北半球仲春平流层行星波活动对臭氧总量分布的影响

采用NCEP/NCAR再分析资料和TOMS臭氧总量资料,分析了1979～2003年4月份平流层行星波1波和2波的变化,及其对北半球中高纬臭氧总量分布的影响.结果表明,在通常情况下,4月份平流层中下层行星波1波强于2波,对应的位势高度场在欧亚大陆北部为一低压涡旋,而北美北部为一高压区.此时,从东北亚到北加拿大为臭氧总量的高值区,而北欧至格陵兰一带为臭氧的低值区.但在有些年份,2波比较强时,相应的位势高度场在极地为一明显的低压涡旋,此时在极地附近会出现臭氧低值区.个别年份如1997年,1波在25年中最强,2波也很强,强低涡中心比常年更靠近北极点,在与之位置相同的地方出现了25年中最明显的臭氧洞.还有一些年份,北极地区主要由高压控制,臭氧总量的高值区基本上出现在北极及其附近.     

Extremely cold and persistent stratospheric Arctic vortex in the winter of 2010-2011

Record ozone loss was observed in the stratospheric Arctic in the spring of 2011. In the present work, we show observational evidence that the record loss of Arctic ozone is due to the extremely cold and persistent stratospheric polar vortex in the winter of 2010-2011. The polar vortex was as usual in early winter, but was intensified twice in middle January and middle February, respectively, and remained anomalously strong and stable until early April, 2011. Record low polar temperatures and record high subpolar zonal winds occurred in February and March. Stratospheric wave activity was anomalously weak because waves were refracted equatorward by the anomalously strong polar night jet. With such an extremely cold and isolated environment, Arctic stratospheric ozone was largely depleted in March and early April, 2011. Corresponding to Arctic ozone depletion, the stratospheric Northern-Hemisphere Annular Mode (NAM) displayed anomalously strong high-polarity, and the positive stratospheric NAM propagated downward and led to anomalously strong positive NAM in the troposphere and near the surface.     

平流层极地臭氧损耗影响对流层气候的研究进展

大气平流层臭氧的严重损耗将导致到达地面的太阳紫外辐射增加已经是公共社会普遍关切的问题。最近几年,平流层臭氧损耗能否对对流层大气环流和气候产生重要影响也引起了广泛的重视,并且已成为大气科学的一个热点问题。观测研究表明近二三十年来在两极臭氧严重损耗的季节,地表气温有明显的变暖趋势,也就是欧亚大陆1—3月份和南极半岛12—5月份的地面温度呈现显著增温。这些增温趋势很可能是平流层两极的严重臭氧损耗造成的。当然,这些增温并非是由臭氧损耗的辐射效应直接造成的,而是通过波－流相互作用以及平流层－对流层相互作用等动力学过程实现的。大量的数值模拟工作也对此问题进行了研究,一些模拟结果与观测结果基本一致,另一些则发现平流层臭氧损耗的强迫作用较弱,也有模拟工作认为其他外界强迫如温室气体增加和热带海面温度升高也非常重要。作者综述了这一研究领域在近几年的最新研究进展,总结有关的观测分析和数值模拟结果,阐述平流层极地臭氧损耗可能影响地面温度的物理机制,以及澄清各种争论要点。     

Monitoring of the 2011 spring low ozone events in the Arctic region

Data from FY-3B SBUS and NOAA SBUV/2 were used to monitor ozone levels in the Arctic region from March 1 to April 5, 2011. Results revealed a significant ozone depletion in the area, with total ozone levels between 200–250 DU. The ozone levels recorded were 100–200 DU below normal, and in some parts the levels were as low as 200 DU, indicating a mini ozone-hole. During the sampling period, the ozone depletion area underwent identifiable expansion and detraction, a rotation around the North Pole from the west to the east, and a longitudinal movement from the Pole, spreading to the mid latitudes. The effects of these rare low ozone events were not only felt in the Arctic, but also extended to densely populated areas between Europe and the middle of Russia. In this region, rapidly increasing levels of ultraviolet radiation were detected at the Earth’s surface. Given the significant risk that this poses to both the environment and people’s health, this occurrence has significant global implications.     

