Seasonal Variability of Thermohaline Front in the Central South China Sea

An upper layer thermohaline front across the South China Sea (SCS) basin from the South Vietnamese coast (around 15°N) to Luzon Island (around 19°N) has been identified using the Navy's open domain Generalized Digital Environmental Model (GDEM) monthly mean temperature and salinity data on a 0.5° × 0.5° grid. This front does not occur at the surface in summer. The strength of this front is around 1°C/100 km at the surface and 1.4°C/100 km at the subsurface (50 m deep). A cross-basin current, inverted using the P-vector method, is associating with the front. Meandering and eddies have been identified along this current. Seasonal and vertical variabilities of the thermohaline structure across this front are reported in this paper. This revised version was published online in July 2006 with corrections to the Cover Date.     

Microphysical Properties of Convective Clouds in Summer over the Tibetan Plateau from SNPP/VIIRS Satellite Data

The Tibetan Plateau (TP) plays an important role in formation and development of the East Asian atmospheric circulation, climate variability, and disastrous weathers in China. Among the many topics on TP meteorology, it is critical to understand the microphysical characteristics of clouds over the TP;however, observations of the cloud microphysics in this area are insufficient mainly due to sparse stations and limited cloud physical data. The Visible Infrared Imaging Radiometer Suite (VⅡRS), onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite, has an improved imaging spectroradiometer with 17 channels of 750-m moderate resolution and 5 channels of 375-m image resolution. The high-resolution instrument has an advantage for observing the small or initial convective clouds. Based on the methodologies that we proposed before for retrieving cloud microphysical properties from SNPP, an automated mapping software package named Automatic Mapping of Convective Clouds (AMCC) has been developed at the scale of satellite swath. The properties of convective clouds are retrieved by AMCC and their values are averaged over 0.33°×0.33° grids based on the SNPP/VⅡRS satellite data over the TP during the summers of 2013-17. The results show that:(1) the temperature of lifting condensation level (TLCL) at Naqu meteorological station and the cloud base temperature (Tb) retrieved from VⅡRS are linearly correlated, with a correlation coefficient of 0.87 and standard deviation (STD) of 3.0℃;(2) convective clouds over the TP have the following macro-and microphysical properties. First, the cloud base temperature (Tb) is about -5℃, the cloud base height above the ground (Hb) ranges between 1800 and 2200 m, and the cloud water content is low. Second, the cloud condensation nuclei concentration (NCCN) is between 200 and 400 mg-1 with 0.7% in maximum supersaturation (Smax);consequently, the condensation growth of water cloud droplet with less NCCN and higher Smax is fast. Third, because the precipitation initiation depth (D14) varies within 1500-2000 m and 500-1000 m at the Yarlung Zangbo River basin and southern Tibet, respectively, the clouds over these areas are more prone to precipitation. Fourth, mean height of the cloud top above sea level (Htop) is between 10 and 13 km, but the cloud depth (Dcld) is rather small, which is about 5000 m in southern TP and gradually reduces to 2500 m in northern TP. Fifth, the glaciation temperature (Tg) ranges from -30℃ in central and southern TP to -25℃ in northern TP, which, combined with the warmer Tg and the Tb less than 0℃, leads to the domination of ice process in the clouds;(3) the macro-and microphysical properties of convective clouds over the TP explain why rainfall there is frequent and lasts over a short time with small amount and large rain drops.     

基于无人机倾斜航空摄影三维点云测量同震倾滑变形研究

2021年5月22日青海玛多发生M_S7.4地震,震源断层错动在地表形成了长达160 km的同震地表破裂。可靠的地震地表破裂带参数是研究震源断层活动机制和评价地震危险性的重要基础。采用无人机倾斜摄影测量技术可以获得高精度的点云数据并产出DOM和DEM数据。通过跨破裂带的地形测量,获取了玛多M_S7.4地震同震地表变形的垂直位移、水平缩短量和水平拉张量等参数。测量结果显示,玛多M_S7.4地震发震断层在不同破裂段具有不同性质和大小的倾滑分量,其中具有压扭性质的野马滩观测点断层垂直位移为0.69～1.01 m,倾向水平缩短量为0.17～0.41 m,倾滑位移为0.71～1.09 m;具有张扭性质的朗玛加合日段断层垂直位移为0.34～0.54 m,倾向水平拉张量为1.99～2.08 m。     

青藏高原东缘汶川地震断层陡坎类型与级联破裂模型(英文)

The post-earthquake field investigations reveal that the MW7.9 Wenchuan earthquake of 12th May 2008 ruptured three NE-striking imbricate reverse faults and another NW-trending reverse fault, along the middle Longmenshan fold-and-thrust belt at the eastern margin of the Tibetan plateau.     

如何确定对场地地震危险性贡献量最大的潜在震源区

分别以北京市清河镇和密云水库大坝邻近地区作为场地,讨论了贡献量最大潜在震源区的确定问题。对于北京市清河镇场地,不同周期下对场地贡献量最大的潜在震源区都是北京潜在震源区;但对于密云水库大坝邻近地区,在年超越概率小于1-00E- 2 条件下,短周期( T= 0-1s) 时对场地贡献量最大的潜在震源区是怀柔潜在震源区,而长周期( T= 1-0s) 时对场地贡献量最大的潜在震源区是夏垫潜在震源区。这种变化说明近源在短周期时所起作用较为明显,而远源对长周期部分的贡献量增大。区分不同周期下贡献量最大的潜在震源区,对于确定期望地震或设定地震以及计算场地地震动持续时间等参数是重要的     

Damage and Seismic Intensity in the Meizoseismal Region of the M_S8.0 Wenchuan Earthquake,Sichuan,China

This paper presents the damage in the meizoseismal region of the Ms8.0 Wenchuan earthquake, Sichuan, China, and the seismic intensifies determined according to "the Chinese Seismic Intensity Scale", and discusses briefly the types of earthquake-generating faults and some features of seismic damage.     

《中国图书馆分类法·地震学专业分类表》的编制修订

本课题是"十五"期间地震科技信息发展的重点课题之一. 运用文献分类技术方法, 对<中国图书馆分类法>(第4版)中的地震学类目进行了扩充, 客观地反映了防震减灾事业的发展, 并将相关类目纳入<中国图书馆分类法>(第5版)中.     

Advances in research of the mid-deep South China Sea circulation

The South China Sea(SCS) is a large marginal sea connecting the Indian and Pacific oceans.Under the factors of monsoons,strait transport,and varied bathymetry,the SCS presents a three-layer structure and strong diapycnal mixing which is far greater than that in the open ocean.Theoretical analysis and observations reveal that internal tides,internal solitary waves,and strong winds are the sources of the strong mixing in the northern SCS.A major consequence of the strong mixing is an active mid-deep circulation system.This system promotes exchange of water between the SCS and adjacent oceans,and also regulates the upper layer of wind-driven circulation,making the 3 dimensional SCS circulation clearly different from that in other tropical and subtropical marginal seas.The mass transport capacity of the mid-deep circulation has a substantial impact on marine sedimentation,the biogeochemical cycle,and other processes in the SCS.This paper summarizes the recent advances in middeep sea circulation dynamics of the SCS,and discusses the opportunities and challenges in this area.     

移动终端的水上便携智能导航系统研发

介绍了一种基于移动终端设备(Windows、iOS、Android)的水上便携智能导航系统的需求分析、主要功能及设计与实现,分析了主要技术难点和系统特点,并对其在船舶导航、智慧引航、电子海图自动更新等方面的应用技术进行了探讨。