Seasonal-to-Decadal Predictability of Arctic Sea Ice

北极海冰的季节到十年的可预测性

• 批准号: RGPIN-2018-04838
• 负责人: Tremblay, Bruno
• 金额: $ 3.13万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=667061
• 关键词: Seasonal; Decadal; Predictability; Arctic; Sea

With the opening of the summer pack ice in 2007, there has been an increased interest in short-term, seasonal and decadal forecasting or projections of sea ice conditions. Methods used in the community to study the predictability of the system on these time scales include coupled ice-ocean models forced with atmospheric fields from reanalyses (with or without data assimilation), fully coupled General Circulation Models with initial conditions derived from observations, or statistical models and heuristic or mixed approaches. For short-term forecasting (1-2 days), thermodynamic effects are less important and fully coupled models are not necessary. In this case, forecasting skill relies on the specification of accurate initial conditions, surface atmospheric stresses and an accurate representation of sea ice and surface ocean physics. For seasonal forecasting, accurate initial conditions are again crucial along with a good representation of ice-ocean-atmosphere physics and feedbacks. For decadal projections, the sensitivity to initial conditions is lost, and predictive skill relies on an accurate representation of the ice-ocean-atmosphere physics, as well as accurate representation of internal variability and external forcing such as CO2, ozone, aerosol, solar irradiance at the top-of-the-atmosphere, etc. The long-term objectives of this research program are to improve short-term to decadal forecasts or projections of sea ice in the Arctic Ocean. The specific objectives of the proposal are to improve sea ice physics (drift and deformation); to quantify potential predictability from observed quantities and reanalysis data (ice speed, concentration, thickness and lower/upper atmospheric circulation); to identify key metrics responsible for predictability in observations and assess whether those metrics are correctly simulated in Global Climate Models (pointing to area of model improvements and improved forecasts); to quantify potential improvements in predictability associated with ocean heat flux (both lateral in the Bering Strait and Barents Sea Opening and vertical via convection and Ekman dynamics). The completion of this work will lead to a better understanding of forecast skill and potential predictability. The novelty in this work is that it assesses predictability directly from observations. This is crucial given that small biases in the simulated mean state of models can lead to significant loss of predictability. This research program will place Canada in a unique position to improve sea ice forecasts for local populations and industry, allowing for safer operations in an Arctic, that is becoming increasingly accessible to navigation. It will also reduce uncertainties in the timeline for when these changes are more likely to occur.

随着2007年夏季浮冰的开放，人们对海冰状况的短期、季节性和年代际预报或预测越来越感兴趣。国际社会用来研究系统在这些时间尺度上可预报性的方法有：再分析(有或没有数据同化)产生的大气强迫的冰-海耦合模式、从观测中得出初始条件的完全耦合的环流模式，或统计模型和启发式或混合式方法。对于短期预报(1-2天)，热力效应不那么重要，完全耦合模式是不必要的。在这种情况下，预报技能依赖于准确的初始条件、表面大气应力的规范以及对海冰和表面海洋物理的准确表示。对于季节性预报，准确的初始条件以及冰-海洋-大气物理和反馈的良好表现再次至关重要。对于年代际预测，失去了对初始条件的敏感性，预测技能依赖于对冰-海洋-大气物理的准确表示，以及对内部可变性和外部强迫(如二氧化碳、臭氧、气溶胶、大气顶部的太阳辐射等)的准确表示。该研究计划的长期目标是改进对北冰洋海冰的短期到年代际预测或预测。这项提议的具体目标是：改进海冰物理(漂移和变形)；根据观测量和再分析数据(冰速、浓度、厚度和下层/上层大气环流)，量化潜在的可预测性；确定对观测中的可预测性负责的关键指标，并评估这些指标在全球气候模型中是否得到正确模拟(指出改进模型和改进预报的领域)；量化与海洋热通量有关的可预测性方面的潜在改善(白令海峡和巴伦支海的横向以及通过对流和埃克曼动力学实现的垂直)。这项工作的完成将使人们更好地了解预测技能和潜在的可预测性。这项工作的新奇之处在于，它直接从观察中评估可预测性。考虑到模型的模拟平均状态中的微小偏差可能会导致严重的可预测性损失，这一点至关重要。这一研究计划将使加拿大处于独特的地位，可以改善对当地人口和行业的海冰预报，允许在日益便于航行的北极地区进行更安全的作业。它还将减少这些变化更有可能发生的时间线中的不确定性。