Extreme climate of the global troposphere and stratosphere in 1940-42 related to El Niño

Although the El Ni?o/Southern Oscillation phenomenon is the most prominent mode of climate variability and affects weather and climate in large parts of the world, its effects on Europe and the high-latitude stratosphere are controversial. Using historical observations and reconstruction techniques, we analyse the anomalous state of the troposphere and stratosphere in the Northern Hemisphere from 1940 to 1942 that occurred during a strong and long-lasting El Ni?o event. Exceptionally low surface temperatures in Europe and the north Pacific Ocean coincided with high temperatures in Alaska. In the lower stratosphere, our reconstructions show high temperatures over northern Eurasia and the north Pacific Ocean, and a weak polar vortex. In addition, there is observational evidence for frequent stratospheric warmings and high column ozone at Arctic and mid-latitude sites. We compare our historical data for the period 1940-42 with more recent data and a 650-year climate model simulation. We conclude that the observed anomalies constitute a recurring extreme state of the global troposphere-stratosphere system in northern winter that is related to strong El Ni?o events.     

Unprecedented Arctic ozone loss in 2011

Chemical ozone destruction occurs over both polar regions in local winter-spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was--for the first time in the observational record--comparable to that in the Antarctic ozone hole. Unusually long-lasting cold conditions in the Arctic lower stratosphere led to persistent enhancement in ozone-destroying forms of chlorine and to unprecedented ozone loss, which exceeded 80 per cent over 18-20 kilometres altitude. Our results show that Arctic ozone holes are possible even with temperatures much milder than those in the Antarctic. We cannot at present predict when such severe Arctic ozone depletion may be matched or exceeded.     

大气臭氧耗损的修复

评述了修复大气臭氧耗损的化学法和物理法，某些化学法如在南极旋涡中注入烃类可能由于生成另外的活性氯原子而不能有效地抑制大气臭氧耗损，某些物理法如利用大气电子电荷修复大气臭氧耗损，这是令人感兴趣的方法，它没有其他的化合物生成，但是会遇到技术和光电子材料的难题。在此，提出了另一类修复大气臭氧耗损的新方法，观测到卤代烃在细颗粒物渗溶冰晶表面的低温粘着系数比在冰晶上的粘着系数大2个数量级。因此有可能利用细颗粒物特性和低温非均相反应消除平流层的卤代烃及氯氟烃等达到阻断大气臭氧耗损的链反应。     

Surface ozone monitoring and background characteristics at Zhongshan Station over Antarctica

Seasonal variation in surface ozone and the relationship between the background ozone concentration and wind were evaluated at Zhongshan Station,Antarctica using 2008 data.The wind frequency from the station area was only 2%,while the prevailing wind frequency was much larger (79.2%).This indicates that the surface ozone observations were not affected by the human activities at the station,and therefore could be counted as background concentrations of surface ozone along Antarctic coast.The concentration of surface ozone shows a distinct annual variation with the yearly mean of 25.0 nmol mol-1 and the maximum in winter,the minimum in summer.The surface ozone concentration had a strong negative correlation with ultraviolet radiation,and the mean values during polar night were one to two times higher than those in summer.These results imply that photochemical destruction of ozone dominates over Antarctica.The ozone depletion events at Zhongshan Station were obviously related to lower temperatures and higher BrO concentrations.Backward trajectory analysis reveals that the ozone depletion events are predominately caused by the high BrO concentrations.     

