Sea ice type distribution in the Antarctic from microwave satellite observations (SITAnt)

微波卫星观测的南极海冰类型分布（SITAnt）

• 批准号: 365778379
• 负责人: Dr. Gunnar Spreen
• 金额: --
• 依托单位: Institut für Meereskunde (IMee)
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/365778379?language=en
• 关键词: Sea; ice; type; distribution; Antarctic

Sea ice is one of the Earth's climate components exhibiting the greatest change during the last decades. For example, sea ice controls the energy and gas fluxes between ocean and atmosphere in polar regions. Due to its high albedo it efficiently reflects shortwave radiation back to space, and affects the ecosystem. While the sea ice area in the Arctic is rapidly decreasing with a rate of about -4%/decade the sea ice area in the Antarctic is slowly increasing (about 1.5%/decade). Especially pronounced is the decrease in thick, multiyear sea ice in the Arctic with a rate of about -13%/decade. The area of multiyear sea ice in the Arctic can be determined from microwave satellite observations. In the Antarctic the area of perennial ice, i.e. sea ice surviving the summer melt, is smaller than in the Arctic, however, with 3 million square kilometres still quite significant. No method exists today to monitor the distribution and temporal development of perennial ice in the Antarctic throughout the season or on decadal time scales. Here we propose to develop a method to observe Antarctic sea ice types, especially perennial ice, from microwave satellite observations.Due to a decrease in salinity after the summer melt the dielectric properties and porosity of the perennial sea ice change, which makes it possible to distinguish from other ice types by active and passive microwave sensors. In the Antarctic the high snow load, which can cause ice flooding, snow melt-refreeze cycles, and sea ice dynamics in the marginal ice zone (leading to increasing ridging, smaller floes, pancake ice) makes the discrimination of sea ice types, e.g. separation of perennial from seasonal ice more challenging. Recently methods were developed to mitigate such influences leading to false ice type classification for the Arctic. We propose here to adapt and extend an ice type retrieval algorithm, which has been applied at the University of Bremen to Arctic sea ice, including two correction schemes for mitigating false classifications to the conditions of Antarctic sea ice. The proposed method relies on combined microwave radiometer and scatterometer observations for the ice type discrimination and on satellite derived sea ice drift and atmospheric reanalysis for the ice type classification correction. The outcome will be the first circumpolar, long-term time series of Antarctic sea ice types (perennial and seasonal ice, and potentially also young ice).

海冰是地球气候的组成部分之一，在过去几十年里表现出最大的变化。例如，海冰控制着极地海洋和大气之间的能量和气体通量。由于其高反照率，它有效地将短波辐射反射回空间，并影响生态系统。北极海冰面积正在以每十年约-4%的速度迅速减少，而南极海冰面积正在缓慢增加（每十年约1.5%）。特别明显的是北极厚的、多年的海冰正在以每十年-13%的速度减少。北极多年海冰的面积可以通过微波卫星观测来确定。在南极，常年冰的面积，即在夏季融化后幸存下来的海冰，比北极要小，然而，300万平方公里的面积仍然相当大。目前还没有办法在整个季节或十年时间尺度上监测南极多年生冰的分布和时间发展。本文提出了一种利用微波卫星观测南极海冰类型，特别是常年海冰类型的方法。由于夏季海冰融化后盐度的降低，常年海冰的介电特性和孔隙度发生了变化，这为利用主动式和被动式微波传感器区分常年海冰提供了可能。在南极，高雪负荷会导致边缘冰带的冰泛滥、雪融化-再冻结循环和海冰动力学（导致脊状突起增加、浮冰变小、煎饼冰），这使得海冰类型的区分（例如多年生冰与季节性冰的分离）更具挑战性。最近开发了一些方法来减轻这种影响，从而导致对北极进行错误的冰类型分类。在此，我们建议对不来梅大学应用于北极海冰的冰型检索算法进行改进和扩展，包括两种校正方案，以减少对南极海冰的错误分类。该方法依靠微波辐射计和散射计联合观测进行冰型判别，依靠卫星海冰漂移和大气再分析进行冰型分类校正。结果将是南极海冰类型（常年冰和季节性冰，可能还有年轻冰）的第一个环极长期时间序列。