Seasonal Prediction of Monthly Precipitation in China Using Large-Scale Climate Indices

In this study, seasonal predictions were applied to precipitation in China on a monthly basis based on a multivariate linear regression with an adaptive choice of predictors drawn from regularly updated climate indices with a two to twelve month lead time.A leave-one-out cross validation was applied to obtain hindcast skill at a 1% significance level.The skill of forecast models at a monthly scale and their significance levels were evaluated using Anomaly Correlation Coefficients(ACC) and Coefficients Of De...     

Verification of the performance of the high resolution QPF model for heavy rainfall event over the Korean Peninsula

The coupled atmospheric (global and local)-diagnostic rainfall model (called QPM) simulation is performed with various resolutions in order to discover the most appropriate nesting process in simulating a heavy rainfall event which led to an extreme amount of rainfall and flash flood in July 2008 over the Korean Peninsula. A series of experiments consists of six QPM simulations given 40 and 20 km global runs, two 7.8 km local runs from single nesting and other two 2.2 km local runs from double nesting. Four verification approaches focused on accuracy and efficiency are carried out in order to evaluate the coupled model system performance. The results show that the QPM simulated total accumulated rainfall from 20 km global run or 7.8 km local runs successfully captures the observed rainfall over a spatial observation network. Furthermore, the evaluation of the peak rainfall amount and the rainfall area over a given time interval demonstrates that the QPM forecast from either 20 km global run or 7.8 km local runs shows the best agreement with observation. In addition, the quantitative evaluation of the model performance by computing simple statistical measures presents the good agreement between the simulations and the observation, especially when the QPM forecasts are produced by the 7.8 km resolution local model. Finally, the modeling system which couples 40 km global-7.8 km local models and the diagnostic rainfall model is proved to be the best nesting approach in the natural disaster prediction system when considering the accuracy and efficiency. However, the verification for the nesting processes over the long-term period still deserves to be studied for a successful prediction system.     

三种云导风资料及其对台风数值预报影响试验的比较分析

由于在海面上缺乏重要的常规观测资料,因而云导风成为研究西太平洋台风一种不可缺少的重要资料。为了对“南京信息工程大学”开发的云导风系统(CWIS)进行质量评价及其对台风研究的贡献,选取了三种云导风资料进行综合对比。通过对比CWIS导出FY2C云迹风数据、中国气象局国家卫星中心(NSMC)导出FY2C云迹风数据和日本气象卫星中心（JMSC）的MTSAT云导风数据,采用逐点比较法分析了不同资料的精度与误差。所得结果发现：CWIS的风速与JMSC风速、NSMC的风向与JMSC风向分别均有较好的一致性。使用三重制约法获得了三种云导风资料的误差信息,风速误差标准差以JMSC最小、NSMC最大;风向误差标准差以JMSC最小、CWIS最大。云导风资料在中尺度对流云带和高空急流云带上,NSMC云导风风速大于CWIS、JMSC;而在台风云系上三种云导风资料没有特别的差异。根据以上比较的三种云导风资料的结果,进行了云导风资料对台风路径数值预报的影响的初步试验。结果表明：加入云导风资料模拟后得到的台风移动路径与实况总体上比较接近,不同的资料导出不同的结果,台风中心位置误差减小到23%~74%。     

朝鲜半岛咸北地区晚二叠世基性火山岩的地球化学特征:岩石成因与地质意义

晚古生代火山作用既是探究朝鲜半岛北部大地构造归属的基本要素,又是认识东北亚大陆两大构造域转折之际地球动力学过程的关键窗口。针对咸北地区会宁基性火山岩开展的离子探针锆石U-Pb年代学和地球化学研究表明,其喷发时代为晚二叠世(257±3Ma);主要岩石类型包括玄武安山岩和安山岩,其Si O2含量介于51.9%~55.3%,Mg#变化于40~58,属于钙碱性系列;岩石富集大离子亲石元素、亏损高场强元素(如Nb,Ta,Ti),并具有高正的锆石εH f(t)(+10~+16)值。元素-同位素地球化学示踪指示该基性火山岩的岩浆源区为俯冲沉积物熔体交代而形成的不均一岩石圈地幔,其部分熔融则可能归因于俯冲后的板内伸展背景。会宁基性火山岩不仅为判定咸北地块属于中亚造山带在朝鲜半岛的东延部分提供了岩石学证据,而且与中国相邻地块上的同期岩浆事件一道,构成见证古亚洲洋东段沿西拉木伦-长春-延边一线断裂带最终闭合的空间标记。     

朝鲜半岛南部三维地壳速度结构成像

对多震相走时层析成像方法进行改进和优化, 使用朝鲜半岛陆地和近海的地震记录, 对朝鲜半岛南部(34.5°N～39°N,125°E～130°E)进行地震波走时反演, 获得了本研究区的三维速度结构成像结果.分析了沉积层、基底、上地壳、康腊面、下地壳和莫霍面的特征.研究了不同地质区的深部结构的主要差别、主要断裂特征、 海陆交界的地壳特征等.可以发现京畿山地与沃川褶皱带、太白山褶皱带、临津江褶皱带深部结构的差异尤为明显.     

