The Effect of Super Volcanic Eruptions on Ozone Depletion in a Chemistry–Climate Model

With the gradual yet unequivocal phasing out of ozone depleting substances(ODSs), the environmental crisis caused by the discovery of an ozone hole over the Antarctic has lessened in severity and a promising recovery of the ozone layer is predicted in this century. However, strong volcanic activity can also cause ozone depletion that might be severe enough to threaten the existence of life on Earth. In this study, a transport model and a coupled chemistry–climate model were used to simulate the impacts of super volcanoes on ozone depletion. The volcanic eruptions in the experiments were the 1991 Mount Pinatubo eruption and a 100 × Pinatubo size eruption. The results show that the percentage of global mean total column ozone depletion in the 2050 RCP8.5 100 × Pinatubo scenario is approximately 6% compared to two years before the eruption and 6.4% in tropics. An identical simulation, 100 × Pinatubo eruption only with natural source ODSs, produces an ozone depletion of 2.5% compared to two years before the eruption, and with 4.4% loss in the tropics. Based on the model results,the reduced ODSs and stratospheric cooling lighten the ozone depletion after super volcanic eruption.     

Impact of increasing stratospheric water vapor on ozone depletion and temperature change

Using a detailed, fully coupled chemistry climate model (CCM), the effect of increasing stratospheric H_{2O on ozone and temperature is investigated. Different CCM time-slice runs have been performed to investigate the chemical and radiative impacts of an assumed 2 ppmv increase in H2O. The chemical effects of this H2O increase lead to an overall decrease of the total column ozone (TCO) by ～1% in the tropics and by a maximum of 12% at southern high latitudes. At northern high latitudes, the TCO is increased by only up to 5% due to stronger transport in the Arctic. A 2-ppmv H2O increase in the model's radiation scheme causes a cooling of the tropical stratosphere of no more than 2 K, but a cooling of more than 4 K at high latitudes. Consequently, the TCO is increased by about 2%--6%. Increasing stratospheric H2O, therefore, cools the stratosphere both directly and indirectly, except in the polar regions where the temperature responds differently due to feedbacks between ozone and H2O changes. The combined chemical and radiative effects of increasing H2O may give rise to more cooling in the tropics and middle latitudes but less cooling in the polar stratosphere. The combined effects of H2O increases on ozone tend to offset each other, except in the Arctic stratosphere where both the radiative and chemical impacts give rise to increased ozone. The chemical and radiative effects of increasing H2O cause dynamical responses in the stratosphere with an evident hemispheric asymmetry. In terms of ozone recovery, increasing the stratospheric H2O is likely to accelerate the recovery in the northern high latitudes and delay it in the southern high latitudes. The modeled ozone recovery is more significant between 2000--2050 than between 2050--2100, driven mainly by the larger relative change in chlorine in the earlier period.}     

热带对流层顶层结构的变化特征和趋势

利用1989～2008年欧洲中期天气预报中心高时空分辨率的再分析资料以及1980～2019年的大气化学—气候模式模拟资料分析了热带对流层顶层(Tropical Tropopause Layer,T TL)结构的变化特征,并且预测了其未来变化趋势.结果表明,TTL结构存在明显的季节和空间变化.其厚度在北半球的春、秋两季比...     

A CASE STUDY OF THE UNCORRELATED RELATIONSHIP BETWEEN TROPICAL TROPOPAUSE TEMPERATURE ANOMALIES AND STRATOSPHERIC WATER VAPOR ANOMALIES

Using the measurements from the Halogen Occultation Experiment(HALOE) and the European Centre for Medium-Range Weather Forecasts(ECMWF) Interim reanalysis data for the period 1994-2005, we analyzed the relationship between tropical tropopause temperature anomalies and stratospheric water vapor anomalies. It is found that tropical tropopause temperature is correlated with stratospheric water vapor, i.e., an anomalously high(low) tropical tropopause temperature corresponds to anomalously high(low) stratospheric water vapor during the period 1994-2005,except for 1996. The occurrence frequency and strength of deep convective activity during the‘mismatched'months is less and weaker than that during the‘matched'months in 1996. However, the instantaneous intensity of four short periods of deep convective activity, caused by strong surface cyclones and high sea surface temperatures, are greater during the ‘mismatched'months than during the ‘matched'months. Water vapor is transported from the lower troposphere to the lower stratosphere through a strong tropical upwelling, leading to an increase in stratospheric water vapor. On the other hand, deep convective activity can lift the tropopause and cool its temperature. In short, the key factor responsible for the poor correlation between tropical tropopause temperature and stratospheric water vapor in1996 is the instantaneous strong deep convective activity. In addition, an anomalously strong Brewer-Dobson circulation brings more water vapor into the stratosphere during the‘mismatched'months in 1996, and this exacerbates the poor correlation between tropical tropopause temperature and stratospheric water vapor.     

