Thank Dr. Diallo for his comments, questions, guidance and suggestions. The replies to his major and minor questions are as follows: Replies for the major questions 1. Equation (5) ignores the time tendency term. If the time tendency term remains, it can be treated as a source or sink term. When the tendency is positive, it is a sink; when the tendency is negative, it is a source. Its relative influence is -1/(a+b) 1/c (∂c)/∂t According to Figure 3 of Rendel et al. (2010), the HCN difference between June and

Correctly calculating the vertical velocity of the Asian summer monsoon anticyclone (ASMA) region is helpful for accurately knowing the ozone stratosphere-troposphere exchange, so as to explore the variation of ozone in the ASMA region. Therefore, the vertical velocity over the ASMA in June, July, August, and September 2012 and 2016 was calculated using the thermodynamic method, which may avoid the deviations produced by the kinematics method using the mass continuity equation. In order to improve the accuracy, we used high-resolution heating rate datasets obtained via the radiation model in Canadian Atmospheric Global Climate Model called CanAM4.3_RAD based on in situ observations and revised satellite data from MLS/AIRS. The vertical velocity calculated by the thermodynamic method (V-T) is then compared with the data from ERA-Interim (VERA-I). In the daytime, values of V-T were similar to VERA-I and were dominated by ascending motion, although V-T showed descending motion at the western edge of the ASMA below 100 hPa. The intensity of V-T was slightly smaller than that of VERA-I at lower levels (200-100 hPa) over the ASMA region and significantly weaker above 100 hPa. The situation was more complex at night. Both V-T and VERA-I showed the convergence of vertical wind at 150 hPa and the divergence at 80 hPa, but V-T had a smaller standard deviation. V-T showed descending in the western and northern ASMA, but VERA-I only descended in the west. The descending motion in the west, seen in both V-T and VERA-I, is produced by the heating difference between the Qinghai-Tibet Plateau and the Iranian Plateau. The difference of the two vertical velocities in the northern ASMA may indicate the different understandings of the local Hadley Circulation and local Brewer-Dobson Circulation.

In this paper on the analysis of the vertical distribution of different-diameter dust aerosols and the potential impacts on East Asia, the sensitivity simulation tests of dust aerosols during 2002–03 were conducted by changing the underlying surface on the Qinghai-Tibet Plateau in the global atmospheric circulation model Community Atmosphere Model (CAM) 3.1. The results show that dust aerosol particles in East Asia are mainly distributed in the diameters of 0.64–5.12 μm. The high concentrations of dust aerosols are centered on the surface in the source areas and gradually raised during the eastward transport across East Asia, reaching a height of 4 km at 120° E. The small dust particles with diameters less than 1.28 μm are transported higher and farther driven by the midlatitude westerlies. The Qinghai-Tibet Plateau desertification leads to increasing concentrations of dust aerosols in all size bins and raisesthe transport height of dust aerosols in East Asia. The long-range transport in the East Asian troposphere is dominated by dust aerosols particles of diameters 0.64–2.56 μm, as well as a large contribution of dust aerosols with diameters larger than 1.28 μm.

Using four satellite data sets（TOMS/SBUV, OMI, MLS, and HALOE）, we analyze the seasonal variations of the total column ozone（TCO） and its zonal deviation（TCO*）, and reveal the vertical structure of the Ozone Low（OV） over the Asian continent. Our principal findings are:（1） The TCO over the Asian continent reaches its maximum in the spring and its minimum in the autumn. The Ozone Low exists from May to September.（2） The Ozone Low has two negative cores, located in the lower and the upper stratosphere. The lower core is near 30 hPa in the winter and 70 hPa in the other seasons. The upper core varies from 10 hPa to 1 hPa among the four seasons.（3）The position of the Ozone Low in the lower and the upper stratosphere over the Asian continent shows seasonal variability.

