Projects in Climate Dynamics

本项目主要涵盖气候动力学大保护伞下的三个重要研究领域，重点关注：a)布鲁尔-多布森环流中热带上升流强度的季节性和年际变化。一个主要目标是确定年周期主要是由高纬度波活动上升通量的变化还是由赤道对流层行星波强度的季节性变化所强迫的。B) 20世纪气候变率。可能的焦点是（i)干旱事件和/或（ii）北半球温带温度的显著年代际变率。c）中频（6-20天周期）变率的结构和动力学，以及它由线性罗斯比波动力学与非线性过程（如破波）主导的程度。此外，该项目还将初步探讨一项战略，以定量评估全球变暖对太平洋西北地区积雪的影响，该战略在抽样波动方面比传统的积雪测量趋势分析更为有力。积雪的温度敏感性（即每°C温度上升积雪损失的百分比）使用四种不同的方法进行评估。这项研究将有助于促进更有力的战略来评估全球变暖的影响，更有效地测量全球变暖的影响，了解造成热带平流层低层温度和微量成分浓度长期趋势的机制，更明确地确定20世纪气候变化的归因，并为长期天气预报提供更可靠的物候学基础。更广泛的影响包括改善天气和气候预报的潜力，以及对几名研究生的培训和指导。

This project mainly covers three important research areas under the broad umbrella of climate dynamics by focusing on:a) Seasonal and year-to-year variations in the strength of the tropical upwelling in the Brewer-Dobson circulation. A major goal is to determine whether the annual cycle is forced primarily by variations in the upward flux of wave activity at high latitudes or by seasonal variations in the strength of the equatorial tropospheric planetary waves.b) 20th century climate variability. Possible foci are (i) drought episodes and/or (ii) the pronounced interdecadal variability of extratropical Northern Hemisphere temperature.c) Structure and dynamics of intermediate frequency (6-20 day period) variability and the degree to which it is dominated by linear Rossby-wave dynamics versus nonlinear processes such as wave breaking.In addition, this project will also explore preliminarily a strategy for quantitatively assessing the impact of global warming upon snowpack over the Pacific Northwest that is more robust with respect to sampling fluctuations than conventional analysis of trends in snowpack measurements. The temperature sensitivity of snowpack (i.e., the percentage loss in snowpack per °C temperature rise) is evaluated using four different approaches. This research will serve to promote more robust strategies for assessing the impacts of global warming, more useful measures of the impacts of global warming, understanding of mechanisms responsible for the secular trends in temperature and concentrations of trace constituents in the tropical lower stratosphere, a more definitive attribution of 20th century climate change, and a more sound phenomelogical basis for long range weather prediction.Broader impacts include the potential for improved weather and climate prediction and the training and mentoring of several graduate students.