Intraseasonal oscillation of the southwest monsoon over Sri Lanka and evaluation of its subseasonal forecast skill

斯里兰卡的雨季发生于5-9月间,主要受西南季风的控制.本文发现该地区的西南季风降水存在很强的次季节变率,主导周期为10-35天.降水的季节内变化与西传的异常气旋有关.进一步,利用S2S比较计划中欧洲中心的数值预报模式(ECMWF)提供的回报试验数据,评估了当今动力模式对斯里兰卡西南季风次季节变化的预报技巧.结果显示,对季风指数的预测技巧超过30天,而对降水指数的预测技巧大约两周,且模式的预报技巧具有明显的年际差异.分析表明,能否正确模拟出大尺度环流对热带对流的响应是影响斯里兰卡降水预测的重要因子.     

Intraseasonal oscillation of the rainfall variability over Rwanda and evaluation of its subseasonal forecasting skill

非洲中东部地区的经济主要依靠自给农业支撑,该地区农业经济对降水的变化尤为敏感.本文以卢旺达为例,观测分析指出卢旺达的次季节降雨主要集中在10-25天;根据次季节尺度降水变率的单点相关方法,发现卢旺达的次季节降水变率和周围区域变化一致;进一步合成结果显示该地区次季节降水变率与异常西风有关,这可追溯到赤道地区西传的赤道Rossby波.最后,本文评估了当前动力模式ECMWF对 卢旺达地区(即非洲中东部)次季节降水变率的预报能力,发现EC模式在对该区域降水和相关风场指数的预报技巧都在18天左右,且预报技巧表现出一定的年际差异,这可能与热带太平洋的背景海温信号有关.该工作增进了当 前对非洲中东部地区的次季节降水变率和预测水平的认知,并且对该地区国家粮食安全和防灾减灾具有启示性意义.     

Variability of Atlantic Meridional Overturning Circulation in FGOALS-g2简

The variability of Atlantic Meridional Overturning Circulation （AMOC） in the pre-industrial control experiment of the Flexible Global Ocean-Atmosphere-Land System model, Grid-point Version 2 （FGOALS-g2） was investigated using the model outputs with the most stable state in a 512-yr time window from the total 1500-yr period of the experiment. The period of AMOC in FGOALS-g2 is double peaked at 20 and 32 years according to the power spectrum, and 22 years according to an auto-correlation analysis, which shows very obvious decadal variability. Like many other coupled climate models, the decadal variability of AMOC in FGOALS-g2 is closely related to the convection that occurs in the Labrador Sea region. Deep convection in the Labrador Sea in FGOALS-g2 leads the AMOC maximum by 3-4 years. The contributions of thermal and haline effects to the variability of the convection in three different regions [the Labrador, Irminger and Greenland-Iceland- Norwegian （GIN） Seas] were analyzed for FGOALS-g2. The variability of convection in the Labrador and Irminger Seas is thermally dominant, while that in the colder GIN Seas can be mainly attributed to salinity changes due to the lower thermal expansion. By comparing the simulation results from FGOALS-g2 and 11 other models, it was found that AMOC variability can be attributed to salinity changes for longer periods （longer than 35 years） and to temperature changes for shorter periods.     

Impacts of the Kuwait Oil Fires on the Mount Qomolangma Region

Mt. Qomolangma (also known as Mt. Everest), the world’s highest mountain, is situated over the world’s highest plateau, the Tibetan Plateau. Because of its height and because of its distance from industrialized areas, the environmental state of the Mt. Qomolangma region can normally be considered “undisturbed”. It is interesting to investigate how this “undisturbed” state has been changing with time and whether it has been influenced by large environmentally disruptive events such as the Kuwait oil fires of 1990 and 1991 (Small, 1991). In order to do this, riv-er water samples were collected from the Rongpu River at Rongpu Temple Station in the summers of 1992 and 1993, as was done in 1975, and aerosol samples were collected in the summer of 1992 at the same station as was done in 1980. River water samples were analyzed using atomic absorption spectroscopy (AAS) at the Chinese Academy of Sciences. Aerosol samples were analyzed using proton-induced x-ray emission (PIXE) at the University of Fudan in Shanghai. The results show that the concentrations of chemical species in the river water at Rongpu Temple Station were much higher in the summer of 1992 than they were in 1975 and 1993, and the concentrations of atmospheric chemical species were much higher in 1992 than they were in 1980. The environment of the north slope of Mt. Qomolangma was therefore heavily polluted before and/or during the summer of 1992, possibly due to the Kuwait oil fires in 1990 and 1991.     

