高原臭氧低值中心异常变化的过程和垂直结构进行了分析。为了探讨1998年这个低值中心出现异常的原因,利用NCEP/NCAR再分析资料,通过1998年高原附近上空位势场和位温的变化,分析了1998年臭氧低值中心异常期间高原上空对流层上层到平流层下层的流场和垂直运动的变化特征。结果表明,1998年11月,青藏高原上空对流顶比正常年份高,无论是对流层上层还是平流层下层,上升运动都比正常年份强。同时高原上空南亚高压也比正常年份强,于是使得1998年高原上空的强臭氧低值中心一直维持到11月。     

青藏高原地区大气臭氧变化的研究

文中综述了对青藏高原夏季大气臭氧低值中心的出现和可能形成的机理的一些研究结果。发现了青藏高原在夏季存在大气臭氧总量低值中心的事实 ,研究了该低值中心的背景环流特征 ;证实了青藏高原地区确为对流层与平流层物质输送的通道之一 ,以及它对青藏高原臭氧低值中心形成所起的作用 ;并用数值模拟方法揭示了该低值中心的形成原因。另外用资料证实了青藏高原地区夏季不但存在大气臭氧低值中心 ,而且该低值中心是一个强大气臭氧递减中心的事实。最后介绍了用数值模拟方法来预测青藏高原地区大气臭氧未来变化的趋势。     

青藏高原雪盖变化对我国气候的影响

青藏高原雪盖是影响我国气候的一个重要因子,除了具有明显的季节变化之外,还有明显的年际变化和年代际变化．它通过改变高原的热力作用而影响东亚季风进程、大气环流以及我国的气温和降水．雪盖具有较为明显的持续性,且具有振幅变化大的特点,人们越来越重视雪盖的气候效应和作为季度预报因子的作用．     

南半球臭氧变化气候效应的数值模拟

采用一个陆气耦合的９层谱模式模拟了南半球臭氧减少所产生的气候效应。数值试验结果表明,南半球臭氧的减少不仅对南半球温度场的 大气环流有影响,而且对北半球的温度场结构和大气环汉也有一定的影响。其气候效应具有全球性。南半球臭氧减少总体上可以使平流层中层以上大气降温、平流层低层增温、对流层顶附近降温。此外,在北半球冬半年期间,南半球臭氧的减少可使南北半球的副热带西风急流都减弱,极锋急流都增强;在北半球夏半     

青藏高原清洁地区近地面层臭氧的特征分析

利用瓦里关1994年8月～2001年12月地面臭氧资料，分析了地面O3年季变化，以及不同天气条件下的日变化特征。结果表明，青藏高原洁净地区地面O3具有明显的季节变化且呈缓慢的上升趋势，春季浓度明显高于冬季，最高值出现在每年夏初，而最低值在12月左右。与低纬的Lzana站相比，瓦里关地区地面O3浓度变化趋势与之比较相近，而且，亦呈逐年上升趋势。不同天气条件下，春、夏、秋、冬四个季节地面O3浓度变化不尽相同，晴天和多云天，春、夏、秋季的地面O3变化趋势基本一致，其中，春秋季，晴天O3值高于多云天和降雨天，而冬季和夏季则不明显，说明晴空天气虽然有利于O3浓度的增加，但并不是重要因子之一。各季节降雨、雪天O3浓度的变化情况来看，地面O3在春、秋、冬三个季节变化不大。而夏季与其它季节明显不同，变化幅度很大，日较差在四个季节中为最大，这与雨、雪的冲刷关系很大，并且可能存在雨、雪以及降雨强度的差异。     

青藏高原上空氮氧化物的分布特征及其与臭氧的关系

利用1992—2002年的HALOE资料,选取青藏高原地区(28°~40°N,75°~105°E)的数据,分析了青藏高原地区NOX混合比的垂直分布特征,并对高原地区不同高度上NOX混合比与同纬度及同经度地区进行了比较,分析了NOX混合比与臭氧混合比纬向分布的关系,以及NOX混合比随时间的变化和O3混合比变化的关系。结果表明:青藏高原地区在300~30 hPa上夏季NOX的混合比高于冬季的混合比;夏季青藏高原地区200~30 hPa气层上NOX的混合比比同纬度其它地区高得多,100~60 hPa气层上NO2混合比比同经度其它地区也高得多;在100~30 hPa上,O3的纬向分布与NOX的纬向分布之间存在较明显的反相关关系;高原地区100 hPa附近和70~35 hPa之间夏季NOX混合比的变化与O3混合比的变化的反相关关系非常好。     

青藏高原臭氧的ENSO

通过对臭氧卫星观测资料及大气环流资料的分析,研究了青藏高原上空臭氧年际变化中的ENSO信号,并与同纬度无山区及赤道地区进行比较.研究指出:在ElNino年(南方涛动指数为负),青藏高原臭氧总量偏大,在LaNina年(南方涛动指数为正),青藏高原臭氧总量偏小.同时讨论了与ENSO事件有关的大气环流物质输送.     

