Multi-frequency microwave remote sensing of summer Arctic sea ice attributes as indicators of climate and biophysical processes

在过去30年中，夏季北极海冰范围迅速减少，导致北极海洋环境的命运和北极利益攸关方的协调存在不确定性。现在有一个全新的北极冰盖，主要是较薄的第一年冰（FYI），而不是较厚的多年冰（MYI）。夏季冰面上的低CO2融化池塘的面积分数，称为池塘分数（PF），增加了由于地形控制洪水范围FYI相比，粗糙MYI。一些实地研究指出，PF演变的耦合率的短波辐射吸收，透光率，上层海洋变暖，冰下初级生产，大气-海洋生物地球化学交换，包括污染物。我们对当地尺度的PF演变和与北极海洋环境组成部分的关系的理解在区域和更大的尺度上是不匹配的。推而广之，PF在大尺度海冰模式，主要是基于当地尺度观测MYI的参数化，是不足以可靠的区域和流域范围内的海冰和气候条件的预测。在所有尺度上，季节内融化状态变化对PF演变和耦合过程的影响知之甚少。需要有一种强有力的手段来监测和评估夏季冰的季节性衰减和相关的生物物理过程。** 合成孔径雷达任务的增加，包括目前和即将进行的星座模式任务，将大大提高我们监测夏季北极海洋环境的能力。频繁的，每天或更好的，区域尺度的观测，无论云量和天气条件将有助于监测和建模研究在几个跨学科领域。这项发现补助金将支持一项研究计划，致力于夏季北极冰层覆盖的海洋环境的区域规模研究。近期目标将侧重于了解FYI和MYI的PF和冰融化状态的时空特征，其控制机制，以及与SAR成像特性（频率，偏振和视角）的关系。研究成果包括为夏季北极冰PF和融化状态以及耦合生物物理过程的新的和事后研究制定一个强有力的、基于卫星地球观测的框架。贡献还包括改进海冰-气候模型参数化，并增强我们利用加拿大雷达卫星2号和即将发射的雷达卫星星座使命的合成孔径雷达图像的能力，以跟踪和研究快速变化的夏季融化期间的海冰。

In the last 30 years, summer Arctic sea ice extent has rapidly declined, leading to uncertainties regarding the fate of the Arctic marine environment and the coordination of Arctic stakeholders. There is now an entirely new Arctic ice pack dominated by thinner first-year ice (FYI) instead of thicker multiyear ice (MYI). The areal fraction of low albedo melt ponds on summer ice, termed pond fraction (PF), has increased due to fewer topographical controls on flooding extent over FYI compared to rough MYI. Several field studies point to the coupling of PF evolution to rates of shortwave radiation absorption, light transmittance, upper ocean warming, under-ice primary production, and atmosphere-ocean biogeochemical exchanges, including contaminants. Our understanding of local scale PF evolution and relationships with components of the Arctic marine environment is not matched at regional and greater scales. By extension, parameterizations of PF in large scale sea ice models, largely based on local scale observations of MYI, are inadequate for reliable regional and basin-wide forecasts of sea ice and climate conditions. At all scales the impact of intra-seasonal melting state variations on PF evolution and coupled processes are poorly understood. A robust means by which to monitor and assess the seasonal decay of summer ice and related biophysical processes is needed. ******The proliferation of synthetic aperture radar (SAR) missions, including current and pending missions operating in constellation mode, will significantly enhance our ability to monitor the summer Arctic marine environment. Frequent, daily or better, regional scale observations regardless of cloud cover and weather conditions will contribute to monitoring and modeling studies within several interdisciplinary realms. This Discovery Grant will support a research program dedicated to the regional scale study of the summer Arctic ice-covered marine environment. Near term objectives will focus on understanding spatiotemporal characteristics of PF and ice melting state on FYI and MYI, their controlling mechanisms, and relationships to SAR imaging characteristics (frequency, polarization, and viewing angle). Research outcomes include the development of a robust, satellite earth observation based, framework for new and hind-cast studies of summer Arctic ice PF and melting state, as well as coupled biophysical processes. Contributions also include improvements to sea ice-climate model parameterizations, and enhancements to our ability to utilize SAR imagery from Canada's Radarsat-2 and pending Radarsat Constellation Mission to track and study sea ice during the fast changing summer melting period.***********