壁面绿化及热效应对浅型街谷内污染物扩散与转化的影响研究

采用经风洞实验验证的CFD数值模型,就壁面绿化和热效应对浅型街谷内污染物扩散和NO_x-O₃光化学转化的影响开展研究。考虑了4种壁面受热模式以及4种叶面积密度的壁面绿化模式,并采用臭氧消耗率衡量光化学反应的剧烈程度。结果表明,壁面受热会改变街道峡谷内的流动结构,背风面受热和地面受热能够增加峡谷内顺时针旋涡的尺度,迎风面受热会削弱该旋涡的尺度,全壁面受热则会破坏旋涡结构。壁面绿化的设置能够有效降低峡谷内平均温度,促进峡谷内旋涡结构的重构,并且不同程度降低平均臭氧消耗率。因此,壁面绿化对缓解城市热岛效应和光化学污染具有积极的意义。     

卫星遥感监测大气臭氧总量分布和变化

 利用卫星紫外仪器TOMS、OMI和TOU的臭氧总量数据(1979-2014年),研究了全球及关键地区臭氧总量的分布及变化。讨论了南北半球臭氧总量分布和变化的差异,探讨了影响臭氧分布和变化的可能因子。重点分析了中国区域、青藏高原和极地的臭氧变化,并利用FY-3数据对南极臭氧洞和北极臭氧低值进行了监测。结果表明,臭氧总量的分布和变化在中高纬度地区具有很强的不均匀性,极地臭氧损耗依然明显,青藏高原的臭氧增长大于同纬度其他地区,其机制更加复杂。     

Arctic microorganisms respond more to elevated UV-B radiation than CO2

Surface ultraviolet-B radiation and atmospheric CO2 concentrations have increased as a result of ozone depletion and burning of fossil fuels. The effects are likely to be most apparent in polar regions where ozone holes have developed and ecosystems are particularly sensitive to disturbance. Polar plant communities are dependent on nutrient cycling by soil microorganisms, which represent a significant and highly labile portion of soil carbon (C) and nitrogen (N). It was thought that the soil microbial biomass was unlikely to be affected by exposure of their associated plant communities to increased UV-B. In contrast, increasing atmospheric CO2 concentrations were thought to have a strong effect as a result of greater below-ground C allocation. In addition, there is a growing belief that ozone depletion is of only minor environmental concern because the impacts of UV-B radiation on plant communities are often very subtle. Here we show that 5 years of exposure of a subarctic heath to enhanced UV-B radiation both alone and in combination with elevated CO2 resulted in significant changes in the C:N ratio and in the bacterial community structure of the soil microbial biomass.     

Detection of bromine monoxide in a volcanic plume

The emission of volcanic gases usually precedes eruptive activity, providing both a warning signal and an indication of the nature of the lava soon to be erupted. Additionally, volcanic emissions are a significant source of gases and particles to the atmosphere, influencing tropospheric and stratospheric trace-gas budgets. Despite some halogen species having been measured in volcanic plumes (mainly HCl and HF), little is known about bromine compounds and, in particular, gas-phase reactive bromine species. Such species are especially important in the stratosphere, as reactive bromine-despite being two orders of magnitude less abundant than chlorine-accounts for about one-third of halogen-catalysed ozone depletion. In the troposphere, bromine-catalysed complete ozone destruction has been observed to occur regularly during spring in the polar boundary layers as well as in the troposphere above the Dead Sea basin. Here we report observations of BrO and SO2 abundances in the plume of the Soufrière Hills volcano (Montserrat) in May 2002 by ground-based multi-axis differential optical absorption spectroscopy. Our estimate of BrO emission leads us to conclude that local ozone depletion and small ozone 'holes' may occur in the vicinity of active volcanoes, and that the amount of bromine emitted from volcanoes might be sufficiently large to play a role not only in the stratosphere, but also in tropospheric chemistry.     

