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

利用 VORCORE 数据研究南极平流层波浪和环流特征

• 批准号: 0732222
• 负责人: Carlos Mechoso
• 金额: --
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-10-01 至 2010-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0732222&HistoricalAwards=false
• 关键词: Studies; Waves; Circulation; Features; Antarctic

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.

Mechoso和他的团队将分析VORCORE活动在南极洲上空进行恒密度气球观测所获得的数据。2005年南方春季，从麦默多站（南纬77.5º）发射了27个这样的气球。这些气球提供的气压和位置信息是研究南极大气波动及其整体环流的独特数据。特别令人感兴趣的是，这些数据用于观测内部重力波。重力波在大气中无处不在。它们的垂直动量输送对大气环流，特别是中层大气环流很重要，所有现代气候模式都包括重力波参数化。这些参数化，但是，只有很少的观测数据的约束。在南极平流层下部，重力波表现不佳可能是许多气候模式所显示的持续冷偏差的原因，为了最佳地利用VORCORE气球数据，已经开发了一种在等密度（对数密度）坐标系中分析重力波场和通量的形式，并将应用于本项目。具体分析将包括：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方面的作用，观测近惯性频率的波场，以前的观测表明，近惯性频率的波谱大大增强，研究2005年平流层最后变暖情况，分析极涡边缘的拉格朗日弥散，验证南极平流层下部的全球分析，并测试同化VORCORE数据对这些分析的影响。Concordiasi是美国和法国之间的合作。Concordiasi观测将于2008年南部春季进行，是美国和法国对国际极地年（IPY）贡献的一部分。Concordiasi使用的恒定密度气球将部署下投式探空仪，测量气球和表面之间的温度，湿度和压力的垂直分布。这些数据将提供有关波从下面传播到气球高度的有价值的信息。1998年在厄瓜多尔进行的一次热带气球活动的有限数据集也将被分析。本研究的重点是研究对流活跃区域上空产生的波的频谱，其更广泛的影响是更好地了解形成臭氧洞的这一大气区域的环流和动态。该项目是对国际极地年期间对极地地区进行密集国际观测的贡献。将培养一名研究生。