确定“隐蔽层”厚度的pc—1500程序

“隐蔽层”用浅层初至波记录不到,而有“隐蔽层”存在时,在折射解释中常常产生两种误差。确定“隐蔽层”的厚度,是工程物探、工程地质和工程地震学中的一个重要问题。本文给出了确定两种“隐蔽层”厚度的pc—1500程序,简便实用。     

重庆2014年9月12-19日连阴雨过程分析

利用NCEP1°×1°的再分析资料及重庆地区逐日、逐时降水资料、TBB资料以及雷达回波资料对2014年9月12-19日连阴雨天气及期间两次暴雨过程进行对比分析。结果表明：此次连阴雨期间欧亚大陆中纬度为“一槽”型,暖湿气流沿台风“海鸥”外围以及副高边缘不断将南海及西太平洋的水汽输送至川渝地区,为连阴雨提供良好的水汽输送条件;比湿的演变对连阴雨期间降水的增强及间歇有明显的指示意义,负的整层水汽通量散度大值区与两次暴雨落区一致。连阴雨前期大气为对流不稳定层结,能量条件好,阻塞高压明显,中高纬度的环流经向度较大,有利于冷空气的快速南下,前期的“9.13”大暴雨的对流性特征更明显;后期“9.17”暴雨则表现为稳定性降水,TBB资料在连阴雨期间的强度演变对两次暴雨过程产生的时段和落区的指示意义较好。在整个连阴雨期间近地层多弱冷空气的影响,中层有偏南风,连阴雨天气得以持续,但是两次暴雨过程开始时,冷平流均有明显的增大,表明冷空气有所加强,冷空气的加强触发了暴雨的产生,同时伴有中层偏南暖湿气流的增强。从两次暴雨过程时多普勒雷达垂直风廓线图也能反映出低层冷空气入侵,中层偏南暖湿气流的增强。     

江苏近10 a高架雷暴特征分析

对2007—2016年发生在江苏地区的冬半年雷暴进行特征分析,筛选出12次典型的高架雷暴天气过程,揭示江苏发生高架雷暴的时空分布特征和典型的环流形势,发现逆温层顶之上的不稳定浅层和上下层强垂直风切变分别为高架雷暴的发生提供弱热力不稳定和强动力不稳定条件。强垂直风切变、850 hPa附近强烈的锋生导致的锋面次级环流,高空槽前正涡度平流随高度增加以及高层辐散、低层辐合造成的抽吸作用,为高架雷暴的发生和维持提供逆温层之上的动力抬升条件。高架雷暴发生时高仰角反射率因子呈现出类似零度层亮带的环形特征,对流单体不断生成在圆环附近。初步归纳了江苏高架雷暴的预报着眼点:500 hPa先后高空槽东移,700 hPa有16 m·s~(-1)以上的西南急流,850 hPa切变线东伸,存在逆温层顶高于1. 5 km,逆温强度大于5℃的较强逆温,0～6 km垂直风切变超过18 m·s~(-1),700 hPa与500 hPa温度差在15℃以上以及700hPa的相对湿度高于80%,且比湿在5～6 g·kg~(-1)。     

黄渤海一次持续性海雾过程形变特征及其成因分析

2016年3月3—5日,渤海和黄海大部出现了一次大范围持续性的海上大雾天气过程。本文从卫星遥感监测上分析海雾在生成、发展和消亡三个阶段的形态演变特征。从海洋气象条件上分析了山东半岛东南近海没有海雾和海雾形态演变的原因。结果表明:(1)在海雾形成初期,在山东半岛东南海域有弱气旋性弯曲,大气层结不稳定,地面形势受低压影响,虽受偏南风控制,但湿度小,无水汽辐合,因此在山东半岛东南近海没有雾。(2)海雾的形成与低层的偏南暖湿气流有关,而这个偏南暖湿气流来源于西北太平洋,雾区对应着水汽辐合区,海气温差为0～1℃的区域与雾区吻合,在海雾发展成熟期,雾顶长波辐射导致雾体降温,出现气温低于海温的现象。(3)925～1000 hPa垂直风切变有利于海雾在逆温层内维持和垂直高度上的发展,形成有一定厚度的海雾。     

大气边界层物理研究进展(2012~2017年)

本文总结了2012~2017年中国科学院大气物理研究所大气边界层物理和大气化学国家重点实验室大气边界层物理研究的最新进展,主要包括不同下垫面（城市、青藏高原、草原、沙漠、湖泊、海洋等）大气边界层观测实验、大气湍流和阵风相干结构的理论研究以及大气数值模拟的参数化改进等,同时对未来几年内大气边界层物理的发展方向做了展望。     

Freeze-thaw processes of active-layer soils in the Nanweng'he River National Natural Reserve in the Da Xing'anling Mountains,northern Northeast China

