EUREC4A mission proposal - Elucidating the Role of Cloud-Circulation Coupling in Climate

信风区的浅层对流是地球上最常见的云类型。这些云将如何应对全球变暖？这个悬而未决的问题是确定气候敏感性的最大不确定性之一，气候敏感性被定义为全球温度上升与CO2增加之间的比率。粗分辨率的全球气候模式以及网格间距为100米的涡旋分辨率模式都提供了非常不同的预测，浅对流将如何响应变化的环境条件。云结构和环境影响因素，特别是大尺度动力学的综合观测，需要推进模式的发展和约束气候预测。法国-德国测量活动EUREC 4A（阐明云-环流耦合在气候中的作用）将面临这一挑战：德国研究飞机HALO将与法国研究飞机ATR 42联合收集一个独特的数据集，描述巴巴多斯以东的浅层对流，时间为2020年1月20日至2月20日。HALO上装有一套广泛的遥感传感器，将在云层上方高空飞行，观测云层结构，并通过沿沿着大圈投放投下式探空仪，评估大气层的大规模动态。与此同时，ATR 42将在云层内飞行，以测量云的几何形状和微物理组成。将通过分析海洋-大气层交换的研究船和巴巴多斯云观测站来补充这一实验，巴巴多斯云观测站利用地面遥感提供了一个长期参考点。

Shallow convection in the trade-wind region is the most frequent type of clouds on Earth. How will these clouds react to global warming? This open question is one of the largest uncertainty in determining the climate sensitivity, which is defined as ratio between global temperature increase and CO2 increase. Both coarse-resolution global climate models as well as eddy-resolving models with grid spacing in the order of 100 m provide very different predictions how shallow convection will respond to changed environmental conditions. Comprehensive observations of both the cloud structures and the ambient influencing factors, in particular the large scale dynamics, are needed to advance model development and to constrain climate predictions. The French-German measurement campaign EUREC4A (Elucidating the Role of Cloud-Circulation Coupling in Climate) will face this challenge: The German research aircraft HALO will jointly with the French research aircraft ATR42 collect a unique dataset describing shallow convection east of Barbados from 20 January to 20 February 2020. HALO equipped with an extensive suite of remote sensing sensors onboard will fly high above the clouds to observe its structure and to assess the large-scale dynamical state of the atmosphere by releasing dropsondes along large circles. In parallel, the ATR42 will fly within the cloud layer to measure the cloud geometry and microphysical composition. The experiment will be complemented by research vessels analyzing the ocean-atmosphere exchange and the Barbados Cloud Observatory, which provides a long-term reference point using ground-based remote sensing.