Thickness distribution and extent of sea ice and snow in Prydz Bay and surrounding waters observed in 2012/2013 austral summer

Three ship-based observational campaigns were conducted to survey sea ice and snow in Prydz Bay and the surrounding waters(64.40°S–69.40°S, 76.11°E–81.29°E) from 28 November 2012 to 3 February 2013. In this paper, we present the sea ice extent and its variation, and the ice and snow thickness distributions and their variations with time in the observed zone. In the pack ice zone, the southern edge of the pack ice changed little, whereas the northern edge retreated significantly during the two earlier observation periods. Compared with the pack ice, the fast ice exhibited a significantly slower variation in extent with its northernmost edge retreating southwards by 6.7 km at a rate of 0.37 km?d-1. Generally, ice showed an increment in thickness with increasing latitude from the end of November to the middle of December. Ice and snow thickness followed an approximate normal distribution during the two earlier observations(79.7±28.9 cm, 79.1±19.1 cm for ice thickness, and 11.6±6.1 cm, 9.6±3.4 cm for snow thickness, respectively), and the distribution tended to be more concentrated in mid-December than in late November. The expected value of ice thickness decreased by 0.6 cm, whereas that of snow thickness decreased by 2 cm from 28 November to 18 December 2012. Ice thickness distribution showed no obvious regularity between 31 January and 3 February, 2013.     

Status of the Recent Declining of Arctic Sea Ice Studies

In the past 30 years, a large-scale change occurred in the Arctic climatic system, which had never been observed before 1980s. At the same time, the Arctic sea ice experienced a special evolution with more and more rapidly dramatic declining. In this circumstance, the Arctic sea ice became a new focus of the Arctic research. The recent advancements about abrupt change of the Arctic sea ice are reviewed in this paper .The previous analyses have demonstrated the accelerated declining trend of Arctic sea ice extent in the past 30 years, based on in-situ and satellite-based observations of atmosphere, as well as the results of global and regional climate simulations. Especially in summer, the rate of decrease for the ice extents was above 10% per decade. In present paper, the evolution characteristics of the arctic sea ice and its possible cause are discussed in three aspects, i.e. the sea ice physical properties, the interaction process of sea ice, ocean and atmosphere and its response and feedback mechanism to global and arctic climate system.     

加强目标观测,服务防灾减灾

以深入浅出的方式介绍了目标观测的定义、历史、确定目标观测敏感区的方法,以及实施目标观测与防灾减灾的关系;并以欧洲中期天气预报中心目标观测业务化为例,简明地概括了目标观测的实施过程;结合国内目标观测研究现状,对中国目标观测的未来提出了看法。     

地理信息服务概述

地理信息服务由于其提供的是空间型信息这一特点,已成为信息服务业中的一个重要组成部分。鉴于综合论述地理信息服务的文章或论著并不多见,文中归纳总结了地理信息服务研究的总体框架,包括技术体系、信息框架、服务模式、应用分析及产业分析,并对各部分进行了简要的综合论述。     

掩星驿站

月掩星是一个很有趣味的观测项目,在掩星之前或之后,被掩星都是在月球附近的。当你看到恒星逐渐接近月球的暗边缘且突然“消失”或恒星突然“出现”的一刹那,你会明显感觉到月球的运动。观测小行星掩星需要观测者比较熟悉星空,可以通过星图准确无误地找到被掩的恒星。观测时,只需要看到被掩的恒星即可。每次新的掩星观测都可能带来潜在的新发现,只要你进行了一次观测,无论是否观测到掩星现象的发生,你的观测结果都是非常有意义的。     

掩星情报站

随着寒冷的冬季来临,掩星事件似乎也少了许多。在今年最后一个月里,我国比较适合观测的月掩星只有两次,分别是12月3日傍晚的月掩摩羯座θ星和16日早晨的月掩巨蟹座δ星。本月有六次适合我国爱好者观测的小行星掩星,这几次中被掩星最亮的为6．8等。     

Swift时代伽马暴的观测及研究进展

Swift卫星从2004年11月20日升空开始运转到现在已有2年多时间.到目前为止,它-共观测到了200多个伽马暴及其余辉现象.由于Swift观测到了早期X射线余辉、短暴余辉和高红移伽马暴等新的重要现象,伽马暴研究进入了新的时代.该文首先对伽马暴的研究历史做简短回顾,然后简要介绍伽马暴的物理图像和Swift卫星的构成及特点,最后全面评述Swift的观测成就及由此引起的理论挑战.     

掩星情报站

今年有多次月掩亮星现象,在本月的三次月掩星中,就有两次月掩亮星现象,分别是10日早晨的月掩人马λ星和27～28日的月掩狮子o星,这两颗被掩星亮度都比较亮,也更适合于观测。发生在我国境内适合观测的小行星掩星也有十次,其中2月17日凌晨在同一地区附近可能会连续两次观测到3056号小行星掩星。在短短的20分钟之内同一小行星连续掩两颗恒星的现象还是比较少见的。     

实测大气折射值的新方法

简单评述了现有各种版本的大气折射表所依据的理论基础和编制方法，指出了实测大气折射值、建立随地形而异的实测大气折射模型的必要性和应具备的基本条件；在分析了长期以来不能直接测定大气折射值的原因后，介绍了一种在不同方向精确测定大气折射值和建立观测点大气折射模型的新方法，以及所依赖的观测仪器具备的特性，最后给出了用实测数据建立的本地大气折射模型。     

星系磁场的射电观测方法

本文主要介绍星系磁场的观测方法，认为射电连续谱的多波段偏振观测可以很好地描绘出星系磁场的总体特和分布结构。