CEDAR: Downward Progression of Temperature Anomalies during Sudden Stratospheric Warmings

极地大气经常表现出意想不到的和显著的温度异常，称为平流层突然警告(SSW)，显示出一种下降的过程。异常的发展可以从接近80公里的中层和较低的热层区域开始，一直向下延伸到大约30公里的对流层高度。由于SSW向下发展，SSW是大气区域间向下耦合的重要过程。它们被认为是行星波和平均大气流动(风)相互作用的产物，但也有人提出，源自较低海拔(重力波)的大气扰动在这种相互作用中发挥重要作用，因为它为下行(预适应)创造了一套正确的条件。这项研究工作将结合一些大气模式来利用最近获得的数据同化运行的结果。高层和中层大气中的向下耦合过程很重要，因为它们可能对平流层臭氧和其他重要成分产生影响。这项工作将包括：(1)利用卫星测量数据和全球大气模式结果分析温度异常和大气波的特征，(2)波传播的数值模拟，并将结果与温度异常的特征进行比较，以及(3)通过集合模拟来研究是否通过零风线高度的变化来进行预适应。这项工作将提高对大气波动在极地高层大气向下耦合中所起作用的理解，并可能提高模拟气候和空间天气扰动的能力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The polar atmosphere often exhibits unexpected and significant temperature anomalies called Sudden Stratospheric Warmings (SSWs) that show a downward progression. The progression of anomalies can start in the mesosphere and lower thermosphere region near 80 km in altitude and go all the way down to tropospheric heights of around 30 km. Because of their downward progression, SSWs represent an important process for downward coupling between atmospheric regions. They are believed to be a product of interaction between planetary waves and the mean atmospheric flow (winds), but it has also been suggested that atmospheric disturbances originating from lower altitudes (gravity waves) play an important role in this interaction by creating the right set of conditions for downward progression (pre-conditioning). The research work will exploit the recently obtained results of data assimilation runs in combination with a number of atmospheric models. The downward coupling processes in the upper and middle atmosphere are important because of their potential impact on the stratospheric ozone and other important constituents. The work will involve (1) analysis of characteristics of the temperature anomalies and atmospheric waves using data from satellite measurements and global atmospheric model results, (2) numerical simulations of wave propagation and comparison of the results with characteristics of the temperature anomalies, and (3) investigation of whether pre-conditioning occurs through a change in the zero-wind line height by running ensemble simulations. This work will improve the understanding of the role that atmospheric waves play in downward coupling in the polar upper atmosphere and can potentially improve the ability to model climate and space weather disturbances.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.