几种地基GPS区域电离层TEC建模方法的比较及其一致性研究   总被引：3，自引：0，他引：3  

柳景斌  王泽民  章红平  朱文耀 《武汉大学学报(信息科学版)》2008,33(5):479-483

利用GPS实测资料实现了中国区域电离层电子含量建模,比较和评估了多项式模型、三角级数模型和低阶球函数模型的监测精度及存在的问题.研究表明,在平静电离层的条件下,多项式模型和低阶球函数模型拟合的精度较好,但前者存在明显的边际效应;三角级数模型在用于大区域拟合时精度较差;高纬度地区模型拟合的精度要优于低纬度地区.根据这些模型参数设置的特点以及电离层本身的变化分布规律,分析了这些差异存在的原因.  相似文献   

高纬度的味觉盛宴     

尤小塔 《海洋世界》2013,(1):62-63

从西雅图出发,沿着海岸线一路向北,穿过加拿大,就是美国的第49个州——阿拉斯加,这里拥有世界闻名的阿拉斯加湾。而从阿拉斯加湾向西一直到白令海,是一片北纬60度附近的高纬度区域,在这里,寒流、  相似文献   

北大西洋臭氧极小值和北太平洋极大值及其相互关系   总被引：2，自引：0，他引：2  

邹捍  李鹏  周立波  马舒坡  季崇萍 《大气科学》2006,30(5):905-912

利用1979～2002年TOMS卫星观测资料,采用臭氧总量纬向偏差和区域强迫的分析方法,研究北大西洋东北部大气臭氧低值与北太平洋西北部臭氧高值的季节变化过程和相互关系.研究表明,(1)北大西洋东北部存在一个大气臭氧极小值,年平均臭氧总量比纬向平均值低20 DU以上,冬季低50 DU以上; 北太平洋西北部存在一个大气臭氧极大值,年平均臭氧总量比纬向平均值高35 DU以上,冬季高70 DU以上.(2)上述两个地区大气臭氧的季节变化具有很强的区域特征,区域大气动力学输送和化学过程对上述两个地区大气臭氧季节变化的强迫分别为50.3%和42.6%.(3)上述两个地区大气臭氧纬向偏差的季节变化间存在很好的反相关,相关系数达到-0.98,说明其臭氧区域强迫之间存在良好的关系.  相似文献   

坏消息：永久冻土层正在融化     

《海洋世界》2008,(10):7-7

北半球高纬度地区的永久冻土层是一个巨大的碳储存库，其碳储存量是大气中碳含量的二倍多。最近。一个由二十几位科学家组成的科研小组研究发现：永久冻土层将给全球气候带来巨大变化，变化的速率取决于它的融化速率。永久冻土层中含有大量的有机物，这些有机物的降解速率非常慢。但是，当永久冻土层融化时，其中的细菌和真菌等微生物的生命活动加快，  相似文献   

现代天文学历史大事记     

王青 《天文爱好者》2010,(9):63-65

两位英国的天文学家分别用高倍望远镜观察太阳。他们同时在一大群形态复杂的黑子群附近,看到了一大片明亮的闪光,发射出耀眼的光芒。这片光掠过黑子群,亮度缓慢减弱,直至消失。在当天和第二天,许多高纬度地区的人看到非常明亮的极光。这一事件使科学家们感到十分震惊。这就是太阳上最为强烈的活动现象——耀斑。  相似文献   

The Relationship between the East Asian Subtropical Westerly Jet and Summer Precipitation over East Asia as Simulated by the IAP AGCM4.0          下载免费PDF全文

YAN Zheng-Bin  LIN Zhao-Hui  ZHANG He 《大气和海洋科学快报》2014,7(6):487-492

Based on a 30-year Atmospheric Model Intercomparison Project（AMIP） simulation using IAP AGCM4.0, the relationship between the East Asian subtropical westerly jet（EASWJ） and summer precipitation over East Asia has been investigated, and compared with observation. It was found the meridional displacement of the EASWJ has a closer relationship with the precipitation over East Asia both from model simulation and observation, with an anomalous southward shift of EASWJ being conducive to rainfall over the Yangtze-Huaihe River Valley（YHRV）, and an anomalous northward shift resulting in less rainfall over the YHRV. However, the simulated precipitation anomalies were found to be weaker than observed from the composite analysis, and this would be related to the weakly reproduced mid-upper-level convergence in the mid-high latitudes and ascending motion in the lower latitudes.  相似文献   

