Studies of Waves and Circulation Features in the Antarctic Stratosphere using VORCORE Data

Mechoso和他的团队将分析VORCORE活动在南极洲上空进行的恒密度气球观测所获得的数据。27个这样的气球是在2005年春天从麦克默多站(77.5度S)发射的。来自这些气球的气压和位置信息是研究南极大气中的波动及其整个环流的独特数据。特别令人感兴趣的是这些数据对观测内部重力波的作用。重力波在大气中无处不在。它们的动量垂直输送对大气环流很重要，特别是在中层大气，所有现代气候模式都包括重力波参数。然而，这些参数化受观测数据的约束很差。为了更好地利用VORCORE气球数据，建立了一个在等轴(对数密度)坐标下分析重力波场和通量的公式，并将其应用于该项目。具体的分析将包括：估计重力波动量通量以限制重力波参数化，确定地形波对大尺度环流的影响及其在创造极地平流层云形成条件中的作用，观测近惯性频率的波场，以前的观测表明波谱强烈增强，研究2005年最终的平流层变暖，分析极地涡旋边缘的拉格朗日弥散，验证南极低平流层的全球分析，并测试同化VORCORE数据对这些分析的影响。Concordiasi是美国和法国的合作项目。康科迪亚西的观测将于2008年春季进行，是美国和法国对国际极地年(IPY)贡献的一部分。Concordiasi使用的恒密度气球将部署投射探测仪，测量气球和表面之间的温度、湿度和压力的垂直分布。这些数据将提供关于从下面传播到气球水平的波的有价值的信息。还将分析1998年厄瓜多尔进行的热带气球运动的有限数据集。这里的重点将是研究在对流活动区域产生的波谱。这项研究的更广泛的影响是更好地了解形成臭氧空洞的大气区域的环流和动力学。该项目是对国际地球年期间对极地区域进行密集的国际观测的一个贡献。一名研究生将接受培训。

Mechoso and his team will analyze data obtained by the VORCORE campaign of constant-density balloon observations over Antarctica. Twenty-seven such balloons were launched from McMurdo Station (77.5ºS) during the Austral spring of 2005. The pressure and position information from these balloons are unique data for studying waves in Antarctic atmosphere and its overall circulation. Of particular interest is the utility of these data for observing internal gravity waves. Gravity waves are ubiquitous in the atmosphere. Their vertical transport of momentum is important for the atmospheric circulation, especially in the middle atmosphere, and all modern climate models include gravity-wave parameterizations. These parameterizations are, however, only poorly constrained by observational data. In the Antarctic lower stratosphere, poorly represented gravity waves may be responsible for the persistent cold biases displayed by many climate models.To make optimal use of the VORCORE balloon data, a formalism for analyzing gravity wave fields and fluxes in isopycnal (log-density) coordinates has been developed, and will be applied in this project. Specific analyses will include: estimating gravity-wave momentum fluxes in order to constrain gravity-wave parameterizations, determining the effects of topographic waves on the large-scale circulation and their role in creating conditions in which polar stratospheric clouds can form, observing the wave field at near-inertial frequencies, where previous observations have indicated the wave spectrum is strongly enhanced, studying the final stratospheric warming of 2005, analyzing Lagrangian dispersion across the edge of the polar vortex, and validating global analyses of the Antarctic lower stratosphere and testing the impact of assimilating VORCORE data on these analyses.Data from the Concordiasi balloon campaign will also be analyzed as they become available. Concordiasi is a collaboration between the United States and France. The Concordiasi observations will be made during the austral spring of 2008 and comprise part of the U.S. and French contributions to the International Polar Year (IPY). The constant density balloons used in Concordiasi will deploy dropsondes, which measure vertical profiles of temperature, humidity, and pressure between the balloon and the surface. These data will provide valuable information about waves propagating to the balloon level from below.A limited set of data from a tropical balloon campaign conducted from Ecuador in 1998 will also be analyzed. The focus here will be on studying the spectra of waves generated over convectively active regions.Broader impacts of this research are in gaining a better understanding of the circulation and dynamics of this atmospheric region in which the ozone hole forms. This project is a contribution to the intense international observations of the Polar Regions during the IPY. A graduate student will be trained.