Understanding snow and sea ice properties at microwave frequencies for remote sensing applications during MOSAiC (MOSAiCmicrowaveRS)

在过去的几十年里，北极海冰的状况发生了巨大的变化。这些变化包括海冰范围、年龄和厚度的迅速下降，以及融化季节的延长。与此同时，北极地区的航运和海上活动量正在增加，需要改进海冰监测。被动和主动微波卫星遥感提供了若干海冰参数的反演，如海冰类型、厚度、漂移和范围。然而，这些参数的检索算法，在某种程度上，依赖于从有限的一组场景中获得的经验关系。它们大多缺乏降雪信息、入射角依赖性和季节变化方面的信息。在全年MOSAiC远征的框架内，我们将改进这些检索算法的帮助下，在现场和空中的观测具有很高的时空变异性。简而言之，该项目包括以下几个方面：- 在微波频率的海冰卫星观测今天被广泛使用，并用于业务应用和气候研究。-合成孔径雷达（SAR），微波辐射计和散射计的分辨率和频率范围广泛，每天都可以使用。-在这里，我们将开发新的和改进现有的方法，从微波观测中获得海冰特性，-2019/2020年在北冰洋中部为期一年的MOSAiC考察将提供必要的信息-现场和空中观测-空中激光扫描仪、电磁冰厚探测和光学图像将使人们能够评价卫星对一个完整季节周期的观测结果。- 现场微波雷达和辐射计测量结合详细的雪和冰的测量将有助于改进辐射传输，发射和散射模型的雪和海冰遥感应用的发展。

Over the past few decades dramatic changes in Arctic sea ice conditions have been observed. These changes include rapid declines in sea ice extent, age, and thickness coupled with extended melt seasons. In parallel the amount of shipping and offshore activities in the Arctic are increasing and demand for improved sea ice monitoring. Passive and active microwave satellite remote sensing offer retrieval of several sea ice parameters such as sea ice type, thickness, drift and extent. However, retrieval algorithms for these parameters are, to some degree, relying on empirical relationships obtained from a limited set of scenarios. They mostly lack snow information, incidence angle dependencies and seasonal variation aspects. In the framework of the year-round MOSAiC expedition we will improve some of these retrieval algorithms with the aid of in-situ and air-borne observations with high spatio-temporal variability. In short, this project covers the following aspects:– Satellite observations of sea ice at microwave frequencies are widely available today and are used both for operational applications and climate studies.– A wide range of resolutions and frequencies from Synthetic Aperture Radar (SAR), microwave radiometers and scatterometers are available on a daily basis.– Here we will develop new and improve current methods to derive sea ice properties from microwave observations, in particular ice type and lead distribution from SAR and snow properties and ice type from microwave radiometers.– The one-year long MOSAiC expedition in the central Arctic Ocean in 2019/2020 will provide necessary in-situ and airborne observations.– Airborne laser scanner, electromagnetic ice thickness sounding, and optical images will allow evaluation of satellite results for a complete seasonal cycle. – In-situ microwave radar and radiometer measurements in conjunction with detailed snow and ice measurements will aid the development of improved radiative transfer, emission, and scattering models for snow and sea ice remote sensing applications.