The South Asian High (SAH) has an important influence on atmospheric circulation and the Asian climate in summer. However, current comparative analyses of the SAH are mostly between reanalysis datasets and there is a lack of sounding data. We therefore compared the climatology, trends and abrupt changes in the SAH in the Japanese 55-year Reanalysis (JRA-55) dataset, the National Centers for Environmental Prediction Climate Forecast System Reanalysis (NCEP-CFSR) dataset, the European Center for Medium-Range Weather Forecasts Reanalysis Interim (ERA-interim) dataset and radiosonde data from China using linear analysis and a sliding t-test. The trends in geopotential height in the control area of the SAH were positive in the JRA-55, NCEP-CFSR and ERA-interim datasets, but negative in the radiosonde data in the time period 1979–2014. The negative trends for the SAH were significant at the 90% confidence level in the radiosonde data from May to September. The positive trends in the NCEP-CFSR dataset were significant at the 90% confidence level in May, July, August and September, but the positive trends in the JRA-55 and ERA-Interim were only significant at the 90% confidence level in September. The reasons for the differences in the trends of the SAH between the radiosonde data and the three reanalysis datasets in the time period 1979–2014 were updates to the sounding systems, changes in instrumentation and improvements in the radiation correction method for calculations around the year 2000. We therefore analyzed the trends in the two time periods of 1979–2000 and 2001–2014 separately. From 1979 to 2000, the negative SAH trends in the radiosonde data mainly agreed with the negative trends in the NCEP-CFSR dataset, but were in contrast with the positive trends in the JRA-55 and ERA-Interim datasets. In 2001–2014, however, the trends in the SAH were positive in all four datasets and most of the trends in the radiosonde and NCEP-CFSR datasets were significant. It is therefore better to use the NCEP-CFSR dataset than the JRA-55 and ERA-Interim datasets when discussing trends in the SAH.

AbstractThis paper presents the background, scientific objectives, experimental design, and preliminary achievements of the Third Tibetan Plateau (TP) Atmospheric Scientific Experiment (TIPEX-III) for 8–10 years. It began in 2013 and has expanded plateau-scale observation networks by adding observation stations in data-scarce areas; executed integrated observation missions for the land surface, planetary boundary layer, cloud–precipitation, and troposphere–stratosphere exchange processes by coordinating ground-based, air-based, and satellite facilities; and achieved noticeable progress in data applications. A new estimation gives a smaller bulk transfer coefficient of surface sensible heat over the TP, which results in a reduction of the possibly overestimated heat intensity found in previous studies. Summer cloud–precipitation microphysical characteristics and cloud radiative effects over the TP are distinguished from those over the downstream plains. Warm rain processes play important roles in the devel...

Since ozone hole in the polar region has been found,ozone depletion aroused extensive concern all over the world.The ozone valley over the Tibetan Plateau(OVTP) and over North America(OVNA) are seasonal ozone lows out of the polar region.They occurred both in middle latitudes and in summer half year.In order to compare their vertical structure and formation mechanism,we calculated ozone zonal deviation rate to show vertical structure of ozone valley over the Tibetan Plateau (OVTP) and North America,using MLS (Microwave Limb Sounder) data from 2005 to 2013,where ozone zonal deviation rate is ratio of ozone zonal deviation to ozone zonal mean,and ozone zonal deviation equals to ozone concentration minus ozone zonal mean.The ozone zonal deviation rate indicates that there are two centers of OVTP and one center of OVNA.One center of OVTP is located in the upper troposphere and lower stratosphere (UTLS) with peak ozone zonal deviation rate of-0.3,the other center is located in the upper stratosphere with peak ozone zonal deviation rate of-0.01.The center of OVNA is also located in the UTLS region with peak value of-0.18.The integration of zonal deviation shows that the UTLS center of OVTP with-15 DU is the strongest,the UTLS center of OVNA with-5 DU is in the middle and the upper center of OVTP with-1 DU is the weakest.Therefore,the vertical structure of ozone valley is clear.Then we analyzed the dynamic and chemical mechanism of the ozone valley.Summer circulation calculated from ERA-interim reanalysis data and summer ozone flux divergence calculated from ERA-interim data show that anticyclones are located over Tibetan Plateau and North America in the UTLS region.The anticyclone domain over the Tibetan Plateau is larger than that over North America.Moreover,corresponding ozone flux divergence over the Tibetan Plateau(1 × 10-12 kg · kg-1 · S-1) is more robust than that over North America(5× 10-13 kg · kg-1 · s-1),which is the main reason why UTLS center of OVTP is stronger than that of OVNA.UTLS center of OVTP,UTLS center and the only center of OVNA are mainly caused by dynamic processes.However,the MLS data implies chemical reaction may play a role in the upper center of OVTP.Zonal deviation of chlorine monoxide and hydrogen chloride are negative while zonal deviation of nitrogen dioxide is positive at 10 hPa over the Tibetan Plateau,which means chlorine monoxide and hydrogen chloride concentration are higher over the Tibetan Plateau than that in the same latitudes.Besides,nitrogen dioxide concentration are lower over the Tibetan Plateau than that in the same latitudes.Higher chlorine monoxide and hydrogen chloride concentration imply that chlorine cata lytic reactions make ozone loss stronger over the Tibetan Plateau.The lower nitrogen dioxide concentrations may slow the reaction which deactivates reactive chlorine into nonreactive chlorine and may strengthen the chlorine catalytic reactions.Consequently,chemical processes may have an effect on the upper center of OVTP.To sum up,there are two centers of OVTP and only one center of OVNA.UTLS center of OVTP with-15 DU is the stron gest,the UTLS center of OVNA with-5 DU is in the middle and the center of OVTP in the upper stratosphere with-1 DU is the weakest.UTLS center of OVTP,UTLS center and the only center of OVNA are mainly caused by dynamic processes.However,chemical processes may have an effect on the upper center of OVTP.

