利用改进的亮温日较差法探测格陵兰冰盖表面融化

Surface Melting Detection of the Greenland Ice Sheet Using Advanced Diurnal Amplitude Variations Algorithm

  • 摘要: 格陵兰冰盖是全球海平面上升的主要贡献源之一,其表面融化和融水径流引发的物质损失约占冰盖总物质损失的60%,研究格陵兰冰盖的表面融化具有重要意义。采用2019年增强分辨率的专用微波成像仪37 GHz垂直极化被动微波数据,提出改进的亮温日较差(advanced diurnal amplitude variations,ADAV)方法,并利用该方法探测格陵兰冰盖的表面融化。与自动气象站的气温数据对比,ADAV方法使用动态阈值探测结果的平均精度高于使用固定阈值的传统日较差方法,且被动微波数据时间对探测精度无明显影响。采用该方法分析格陵兰冰盖冻融发现,2019年冰盖融化天数最多达165 d,7月31日融化面积达到最大,占冰盖总面积的67%;夏季3次出现融化峰值,且南部沿岸发生了冬季融化事件。

     

    Abstract:
    Objectives The Greenland ice sheet is one of the main contributors to the global sea level rise, and the mass loss caused by its surface melting and meltwater runoff accounts for about 60% of the total mass loss of the ice sheet, so it is of great significance to study the surface melting of the Greenland ice sheet.
    Methods Based on the 37 GHz vertical polarization passive microwave data of special sensor microwave imager sounder, the advanced diurnal amplitude variations (ADAV) method is proposed to detect the surface melting of the Greenland ice sheet.
    Results Compared with the air temperature data of automatic weather stations, the average accuracy of the detection results of the ADAV method using dynamic threshold is better than that of the traditional diurnal amplitude variations method using a fixed threshold, and the passive microwave data time has no obvious influence on the detection accuracy.
    Conclusions The freeze-thaw analysis of the Greenland ice sheet based on this method found that in 2019, the area with the most melting days on the ice sheet melted up to 165 d. The melting area reached the maximum on July 31st, accounting for 67% of the total ice sheet area. Three melting peaks arose in summer, and there were several winter melting events on the south coast. The ADAV method and its application to high spatial resolution passive microwave data have promoted the development of refining ice sheet freezing and thawing observations.

     

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