北半球冬季平流层温度和Brewer-Dobson环流对11 a太阳循环的响应

采用北京气候中心大气辐射模式(BCC-RAD)、日本气象厅JRA-55月平均再分析资料,研究了北半球冬季低纬度平流层上、下两个温度异常区对太阳周期的响应及其机制。结果表明,太阳活动偏强年,低纬度的上平流层温度暖异常是由臭氧短波加热异常引起的,它在中纬度的上平流层激发出异常强西风,阻碍行星波正常上传,由波破碎驱动的Brewer-Dobson环流也减弱,该环流上升支减弱的动力加热作用导致了低纬度的下平流层暖异常。     

海河流域水汽输送及其变化特征分析

根据海河流域测站降水资料、NCEP/NCAR再分析资料和日本气象厅JRA-25资料,分析了1951—2008年夏季海河流域大气水汽含量的变化以及不同环流形势下的水汽输送特征,结果表明：海河流域大气水汽含量存在显著的年代际变化特征,与降水量存在显著统计相关;海河流域上空纬向水汽输送主要发生在850~700 hPa之间,经向水汽输送在850 hPa以下存在强的水汽输送带,它是海河流域水汽的主要贡献者,也是影响海河流域降水的最主要因素之一。气旋型环流和南风型环流对海河流域水汽输送有较大影响。     

大气环流模式降水的模拟对水汽方程差分方案的敏感性试验

分别采用3种应用比较广泛的水汽方程差分方案:多维正定平流传输方案(MPDATA)、通量修正传输方案(FCT)和两步保形平流方案(TSPAS),对大气物理所9层大气环流模式(IAP 9L AGCM)的降水模拟作敏感性试验,分析比较3种方案下模式降水气候平均场的差异,从而揭示模式降水对水汽方程差分方案的敏感性.试验结果显示,不同的水汽方程差分方案对大气环流模式降水的气候模拟有较大影响,并由此从3种差分方案中为IAP 9L AGCM寻找出一种较好的水汽计算方案.     

Simulation of the Madden-Julian Oscillation in Wintertime Stratospheric Ozone over the Tibetan Plateau and East Asia: Results from the Specified Dynamics Version of the Whole Atmosphere Community Climate Model

The authors examined the Madden-Julian Oscillation(MJO) in stratospheric ozone during boreal winter using a simulation from the Specified Dynamics version of the Whole Atmosphere Community Climate Model(SD-WACCM) in 2004 and 2010. Comparison with European Centre for Medium-Range Weather Forecasts Interim Reanalysis(ERA-Interim) data suggested that the model simulation represented well the three-dimensional structure of the MJO-related ozone anomalies in the upper troposphere and stratosphere(i.e., between 200 and 20 h Pa). The negative ozone anomalies were over the Tibetan Plateau and East Asia in MJO phases 3–7, when the MJO convective anomalies travelled from the equatorial Indian Ocean towards the equatorial western Pacific Ocean. Due to the different vertical structures of the MJO-related circulation anomalies, the MJO-related stratospheric ozone anomalies showed different vertical structure over the Tibetan Plateau(25–40°N, 75–105°E) and East Asia(25–40°N, 105–135°E). As a result of the positive bias in the model-calculated ozone in the upper troposphere and lower stratosphere, the amplitude of MJO-related stratospheric ozone column anomalies(10–16 Dobson Units(DU)) in the SD-WACCM simulation was slightly larger than that(8–14 DU) in the ERA-Interim reanalysis.     

川西高原持续性暴雨特征和水汽输送

利用常规资料、NCEP FNL分析资料和HYSPLIT模式,对2008—2017年川西高原持续性暴雨过程的时空分布、环流分型、水汽源地和输送路径进行分析。结果表明:①2008—2017年川西高原单站持续性暴雨的总频次为337次,在21次区域持续性暴雨中,位于高原与盆地过渡区的泸定、康定、汶川出现持续性暴雨次数最多;②7月发生频率最高,持续时间多为3～4天;③将影响川西高原暴雨的环流分型为两槽一脊型、一脊一槽型、西风槽型和偏西气流型,其中孟加拉湾气旋影响有16例,6—7月个例都有孟加拉湾气旋的存在;④川西高原上空气团主要通过4条路径进入,源自北大西洋、地中海和伊朗中北部的西北路径占比29%,源自里海到咸海之间地区的东北路径占比17%,源自热带印度洋洋面的西南和东南路径各占比43%和11%,偏北路径的空气质点起始高度比偏南路径的高,相应的温度和水汽含量也偏低;⑤将水汽输送分为"S"型、偏西气流型和偏南气流型3个类型。     

海气耦合模式FGOALS_gl模拟的水汽和云辐射反馈过程

本文分析了中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG)发展的快速耦合模式FGOALS_gl对低纬太平洋区域水汽温室效应(Ga)和云辐射强迫特征的模拟能力,讨论了模拟偏差的成因.结果表明,FGOALS_gl能合理再现Ga、云辐射强迫的气候态空间分布特征,但也存在明显的偏差.模式低估了冷...     

