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Annual observations of first-year ice(FYI) and second-year ice(SYI) near Zhongshan Station, East Antarctica,were conducted for the first time from December 2011 to December 2012. Melt ponds appeared from early December 2011. Landfast ice partly broke in late January, 2012 after a strong cyclone. Open water was refrozen to form new ice cover in mid-February, and then FYI and SYI co-existed in March with a growth rate of 0.8 cm/d for FYI and a melting rate of 2.7 cm/d for SYI. This difference was due to the oceanic heat flux and the thickness of ice,with weaker heat flux through thicker ice. From May onward, FYI and SYI showed a similar growth by 0.5 cm/d.Their maximum thickness reached 160.5 cm and 167.0 cm, respectively, in late October. Drillings showed variations of FYI thickness to be generally less than 1.0 cm, but variations were up to 33.0 cm for SYI in March,suggesting that the SYI bottom was particularly uneven. Snow distribution was strongly affected by wind and surface roughness, leading to large thickness differences in the different sites. Snow and ice thickness in Nella Fjord had a similar "east thicker, west thinner" spatial distribution. Easterly prevailing wind and local topography led to this snow pattern. Superimposed ice induced by snow cover melting in summer thickened multi-year ice,causing it to be thicker than the snow-free SYI. The estimated monthly oceanic heat flux was ～30.0 W/m2 in March–May, reducing to ～10.0 W/m2 during July–October, and increasing to ～15.0 W/m2 in November. The seasonal change and mean value of 15.6 W/m2 was similar to the findings of previous research. The results can be used to further our understanding of landfast ice for climate change study and Chinese Antarctic Expedition services. 相似文献
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基于力学平衡原理,提出了一种联合验潮与GPS测量极区海冰厚度的新方法。由海冰上的GPS观测可得到海冰上表面高,验潮可提供海水面高,联合两种观测数据可计算得到海冰干弦高度,再结合海冰表面积雪厚度与冰雪密度数据,由力学平衡原理可构建海冰厚度的计算模型。根据这一原理,通过中国第28次南极科考队在中山站附近海冰上的实验,监测到了2012年9月22日至11月9日的海冰厚度变化。与钻孔实测冰厚相比,其总体精度达到了cm级,最大差异为8.9cm,差异的均方根为5.4cm。 相似文献
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随着空间大地测量精度的提高与需求的发展,地心运动的研究与监测日益重要,它是精确实现地球质心参考框架的关键之一.本文详解了地心运动的原因(地球系统中的质量迁移)及对空间大地测量与地球物理学的影响,总结了常用的四种地心运动监测方法(网移动法,运动学法,动力学法和一阶形变法)及部分成果和应用,讨论了各方法和SLR,DIRIS,GPS和VLBI四种空间大地测量技术在地心运动监测中的特点,并给出了一些削减误差的建议.为满足地球动态环境研究的需要,地心运动监测的精度与可靠性仍需进一步提高,这依赖于观测精度的提高,地球物理模型的完善和数据处理方法的发展. 相似文献
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利用北斗/GPS双系统四频率接收机,于2011年10月至2012年4月采集了中国第28次南极考察沿线的北斗和GPS实测数据,跨度北至中国天津,南至南极内陆昆仑站。从C/A码伪距的信噪比和多路径、可见卫星数、PDOP值、标准定位的精度等方面对比分析了北斗和GPS系统在航线上不同区域,尤其是在远洋及南极地区不同运动状态下的定位效果。结果表明现阶段的北斗系统信号质量总体上与GPS相当;在45°以内的中低纬度地区,动态定位精度与GPS相当,水平和高程方向分别可达10 m和20 m左右,而静态定位水平方向精度为米级,与GPS相当,高程方向10 m左右,较GPS略差;在中高纬地区,由于可见卫星数较少、卫星分布较差,定位精度较差或无法定位。 相似文献
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