Modeling Studes of the Interannual Variability of Large- Scale Waves and Circulation

Am-9526136，华盛顿大学Ka Kit大学题目：大尺度波动和环流国际变率的模拟研究国际大气物理研究所以前的国家自然科学基金项目涉及：(A)热带外大尺度行星波的内部变率，和(B)赤道准同步振荡引起的热带外波动和环流的年际变率。在目前拟议的项目中，PI将模拟热带外平流层，以响应(I)指定的、可变的、在对流层顶观测到的12年期间的行星波幅度和(Ii)赤道QBO在纬向风中的变化相位。包含所需成分和机制的数值模式已经由Kinnersley建立和检验，并产生了真实的波动和环流气候学，以及1980年5月至1981年4月一年期间行星波1、2和3的真实随时间变化的气候。在拟议的项目中，该模式将与1980-1992年观测到的对流层顶行星波强迫一起运行。温带外平流层年际变化的第二个原因是赤道QBO位相对热带外波导中行星波的传播和破裂位置的影响，就示踪剂的不可逆混合和平均环流强迫而言，这可能是更重要的原因。该机制最早是由Holton和Tan提出的，涉及零风线的位置。提出了一种改进的PI机制，该机制考虑了赤道准BO对驻波热带外波导的影响，以及导波变化对行星波破裂和混合的影响。这些机制将在拟议的项目中进行测试。为了验证假设，将模拟结果与观测结果进行了比较。比较将涉及纬向平均温度和纬向风、行星波幅和从示踪剂分布推断的经向环流。这项研究很重要，因为它试图促进对与天气和气候有关的大气环流特征的长期变异性的理解。

Abstract ATM-9526136 Tung, Ka Kit University of Washington Title: Modeling Studies of the International Variability of Large-Scale Waves and Circulation Previous NSF projects by the PI were concerned with (a) internal variability of the large- scale planetary waves in the extra-tropics, and (b) year-to-year variability of the extra-tropical waves and circulation caused by the equatorial QBO. In the current proposed project, the PI will model the extra-tropical stratosphere in response to (i) specified, variable, observed planetary wave amplitude at the tropopause for a 12-year period and (ii) the changing phase of the equatorial QBO in zonal wind. The numerical model containing the needed ingredients and mechanisms has already been built and tested by Kinnersley and has produced realistic climatology in waves and circulation and realisitic time-dependent evolution for planetary waves one, two and three for the one-year period May 1980 to April 1981. In the proposed project, the model will be run with the observed tropopause planetary wave forcing from 1980 to 1992. A second cause of year-to-year variability in the extratropical stratosphere, which is perhaps the more important one as far as irreversible mixing of tracers and forcing of mean circulation are concerned, is the effect of the phase of equatorial QBO on the propagation and location of breaking of planetary waves in the extra-tropical wave-guide. The mechanism was first proposed by Holton and Tan involving the location of zero-wind lines. A modified mechanism was proposed by the PI involving the effect of the equatorial QBO on the extra-tropical wave-guide for stationary waves, and the effect of the wave-guide changes on the breaking and mixing of the planetary waves. These mechanisms will be tested in the proposed project. To validate the hypothesis, the simulated result will be compared with observation. The comparison will involve zonal mean temperature and zonal wind, planetary wave amplitud es, and meridional circulation as inferred from the distribution of tracers. This research is important because it seeks to advance the understanding of long-term variability of weather- and climate- related atmospheric circulation features.