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

夏季北极海冰属性的多频微波遥感作为气候和生物物理过程的指标

• 批准号: RGPIN-2015-05540
• 负责人: Scharien, Randall
• 金额: $ 1.46万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=707947
• 关键词: Multi; frequency; microwave; remote; sensing

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.

过去30年来，夏季北极海冰范围迅速缩小，导致北极海洋环境的命运和北极利益相关者的协调存在不确定性。现在有一个全新的北极冰层，主要是较薄的一年冰（FYI），而不是较厚的多年冰（MYI）。夏季冰上低反照率融化池塘的面积比例（称为池塘比例（PF））有所增加，因为与粗略的 MYI 相比，FYI 上对洪水范围的地形控制较少。一些实地研究指出，PF 演化与短波辐射吸收率、透光率、上层海洋变暖、冰下初级生产以及大气-海洋生物地球化学交换（包括污染物）之间存在关联。我们对局部尺度PF演变以及与北极海洋环境组成部分关系的理解在区域和更大尺度上并不匹配。推而广之，大规模海冰模型中的 PF 参数化主要基于 MYI 的局部尺度观测，不足以对海冰和气候条件进行可靠的区域和流域预测。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（SAR）任务的激增，包括当前和即将执行的星座模式任务，将显着增强我们监测夏季北极海洋环境的能力。无论云量和天气条件如何，频繁、每日或更佳的区域尺度观测将有助于多个跨学科领域的监测和建模研究。该发现补助金将支持一项致力于对夏季北极冰雪覆盖的海洋环境进行区域规模研究的研究项目。近期目标将侧重于了解 FYI 和 MYI 上 PF 和冰融化状态的时空特征、它们的控制机制以及与 SAR 成像特征（频率、偏振和视角）的关系。研究成果包括开发一个基于卫星地球观测的强大框架，用于夏季北极冰 PF 和融化状态以及耦合生物物理过程的新研究和事后研究。贡献还包括改进海冰气候模型参数化，以及增强我们利用加拿大 Radarsat-2 和即将实施的 Radarsat Constellation Mission 的 SAR 图像在快速变化的夏季融化期间跟踪和研究海冰的能力。