A Dipole Pattern of Summer Precipitation over Mid-high Latitude Asia and Related Snow Cover Anomalies in the Preceding Spring          下载免费PDF全文

HAN Jin-Ping  LIU Ge  XIN Yu-Fei 《大气和海洋科学快报》2014,(4):364-368

A dipole pattern of summer precipitation over the mid-high latitudes of Asia, which is characterized by opposing summer precipitation variations between the Mongolian and Northeast China （MNC） region and the West Siberian Plain （WSP）, is found to be clear and stable on both interdecadal and interannual scales during 1981- 2011. Spring snow cover anomalies over a small region within the WSP and the Heilongjiang River （HR） region are closely related to the variation of this dipole mode during the subsequent summer, and they can therefore be considered as forecasting factors. Our statistical results imply a potential process explaining the relationship between the spring snow anomalies and the summer rainfall dipole. Corresponding to the snow anomalies, Rossby waves propagate along a path from the WSP region, via the Mongolian Plateau, to the Stanovoy Range during summer. At the same time, Rossby-wave energy divergences and convergences along this path maintain and reinforce an anomalous cyclone and anticyclone pairing over the Asian continent, which is significantly linked to opposite summer precipitation anomalies between the MNC and WSP regions. Numerical experiments are need- ed to further confirm the above conjecture and demonstrate the detailed physical mechanisms linking the spring snow cover anomalies and summer precipitation dipole.  相似文献   

Impact of vegetation feedback on the mid-Pliocene warm climate     

ZHANG Ran  JIANG Dabang 《大气科学进展》2014,31(6):1407-1416

Studying the vegetation feedback during warm periods of the past can lead to better understanding of those in the future.In this study,we conducted several simulations to analyze vegetation feedback during the mid-Pliocene warm period.The results indicate that the main features of vegetation change in the mid-Pliocene were a northward shift of needleleaf tree,an expansion of broadleaf tree and shrub,and a northward expansion of grass,as compared to the pre-industrial period.The global annual mean warming ratio caused by vegetation feedback was 12.1％,and this warming ratio was much larger in northern middle and high latitudes.The warming caused by vegetation change was directly related to the surface albedo change and was further amplified by snow/sea ice-albedo feedback.  相似文献   

高纬度BDS/GPS PPP中的对流层延迟改正模型优选     

周润杨  薛玫娇 《测绘工程》2018,(2):20-25,31

由于高纬度地区气温气压值及变化率与中低纬度地区有较大差异,因此目前发布的多种对流层延迟模型在高纬度地区使用的精度会不同。为了给高纬度地区BDS/GPS用户提供更好的对流层延迟模型选择,文中采用UNB3,EGNOS和GPT2模型,以IGS发布的ZPD产品和SINEX文件作为参考,对比基于这三种对流层延迟模型计算的天顶对流层总延迟量以及精密单点定位精度,可知GPT2较UNB3和EGNOS在高纬度地区定位中有更好的精度表现。  相似文献   

The Role of Southern High Latitude Wind Stress in Global Climate     

MA Hao  WU Lixin  LI Chun 《大气科学进展》2010,27(2):371-381

In this paper, the role of westerly winds at southern high latitudes in global climate is investigated in a fully coupled ocean-atmosphere general circulation model. In the model, the wind stress south of 40°S is turned off with ocean and atmosphere fully coupled both locally and elsewhere. The coupled model explicitly demonstrates that a shutdown of southern high latitude wind stress induces a general cooling over the Antarctic Circumpolar Current (ACC) region, with surface Ekman flow and vertical mixing p...  相似文献