Trend uncertainty in the ozone valley over the Tibetan Plateau (OVTP) and the South Asian high (SAH) during 1979–2009 in ERA-Interim (interim reanalysis data from the ECMWF), JRA-55 (55-yr reanalysis data from the Japan Meteorological Agency), and NCEP-CFSR (Climate Forecast System Reanalysis) datasets was evaluated. The results showed that the NCEP-CFSR OVTP became strong in the summers of 1979–2009, whereas it became weak according to ERA-Interim and JRA-55. Satellite data merged with TOMS (Total Ozone Mapping Spectrometer) and OMI (Ozone Monitoring Instrument) agreed with the OVTP trend of NCEP-CFSR. The OVTP strengthening in NCEP-CFSR may have been caused by SAH intensification, a rising tropopause, and increasing ozone over non-TP (non-Tibetan Plateau) areas (27°–37°N, < 75°E and > 105°E). Analogously, the OVTP weakening in ERA-Interim and JRA-55 may have been affected by weakening SAH, descending tropopause, and decreasing non-TP ozone.

利用全大气气候通用模式(WACCM3)对政府间气候变化专门委员会排放情景特别报告中2001年到2099年A1B、A2、B1三种排放情景进行了模拟,分析了三种排放情景下青藏高原地区未来百年臭氧总量在夏季(6-8月)的变化趋势及引起该变化的可能机制.结果表明:在三种排放情景下未来百年夏季高原区臭氧总量均呈现增长趋势,其中A2情景下臭氧增长最快,B1情景下增长最慢,但相对于同纬度其他地区,高原区的臭氧总量增长较慢,即高原区臭氧谷加深.高原区高空污染物的减少以及局域Hadley环流的减弱是未来高原区臭氧总量增加的原因;而南亚高压的增强,以及与之相对应的辐散增强则可能是高原区臭氧谷继续加深的原因.

利用全球气候模式CAM5.1的20年(1991-2010年)沙尘气溶胶排放量模拟,分析全球沙尘气溶胶排放量的时空变化及其大气环流影响因子.结果表明:20年全球年平均沙尘气溶胶排放总量为1 152±28 Mt,全球沙尘气溶胶排放源主要集中在北非、阿拉伯半岛和中亚、东亚、澳大利亚及北美沙漠地区.北非沙漠地区作为全球最大的沙尘排放源区,占全球沙尘源总量的61.8％.各沙漠区均有显著的沙尘排放的季节变化和年际波动,沙尘气溶胶呈现春、夏季强排放和秋、冬季弱排放的季节循环.相对于沙尘排放的季节变化,其年际变化幅度明显偏弱.基于大气环流指数与沙尘气溶胶排放年际变化的相关显著程度,确定主要影响全球和主要沙漠地区沙尘排放量的大气环流因子:南方涛动指数SOI、北极涛动AO、南极涛动AAO、大西洋年际振荡指数AMO、北太平洋遥相关指数NP以及西太平洋指数WP.全球主要沙漠地区沙尘排放量与大气环流因子之间的相关性具有明显的区域分布特征,在同一沙漠的不同区域甚至可以表现出正负相反的相关性.热带海气相互作用的ENSO循环中,拉尼娜年(厄尔尼诺年)北非地区的沙尘排放量偏多(少),阿拉伯半岛和中亚地区的沙尘排放量偏少(多).