Atmospheric science: early peak in Antarctic oscillation index

The principal extratropical atmospheric circulation mode in the Southern Hemisphere, the Antarctic oscillation (or Southern Hemisphere annular mode), represents fluctuations in the strength of the circumpolar vortex and has shown a trend towards a positive index in austral summer in recent decades, which has been linked to stratospheric ozone depletion and to increased atmospheric greenhouse-gas concentrations. Here we reconstruct the austral summer (December-January) Antarctic oscillation index from sea-level pressure measurements over the twentieth century and find that large positive values, and positive trends of a similar magnitude to those of past decades, also occurred around 1960, and that strong negative trends occurred afterwards. This positive Antarctic oscillation index and large positive trend during a period before ozone-depleting chemicals were released into the atmosphere and before marked anthropogenic warming, together with the later negative trend, indicate that natural forcing factors or internal mechanisms in the climate system must also strongly influence the state of the Antarctic oscillation.     

Analysis for retrieval and validation results of FY-3 Total Ozone Unit (TOU)

Retrieval experiment was made for global total column ozone using the first year measurements of Total Ozone Unit (TOU) on board the second generation polar orbiting meteorological satellite of China, FY-3/A. The retrieval results were analyzed and validated by comparison with AURA/OMI, Meteop/GOME-2 global ozone products and ground-based ozone measurement data. The qualititative comparisons over the globe especially over Antarctica and the Tibetan Plateau show that the spatial and temporal distribution characteristics are consistent with OMI and GOME-2 products. The quantitative comparisons with ground-based measurements and AURA/OMI ozone product were made over 74 stations, the TOU total ozone retrieval has a 3% rms relative error compared with AURA/OMI ozone product and 4.2% rms relative error with ground-based measurements. The maximum difference between satellite retrieval and ground-based measurements was found in the Antarctica ozone hole. The TOU global ozone product is operational and distributed to all users.     

Observational responses of stratospheric sudden warming to blocking highs and its feedbacks on the troposphere

The influences of tropospheric blocking high on the stratospheric sudden warming (SSW) and the SSW-induced feedback on the lower atmosphere are analyzed with NCEP (National Center for Environmental Prediction) 2 reanalysis data. Daily mean data from 1979 to 2010 are used to perform statistical and dynamical analyses. According to different distribution features of polar vortex, which can be ascribed to different activities of blocking highs, we have obtained two warming patterns in vortex splitting and displacement patterns. For vortex splitting events, in the Eurasian-North American (ENA) paratype, with disturbances of Atlantic and Aleutian blocking highs, polar vortex is split into two parts that locate at Eurasian and North American continents respectively, while in the Atlantic-East Asian (AEA) paratype, two low-pressure centers derived from the split vortex are situated in the Atlantic and East Asian regions, and two blocking systems occurring in the Urals and North American areas precede these splitting processes. For vortex displacement events, in the Aleutian-Intrusion (AI) paratype, the polar vortex is displaced to the west European and Atlantic areas by the intrusive Aleutian high and this pattern always corresponds to the blocking events occurring in the Pacific basin only. Similarly, the vortex is pushed to the west Eurasian continent by the intrusive North American high-pressure system in the North American-Intrusion (NAI) paratype, which is closely related to the blocking over these areas. The second subject of the research is that whether the anomalous stratospheric signals can be propagated to the lower atmosphere, which is depended on the intensity, duration and position of the disturbed vortex. According to our case studies, geopotential height anomalies can be propagated to the troposphere in strong SSW years, taking about 10-15 d for the decrease from 10 to 500 hPa, leading to apparent variations in the geopotential height and temperature fields.     

