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

根据AGS-PRF的建议，研究人员将使用一系列模型来研究臭氧和太阳变化对Brewer-Dobson环流（BDC）的影响。BDC是平流层中赤道上升、两极下沉的纬向-垂直环流，它对平流层臭氧的纬向分布和极地平流层臭氧浓度起着关键作用。最近的工作表明，BDC有两个分支，一个浅的局限于平流层下部，一个上部延伸到中间层下部。结果表明，在低分支的热带上升流将增加，作为全球变暖的后果，因为副热带和热带外波强迫的变化，这是不是很清楚。一个可能的影响因素是副热带急流加速，因此也是决定地形重力和Rossby波强迫高度的波浪破碎的关键层。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力。PI还指出，虽然全球变暖预计将导致急流向极地转移，但臭氧恢复预计将产生相反的影响，两者都对中纬度重力波驱动BDC产生影响。此外，BDC的深层分支预计将对臭氧、温室气体和11年太阳周期的变化作出反应。 新得出的太阳变化数据集表明，在关键紫外线波长范围内的太阳变化可能比以前所了解的大4-6倍。因此，有必要确定对11年太阳周期的反应。 PI建议使用一系列模型研究BDC变化，其中包括全物理，全化学全大气社区气候模型（WACCM），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痕量气体。此外，PI将开发和使用一个更简单的理想化大气环流模式（IGCM），这是一个干燥的动力核心模式，具有辐射-光化学平衡和扰动加热（我相信）的热松弛，以代表从观测或WACCM未来气候情景集成中指定的臭氧变化。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联合收割机来产生BDC的变化;（2）确定新修订的太阳周期测量将如何影响BDC，以及这些变化与以前的BDC-太阳周期分析相比如何;以及（3）确定SC-WACCM和理想化IGCM是否能够以足够的保真度再现完整版本的WACCM的结果，从而使它们成为以一小部分计算费用研究气候变化的可行工具。

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.