In this study, comparison of model results and satellite observations reveals that the Whole-Atmosphere Community Climate Model（WACCM-3） reasonably well reproduced the distributions and seasonal variations of Cl O and HCl concentrations. In three greenhouse gas emission scenarios（A1B, A2, and B1）,the Cl O, Cl, Cl ONO2, and HCl concentrations would gradually decrease with time as emissions of ozone depleting substances（ODS） steadily decrease. The rates of the changes in the Cl O, Cl, Cl ONO2, and HCl concentrations are different in the same emission scenario and the rates of change in the same composition concentration are different for different emission scenarios. The Cl O, Cl, and Cl ONO2 concentrations decrease fastest in scenario A2, next fastest in scenario A1 B, and slowest in scenario B1. In contrast, the HCl concentration decreases fastest in scenario B1. The ozone concentration recovers quickly, and is highest in scenario A2. The results show that a rapid decrease in the Cl O concentration is an important reason for the accelerated recovery of the ozone layer in scenario A2.

基于全球大气环流模式CAM3.1对2002-2003年模拟的全球沙尘气溶胶分布及其变化的评估,通过去除东亚沙漠(局地源)的敏感性模拟试验来分析北非、阿拉伯和中亚地区沙漠区(外部源)的沙尘气溶胶跨亚欧大陆传输对东亚地区大气沙尘气溶胶的贡献.结果表明,受到大气沙尘气溶胶的跨亚欧大陆传输的影响,东亚以外沙尘源对青藏高原大气贡献率最大,对我国北方干旱半干旱地区大气贡献率最小,对中国南方地区和日韩及邻近的西北太平洋地区大气贡献率基本相当.东亚地区秋(冬)季大气受到东亚以外沙尘源的影响最弱(强).我国北方干旱半干旱地区近地层大气沙尘气溶胶的外源贡献率秋季最小(约5％),冬季最大(约30％).青藏高原冬季60％～ 80％的近地面大气沙尘气溶胶来自东亚以外的沙漠区,而在秋季则只有约20％～ 60％.外源对东亚大气沙尘气溶胶柱浓度和对近地面大气沙尘气溶胶的影响具有基本一致的季节特征,但对柱浓度的贡献率一般偏大10％ ～ 40％.沙尘气溶胶跨亚欧大陆传输对东亚地区的影响主要集中在2～6 km的自由对流层.随对流层高度的增加东亚各地区外源贡献率均增加.青藏高原地区以年平均对流层沙尘气溶胶外源贡献率62％～81％成为东亚地区最大的影响区域.

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 150–50-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 150–50 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 150–50 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.

分析SAGE II资料发现:青藏高原对流层顶最高不超过17.6 km,夏季平均在17 km以下:来自对流层中低层的物质很少能被输送到17.5 km以上,来自对流层中低层的输送不会长时间持续地影响17.5 km以上的区域。青藏高原以及同纬度地区在15 20 km高度温度低于210 K,非均相化学反应可能在此起着重要作用。夏季青藏高原臭氧低谷的形成高度主要是15—20km,而且是长时间持续性的。分析结果显示:15—20km非均相化学过程在夏季青藏高原臭氧低谷的形成中可能起重要作用,特别在17.5—20km高度其所起的作用可能是主要的;而在17.5 km以下,从以往的研究可以知道青藏高原的动力和热力作用对夏季青藏高原臭氧低谷的形成起着主要作用。在春季和秋季,青藏高原上15—20km的臭氧"亏损"也可能是由于非均相化学过程造成的,使得青藏高原臭氧低谷每年从4月持续到10月。并且,影响非均相化学过程的主导因素可能是温度。

