COntrails Spreading Into Cirrus (COSIC)

背景近50年来，航空业发展迅速，上半年航空运输量年增长率近9%(约为国内生产总值平均增长率的2.5倍)，下半年年增长率约为5%。根据最新的估计，航空气候影响占与气候变化有关的全球辐射强迫的2-8%。由于未来几十年空中交通的预期增加，空中交通对气候变化的相对重要性预计将显著增加。对COSIC和AIMS的需求航空最大的影响之一很可能是由于尾迹及其扩散到卷云中。这可能比二氧化碳排放增加的影响要大得多，但这一轨迹-卷云仍然无法量化。之前对联合航空造成的云层的估计表明，扩散的轨迹可能是重要的。然而，这些研究依赖于空中交通与卷云覆盖的关联，存在很大的不确定性和方法问题。这项提议的最终目标是，第一次建立一个基于物理的轨迹-卷云-的参数化，以确定它在气候变化中的作用，测试它是否比线形轨迹有更大的作用。为了实现这一最终目标，将利用FAAM(研究机)飞行和卫星观测来观测轨迹特性及其扩散。然后，将使用模型的层次结构在气象局统一模式中开发轨迹卷云参数化，与气象局和德国航空航天中心(DLR)的合作伙伴密切合作，并通过曼彻斯特大学和气象局研究人员在飞机活动期间所做的观测来约束所开发的参数化。WP1工作计划将执行一项飞机活动，对2009年期间在英国西南部飞行走廊外的一个区域内扩散的轨迹进行6次“案例研究”观察。我们将使用一种新颖的“八字”飞行模式来制造和监测我们自己的轨迹，特别是跟踪它演变为卷云的过程。我们将使用GERB和SEVIRI地球静止仪器，通过上下飞行截面和从空间进行监测来测量它的辐射强迫。我们将利用英国气象局和曼彻斯特大学研究小组所做的最先进的观察。我们还将依靠雷丁大学小组使用欧洲中心预报提供的冰过饱和度预报。WP2将使用DLR提供的理想化建模数据和在WP1期间进行的详细观察来模拟在飞机战役期间观察到的具体案例研究。将特别注意轨迹生命周期的后期阶段。WP3将再次利用理想化的DLR数据和我们自己(以及其他人)的案例研究数据，为英国气象局统一模型建立一个预测轨迹-卷云方案。WP4将使用具有此参数的统一模式来预测轨迹卷云的辐射强迫和气候影响，将其气候影响与对线形轨迹的估计进行比较。

BACKGROUND In the last fifty years aviation has experienced very rapid development, with air traffic recording an almost 9% yearly growth rate in the first half of the period (approximately 2.5 times the average GDP growth rate) and approximately 5% yearly growth rate in the second half of the period. According to the most recent estimates, aviation climatic impact amounts to 2-8% of the global radiative forcing associated with climate change. As a result of the expected increase in air traffic in the next decades, the relative importance of air traffic on climate change is expected to increase significantly. THE NEED FOR COSIC AND AIMS One of aviation's largest effects is likely to be that due to contrails and their spreading into cirrus. This could be considerably larger than the effects of increased CO2 emissions but this contrail-cirrus remains unquantified. Previous estimates of combined aviation induced cloudiness suggest that spreading contrails could be important. However, these studies rely on correlating air traffic with cirrus coverage and have large uncertainties and methodological problems. The ultimate aim of this proposal is, for the first time, to build a physically based parameterisation of contrail-cirrus - to determine its role in climate change, testing whether it has a larger role than line-shaped contrails. To achieve this ultimate goal, observations of contrail properties and their spreading will be made with FAAM (research aircraft) flights and satellite observations. Then a hierarchy of models will be used to develop a contrail-cirrus cloud parameterisation within the Met Office Unified Model, working closely with both the Met Office and the Deutsches Zentrum für Luft- und Raumfahrt (DLR) partners, and constraining the developed parameterisations by the observations made by University of Manchester and Met Office researchers during the aircraft campaign. WORKPLAN WP1 will perform an aircraft campaign making 6 'case study' observations of spreading contrail during 2009 in an area out of the flight corridor to the southwest of the UK . We will use a novel 'figure of eight' flight pattern to make and monitor our own contrail and, in particular, track its evolution into cirrus. We will measure its radiative forcing by flying cross sections above and below and by monitoring from space using the GERB and SEVIRI geostationary instruments. We will make use of state-of-the-art observations made by the Met Office and University of Manchester groups. We will also rely on ice supersaturation forecasts supplied by the University of Reading group using European Centre forecasts. WP2 will use idealised modelling data supplied by DLR and the detailed observations made during WP1 to simulate specific case studies observed during the aircraft campaign. Particular attention will be made to the later stages of contrail lifecycle. WP3 will again make use of idealised DLR data and our own (and others) case-study data to build a prognostic contrail-cirrus scheme for the Met Office Unified Model. WP4 will employ the Unified Model with this parameterisation to predict the radiative forcing and climate impact from contrail-cirrus, comparing its climate impact to that estimated for line-shaped contrails.