青藏高原臭氧总量低中心与落基山臭氧低槽的基本特征——兼论高山静力亏损的成因

采用小间隔O3值作细微天气学分析,定出高原O3低中心和落基山脉O3低槽。根据这些客观实体,明确其基本特征,研究其形成。青藏高原O3低中心常年存在,位于30^oN以南,稳定少动,具有年较差小,春浅薄、秋深陷等基本特征。其形成主要靠高山的静力亏损。另一类O3低中心生于6月灭于9月,位于30^oN以北,变化多动,是由位于30^oN以南的主体低中心派生出来的,但其维持与发展只是部分与100hPa上的青藏高压及其环流相联系并符合动力一热力观点。落基山脉O3低谷呈现分段低槽型,在山高、紧临大洋地段低槽明显,一年四季存在,夏季低槽分段更为清晰,是由热带、副热带低浓度O3侵袭而来。从整个南北走向来看,静力亏损是其基本成因。为了求出高山静力亏损率的概数,用分布在全球各处高于491m的22个高山站（含491m站）直接观测的O3资料,在求出气层O3总量后,根据最小二乘法计算,得到高山每上升1kmO3平均亏损率为4．4DU。由于这是小尺度的现象,所以对于高山O3低谷,需要采用细微分析方法,研究O3平面场。     

青藏高原臭氧的ENSO

通过对臭氧卫星观测资料及大气环流资料的分析，研究了青藏高原上空臭氧年际变化中的 ＥＮＳＯ信号，并与同纬度无山区及赤道地区进行比较。研究指出：在 Ｅ１ Ｎｉｎｏ年（ＳＯＩ指数为负）青藏高原臭氧总量增加，在 Ｌａ Ｎｉｎａ年（ＳＯＩ指数为正）青藏高原臭氧总量减小。本文同时讨论了与ＥＮＳＯ事件有关的大气环流物质输送。     

1979～2020年北极和青藏高原臭氧低值区的动力输送特征比较

基于ERA5月平均再分析资料,利用Lorenz环流分解方法从定常和瞬变以及基流和涡旋的角度对比了北极与青藏高原臭氧低值区的动力输送特征。结果表明：动力总输送在两地上平流层作用最强,均使其臭氧浓度降低,且定常输送均强于瞬变输送,纬向与经向输送的作用均大致相反。然而,动力输送在北极地区的作用强度远大于青藏高原地区。北极地区纬向输送使得平流层中上层臭氧浓度降低,平流层下层臭氧浓度升高,经向输送的作用与之相反且强度明显偏弱,二者均主要作用于上平流层。青藏高原地区纬向和经向输送除在上平流层均使得臭氧浓度降低外,二者作用大致相反且强度相当,输送大值区在垂直方向上存在双中心结构,分别位于上平流层与上对流层—下平流层（Upper Troposphere–Lower Stratosphere,简称UTLS）区。两地区纬向和经向输送的差异均主要由定常涡旋输送所造成。青藏高原地区定常与瞬变输送的强度差异没有北极地区大。此外,两地定常和瞬变输送中涡旋对臭氧纬向平均的输送均起到主要作用,体现出涡旋输送在两地臭氧浓度变化的动力输送过程中发挥着至关重要的作用。     

青藏高原大气臭氧研究

总结了国内外有关青藏高原大气臭氧方面开展的研究工作，并简要地介绍了1996－1999年利用NILUV观测仪器在拉萨地区进行臭氧和紫外辐射观测的初步结论。     

Study on Ozone Change over the Tibetan Plateau

This paper reviewed the main results with respect to the discovery of low center of total column ozone (TCO) over the Tibetan Plateau (TP) in summer, and its formation mechanism. Some important advances are summarized as follows: The fact is discovered that there is a TCO low center over the TP in summer, and the features of the background circulation over the TP are analyzed; it is confirmed that the TP is a pathway of mass exchange between the troposphere and stratosphere, and it influences the TCO low center over the TP in summer; models reproduce the TCO low center over the TP in summer, and the formation mechanism is explored; in addition, the analyses and diagnoses of the observation data indicate that not only there is the TCO low center over the TP in summer, but also TCO decrease trend over the TP is one of the strong centers of TCO decrease trend in the same latitude; finally, the model predicts the future TCO change over the TP.     

