| 基于卫星测高后向散射系数的极区海冰分布特性研究 |
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| 引用本文： | 杨磊,常晓涛,郭金运,柯宝贵,黄昆学,刘晓辉.基于卫星测高后向散射系数的极区海冰分布特性研究[J].测绘学报,2013,42(5):676-681. |
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| 作者姓名： | 杨磊 常晓涛 郭金运 柯宝贵 黄昆学 刘晓辉 |
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| 作者单位： | 1. 中国测绘科学研究院;2. 国家测绘局卫星测绘应用中心;3. 山东科技大学 测绘学院;4. 武汉大学信息学部测绘遥感信息工程国家重点实验室;5. 国家测绘地理信息局卫星测绘应用中心；武汉大学; |
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| 基金项目： | 国家自然科学基金(40974016;40974004);地理空间信息工程国家测绘地理信息局重点实验室开放研究基金课题(201306) |
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| 摘 要： | 海冰对气候变化非常敏感，了解极地海冰分布范围和表面属性不仅对于极地环境非常重要，对全球温度趋势估计和建立全球气候模型非常关键。ENVISAT卫星可覆盖至南北纬81.4°，其携带的RA2雷达高度计为极地海冰研究提供了周期性的主动微波海冰探测途径。本文用ENVISAT雷达高度计探测的Ku波段后向散射系数对2011年南极和北极各月份的海冰覆盖特征（范围和海冰表面属性）进行了详细研究，利用海水和海冰的不同散射特征，设置后向散射系数阈值为13db可成功分离海冰和海水。除夏季外，雷达高度计和美国冰雪数据中心基于辐射计获取的极区海冰覆盖边界高度符合。因北极中央区域（81.4°N以北）没有轨迹覆盖，本文只估计了南极海冰的覆盖面积，夏季海冰的覆盖范围面积比辐射计探测结果偏大，这和雷达高度计对离散薄冰较强的观测能力关，在海冰密集分布的其他季节结果则有很好的符合，其中冬季面积平均差异为0.17 Mkm2。分析了南极和北极海冰的分布特征差异，和南极相比北极冬季海冰表面较粗糙干燥，而夏季海冰表面湿度较大。本文研究结果表明ENVISAT雷达高度计可准确的探测包括海冰覆盖和海冰表面属性变化在内的海冰季节性演变过程，可在海冰监测、极地科考等领域中发挥重要作用。
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| 关 键 词： | 后向散射系数，卫星测高，海冰覆盖，表面湿度 |
| 收稿时间： | 2012-12-07 |
| 修稿时间： | 2013-01-31 |
Research on distribution characteristics of polar seaice by the altimetry backscatter coefficient |
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| YANG Lei;CHANG Xiaotao;GUO Jinyun;KE Baogui;HUANG Kunxue;LIU Xiaohui.Research on distribution characteristics of polar seaice by the altimetry backscatter coefficient[J].Acta Geodaetica et Cartographica Sinica,2013,42(5):676-681. |
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| Authors: | YANG Lei;CHANG Xiaotao;GUO Jinyun;KE Baogui;HUANG Kunxue;LIU Xiaohui |
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| Institution: | YANG Lei;CHANG Xiaotao;GUO Jinyun;KE Baogui;HUANG Kunxue;LIU Xiaohui;First Institute of Oceanography,State Oceanic Administration;College of Geodesy and Geomatics,Shandong University of Science and Technology;Satellite Surveying and Mapping Application Center of NASMG;Chinese Academy of Surveying and Mapping;Key Laboratory of Surveying and Mapping on Island and Reef of NASMG;School of Geodesy and Geomatics,Wuhan University; |
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| Abstract: | Seaice is a sensitive indicator of climate change. The knowledge of sea ice extent and surface humidity are not only of great importance to polar region, but also very crucial to the prediction of future temperature trend and the establishment of global climate model. The tracks of ENVISAT RA2 altimeter can reach up to the high latitude of 81.4°of north and south, which provides a way of active microwave sensing to monitor sea ice. In this paper, we developed a method using backscatter coefficients (sigma0) based on the ENVISAT satellite radar altimeter RA2 to detect the monthly changes of polar sea ice extent and surface properties. Considering the variations of scattering characteristics of the sea water and ice surface, we prove that a threshold of 13db for sigma0 can distinguish the sea ice cover from sea.Except for summer times, a highly correspondence between seaice boundaries from altimeter and from radiometer released by NSIDC is presented. For lacking of satellite tracks on the central areas of arctic, we only estimated the seaice extent of antarctic zones. And the ENVASAT altimeter gives a greater value in summer months compared to the radiometer result from NSIDC, which relates to the excellent capacity of altimeter to sensing the dispersed thin ice. In other seasons with high seaice concentration, the difference of sea ice extent is pretty small as the mean difference of winter is just 0.17Mkm2.We also research the discrepancy of sea ice properties over two polar zones, and the result shows that in arctic the sea ice surface is more rough and dry in in the winter and more wet in the summer than antarctica.Based on this research, the ENVISAT radar altimeter can precisely detect seasonal evolution of sea ice cover and surface properties and is proved to be a useful tool in sea ice monitoring and polar exploration. |
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