Variation in Brewer–Dobson Circulation During Three Sudden Stratospheric Major Warming Events in the 2000s

As the strongest subseasonal atmospheric variability during boreal winter, three remarkable sudden stratospheric major warming(SSW) events in the 2000 s are investigated in terms of the Brewer–Dobson circulation(BDC) response. Our study shows that the changes of cross-isentropic velocity during the SSWs are not only confined to the polar region, but also extend to the whole Northern Hemisphere: enhanced descent in the polar region, as well as enhanced ascent in the tropics. When the acceleration of the deep branch of the BDC descends to the middle stratosphere, its strength rapidly decreases over a period of one to two weeks. The acceleration of the deep branch of the BDC is driven by the enhanced planetary wave activity in the mid-to-high-latitude stratosphere. Different from the rapid response of the deep branch of the BDC, tropical upwelling in the lower stratosphere accelerates up to 20%–40% compared with the climatology, 20–30 days after the onset of the SSWs,and the acceleration lasts for one to three months. The enhancement of tropical upwelling is associated with the large-scale wave-breaking in the subtropics interacting with the midlatitude and tropical Quasi-Biennial Oscillation–related mean flow.     

2006年川渝伏旱同期环流场和水汽场异常特征分析

2006年盛夏川渝地区发生了严重的伏旱灾害,通过对同期大气环流异常的诊断分析表明,2006年盛夏期间,我国川渝地区上空存在由东北向西南的异常水汽输送,从中南半岛到西南地区持续存在经向水汽输送的负异常中心,导致川渝地区上空维持着一个水汽输送辐散异常的中心,这种水汽输送形势有利于伏旱灾害的发展.西太平洋副高较常年持续异常偏北、偏西,强度偏强,它与东伸的伊朗高压及异常的青藏高压一起构成一条高压带,这也在很大程度上促进了川渝地区持续伏旱灾害的发展.     

青藏高原地区大气红外探测器（AIRS）资料质量检验及揭示的上对流层水汽特征

上对流层水汽（UTWV）是大气中最重要的温室气体,对全球气候变暖有重要贡献; 而青藏高原被认为是UTWV进入平流层的重要通道,在平流层－对流层水汽交换及平流层水汽变化中扮演着重要角色。首先利用高原探空站资料对大气红外探测器（AIRS）反演的水汽数据在高原地区的质量进行了检验,发现AIRS反演的水汽数据与探空实测数据是相当一致的。其中全年和夏半年AIRS的可信度较好,而冬半年,尤其是上对流层AIRS水汽可信度相对较低,但在缺乏高精密数据时仍部分可用。利用AIRS资料对青藏高原地区UTWV季节变化特征进行了分析,结果表明,高原冬季偏干,而夏季显著偏湿,并且空间分布具有明显的不均匀性。经验正交函数(EOF)分析显示,夏季高原UTWV主要存在三种空间分布型,即全区一致型,高原东西偶极型和南北带状偶极型。一致型分布具有明显的季节变化,而偶极型则以季节内振荡为主。在此基础上,重点研究夏半年高原地区UTWV季节内振荡特征,结果表明,UTWV季节内振荡的显著周期位于10～20天和30～60天。前者主要表现为纬向东传,并且可以越过高原进入我国江淮流域上空;而后者主要向南移动,基本表现为高原局地振荡。最后,进一步探讨了高原UTWV季节内振荡的可能机制,结果表明,高原地区UTWV的低频变化主要与高原热状况、南亚高压活动及其与二者相耦合的对流活动有关。     

川渝地区空中水资源分布及水汽输送特征

利用NCEP/NCAR全球1948~2003年共56年月平均再分析网格点(2.5°×2.5°)资料,计算并分析了川渝地区(100~110°E,25~35°N)空中水资源的逐年变化特征、时空分布、水汽输送特征、水汽收支状况以及大气可降水能力。结果表明:近56年来,川渝地区整层水汽含量总体是略呈下降趋势,但夏冬两季水汽呈上升态势;区域内水汽含量的水平分布表现为以四川盆地东南部至重庆涪陵为湿中心,自东南向西北逐渐减少的趋势;水汽输送以西南和东南方向为主;全年水汽收支呈现净输入的状态;秋、夏、春三季皆有较大的可降水量,空中潜在水资源丰富。     

