丹麦海峡海洋锋时空变化特征研究

丹麦海峡海洋锋可为局地气候变化、海峡鱼类分布以及海峡中尺度涡等方面研究提供参考,在军事领域也具有较高应用价值。然而目前国内外缺乏对于丹麦海峡锋的系统研究。本文利用WOA13数据,对丹麦海峡锋位置、强度空间分布以及相应的季节变化进行了分析。结果显示,锋轴线位置在34°W以西150 m以浅相对稳定,34°W以东锋轴线随深度和季节均有摆动。锋强度在水平和垂直方向分布不均匀,水平方向上锋轴线最大值与最小值差值一般在3倍以上。垂直方向盐度锋主要集中在100 m以浅,且强度随深度不断减小;温度锋强度最大值在表层以下且在300 m以深随深度增加锋强度减小,但有一些区域如27°W和28°W附近,受到海底地形的影响温度锋强度随着深度的变化有大幅度增加的特点。     

北京连续降雪过程分析

该文对2002年12月份北京出现的1841年以来历史上最长的连续6天的降雪天气进行了合成分析和诊断分析。北半球合成环流形势显示,连续降雪发生在东亚稳定的纬向环流形势下,其上游地区强大经向环流和阻塞高压使中纬度东亚和西太平洋纬向环流得以维持。东亚合成环流的垂直结构表明,连续降雪期间华北地区始终处于锋区中,并存在低空辐合、高空辐散的散度场垂直分布结构。卫星水汽云图显示出有水汽通道向河套倒槽云系输送水汽。华北地区的诊断分析表明,地面和边界层中山东地区分裂高压南侧向北回流的偏南气流是造成降雪的主要水汽通道。变形场的流场结构使水汽在北京附近辐合。垂直剖面展现了华北回流降雪天气近地面层的浅薄的冷空气垫,和暖湿空气回流在冷空气垫上的爬升,并在其上形成一个浅薄的饱和层。     

Climatic changes in areas adjacent to the North Atlantic during the last glacial-interglacial transition (14-9 ka BP): A contribution to IGCP-253

This paper presents a summary of the evidence for climatic changes during the last glacial-interglacial transition (14-9 ka BP) in land areas adjacent to the North Atlantic. It is a synthesis of the results of the 12 regional summaries compiled by contributors to the North Atlantic Seaboard Programme of IGCP-253 that are published separately in this issue of Journal of Quaternary Science. Eighteen palaeotemperature curves are compared and arranged in three transects, one from southern Europe to Spitsbergen, a second from Ireland to Poland, and the third from southern New England to the Labrador-Baffin Shelf area. Ten maps are presented that summarise the synoptic climatic conditions of the region in 500-year time periods. The purpose of the exercise is to examine the extent to which any emerging patterns support the Ruddiman and Mclntyre model of large-scale shifts in the position of the oceanice Polar Front during the last glacial-interglacial transition. Some broad agreement emerges, although the influence of oceanic changes is diminished in areas that lay in close proximity to the Laurentide and Fennoscandian ice sheets. Attention is drawn to limitations in the compilations and to the potential for improved models in the future.     

锋面通过台湾海峡时引起的快速成长波高推算

每年冬季因中国北方冷空气前缘东移出海南下而形成的锋面是造成台湾海峡内恶劣海况的原因之一，锋面的到临常引发快速增高的波浪，这种海况是目前作业化数值预报模式在操作上不易反映的。经验证明根据元素波模式推衍所得的面积风域法推算波浪，适合于推导季风期间海况的一种方法。本文将锋面期间风域是移动的特性结合面积风域理论，作为推算锋面抵达时推算波高的方法。本文提出加权风场内插法计算各时刻各网格点的风速，使得面积风域理论简化为在网格点上的离散计算。文中根据锋面期间实际观测数据计算波能传播速率与风能传播系数等参数，经由案例分析的结果显示这个离散化面积风域法可以合理地推算锋面期间快速成长的波高。     

A Diagnostic Analysis of the Simulated Structure of a Meiyu Front System in 1999

A numerical simulation of a torrential rain event occurring in the Jiang-Huai Valley of China from 22-24 June 1999 is performed and analyzed by using the PSU/NCAR MM5 mesoscale non-hydrostatic model. The high-resolution model output data are utilized to diagnose the double front structure, and the distributions of potential temperature, equivalent potential temperature, and specific humidity in the vicinity of the Meiyu Front System （MYFS） in the Jiang-Huai Valley. The results show that both the potential temperature gradient and the specific humidity gradient have important impacts on the two strong equivalent potential temperature gradient zones associated with the double front structure of the MYFS, but the latter （moisture gradient） is more important. In addition, the tendency equation of specific humidity gradient is theoretically derived. It shows that variations of the specific humidity gradient are related to the advection, convergence/divergence, horizontal and vertical vorticities （secondary circulation） effects and the gradient of water vapor source/sink. As an example, the budget of the meridional component of the tendency equation is selected and diagnosed by using the above model simulation data of the torrential rain event. It is shown that the variation of the specific humidity gradient averaged throughout the simulation is mainly controlled by the convergence/divergence effect, the secondary circulation effect associated with the horizontal vorticities, and the water vapor source/sink effect. Since the water vapor source/sink is often formed from the phase change processes of water vapor in the air and thus directly associated with cloud and precipitation microphysics processes, the variation of the specific humidity gradient is closely related with cloud and precipitation microphysics and the distribution, development and evolution of cloud and rainfall systems. The double front structure of the MYFS provides an advantageous environmental condition for the development and movement of the mesoscale torrential rain system nearby. In turn, the development of the torrential rain exerts a signifiant impact on the MYFS through changing the thermal and moisture distributions.     

