Testing and Improving Stratosphere-Troposphere Analyses Through Tracer Transport Studies

气象中心对全球大气风和温度进行分析，通常是6小时一次。这些场现在延伸到平流层顶上方，是通过将观测(来自卫星、探空仪、地面观测等)同化到数值天气预报(NWP)模式中而产生的。这些分析的主要用途是初始化短期天气预报。对于研究大气污染的研究人员来说，这些全球风场和温度场也是一个巨大的潜在资源，他们需要对大气中痕量气体的分布进行建模(化学传输模型)。事实上，这些风被广泛用于许多大气化学研究，结果严重依赖于这些分析的质量。然而，近年来已变得明显的是，许多中心提供的全球分析风场并不能很好地代表这种示踪剂运输。风往往会在地区之间造成太多的示踪剂运输。在这个项目中，利兹大学在化学运输模型方面拥有丰富的经验，它将与3个领先的气象中心合作，测试目前可用的一系列分析在一系列重要示踪剂运输问题上的表现。根据这一系统比较，利兹将直接与ECMWF合作，以测试不同分析中不同示踪剂传输行为的原因。将进行新的测试分析，并向气象中心提供有关示踪剂运输的最佳分类系统的信息。最后，将使用最现实的分析来详细研究进入、穿过和流出热带对流层顶层的示踪剂输送。这一区域控制着污染物进入平流层的速度，而通过这一区域的过境时间目前没有得到很好的量化。对这一数量的估计有很大的差异，这取决于所使用的分析和在特定模型中使用这些分析的方法。对这些新的分析进行详细的调查，强制建立一个可以在各种配置下运行的3D模型，将提供更好的估计。

Meteorological centres produce global analyses of atmospheric winds and temperatures, typically on a 6-hour basis. These fields, which now extend above the stratopause, are produced by the assimilating of observations (from satellites, sondes, surface observations etc) into a numerical weather prediction (NWP) model. The primary use of these analyses is to initialise short-term weather forecasts. These global wind and temperature fields are also a huge potential resource for researchers who study atmospheric pollution and need to model the distribution of trace gases in the atmosphere (chemical transport modellers). Indeed, these winds are widely used for many studies of atmospheric chemistry where results depend critically on the quality of these analyses. However, it has become apparent in recent years that global analysed windfields available from many centres do not represent this tracer transport well. The winds tend to cause too much transport of tracers between regions. In this project the University of Leeds, which has extensive experience in chemical transport modelling, will collaborate with 3 leading meteorological centres to test how well a range of currently available analyses perform for a range of important tracer transport questions. Following on from this systematic comparison, Leeds will collaborate directly with ECMWF in order to test the causes of different tracer transport behaviour in the different analyses. New test analyses will be produced and information on the best assmilation system for tracer transport will provided to the meteorological centres. Finally, the most realistic analyses will be used to study in detail tracer transport into, through and out of the tropical tropopause layer (TTL). This region controls the rate at which pollutants enter the stratosphere and the transit time through this region is currently poorly quantified. There are large variations in estimates of this quantity depending on the analyses used and the method of employing them in a particular model. Detailed investigations with these new analyses, forcing a 3D model which can be run in in a variety of configurations, will provide a better estimate of this.