Past and future evolution of the 3D Brewer-Dobson circulation

Brewer-Dobson环流（BDC）是指中层大气（10- 100 km）的时间平均质量环流。BDC由行星波、天气尺度波和重力波驱动，将臭氧（O3）、水蒸气（H2O）和其他微量气体成分从热带输送到中纬度和极地。纬向平均（2D）BDC在气候变化中的演变及其与平流层臭氧层的相互作用是当前研究的一个重要问题。然而，2D BDC和波驱动的长期变化在所使用的模型和观测之间存在很大差异。基于三维（3D）BDC公式的检查可能会导致更详细的图片和更好地了解BDC在气候变化中的作用，该项目的目的是调查过去和未来的变化的三维BDC和本地波驱动的基础上的财团模拟与地球系统模型MPI-ESM的时间段1960- 2005年气候预测和2100年气候预测（CMIP 5）。对于CMIP 5模拟无法单独实现的验证和方面，还将根据高空大气环流和化学模式HAMMONIA（1957-2006）的模拟、再分析（ERA-Interim 1979-2012，MERRA，1979-2012）和最近的卫星数据（Aura/MLS 2004-2012）分析三维BDC。将开发一种算法，从Aura/MLS数据中导出每日平均风场的新数据集，这将为验证3D BDC提供合适的工具，特别是在当地风测量非常稀疏的高度（约200米）。30- 80公里）。将根据收支方程的线性解分析3D BDC对中层大气中O3、H2O、温度和涡度的局部长期变化的影响，特别是对超长驻波的影响。控制耦合的中层大气三维BDC，对流层波活动和风驱动的洋流的过程将进行检查的基础上额外的模型灵敏度模拟与MPI-ESM，包括规定的调制表面温度，对流层和平流层涡流通量，和中层大气吸收分布来自观测。还计划根据化学-气候模式（CCM）验证项目（平流层过程及其在气候中的作用）进行和提供的CCM模拟，研究3D BDC对平流层O3和中层大气H2O的局部长期变化的影响。

The Brewer-Dobson circulation (BDC) denotes the time-mean mass circulation of the middle atmosphere (10-100km). The BDC is driven by planetary waves, synoptic-scale waves and gravity waves, and transports ozone (O3), water vapour (H2O) and other trace gas constituents from the tropics to mid- and polar latitudes. The evolution of the zonal mean (2D) BDC in a changing climate and its interaction with the stratospheric ozone layer is an important issue of current research. However, the long-term changes of the 2D BDC and the wave driving strongly differ between the used models and the observations. Examinations based on a formulation of the three-dimensional (3D) BDC might lead to a more detailed picture and an improved understanding of the role of the BDC in a changing climate, but they are very sparse.The aim of the project is to investigate the past and future changes of the 3D BDC and the local wave driving based on the consortia simulations with the Earth-System Model MPI-ESM for the time period 1960-2005 and the climate projections up to the year 2100 (CMIP5). For validation and aspects which cannot be achieved by the CMIP5 simulations alone, the 3D BDC will also be analysed based on simulations with the high-altitude general circulation and chemistry model HAMMONIA (1957-2006), reanalysis (ERA-Interim 1979-2012, MERRA, 1979-2012) and recent satellite data (Aura/MLS 2004-2012). An algorithm will be developed to derive a new data set of daily-mean wind fields from the Aura/MLS data, which will provide a suitable tool for validating the 3D BDC particularly at altitudes where local wind measurements are very sparse (ca. 30-80km). The impact of the 3D BDC on the local long-term changes of O3, H2O, temperature and vorticity in the middle atmosphere, particularly on the ultra-long stationary waves, will be analysed based on linear solutions of the budget equations. The processes controlling the coupling the middle atmospheric 3D BDC, the tropospheric wave activity and wind-driven ocean currents will be examined based on additional model sensitivity simulations with the MPI-ESM including prescribed modulations of surface temperatures, tropospheric and stratospheric eddy fluxes, and middle atmospheric absorber distributions derived from observations. It is also planned to examine the impact of the 3D BDC on the local long-term changes of stratospheric O3 and middle atmospheric H2O based on the chemistry-climate model (CCM) simulations performed and provided by the SPARC (Stratospheric Processes and their Role in Climate) CCM-Validation project.