Predictability of Open Water in the Chukchi/Beaufort Seas and Other Regions

这笔赠款支持评估和实施各种办法，以预测北极沿海海域秋季结冰和春夏冰川消退的时间。这项研究的动机是认识到，北冰洋正在变得更容易进行资源勘探、海洋运输、旅游和其他活动，这增加了对冰情可靠的季节性预测的需要。该项目将侧重于区域规模，以满足利益攸关方的需求。所有北极沿岸海域和加拿大北极群岛的海峡都将被考察，但重点将放在楚科奇海和波弗特海。这承认这些地区是资源勘探的重点地区，经由白令海峡进入或离开北冰洋的船只必须通过，并作为支持自给性狩猎的季节性弓头鲸迁徙路线的一部分。拟议办法的核心是，春季/夏季海冰退缩到某一给定位置(例如大陆架破裂)的日期可以用来预测秋季向该位置推进的日期(即冻结)，从而预测开放水域的时间。这反映了反照率反馈和海洋热量吸收过程，这些过程一直是海冰系统的一部分。简而言之，较早的季节性海冰融化和消退导致较早暴露在容易吸收太阳辐射的黑暗开阔水域，这意味着夏季结束时海洋混合层中会有更多热量，从而推迟秋季冰层的增长。这表现在：楚科奇海开放水期的上升趋势更多地是由晚秋冰的回流驱动的，而不是由较早的春夏退缩驱动的，在这两个变量的反趋势时间序列中，冰退与回流之间存在着很强的关系。大气可变性和海洋热输送等因素被视为反照率反馈和海洋热吸收的调节性表达；这些变量以及季节性气候预报将被视为额外的预测因子。它将确定哪些部门的预测最熟练和最不熟练，这些差异的原因，以及不断变化的海冰状况(例如，变化的冰层厚度)是否正在改变可预测性。此外，将考察多种过程，包括冬季大气条件、海洋热量输送、冰层厚度和表面融化开始，作为撤退日期的可预报性来源。这项研究将利用卫星观测的海冰范围和浓度、表面融化开始、冰运动、厚度和年龄、海洋热通量测量和NCEP耦合气候预报系统第二版的输出，以及来自两个现代大气再分析的海平面气压、温度和其他变量的场。北冰洋，特别是楚科奇海和波弗特海，对我国的战略重要性与日俱增。拟议中的努力旨在提供对区域范围内海冰状况的巧妙季节性预测，目的是通过满足不同利益攸关方的需求，包括海洋航运机构、采掘业和自给性狩猎，改进将科学与决策联系起来的方法。支持研究生和本科生帮助培养下一代科学家，研究成果将被吸收到科罗拉多大学的北极气候课程中。

This grant supports an effort to assess and implement approaches to predict the timing of autumn freeze-up and spring-summer ice retreat in the Arctic coastal seas. The study is motivated by recognition that the Arctic Ocean is becoming more accessible for resource exploration, marine shipping, tourism and other activities, increasing the need for reliable seasonal predictions of ice conditions. The project will focus on regional scales addressing stakeholder needs. All Arctic coastal
seas and the channels of the Canadian Arctic Archipelago will be examined, but emphasis will be placed on the Chukchi and Beaufort Seas. This recognizes these regions as foci for resource exploration, where ships entering or exiting the Arctic Ocean via Bering Strait must pass, and as part of the seasonal bowhead whale migration route supporting subsistence hunting. The core of the proposed approach is that the date of the spring/summer sea ice retreat to a given location (e.g., the continental shelf break) can be used to predict the date of the autumn advance back to that location (i.e. freeze-up), and hence the open water period. This reflects albedo feedback and ocean heat uptake processes that have always been part of the sea ice system. Briefly, earlier seasonal sea ice melt and retreat leads to earlier exposure of dark open water areas that readily absorb solar radiation, meaning more heat in the ocean mixed layer at summer's end, delaying autumn ice growth. This is manifested in observations that the upward trend in the open water period in the Chukchi Sea is driven more by later autumn return of ice than an earlier spring/summer retreat, and that there is a strong relationship between ice retreat and return in de-trended time series of the two variables. Factors such as atmospheric variability and ocean heat transport are viewed as modulating expressions of albedo feedback and ocean heat uptake; such variables, along with seasonal climate forecasts, will be examined as additional predictors. It will be determined in which
sectors predictions are most and least skillful, the reasons for these differences, and whether
the changing sea ice regime (e.g., changing ice thickness) is changing predictability. In
addition, multiple processes, including winter atmospheric conditions, ocean heat transport, ice thickness and surface melt onset, will be examined as sources of predictability on the
date of retreat. The study will utilize satellite observations of sea ice extent and concentration, surface melt onset, ice motion, thickness and age, ocean heat flux measurements, and output
from the NCEP coupled Climate Forecast System, Version 2, along with fields of sea level pressure, temperature and other variables from two modern atmospheric reanalyses. The Arctic Ocean, particularly the Chukchi and Beaufort seas, is of growing strategic importance
to our nation. The proposed
effort to provide skillful seasonal predictions of sea ice conditions at the regional scale
serves the goal of improving methods of connecting science with decision making through addressing diverse stakeholder needs, including marine
shipping agencies, extraction industries and subsistence hunting. Support is included for a graduate student and undergraduate students to help educate the next generation of scientists, and study results will be assimilated
into an Arctic climate course at the University of Colorado.