雷达卫星显示南极冰损

五十多年来，五年雷达卫星观察的价值显示，西南南极半岛西部帕尔默陆地30冰川的冰丧失的加速。研究'Geophysical Research Letters' combines over 24 years of radar data from satellites including ESA’s Envisat and ERS missions, as well as from the Copernicus Sentinel-1 mission.

Radar is particularly suited for monitoring polar regions that are prone to bad weather and long periods of darkness because it can collect information regardless of cloud cover, day or night.

Mapping 30 glaciers in the region, the research team found that between 1992 and 2016, most of the glaciers sped up by 20 and 30 cm per day. This is equivalent to an average 13% increase in flow speed across the area as a whole. The team also combined their satellite observations with an ice-flow model to fill in gaps where no satellite data were available. This allowed the scientists to estimate that the glaciers’ speed increase has led to the discharge of 15 cubic km of ice per year into the surrounding ocean.

The findings differ from an earlier study that estimated the region was losing three times this amount of ice than the findings published today.

Warmest layer

This new research – which is the first to map the actual change in ice speed – deviates from the previous interpretation, because the glacier speedup is in fact far too small, said Anna Hogg, lead author and researcher at the UK Centre for Polar Observation and Modelling. The greatest acceleration in flow was observed at glaciers that were grounded at depths more than 300 m below the ocean surface.

The team looked at water temperatures in front of the glaciers which have sped up the most, and found that they flow through deep bedrock channels into the warmest layer of the ocean, explained Dr Hogg. This circumpolar deep water, which is relatively warm and salty compared to other parts of the Southern Ocean, has warmed and shoaled in recent decades, and can melt ice at the base of glaciers which reduces friction and allows them to flow more freely.

随着西帕尔默的大部分冰块躺在海平面下方，重要的是要监测偏远地区如何应对该地区的进一步变暖，因为气候变化。

欧洲的欧洲哥伦塞尔的双卫星哨兵-1任务经常监控极地区域，以高分辨率，继续从欧洲卫星的长期数据记录。

资料来源：esa。