A comparison of permafrost prediction models along a section of Trail Ridge Road, Rocky Mountain National Park, Colorado, USA

The distribution of mountain permafrost along Trail Ridge Road (TRR) in Rocky Mountain National Park, Colorado, was modeled using ‘frost numbers’ and a ‘temperature of permafrost model’ (TTOP) in order to assess the accuracy of prediction models. The TTOP model is based on regional observations of air temperature and heat transfer functions involving vegetation, soil, and snow; whereas the frost number model is based on site-specific ratios of ground temperature measurements of frozen and thawed degree-days. Thirty HOBO© temperature data loggers were installed near the surface as well as at depth (30 to 85 cm). From mid-July 2008 to 2010, the mean annual soil temperature (MAST) for all surface sites was − 1.5 °C. Frost numbers averaged 0.56; TTOP averaged − 1.8 °C. The MAST was colder on western-facing slopes at high elevations. Surface and deeper probes had similar MASTs; however, deeper probes had less daily and seasonal variation. Another model developed at the regional scale based on proxy indicators of permafrost (rock glaciers and land cover) classified 5.1 km² of permafrost within the study area, whereas co-kriging interpolations of frost numbers and TTOP data indicated 2.0 km² and 4.6 km² of permafrost, respectively. Only 0.8 km² were common among all three models. Three boreholes drilled within 2 m of TRR indicate that permafrost does not exist at these locations despite each borehole being classified as containing permafrost by at least one model. Addressing model uncertainty is important because nutrients stored within frozen or frost-affected soils can be released and impact alpine water bodies. The uncertainty also exposes two fundamental problems: empirical models designed for high latitudes are not necessarily applicable to mountain permafrost, and the presence of mountain permafrost in the alpine tundra of the Colorado Front Range has not been validated.     

当今世界测井技术的前沿——访“斯伦贝谢-道尔研究中心”

当今世界测井技术的前沿是什么?用一句话来概括:成象测井技术是当今世界测井技术的前沿.在本世纪末或下世纪初,成象测井技术将会取代数控测井技术.“新伦贝谢-道尔研究中心”从事当今世界测井技术前沿的研究.1992年6月,笔者参观访问了该研究中心.本文叙述参观访问该研究中心从事测井技术前沿研究的所见所闻,供测井界借鉴和参考.     

Variability of the Subtropical Front in the Indian Ocean south of Australia

A detailed high resolution survey of a small region (68 × 68 km) of the Subtropical Front south of Australia over a period of 14 days is used to study the interaction between the mixed layer and the permanent frontal structure underneath during summer conditions. The front extends through the mixed layer as a salinity front, while its temperature structure is modified by seasonal warming. Wind-driven movement of the mixed layer combines with the short-time development of indentations and filaments in the front to produce some degree of decoupling between the mixed layer and the underlying structure, and the front is not always found at the same location in and below the mixed layer. Intrusions and parcels of distinct water properties are found just below the mixed layer, produced as a result of the relative movement of the front in and below the mixed layer. These parcels are typically 10 km in width and 10–50 m in depth. Successive surveys of the front with a time separation of 2 days showed that these features persist over at least 1 week. Large scale surveys of the front show that parcels are ubiquitous along the Subtropical Front over a distance of several hundred kilometres. The results suggest that any study aimed at understanding the intricate interaction between the mixed layer and the layers below in oceanic fronts will have to address wind-driven dynamics and frontal dynamics together.This revised version was published online February 2005 with corrections to figures. Unfortunately the figures were reproduced in black and white and in the new version they are in color.     

AutoCAD VBA在机场净空测量中的应用

AutoCAD已经广泛的应用在各个行业,同时也是测绘行业软件二次开发的主要平台,本文介绍了用AutoCADVBA实现机场净空测量数据的批量处理,并自动绘制交会点位图。     

Frontogenesis, evolution and the time scale of front formation

Ｆｒｏｎｔｏｇｅｎｅｓｉｓ,ＥｖｏｌｕｔｉｏｎａｎｄｔｈｅＴｉｍｅＳｃａｌｅｏｆＦｒｏｎｔＦｏｒｍａｔｉｏｎＦａｎｇＪｕａｎ（方娟）ａｎｄＷｕＲｏｎｇｓｈｅｎｇ（伍荣生）ＳｅｖｅｒｅＭｅｓｏｓｃａｌｅｍｅｔｅｏｒｏｌｏｇｉｃａｌＲｅｓｅａｒｃｈＬａｂ...