Numerical Simulation of the Effect of the SST Anomalies in the Tropical Western Pacific on the Blocking Highs over the Northeastern Asia

The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributions of the SST anomalies in the tropical western Pacific,respectively.Firstly,the atmospheric circulation anomalies during July and August,1980 are simulated by three anomalous experiments including the global SST anomaly experiment,the tropical SST anomaly experiment and the extratropical SST anomaly experiment,using the observed SST anomalies in 1980.It is shown that the SST anomalies in the tropical ocean greatly influence the formation and maintenance of the blocking high over the northeastern Asia,and may play a more important role than the SST anomalies in the extratropical ocean in the influence on the atmospheric circulation anomalies.Secondly,the effects of the SST anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are also simulated w     

与西太平洋暖池上空对流年际变化相关联的大气环流和海温

诊断分析了热带西太平洋暖池上空对流弱和强的情况下,大气环流和海温所表现出来的差异。本文中西太平洋暖池是指（１１０－１６０°Ｅ,１０－２０°Ｎ）地区,向外射出长波辐射（ＯＬＲ）在该地区具有明显的年际变率。对西太平洋暖池对流弱和强之间大气环流和海温的差别进行了合成分析。首先,利用 ＮＣＥＰ／ ＮＣＡＰ再分析资料和卫星观测的 ＯＬＲ资料进行了分析。之后,利用欧洲中期天气预报中心再分析资料和再分析计算而得的ＯＬＲ资料重复进行了合成分析。合成结果表明由这两套资料所分析得到的结果非常相象。与西太平洋暖池上空弱（强）对流显著对应的大气环流表现为北太平洋副热带高压的西伸（东退）,以及副高西北侧更强（弱）的西风。此外,在局地（即暖池）上空,还显著对应着东（西）风异常和下沉（上升）气流异常。对应于西太平洋暖池对流强弱,最为显著的海温差别（对流弱减去对流强）为印度洋、孟加拉湾和南海的正海温异常。也就是说,西太洋暖池上空的对流与局地海温异常只有微弱的联系,而与其西部的海温异常密切相关。     

STATISTICAL ANALYSIS OF CYCLONE TRACKS IN WESTERN ANTARCTIC REGION

The paper shows the statistical analysis of cyclone tracks that have influence on the western Antarcticregion.Based on the conditions of cyclone movement and its impact upon the weather,cyclone tracks areclassified into three categories,i.e.,the track moving towards the northern tip of the Antarctic Peninsula,southern track,and northern track.Moreover,in this paper,the frequency distributions of cyclone tracks,the major tracks with higherfrequencies,the original region of Antarctic cyclones and the seasonal features of Antarctic cyclones have beenanalyzed.The results show that there are higher cyclogeneses in summer,whereas relatively fewer cycloge-neses in winter,and cyclone numbers in transitional seasons are close to the climatological average.Theanalysis also shows that the moving velocity of Antarctic cyclone is about the same in winter and summer.It obviously speed up during the transitional season.     

Lithospheric composition and structure beneath the northern margin of the Qinling orogenic belt——On deep-seated xenoliths in Minggang region of Henan Province

Swarms of mafic-intermediate volcaniclastic bodies occur in the Minggang region of Henan Province, a tectonic boundary between the North Qinling and the North China Block, and emplaced at (178.31±3.77) Ma. These volcanic rocks are subalkaline basaltic andesites and contain abundance of lower crust and mantle xenoliths. Thus this area is an ideal place to reveal the lithospheric composition and structure beneath the northern margin of the Qinling orogenic belt. Geochemical data indicate that these mafic granulites, eclogites and metagabbros have trace elemental and Pb isotopic characteristics very similar to those rocks from the South Qinling Block, representing the lower part of lower crust of the South Qinling which subducted beneath the North China Block. Talcic peridotites represent the overlying mantle wedge materials of the North China Block, which underwent the metasomatism of the acidic melt/fluid released from the underlying lower crust of the South Qinling Block. Deep tectonic model proposed i     

A study of water balance in china

The water balance in C'hina is studied in this paper, which follows the papers on the radiation balance and the heat balance in China. Using the data from more than 200 meteorological stations for 1961-1970 and about 200 hydrometric stations bcforc1972, we, through the equation of water balance, have calculated the monthly and annual amounts of precipitation, evaporation, run-off and soil water variation. The water balance and the hydroclimatological characteristics of China arc given.     

Determination of the degree 120 time-variable gravity field in the Sichuan-Yunnan region using Slepian functions and terrestrial measurements

The terrestrial time-variable gravity measurements are characterized by a high signal-to-noise ratio and sensitivity to the sources of mass change in the Earth's crust. These gravity data have many applications, such as surface deformation, groundwater storage changes, and mass migration before and after earthquakes. Based on repeated terrestrial gravity measurements at 198 gravity stations in the Sichuan-Yunnan region (SYR) from 2015 to 2017, we determine a time series of degree 120 gravity fields using the localized spherical harmonic (Slepian) basis functions. Our results show that adopting the first 6 Slepian basis functions is sufficient for effective localized Slepian modeling in the SYR. The differences between two gravity campaigns at the same time of year show an obvious correlation with tectonic features. The degree 120 timevariable gravity models presented in this paper will benefit the study of the regional mass migration inside the crust of the SYR and supplement the existing geophysical models for the China Seismic Experimental Site.