气候变化对北半球臭氧总量变化影响的研究

发布时间：2018-05-07 16:33

  本文选题：臭氧柱总量 + 平流层臭氧　； 参考：《兰州大学》2016年博士论文

【摘要】：过去几十年,全球臭氧柱总量(Total Ozone Column,TOC)大体经历了先减小后增加的变化趋势。但是,不同纬度和不同高度的臭氧恢复速率存在显著的差异。气候系统内部变率、气候变化以及人类排放会对臭氧的长期变化造成重要的影响,这使得我们对未来臭氧变化趋势的评估存在较大的不确定性。一般而言,气候系统变率和气候变化与下垫面强迫变化(如海温、陆温和海冰的变化)存在紧密的联系。本文利用多种再分析资料和臭氧观测资料,结合全球大气化学气候模式,研究了过去30年气候变化背景下,北半球不同纬度带下垫面强迫的变化对北半球TOC的影响并讨论了相关的物理机制,得到以下主要结论:1.热带地区ENSO型海温变化会对北半球中纬度臭氧造成显著的影响,即El Ni?o事件会造成冬春季北太平洋、美国南部、北非东部和东亚地区的TOC相比气候平均值异常偏高,而使得中欧和北大西洋地区的TOC异常偏低;La Ni?a事件对北半球中纬度臭氧的影响几乎与El Ni?o型海温的影响相反。整体而言,在北半球冬春季,ENSO型海温变化对北半球中纬度TOC年际变率的贡献可达20-30%,其中在北太平洋区域甚至可达50%。ENSO型海温变化主要通过调节中纬度行星波和对流层顶高度来影响北半球中纬度臭氧分布。在ENSO期间赤道中东太平洋深对流活动异常,在上对流层激发异常的行星波波列传向中纬度地区,这些传播的行星波波列可分为沿北太平洋-北美大陆传播的长波波列和沿着北非-东亚急流带传播的短波波列,它们可以通过调节中纬度对流层顶高度和上对流层下平流层(Upper Troposphere Lower Stratosphere,UTLS)区域的局地环流影响UTLS内的臭氧浓度,最终改变臭氧的垂直分布并造成TOC的变化。另外,El Ni?o(La Ni?a)事件会使得北太平洋和美国南部西风急流增强(减弱),进而造成急流北侧的天气尺度Rossby波破碎频率相应增加(减少),造成更强(弱)的涡动次级环流,最终导致TOC的增加(减小)。上述的这些过程也造成了中国地区TOC和地表晴空紫外辐射强度对ENSO事件响应的异常中心从冬季位于中国南部到夏季向北移动至中国北方,同时强ENSO事件可引起冬季长江中下游和春季青藏高原西北部6-10%地表晴空紫外辐射强度的变化。2.在中纬度地区,“冷海洋-暖大陆”(Cold-Ocean Warm Land,COWL)和北太平洋(North Pacific,NP)型遥相关的变化对应着过去30年间阿留申低压、冰岛低压和亚速尔高压的减弱,这些系统的变化呈现很强的正压结构,从对流层低层一直延伸至平流层低层,而下平流层(70-300 h Pa)位势高度的变化直接造成了TOC出现纬向非均匀变化特征,即1979-2010年期间,北太平洋上空TOC一直呈现负趋势,而北美大陆上空的TOC则为正趋势。资料诊断和WACCM3模式模拟结果进一步表明,北太平洋和大西洋海温的变化可以通过影响COWL和NP型遥相关对北半球中纬度臭氧纬向非均匀分布造成显著影响。本文研究还发现高原冬春季地表增暖引起的对流层顶抬升和与之伴随的热带地区低浓度臭氧空气向高原输送增多,共同造成了2000-2009年间高原冬春季“臭氧低谷”的显著加深,高原地表增暖引起的热力、动力过程变化造成了过去30年冬季高原TOC约50%的减小。3.在高纬度和北极地区,2000年代北极海冰尤其是巴伦支海-喀拉海地区的海冰相比1980年代明显减少,以及过去几十年内欧亚大陆积雪的增加,共同造成欧亚大陆北侧海域对流层中下层温度升高,产生更多的斜压波动造成欧亚大陆一侧的低平流层出现冷性涡旋,最终导致近10年晚冬(2月)的北极极涡向欧亚大陆偏移。极涡向欧亚大陆偏移后,极涡内部具有高浓度活性溴氯的空气被输送至欧亚大陆上空,引起了该地区平流层臭氧化学损耗的加强,使得该地区冬季TOC的下降趋势强于同纬度其他地区。4.论文最后研究了北极涛动(Arctic Oscillation,AO)对北半球TOC和平流层臭氧的影响,结果表明,相比AO负位相时期,AO正位相下,北半球中高纬度平流层臭氧存在三个负异常中心,分别位于极地中平流层、UTLS区域和中纬度UTLS区域,这些异常中心在冬春季最强。其中,极地中平流层臭氧的负异常中心主要是由于Brewer-Dobson(BD)环流的经向输送减弱造成的,而极地UTLS区域臭氧的负异常中心则主要是由对流层顶高度异常抬升、BD环流垂直输送项减弱、中高纬度与极区的空气交换减弱以及异相化学反应增强等共同作用所造成的。中纬度UTLS区域臭氧的负异常中心则主要是由于臭氧空气从中纬度向热带地区涡动传输过程增强导致的;相比之下,从极地平流层传输至中纬度的低浓度臭氧空气贡献较小。
[Abstract]:In the past few decades, the global ozone column (Total Ozone Column, TOC) has generally experienced a trend to decrease first and then increase. However, there are significant differences in the rate of ozone recovery at different latitudes and at different heights. The internal variability of the climate system, climate change and human emissions will have an important effect on the long-term changes in ozone. There is a large uncertainty in our assessment of future trends in ozone change. In general, there is a close relationship between climate system variability and climate change and the underlying surface coercion (such as sea temperature, land mild sea ice). Under the background of climate change over the past 30 years, the effects of the forced changes in the lower latitudes of the northern hemisphere on the TOC in the northern hemisphere and the related physical mechanisms are discussed. The following main conclusions are obtained: 1. the changes in the ENSO type SEA SST in the tropics will cause significant impact on the mid latitude ozone in the northern hemisphere, that is, the El Ni? O event will cause the North Pacific in the winter and spring season, Compared to the TOC in the south, North Africa, East and East Asia, the average climate of the North Atlantic and North Atlantic is abnormally high, but the TOC in central and North Atlantic regions is abnormally low; the effect of La Ni a on the middle latitude ozone in the northern hemisphere is almost the opposite of the El Ni? O type sea temperature. In the winter and spring of the northern hemisphere, the change of ENSO type to the middle latitude of the northern hemisphere. The contribution of the interannual variability of degree TOC can reach 20-30%. In the North Pacific region even the 50%.ENSO type SEA SST changes mainly by adjusting the mid latitude planetary and tropospheric heights to affect the mid latitude ozone distribution in the northern hemisphere. During the ENSO, the deep convection in the equatorial Middle East Pacific is abnormal and the anomalous planetary wave excite in the upper troposphere. In the middle latitudes, these propagating planetary waves can be divided into long wave columns along the North Pacific and the North American continent and short waves propagating along the North Africa East Asia jet zone. They can be used to regulate the position of the upper tropospheric top and the upper troposphere (Upper Troposphere Lower Stratosphere, UTLS) region. The surface