Role of the Stratosphere in 11-Yr Solar Forcing of Surface Climate: Diagnostic Comparisons of Observations With Model Simulations

本项目考虑平流层下层和地表气候对伴随11年太阳黑子周期的日照变化的响应。假定日照变化会影响平流层温度，因为太阳紫外线（UV）辐射的增加会引起平流层臭氧的增加，从而导致平流层温度的增加（在热带地区最大）和中纬度纬向风的增加。平流层纬向风的增加通过与“向下控制”机制相关的波-平均流相互作用影响低层环流，产生一种海平面气压异常模式，包括极地低压和北太平洋北部高压。根据该奖项开展的工作将在两个气候模式的模拟中研究太阳变率对地表气候影响的“自上而下”机制，其中一个气候模式通过卫星观测指定太阳引起的臭氧异常，另一个（全大气群落气候模式，或WACCM），其中臭氧变化是由模式响应日照变化而在内部产生的。在WACCM模拟中，日晒变化将根据对其光谱分布的几种估计来规定，以确定对11年太阳强迫中紫外线分量的不确定性响应的敏感性。WACCM模拟还将用于探索响应对附加因素的敏感性，包括平流层准两年一次振荡的相位。通过研究生的支持和培训，这项工作将产生更广泛的影响，这将发展该科学领域的科学劳动力。此外，更好地了解太阳变率对气候的影响可能有助于了解气候对外部强迫的敏感性以及确定气候响应的机制。这些信息可能有利于参与气候变化政策决策的决策者。

This project considers the response of lower stratospheric and surface climate to the changes in insolation accompanying the 11-year sunspot cycle. Insolation changes are hypothesized to affect stratospheric temperature as increases in solar ultraviolet (UV) radiation cause increases in stratospheric ozone which in turn lead to increases in stratospheric temperature (maximizing over the tropics) and midlatitude zonal winds. The increased stratospheric zonal winds then affect circulation at lower levels through the wave-mean flow interactions associated with the "downward control" mechanism, producing a pattern of sea level pressure anomalies including low pressure over the poles and high pressure over the northern North Pacific. Work conducted under this award would examine this "top down" mechanism for the influence of solar variability on surface climate in simulations from two climate models, one in which the solar-induced ozone anomalies are specified from satellite observations, and another (the Whole Atmosphere Community Climate Model, or WACCM) in which the ozone changes are generated internally by the model in response to the insolation change. In the WACCM simulations, the insolation change will be prescribed according to several estimates of its spectral distribution, to determine the sensitivity of the response to uncertainty in the UV component of the 11-year solar forcing. WACCM simulations will also be used explore the sensitivity of the response to additional factors including the phase of the stratospheric quasi-biennial oscillation.The work will have broader impacts through the support and training of a graduate student, which will develop the scientific workforce in this scientific area. In addition, a better understanding of the impact of solar variability on climate may prove useful for understanding the sensitivity of climate to external forcing, and the mechanisms which determine the climatic response. Such information may benefit decision makers engaged in policy decisions regarding climate change.