Using a regional climate model MM5 nested with an atmospheric global climate model CCM3,a series of simulations and sensitivity experiments have been performed to investigate responses of the mid-Holocene climate to different factors over China.Model simulations of the mid-Holocene climate change,especially the precipitation change,are in good agreement with the geologic records.Model results show that relative to the present day(PD)climate,the temperature over China increased in the mid-Holocene,and the increase in summer is more than that in winter.The summer monsoon strengthened over the eastern China north of 30°N,and the winter monsoon weakened over the whole eastern China;the precipitation increased over the west part of China,North China,and Northeast China,and decreased over the south part of China. The sensitive experiments indicate that changes in the global climate(large-scale circulation background), vegetation,earth orbital parameter,and CO_2 concentration led to the mid-Holocene climate change relative to the PD climate,and changes in precipitation,temperature and wind fields were mainly affected by change of the large-scale circulation background,especially with its effect on precipitation exceeding 50%.Changes in vegetation resulted in increasing of temperature in both winter and summer over China,especially over eastern China;furthermore,its effect on precipitation in North China accounts for 25%of the total change. Change in the orbital parameter produced the larger seasonal variation of solar radiation in the mid-Holocene than the PD,which resulted in declining of temperature in winter and increasing in summer;and also had an important effect on precipitation with an effect equivalent to vegetation in Northeast China and North China.During the mid-Holocene,CO_2 content was only 280×l0~(-6),which reduced temperature in a very small magnitude.Therefore,factors affecting the mid-Holocene climate change over China from strong to weak are large-scale circulation pattern,vegetation,earth orbital parameter,and CO_2 concentration.

Present and Mid-Holocene climates are simulated with a global climate model CCM3 nested with a regional model MM5.From the model results,it is found that in Mid-Holocene,the center of the effective precipitation variation changes with season.A maximum of 3 mm/d effective precipitation variation occurs over Northeast China and the eastern part of Inner Mongolia in summer.Meanwhile,precipitation between the Huanghe River and the Yangtze River decreases with a maximum of 2 mm/d.Cloud cover in North China increases while that over the middle and downstream of the Yangtze River basin reduces.Changes of low cloud amount are the most in three types of clouds with a maximum of more than 0.2,but high cloud changes are the least among them.Temperature between the Huanghe River and the Yangtze River rises the most due to the cloud cover reduction in summer.Water vapor and relative humidity over this region decrease,in accordance with the cloud cover reduction.Water vapor changes in South China are different with seasons.Water vapor and relative humidity in Northeast China increase,which results in cloud cover and precipitation increase.The model results illustrate that the relative humidity isn't a conservative factor,the maximum change of which is more than 15%.Moreover,temperature increases in some regions while water vapor decreases.However,in Last Glacial Maximum,when temperature decreases,water vapor consistently reduces.These indicate that temperatures decrease can result in water vapor reduction,but temperature increase does not always bring about water vapor enhancement.This is different from the fact that at the global scale the relative humidity is conserved.In Mid-Holocene,the Yangtze River basin became warmer and drier in all seasons except spring.Meanwhile,Northeast China and the eastern part of Inner Mongolia became more rainy and wetter.

The impact of chemical production and transport on diurnal ozone behavior in June 2006 at a mountainous site (Mt. Tai) in North China Plain (NCP) was studied by regional chemical transport coupled with a process analysis and a tagged tracer method. The observed diurnal variation in the morning minimum-afternoon maximum was reproduced well. The results showed that regional transport contributed similar to 60 ppbv to "background" ozone, with no significant diurnal variations (< 7 ppbv), while the chemistry (similar to 25 ppbv) in the surrounding region (an area of 150,000 km(2)) which demonstrated an afternoon-maximum explained the causes of diurnal ozone behavior. The process analysis also suggested that in-situ chemistry accounted for most of the increase in ozone from morning to mid-afternoon (rather than the ozone concentration itself), with a minor contribution from vertical transport. A comparison was conducted between Mt. Tai and a mountainous site in Japan (Happo) to determine the regional variability in photochemistry and transport over Eastern Asia. The results showed that photochemical activities around Mt. Tai were stronger than those around Happo, where dynamic processes, rather than in-situ chemistry, played a dominant role in the diurnal behavior of ozone at midnight (0:00-3:00 local time (LT) and at the maxima-minima before noon (11:00 LT).

