南极半岛巴赫冰架冰面融水动态遥感监测

Evolution of surface meltwater on the Bach Ice Shelf of the Antarctic Peninsula

南极半岛巴赫冰架(Bach Ice Shelf)是全南极冰盖消融最剧烈的区域之一。每年消融期,大量融水在巴赫冰架冰面存储和输送,对冰架稳定性产生重要影响。但目前对巴赫冰架冰面融水的长期动态变化了解较少。本研究利用2013—2020年21期Landsat-8 OLI(Operational Land Imager)影像提取了巴赫冰架长时序冰面融水遥感信息,统计了融水的面积和体积。综合MERRA-2再分析数据集与冰架高空间分辨率数字高程模型REMA,分析了巴赫冰架冰面融水面积与体积的动态变化,并将遥感反演的冰面融水体积与MERRA-2模型模拟的冰面融水径流量进行对比。结果表明:(1)2013—2020年研究区91.7%的冰面融水分布在巴赫冰架上,且冰架上>90%的融水与触地线距离较近(<7 km);(2)融水通过冰面水系在冰面湖之间输送,但并未到达巴赫冰架前端进入大洋;(3)2013—2020年巴赫冰架冰面融水面积与体积均呈上升趋势,每年12月中旬冰面融水出现在触地线周围,随后开始向冰架前端扩张,次年1月中下旬达到最大值,之后开始消退;(4)遥感反演的冰面融水体积小于MERRA-2模拟获得的融水径流量,MERRA-2模型可能过高地模拟了冰面实际径流量。

The Bach Ice Shelf in the Antarctic Peninsula is one of the most rapidly melting area of the Antarctic ice sheet.Each summer,large volumes of meltwater are stored and routed on the ice surface and significantly impact the stability of the ice shelf.However,our knowledge of long-term dynamic variation of the surface meltwater of the Bach Ice Shelf remains limited.We extracted surface meltwater on the Bach Ice Shelf using 21 scenes of Landsat-8 Operational Land Imager(OLI)images,and we compared the remotely sensed volume of meltwater and the surface runoff simulated by the MERRA-2 model.Results show that:(1)91.7%of surface meltwater ponds on the ice shelf are outside the grounding line,and>90%of meltwater on the ice shelf is close to the grounding line(<7 km);(2)surface meltwater is routed among different supraglacial lakes through supraglacial river networks,and does not reach the front edge of the ice shelf or enter the ocean;(3)in general,the area and volume of remotely sensed surface meltwater increased from 2013 to 2020.Surface meltwater commonly appears in the middle of December around the grounding line,expands until mid-January,and then starts to shrink around late January as the surface runoff declines;(4)the volume of surface meltwater is significantly smaller than the cumulative surface runoff simulated by the MERRA-2,implying that the MERRA-2 model may overestimate surface meltwater runoff.