Scientific Program Overview (SPO): Cold Air Outbreak Experiment in the Sub-Arctic Region

科学计划概述（SPO）：亚北极地区的冷空气爆发实验

• 批准号: 2016368
• 负责人: Paquita Zuidema
• 金额: $ 2.82万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2016368&HistoricalAwards=false
• 关键词: Scientific; Program; Overview; SPO; Cold

The Arctic is the region on planet Earth warming the most rapidly with rapid sea ice loss and increasing air temperatures reinforcing each other. Changing ice cover posts great uncertainties on Arctic winter weather and significant impacts upon coastal communities and local transportation. In addition, how the high-latitude changes connect to the mid-latitude and the global climate system is another challenging question. One particularly poorly understood weather regime is cold-air outbreaks when cold Arctic air streaming over relatively warm open ocean water. During cold-air outbreaks, relatively warm moist air is transported up in forming lines of clouds. Little is known about the cloud properties and their rain and snowfall amount in relation with the accompanying vertical air movement and sea surface conditions. Cold air outbreaks occasionally spawn into intense circular air movements, “polar lows”. Cold-air outbreaks have significant impacts on the global heat and water transport as well as ocean circulations. Despite their impacts on weather and climate, cold-air outbreaks remain difficult to predict. This awarded project is to plan a dedicated field study, Cold Air Outbreak Experiment in the Sub Arctic Region (CAESAR) that has the goal to gather the necessary measurements to understand the mysterious cloud regime associated with cold-air outbreaks. The planned field campaign will be in collaboration with Scandinavian scientists and provide unique training opportunities to students to be the next generation of atmospheric scientists. The CAESAR field campaign is anticipated in February-March 2022 over the Norwegian Sea, a spot where cold-air outbreaks are prevalent. The NSF/NCAR C-130 aircraft with a suite of radars, Lidars, radiometers, aerosol, cloud, precipitation and trace gas probes will be deployed from northern Sweden or Norway. The goal is to study the structure of marine boundary layer clouds during cold-air outbreaks with a focus on fully sampling microphysical (liquid and ice) properties of cloud particles and the accompanying dynamics. Flight plans are designed to investigate cold-air outbreaks throughout their entire evolution from their initiation over the Arctic sea ice edge to well-developed cloud structures far downstream. The CAESAR measurements will not only afford new insights of development of fine-scale cloud structures but also constrain a hierarchy of numerical models ranging from eddy simulations capable of capturing the nuanced small-scale cloud and dynamical processes to numerical weather and climate models. A dedicated model-observational intercomparison project is planned to improve numerical models particularly their performance in the ‘grey-zone’ where state-of-the-art weather models fail to capture the relevant cloud and dynamical processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

北极是地球上变暖最快的地区，海冰迅速消失和气温升高相互促进。冰盖变化给北极冬季天气带来很大的不确定性，并对沿海社区和当地交通产生重大影响。此外，高纬度变化如何与中纬度和全球气候系统联系起来也是另一个具有挑战性的问题。一种人们尤其知之甚少的天气状况是，当北极冷空气流过相对温暖的开放海水时，冷空气就会爆发。在冷空气爆发期间，相对温暖的潮湿空气会向上输送，形成云线。 人们对云的性质及其雨雪量与伴随的垂直空气运动和海面条件的关系知之甚少。冷空气的爆发偶尔会产生强烈的循环空气运动，即“极地低压”。冷空气的爆发对全球热量和水的输送以及海洋环流产生重大影响。尽管冷空气对天气和气候有影响，但其爆发仍然难以预测。该获奖项目旨在计划一项专门的实地研究，即“亚北极地区冷空气爆发实验”(CAESAR)，其目标是收集必要的测量数据，以了解与冷空气爆发相关的神秘云状况。计划中的实地活动将与斯堪的纳维亚科学家合作，为学生提供独特的培训机会，使其成为下一代大气科学家。 CAESAR 现场行动预计将于 2022 年 2 月至 3 月在挪威海上空进行，该地区是冷空气爆发的地区。配备一套雷达、激光雷达、辐射计、气溶胶、云、降水和痕量气体探测器的 NSF/NCAR C-130 飞机将从瑞典北部或挪威部署。目标是研究冷空气爆发期间海洋边界层云的结构，重点是对云粒子的微物理（液体和冰）特性以及伴随的动力学进行充分采样。飞行计划旨在调查冷空气爆发的整个演变过程，从北极海冰边缘上空的爆发到下游远处发达的云结构。 CAESAR 测量不仅为精细尺度云结构的发展提供了新的见解，而且还限制了数值模型的层次结构，从能够捕获微妙的小尺度云和动态过程的涡流模拟到数值天气和气候模型。计划开展一个专门的模型观测比对项目，以改进数值模型，特别是其在“灰色地带”的性能，其中最先进的天气模型无法捕获相关的云和动态过程。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。