The active-layer soils overlying the permafrost are the most thermodynamically active zone of rock or soil and play important roles in the earth-atmosphere energy system. The processes of thawing and freezing and their associated complex hydrothermal coupling can significantly affect variation in mean annual temperatures and the formation of ground ice in permafrost regions. Using soil-temperature and-moisture data obtained from the active layer between September 2011 and October 2014 in the permafrost region of the Nanweng'he River in the Da Xing'anling Mountains, the freeze-thaw characteristics of the permafrost were studied. Based on analysis of ground-temperature variation and hydrothermal transport characteristics, the thawing and freezing processes of the active layer were divided into three stages:(1) autumn-winter freezing,(2) winter freeze-up, and(3) spring-summer thawing. Variations in the soil temperature and moisture were analyzed during each stage of the freeze-thaw process, and the effects of the soil moisture and ground vegetation on the freeze-thaw are discussed in this paper. The study's results show that thawing in the active layer was unidirectional, while the ground freezing was bidirectional(upward from the bottom of the active layer and downward from the ground surface).During the annual freeze-thaw cycle, the migration of soil moisture had different characteristics at different stages. In general, during a freezing-thawing cycle, the soil-water molecules migrate downward, i.e., soil moisture transports from the entire active layer to the upper limit of the permafrost. In the meantime, freeze-thaw in the active layer can be significantly affected by the soil-moisture content and vegetation.     

北极扬马延岛大气边界层高度的气候特征分析

基于1973—2015年间的全球综合无线电探空资料(IGRA),采用总体理查逊数(Bulk Richardson Number)方法,分析了北极扬马延岛43年间的大气边界层高度变化特征,并对其多年月均大气边界层高度变化以及年均大气边界层高度变化进行深入分析探讨。结果显示,扬马延岛白天对流边界层高度高于夜晚稳定边界层高度,夏季多年月均大气边界层高度远低于冬春季节的高度,夏季平均高度仅为262 m,而冬春季节高度在600 m附近。大气边界层高度的变化与地面相对湿度的变化呈现较好的反相关关系。由于受到墨西哥湾暖流的影响,岛屿全年温差较小,夏季的相对湿度较大,导致潜热通量较多,抑制了边界层内的对流过程,造成夏季大气边界层高度较低。此外,其年均高度在1973—1988年间出现波动下降,而后在1988—1995年快速上升,最后于1995—2015年间变化平稳。     

一种基于FY3D/MERSI2的AOD遥感反演方法

针对目前国产卫星对气溶胶遥感监测应用较少的情况,本研究综合暗象元和SARA算法优势,基于FY-3D MERSI2数据构建了一套气溶胶光学厚度(Aerial Optical Depth, AOD)快速遥感反演方法。首先,引入了传统暗象元算法中的地表反射率经验关系,然后利用AERONET长时间序列的地基观测数据,构建了红波段和蓝波段气溶胶光学厚度、不对称因子和单次散射率之间的关系,最后利用MOD04和AERONET的AOD产品对研究反演结果进行了验证和评估分析。结果发现：① 本研究反演的AOD不仅保持了与MODIS的气溶胶产品空间分布的一致性,而且合理地呈现了AOD的高值分布,改进了MOD04气溶胶产品在云和亮目标方面反演缺失问题;② 利用AERONET地基观测结果对本研究获取的MERSI2的AOD反演结果进行了对比分析,发现二者具有较高的线性相关性,蓝波段AOD线性相关系数超过0.85;③ 利用MERSI2数据完整地捕捉到了2018年3月9—14日京津冀及周边区域的一次重污染过程中气溶胶时空分布变化情况,这也说明了FY3D卫星具备良好的气溶胶遥感监测能力,为我国灰霾监测和预警提供参考依据。本研究对大力发展国产卫星在大气环境遥感的应用有重要参考意义。     

Some scientific problems facing research on hydrological processes in an inland river basin

The challenge is put forward to scientific hydrology by the advancement of water sciences; that is, how should we carry out a multidisciplinary, integrated and cooperative research on hydrological processes in the basin, regional and global scales, in order to better understand the role water plays in the changes of the natural resources and environment of the earth, and to understand the hydrosphere and its interactions with the atmosphere, lithosphere and biosphere. How the changes and transformation of the components of the water cycle and water balance occur in an inland river basin has yet to be understood. We also need to understand what the interactions of water cycle, ecosystems and environment are, and what the responses and feedback of the changes to global change and to human activities are. The water cycle in an inland river basin characterizes the runoff generation region of the mountains upstream, the artificial oases region of water resources exploitation and utilization midstream and the natural desert oases region of runoff dissipating downstream. The mountain hydrological processes are discussed from water cycle, energy balance, water balance and ecological processes. The interactions of water and vegetation are discussed in relation to ecohydrology, and the hydrological processes in the ground water-soil-vegetation layer are discussed from the concept of the critical zone newly put forward abroad. The basic frame is put forward to carry out the field measurement, experiment and studies of hydrological processes in a typical inland river basin. __________ Translated from Advances in Earth Science, 2007, 22(9): 940–953 [译自: 地球科学进展]     

Spatial operations in a GIS-based karst feature database

This paper presents the spatial implementation of the karst feature database (KFD) of Minnesota in a GIS environment. ESRI’s ArcInfo and ArcView GIS packages were used to analyze and manipulate the spatial operations of the KFD of Minnesota. Spatial operations were classified into three data manipulation categories: single layer operation, multiple layer operation, and other spatial transformation in the KFD. Most of the spatial operations discussed in this paper can be conducted using ArcInfo, ArcView, and ArcGIS. A set of strategies and rules were proposed and used to build the spatial operational module in the KFD to make the spatial operations more efficient and topographically correct.