Observational Diagnosis of Cloud Phase in the Winter Antarctic Atmosphere for Parameterizations in Climate Models

The cloud phase composition of cold clouds in the Antarctic atmosphere is explored using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instruments for the period 2000--2006. We used the averaged fraction of liquid-phase clouds out of the total cloud amount at the cloud tops since the value is comparable in the two measurements. MODIS data for the winter months (June, July, and August) reveal liquid cloud fraction out of the total cloud amount significantly decreases with decreasing cloud-top temperature below 0oC. In addition, the CALIOP vertical profiles show that below the ice clouds, low-lying liquid clouds are distributed over ～20% of the area. With increasing latitude, the liquid cloud fraction decreases as a function of the local temperature. The MODIS-observed relation between the cloud-top liquid fraction and cloud-top temperature is then applied to evaluate the cloud phase parameterization in climate models, in which condensed cloud water is repartitioned between liquid water and ice on the basis of the grid point temperature. It is found that models assuming overly high cut-offs (》-40oC) for the separation of ice clouds from mixed-phase clouds may significantly underestimate the liquid cloud fraction in the winter Antarctic atmosphere. Correction of the bias in the liquid cloud fraction would serve to reduce the large uncertainty in cloud radiative effects.     

What Causes the Springtime Tropospheric Ozone Maximum over Northeast Asia？

Scientists have long debated the relative importance of tropospheric photochemical production versus stratospheric influx as causes of the springtime tropospheric ozone maximum over northern mid-latitudes. This paper investigates whether or not stratospheric intrusion and photochemistry play a significant role in the springtime ozone maximum over Northeast Asia,where ozone measurements are sparse.We examine how tropospheric ozone seasonalities over Naha(26°N,128°E),Kagoshima(31°N,131°E),and Pohang(36°N,129°E),which are located on the same meridional line,are related to the timing and location of the jet stream.The ozone seasonality shows a gradual increase from January to the maximum ozone month,which corresponds to April at Naha,May at Kagoshima,and June at Pohang.In order to examine the occurrence of stratospheric intrusion,we analyze a correlation between jet stream activity and tropospheric ozone seasonality.From these analyses,we did not find any favorable evidence supporting the hypothesis that the springtime enhancement may result from stratospheric intrusion.According to trajectory analysis for vertical and horizontal origins of the airmass,a gradual increasing tendency in ozone amounts from January until the onset of monsoon was similar to the increasing ozone formation tendency from winter to spring over mainland China,which has been observed during the build-up of tropospheric ozone over Central Europe in the winter-spring transition period due to photochemistry.Overall,the analyses suggest that photochemistry is the most important contributor to observed ozone seasonality over Northeast Asia.     

Preliminary Results of the Ground-Based Orographic Snow Enhancement Experiment for the Easterly Cold Fog （Cloud） at Daegwallyeong during the 2006 Winter

The snow enhancement experiments, carried out by injecting AgI and water vapor into orographically enhanced clouds (fog), have been conducted to confirm Li and Pitter’s forced condensation process in a natural situation. Nine ground-based experiments have been conducted at Daegwallyeong in the Taebaek Mountains for the easterly foggy days from January–February 2006. We then obtained the optimized condi- tions for the Daegwallyeong region as follows: the small seeding rate (1.04 g min-1) of AgI for the easte...     

Evaluation of the twentieth century reanalysis dataset in describing East Asian winter monsoon variability

The Twentieth Century Reanalysis （20thCR） dataset released in 2010 covers the period 1871-2010 and is one of the longest reanalysis datasets available worldwide. Using ERA-40, ERA-Interim and NCEP-NCAR reanalysis data, as well as HadSLP2 data and meteorological temperature records over eastern China, the performances of 20thCR in reproducing the spatial patterns and temporal variability of the East Asian winter monsoon （EAWM） are examined. Results indicate that 20thCR data： （1） can accurately reproduce the most typical configuration patterns of all sub-factors differences in the main circulation fields over East Asia involved in the EAWM system, albeit with some in comparison to ERA-40 reanalysis data; （2） is reliable and stable in describing the temporal variability of EAWM since the 1930s; and （3） can describe the high-frequency variability of EAWM better than the low-frequency fluctuations, especially in the early period. In conclusion, caution should be taken when using 20thCR data to study interdecadal variabilities or long-term trends of the EAWM, especially prior to the 1930s.     

Observation and Numerical Simulations with Radar and Surface Data Assimilation for Heavy Rainfall over Central Korea

This study investigated the impact of multiple-Doppler radar data and surface data assimilation on forecasts of heavy rainfall over the central Korean Peninsula;the Weather Research and Forecasting(WRF) model and its three-dimensional variational data assimilation system(3DVAR) were used for this purpose. During data assimilation,the WRF 3DVAR cycling mode with incremental analysis updates(IAU) was used. A maximum rainfall of 335.0 mm occurred during a 12-h period from 2100 UTC 11 July 2006 to 0900 UTC 12 July 2006.Doppler radar data showed that the heavy rainfall was due to the back-building formation of mesoscale convective systems(MCSs).New convective cells were continuously formed in the upstream region,which was characterized by a strong southwesterly low-level jet(LLJ).The LLJ also facilitated strong convergence due to horizontal wind shear,which resulted in maintenance of the storms.The assimilation of both multiple-Doppler radar and surface data improved the accuracy of precipitation forecasts and had a more positive impact on quantitative forecasting(QPF) than the assimilation of either radar data or surface data only.The back-building characteristic was successfully forecasted when the multiple-Doppler radar data and surface data were assimilated.In data assimilation experiments,the radar data helped forecast the development of convective storms responsible for heavy rainfall,and the surface data contributed to the occurrence of intensified low-level winds.The surface data played a significant role in enhancing the thermal gradient and modulating the planetary boundary layer of the model,which resulted in favorable conditions for convection.