circulation affects the ozone concentration in UTLS, eventually changing the vertical distribution of ozone and causing the change of TOC. In addition, the El Ni? O (La Ni? A) event will increase the North Pacific and the southern United States westerly jet (weakened), and then cause the frequency of the weather in the north side of the jet to increase (decrease) and cause a stronger (weak) vortex subprime. The circulation, which eventually leads to the increase (decrease) of TOC. These processes also cause the abnormal center of the TOC and the surface clear air ultraviolet radiation intensity to the ENSO event from the southern part of China to the north in the summer, and the strong ENSO event can cause the winter of the middle and lower reaches of the Yangtze River and the northwest of the Qinghai Tibet Plateau in winter 6 The changes in the intensity of -10% surface clear air ultraviolet radiation.2. in the middle latitudes, "Cold Ocean warm continent" (Cold-Ocean Warm Land, COWL) and the North Pacific (North Pacific, NP) type teleconnection corresponding to the abate of Aleutian low, Iceland low pressure and altore high pressure in the past 30 years, and the changes of these systems present a strong positive pressure structure. From the lower troposphere to the lower stratosphere, the lower stratosphere (70-300 h Pa) potential height changes directly caused the zonal inhomogeneous variation of TOC. That is, during the 1979-2010 year period, the TOC over the North Pacific has been showing a negative trend, while the TOC over the North American continent is a positive trend. Data diagnosis and WACCM3 model simulation results are found. It is further indicated that the changes in sea temperature in the North Pacific and the Atlantic can affect the non-uniform distribution of ozone zonal distribution in the middle latitudes of the northern hemisphere by affecting the teleconnection of the COWL and NP types. The increase has resulted in a remarkable increase in the winter and spring "Ozone Valley" of the plateau in the past 2000-2009 years, the heat caused by the plateau surface warming, and the change of the dynamic process caused by the decrease of TOC about 50% of the plateau in the past 30 years in the high latitudes and the Arctic region, and in 2000s the Arctic sea ice was especially 198 compared to the sea ice in the Barents Kara Sea region. The decrease in 0s and the increase of snow in Eurasia in the past few decades have resulted in the increase of the lower layer temperature in the troposphere in the north of Eurasia, resulting in more baroclinic fluctuations that cause cold vortices in the low stratosphere on the Eurasian continent and eventually lead to the polar vortex in the last 10 years (February) to the Eurasian continent. After the migration to Eurasia, the air with high concentration of active bromide in the polar vortex is transported over the Eurasian continent, causing the enhancement of the ozone chemical loss in the stratosphere of the region, which makes the TOC decline in winter in the region stronger than the.4. paper in the other latitudes at the end of the study of the Arctic Oscillation (Arctic Oscillation, AO) to the northern hemisphere TOC The effect of ozone in the peace flow layer shows that there are three negative anomalous centers in the middle and high latitudes of the northern hemisphere compared with the negative phase of the AO negative phase, in the middle and high latitudes of the northern hemisphere, which are located in the polar middle advection layer, the UTLS region and the middle latitude UTLS region, which are the strongest in the winter and spring, and the negative center of the ozone in the polar middle stratosphere is the main center. If the meridional transport of the Brewer-Dobson (BD) circulation is weakened, the negative center of ozone in the polar UTLS region is mainly caused by the abnormal uplift of the tropospheric top, the weakening of the vertical transport term of the BD circulation, the weakening of the air exchange in the middle and high latitudes and the increase of the chemical reaction in the polar region, and the middle latitude UTLS. The negative anomaly center of regional ozone is mainly due to the enhancement of the ozone air from the middle latitude to the tropical zone. In contrast, the low concentration ozone air from the polar stratosphere to the middle latitude contributes less.

【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P467;P402
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本文编号：1857650