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，气温上升相互加强。不断变化的冰盖给北极冬季天气带来了很大的不确定性，并对沿海社区和当地交通产生了重大影响。此外，高纬度变化如何与中纬度和全球气候系统联系是另一个具有挑战性的问题。一个特别不为人知的天气状况是当寒冷的北极空气流过相对温暖的开放海洋时的冷空气爆发。在冷空气爆发期间，相对温暖的潮湿空气被输送上来形成云线。 人们对云的性质及其降水量和降雪量与伴随的垂直空气运动和海面条件的关系知之甚少。冷空气爆发偶尔会产生强烈的循环空气运动，“极地低压”。冷空气爆发对全球的热量和水分输送以及海洋环流都有重要影响。尽管它们对天气和气候有影响，但冷空气的爆发仍然难以预测。该获奖项目计划进行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系。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，使他们成为下一代大气科学家。CAESAR实地活动预计将于2022年2月至3月在挪威海进行，这是一个冷空气爆发流行的地方。NSF/NCAR C-130飞机配备了一套雷达、激光雷达、辐射计、气溶胶、云、降水和痕量气体探测器，将从瑞典北方或挪威部署。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）特性及其伴随的动力学进行全面取样。飞行计划的目的是调查冷空气爆发的整个演变过程，从北极海冰边缘开始到下游很远的发展良好的云结构。CAESAR测量不仅将为精细尺度云结构的发展提供新的见解，而且还将限制从能够捕捉细微差别的小尺度云和动力过程的涡动模拟到数值天气和气候模型的数值模型的层次结构。一个专门的模式观测相互比较项目计划，以提高数值模式，特别是在“灰色地带”，最先进的天气模型无法捕捉相关的云和动力过程的性能。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。