青藏高原及周边地区水汽、水汽输送相关研究综述

本文对近几十年来,青藏高原及周边地区水汽、水汽输送相关研究进行了收集整理,重点回顾、归纳了青藏高原及周边地区水汽分布和源地、水汽输送特征以及该区域在我国水汽输送中的重要地位等方面的研究成果,同时也总结了近几十年来高原及周边地区水汽、水汽输送变化特征及带来的影响方面的相关研究结论,最后在综述的基础上对未来的研究方向进行了展望。      

2017年盛夏湖南持续性暴雨过程的水汽输送和收支特征分析

利用NCEP/NCAR再分析资料,首先分析了2017年6月下旬至7月初湖南持续性暴雨天气过程的环流背景和大尺度水汽输送特征,然后引入NOAA的轨迹模式HYSPLIT,分阶段定量分析了暴雨的水汽输送特征以及区域水汽收支情况。结果表明：天气系统的有效配置和稳定维持是强降雨持续的主要原因,持续性暴雨与全球范围的水汽输送和水汽辐合相联系,低空急流的演变和进退与暴雨落区和强度的演变关系密切。影响此次强降水过程的水汽通道主要有三支,第一支由索马里越赤道急流经孟加拉湾和我国西南地区输入暴雨区,第二支由印度洋中东部越赤道气流经孟加拉湾南部和南海北部输入暴雨区,第三支由来自南半球的越赤道气流自南海南部一路北上输入暴雨区,第三阶段还有一支水汽由赤道西太平洋穿越菲律宾进入南海后再北上输入暴雨区。过程第一、二阶段的水汽输送主要来自孟加拉湾,其次是南海,第三阶段来自孟加拉湾和南海（包括西太平洋）的水汽输送各占一半。受地形影响,孟加拉湾通道的水汽主要输送至暴雨区700 hPa,其他来自低纬洋面的通道水汽主要输送到850 hPa及以下各层。暴雨区水汽输入主要来自南边界和西边界,且主要由低层输入暴雨区,以水平水汽通量辐合的形式在暴雨区上空低层大量汇聚,经由强烈的垂直上升运动输送至对流层中高层积累和凝结,从而导致降水的产生,降水的强弱与边界水汽输入和区域水汽辐合的强弱变化一致。     

大气水汽变化及其反馈效应研究进展

大气水汽变化的反馈作用是影响平衡气候系统敏感性的最大反馈作用之一,能够放大其他温室气体增暖的效应,并可能导致极端天气气候事件的发生趋多趋强。因此,全面分析大气水汽的时空分布特征及其长期变化趋势,评估大气水汽反馈的区域气候效应,对于我们深入认识和理解全球变暖背景下区域气候响应的机理具有重要意义。综合国内外最新研究,已基本能够确定水汽反馈效应为一种使得全球增暖加快近一倍的强烈正反馈,并已能够估计其大致变化范围,但是此估计仍存在较大不确定性。随着卫星和探空技术的发展,目前已有的长期水汽资料日趋丰富,但资料之间也存在一些不确定性问题,同时单个资料本身也存在非均一性问题。最新的气候系统模式已能够大致模拟大气水汽的反馈效应,但近年的进展速度却并不令人乐观。我国的水汽观测和水汽反馈效应的研究也已取得长足进步,可以基本确定为水汽变化与地面温度存在正反馈关系,而与降水的关系虽然也较为密切,但因区域气候变化仍存在较大的不一致性。     

三江源地区水汽输送的时空变化特征及其机理研究

利用ERA5小时再分析资料分析了1981~2019年三江源地区水汽总量和水汽通量的时空演变规律及其可能成因。结果表明：三江源地区平均水汽总量和水汽通量的空间分布总体呈东南向西北递减的态势;其中,7月水汽表现出明显的异质性,对应平均水汽总量在可可西里和黄河源区的两个高值中心,平均水汽通量则恰好是两个低值区,该月水汽输送在曲麻莱、清水河一带和久治形成两个辐合区;近39年,平均水汽总量与平均水汽通量的经向输送呈增多趋势,但夏季平均水汽通量纬向输送的显著减少导致了其年值的减少;而平均水汽总量与平均水汽通量的年内分配分别呈“单峰”型、“双峰”型分布;西风环流减弱、高原夏季风以及南海夏季风增强,有利于水汽总量的增加和经向输送,而夏季高原热力作用则对水汽经向输送起到一定的扰动作用。     

我国可降水量同地面水汽压关系的经验表达式

本文根据1992～1993年全国20个台站地面及高空气象要素资料，拟合出各个站所在地区整层大气可降水量和有效水汽含量同地面水汽压之间的经验关系式。计算结果表明，可降水量和相应的地面水汽压之间，存在着良好的数值对应关系。仅利用地面水汽压计算出的整层大气可降水量和有效水汽含量，同实际情况符合得很好，平均相对误差普遍小于15％。因此，这些经验关系式具有良好的实际应用价值。     

滇西北高原机场一次暴雨过程的水汽输送特征分析

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