Using a regional climate model MM5 nested to an atmospheric global climate model CCM3, a series of simulations and sensitivity experiments have been performed to investigate the relative LGM climate response to changes of land-sea distribution, vegetation, and large-scale circulation background over China. Model results show that compared with the present climate, the fluctuations of sea-land distribution in eastern Asia during the LGM result in the temperature decrease in winter and increase in summer. It has significant impact on the temperature and precipitation in the east coastal region of China. The impact on precipitation in the east coastal region of China is the most significant one, with 25%-50% decrease in the total precipitation change during the LGM. On the other hand, the changes in sea-land distribution have less influence on the climate of inland and western part of China. During the LGM, significant changes in vegetation result in temperature alternating with winter increase and summer decrease, but differences in the annual mean temperature are minor. During the LGM, the global climate, i.e., the large-scale circulation background has changed significantly. These changes have significant influences on temperature and precipitation over China. They result in considerable temperature decreases in this area, and direct the primary patterns and characteristics of temperature changes. Results display that, northeastern China has the greatest temperature decrease, and the temperature decrease in the Tibetan Plateau is larger than in the eastern part of China located at the same latitude. Moreover, the change of large-scale circulation background also controls the pattern of precipitation change. Results, also show that, most of the changes in precipitation over western and northeastern parts of China are the consequences of changing large-scale circulation background, of which 50%-75% of precipitation changes over northern and eastern China are the results of changes in large-scale circulation background. Over China, the LGM climate responses to different mechanisms in order of strength from strong to Weak are, the large-scale circulation pattern, sea-land distribution, vegetation, CO2 concentration, and earth orbital parameters.

A global 3-D CTM model (OsloCTM2) has been used to study the tropospheric ozone distribution and budget over China. An area covering China and most of East Asia is chosen as the study area. Because of the very nevenly distributed emissions and population in China, the budget study has been done by splitting China into three sub-areas, according to the emission distribution and topography of the country. The model results indicate that in Western China (Area1) dynamic processes are dominating, and the contribution from photochemical ozone production is small. Central and South-East China (Area2) has on average 65% of the photochemical ozone production in China, since more than 80% of the anthropogenic emissions come from this area. Northeast China (Area3) is influenced both by natural and*9nthropogenic emissions. The seasonal variation of ozone budgets was calculated in order to understand how different processes vary with the seasons. The strongest influences of emissions from the continent over the West Pacific region are found in spring, because of the large eastward transport and increased photochemical activities. Most NOx is consumed close to the emission sources; therefore, only 4% of emitted NOx is transported out of China, whereas 70% of the emitted CO is exported. It is calculated that the average net chemical ozone production efficiency by NOx loss is 7.2 in China.

It is found from the analysis of SAGE II dataset that there was a decreasing trend of stratospheric ozone over the Tibetan Plateau(TP) in 1985-2004.The changes in total column ozone mainly resulted from the ozone from 15 km to 50 km,wherein the role of the ozone from 25 km to 50 km was almost equal to that from 15 km to 25 km.From comparing the ozone changes between the TP and east part of China(ECHN),it can be clearly seen that the differences between the two areas was mostly ascribed to the difference of ozone changes from 15 km to 25 km.The trend for May to July was similar to that for yearly average,and the difference of trends between the two areas also mainly occurred in the low stratosphere from 15 km to 25 km.Time serials of aerosol area density over the TP show that big volcanic eruptions significantly affected the stratospheric aerosols over the TP, and the influences continuously lasted for about 6 years.Since 1997 the aerosol area density has increased between 18 km and 25 km over the TP,with a maximum growth of about 4% to 5% per year at 23 km,but decreased between 16 km and 17 km.Meanwhile,the temperature below 37 km has decreased over the TP,and it decreased faster over the TP than over the ECHN.From 37 km to 50 km,the temperature has increased,and it increased faster over the TP than over the ECHN.Both the aerosol increase and temperature decrease in the low stratosphere over the TP would all enhance the role of heterogeneous reactions.