Dynamic Effects of the South Asian High on the Ozone Valley over the Tibetan Plateau

In this study, the TOMS/SBUV (Total Ozone Mapping Spectrometer/Solar Backscatter Ultraviolet Radiometer) data and SAGE (Stratospheric Aerosol and Gas Experiment) II data were employed to calculate the monthly total zonal ozone deviations over the Tibetan Plateau and the 150?C50-hPa zonal ozone variations. The results show that there is a significant correlation between the two, with a correlation coefficient of 0.977. From 150 to 50 hPa, the ozone valley over the Tibetan Plateau (OVTP) becomes the strongest based on the SAGE II data, and the South Asian high (SAH) is the most active according to the 40-yr reanalysis data of the European Centre for Medium-Range Weather Forecasts (ERA40), so a correlation between the SAH and the OVTP may exist. The WACCM3 (Whole Atmosphere Community Climate Model version 3) simulation results show that both SAH and OVTP could still present within 150?C50 hPa with reduced strength even when the height of the Tibetan Plateau was cut down to 1500 m. It is also shown that the seasonal variation of SAH would result in a matched seasonal variation of the OVTP, which suggests a meaningful effect of SAH on the OVTP. Meanwhile, it is found that the atmospheric circulation would impose different effects on the OVTP, depending on the SAH??s evolution stages and movement directions. At 150?C50 hPa, as the SAH approaches the plateau, the SAH zonal (meridional) transport would make the OVTP deeper (shallower), while the vertical transport of ozone produces a deeper (shallower) OVTP at the lower (higher) level; the combined dynamic effects lead to a weakened OVTP. When the SAH stabilizes over the plateau, the zonal (meridional) transport results in a shallower (deeper) OVTP while the vertical transport would create a deeper (shallower) OVTP at the middle (bottom and top) levels; the combined dynamic effects produce a deeper OVTP. As the SAH retreats from the plateau, the OVTP becomes deeper (shallower) under the zonal (meridional) effect or shallower under the vertical effect; the combined dynamic effects contribute to a deeper (shallower) OVTP at the middle (bottom and top) levels. The SAH would have a weak effect on the OVTP over the plateau when positioned over the tropical Pacific.     

Evaluating the Ozone Valley over the Tibetan Plateau in CMIP6 Models

Total column ozone (TCO) over the Tibetan Plateau (TP) is lower than that over other regions at the same latitude, particularly in summer. This feature is known as the “TP ozone valley”. This study evaluates long-term changes in TCO and the ozone valley over the TP from 1984 to 2100 using Coupled Model Intercomparison Project Phase 6 (CMIP6). The TP ozone valley consists of two low centers, one is located in the upper troposphere and lower stratosphere (UTLS), and the other is in the middle and upper stratosphere. Overall, the CMIP6 models simulate the low ozone center in the UTLS well and capture the spatial characteristics and seasonal cycle of the TP ozone valley, with spatial correlation coefficients between the modeled TCO and the Multi Sensor Reanalysis version 2 (MSR2) TCO observations greater than 0.8 for all CMIP6 models. Further analysis reveals that models which use fully coupled and online stratospheric chemistry schemes simulate the anticorrelation between the 150 hPa geopotential height and zonal anomaly of TCO over the TP better than models without interactive chemistry schemes. This suggests that coupled chemical-radiative-dynamical processes play a key role in the simulation of the TP ozone valley. Most CMIP6 models underestimate the low center in the middle and upper stratosphere when compared with the Microwave Limb Sounder (MLS) observations. However, the bias in the middle and upper stratospheric ozone simulations has a marginal effect on the simulation of the TP ozone valley. Most CMIP6 models predict the TP ozone valley in summer will deepen in the future.     

Formation and Variation of the Atmospheric Heat Source over the Tibetan Plateau and Its Climate Effects

To cherish the memory of the late Professor Duzheng YE on what would have been his 100 th birthday, and to celebrate his great accomplishment in opening a new era of Tibetan Plateau(TP) meteorology, this review paper provides an assessment of the atmospheric heat source(AHS) over the TP from different data resources, including observations from local meteorological stations, satellite remote sensing data, and various reanalysis datasets. The uncertainty and applicability of these heat source data are evaluated. Analysis regarding the formation of the AHS over the TP demonstrates that it is not only the cause of the atmospheric circulation, but is also a result of that circulation. Based on numerical experiments, the review further demonstrates that land–sea thermal contrast is only one part of the monsoon story. The thermal forcing of the Tibetan–Iranian Plateau plays a significant role in generating the Asian summer monsoon(ASM), i.e., in addition to pumping water vapor from sea to land and from the lower to the upper troposphere, it also generates a subtropical monsoon–type meridional circulation subject to the angular momentum conservation, providing an ascending-air large-scale background for the development of the ASM.     