The search for signs of recovery of the ozone layer

Evidence of mid-latitude ozone depletion and proof that the Antarctic ozone hole was caused by humans spurred policy makers from the late 1980s onwards to ratify the Montreal Protocol and subsequent treaties, legislating for reduced production of ozone-depleting substances. The case of anthropogenic ozone loss has often been cited since as a success story of international agreements in the regulation of environmental pollution. Although recent data suggest that total column ozone abundances have at least not decreased over the past eight years for most of the world, it is still uncertain whether this improvement is actually attributable to the observed decline in the amount of ozone-depleting substances in the Earth's atmosphere. The high natural variability in ozone abundances, due in part to the solar cycle as well as changes in transport and temperature, could override the relatively small changes expected from the recent decrease in ozone-depleting substances. Whatever the benefits of the Montreal agreement, recovery of ozone is likely to occur in a different atmospheric environment, with changes expected in atmospheric transport, temperature and important trace gases. It is therefore unlikely that ozone will stabilize at levels observed before 1980, when a decline in ozone concentrations was first observed.     

关于大气臭氧问题的主要研究进展

大气臭氧是非常重要的温室气体,其在全球的分布具有不均匀性,受到人类活动的显著影响,近几十年来由于对流层臭氧增加造成正的辐射强迫会增加大气温室效应,而平流臭氧减少会使其吸收的紫外线辐射减少,为负的辐射强迫,使得平流层大气降温。因此关于大气臭氧浓度变化及其对气候的影响是非常复杂的,一直是科学界研究的热点和难点问题。自从20世纪50年代末到70年代就发现臭氧浓度有减少的趋势。1985年英国南极考察队在南纬60°地区观测发现存在大气臭氧层空洞;自此开始,大气臭氧问题引起了世界各国的极大关注,并给予很多研究。目前,平流层和对流层臭氧浓度的观测仍然是研究的重点。鉴于对流层臭氧浓度持续升高和平流层臭氧浓度的不断下降,以及他们在对流层和平流层大气温度中所起的不同作用,本文将主要针对近五年来大气臭氧相关的研究进展进行简要的综述,包括对流层和平流层臭氧浓度及其观测研究,和人类活动的影响等方面进行分述。最后给出目前研究工作的不足和未来工作展望。     

昭通市2次低温雨雪冰冻灾害天气过程对比分析

对2008年1月12日～2008年2月20日和2011年1月1日～2011年2月2日发生在昭通市的持续性低温雨雪冰冻灾害天气进行了对比分析,结果表明:2次过程均发生在拉尼娜事件年大气纬向环流异常期,500 hPa极涡偏离极地向亚洲和北美伸出2个槽,亚洲极涡面积偏大,南支槽活跃,地面蒙古冷高压偏强,滇黔静止锋偏强且维持时间长.不同的是:500 hPa上2008年1月乌拉尔山地区为倒Ω槽,而2011年1月乌拉尔山地区阻高脊线北伸到65°N附近,脊前新疆北部及蒙古西部为一冷槽;拉尼娜强度2011年比2008年强.     

Surface ozone observations during voyages to the Arctic and Antarctic regions

Surface ozone concentration and UV-B data between 75° N and 70° S were obtained aboard the Chinese polar scientific vessel “Xue -long” (Snow-Dragon) during the first voyage to the Arctic and the 16th to the Antarctic in 1999–2000. Analysis of these data presents that variations of the surface ozone concentration have small amplitude during voyages except the mid-latitude in the Northern Hemisphere. As a whole, average surface ozone concentration in the Northern Hemisphere is higher than that in the Southern, and high value occurred when the ship sailed close to the continents. The average diurnal variations of the surface ozone in the Northern Hemisphere are also higher compared to the southern counterparts, and high diurnal variations were found at low latitudes, and relative low level in the polar region.     

South-polar features on Venus similar to those near the north pole

Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright 'dipole' feature surrounded by a cold 'collar' at its north pole. The polar dipole is a 'double-eye' feature at the centre of a vast vortex that rotates around the pole, and is possibly associated with rapid downwelling. The polar cold collar is a wide, shallow river of cold air that circulates around the polar vortex. One outstanding question has been whether the global circulation was symmetric, such that a dipole feature existed at the south pole. Here we report observations of Venus' south-polar region, where we have seen clouds with morphology much like those around the north pole, but rotating somewhat faster than the northern dipole. The vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper. The spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition.