AGS-PRF: A Hierarchical Modeling Approach to Quantifying the Effects of Changes in Ozone and Solar Variability on the Brewer-Dobson Circulation and Tropospheric Climate

在AGS-PRF的提议下，研究人员将使用一个层次模型来检查臭氧变化和太阳变率对布鲁尔-多布森环流（BDC）的影响。BDC是平流层的经向垂直环流，在赤道处运动上升，在两极附近运动下降，它对平流层臭氧的经向分布和极地平流层臭氧浓度起着关键作用。最近的研究表明，BDC有两个分支，一个局限于平流层下层的浅层分支和一个延伸到中间层下层的上层分支。结果表明，由于全球变暖导致的副热带和温带波强迫的变化，下游分支的热带上升流将增加。一个可能的影响因素是副热带急流加速，以及决定地形重力高度和罗斯比波强迫的破波关键层。这导致临界层的高度上升，从而增加了重力波进入平流层的穿透。PI还指出，虽然全球变暖预计会导致急流向极地移动，但臭氧恢复预计会产生相反的效果，两者都对中纬度重力波驱动BDC产生影响。此外，BDC的深层分支预计会对臭氧、温室气体（GHGs）和11年太阳周期的变化做出响应。新导出的太阳变率数据集表明，关键紫外波长范围内的太阳变率可能比以前了解的大4-6倍。因此，有必要确定对11年太阳周期的响应。PI建议使用一系列模型来研究BDC的变化，其中包括全物理、全化学全大气群落气候模型（WACCM），其中包括预测臭氧浓度，以及指定化学WACCM (SC-WACCM)，其中规定了臭氧和其他微量气体。此外，PI将开发和使用一个更简单的理想环流模式（IGCM），这是一个干燥的动力核心模式，具有热松弛到辐射光化学平衡和扰动加热（我相信），以代表从WACCM的观测或未来气候情景整合中指定的臭氧变化。因此，PI将实现三个目标：(1)研究臭氧损失和恢复的高度、纬度和半球结构的变化如何结合起来产生BDC的变化；(2)确定新修正的太阳周期测量值将如何影响BDC，并将这些变化与之前的BDC-太阳周期分析进行比较；(3)确定SC-WACCM和理想化的IGCM是否能够以足够的保真度再现完整版WACCM的结果，从而使它们成为研究气候变化的可行工具，而计算费用只是其中的一小部分。

Under this AGS-PRF proposal, the researcher will use a hierarchy of models to examine the effects of changes in ozone and solar variability on the Brewer-Dobson circulation (BDC). The BDC is a meridional-vertical circulation in the stratosphere with rising motion at the equator and sinking near the poles, and it plays a key role in determining the meridional distribution of stratospheric ozone and the concentration of ozone in the polar stratosphere. Recent work suggests that the BDC has two branches, a shallow one confined to the lower stratosphere and an upper one which extends as high as the lower mesosphere. Results indicate that the tropical upwelling in the lower branch will increase as a consequence of global warming, because of changes in subtropical and extratropical wave forcing which are not well understood. A likely contributing factor is the subtropical jet streams accelerate, and so too the critical layer for wave breaking that determines the height of orographic gravity and Rossby wave forcing. This results in a rising of the height of the critical layer and hence an increase in the penetration of gravity waves into the stratosphere. The PI also notes that while global warming is expected to cause poleward shifts of the jet streams, ozone recovery is expected to have the opposite effect, and both have consequences for the driving of the BDC by midlatitude gravity waves. In addition, the deep branch of the BDC is expected to respond to changes in ozone, greenhouse gases (GHGs), and the 11-year solar cycle. Newly derived solar variability data sets suggest that solar variability in the key UV wavelength range may be 4-6 times larger than previously understood. Thus there is a need to determine the response to the 11-year solar cycle. The PI proposes to study BDC change using a hierarchy of models which includes the full-physics, full-chemistry Whole Atmosphere Community Climate Model (WACCM), with prognostic ozone concentration, and the Specified Chemistry WACCM (SC-WACCM), in which ozone and other trace gases are prescribed. In addition, the PI will develop and use a simpler Idealized General Circulation Model (IGCM), a dry dynamical core model with thermal relaxation to a radaitive-photochemical equilibrium and perturbation heating (I believe) to represent changes in ozone specified from either observations or future climate scenario integrations of WACCM. Thus the PI will accomplish three goals: (1) examine how changes in the height, latitude, and hemispheric structure of ozone loss and recovery combine to produce changes in the BDC; (2) determine how the newly revised measurements of the solar cycle will affect the BDC and how these changes compare to previous BDC-solar cycle analysis; and (3) determine whether SC-WACCM and the idealized IGCM can reproduce the results of the full version of WACCM with enough fidelity as to make them viable tools for studying climate change at a fraction of the computational expense.