Air Temperature Changes over the Tibetan Plateau and Other Regions in the Same Latitudes and the Role of Ozone Depletion

Using radiosonde and satellite observations, we investigated the trends of air temperature changes over the Tibetan Plateau （TP） in comparison with those over other regions in the same latitudes from 1979 to 2002. It is shown that Over the TP, the trends of air temperature changes in the upper troposphere to lower stratosphere were out of phase with those in the lower to middle troposphere. Air temperature decreased and a decreasing trend appeared in the upper troposphere to lower stratosphere. The amplitude of the annual or seasonal mean temperature decreases over the TP was larger than that over the whole globe. In the lower to middle troposphere over the TP, temperature increased, and the increasing trend was stronger than that over the non-plateau regions in the same latitudes in the eastern part of China. Meanwhile, an analysis of the satellite observed ozone data in the same period of 1979-2002 shows that over the TP, the total ozone amount declined in all seasons, and the ozone depleted the most compared with the situations in other regions in the same latitudes. It is proposed that the difference between the ozone depletion over the TP and that over other regions in the same latitudes may lead to the difference in air temperature changes. Because of the aggravated depletion of ozone over the TP, less （more） ultraviolet radiation was absorbed in the upper troposphere to lower stratosphere （lower to middle troposphere） over the TP, which favored a stronger cooling in the upper troposphere to lower stratosphere, and an intenser heating in the lower to middle troposphere over the TP. Therefore, the comparatively more depletion of ozone over the TP is possibly a reason for the difference between the air temperature changes over the TP and those over other regions in the same latitudes.     

夏季青藏高原O3低值与南亚高压东西振荡的关系

利用O3监测仪(Ozone Monitoring Instrument,OMI)卫星O3廓线资料和NCEP/NCAR再分析资料,研究了2006年夏季南亚高压偏西型和偏东型条件下青藏高原地区O3垂直结构和变化特征差异.结果表明,夏季南亚高压东西振荡与青藏高原O3分布存在密切的关系,在西(东)部型南亚高压条件下,夏季青藏高...     

气溶胶对青藏高原气候变化影响的数值模拟分析

利用美国大气研究中心(NCAR)提供的2组数值试验结果对比,分析了只考虑温室气体增加(1%CO2试验)和综合考虑大气温室气体与气溶胶持续增加(50yrs试验)条件下,青藏高原地区地表温度、积雪深度及其他气候要素的变化,并在此基础上探讨了大气气溶胶含量变化对高原气候变化的可能影响.分析结果表明:只考虑大气CO2含量每年增加1%的变化时,青藏高原相对邻近地区地表温度显著增加,春、夏、秋及冬季地表温度线性增温率均表现出随着海拔高度升高而增强.例如,在海拔1.5～2 km,3～3.5 km和4.5～5 km范围内对应的冬季增温趋势分别为0.29 ℃/10 a,0.36 ℃/10 a和0.50 ℃/10 a.在温室气体引起的高原增暖过程中地表积雪深度普遍降低,且高海拔地区的积雪减少愈加明显.当综合考虑气溶胶和温室气体含量共同增加时,青藏高原地表增暖相对偏弱,春、夏和秋季增温也随海拔高度上升而加强,但冬季地面增温幅度随海拔上升反而下降,海拔1.5～2 km,3～3.5km和4.5～5 km范围内对应的冬季增温趋势分别为0.02 ℃/10 a,-0.03 ℃/10 a和-0.13 ℃/10 a.对比分析发现,大气气溶胶增加造成青藏高原冬季增温不明显甚至出现变冷趋势,地面积雪也随之增多,这可能歪曲了青藏高原地区气候变暖对海拔高度的依赖性.     

1997—1998年青藏高原大气低频振荡及对降水影响

利用1979—1998年NCEP/DOE逐日再分析资料和国家气象信息中心的常规观测站资料,研究了1997/1998年冬季、1998年夏季青藏高原 (简称高原) 季风的低频振荡特征,研究夏季高原和周边区域高低层大气低频环流系统的配置及其与我国降水的联系。结果表明:1997/1998年冬季和1998年夏季,高原季风不仅表现出很强的30~60 d的周期振荡特征,还伴随有较强的准双周低频振荡;相应区域对流层上层200 hPa上的环流系统则是30~60 d为主的周期变化。1998年夏季,高原地面气压也存在两个频带的低频振荡变化,且其强度存在明显的经向变化,即自南向北30~60 d低频振荡信号有逐渐减弱趋势,准双周信号则呈增强趋势。对30~60 d的低频信号而言,高原夏季风低频信号较强 (弱) 时,高原地面表现为低频低 (高) 压环流系统,在同纬度带的我国东部地区和西太平洋沿岸,是较强的低频北 (南) 风和低 (高) 压环流系统;相应地,在80°~90°E之间,自孟加拉湾到我国西北中部地区,是低频反气旋-气旋-反气旋的经向低频波列;受低频环流系统影响,高原东部、长江中下游地区降水偏多 (少)、川西高原、云南西南部降水偏少 (多)。