Tropical Cyclogenesis and Climate: Physical Basis, Predictability and Prediction

对热带气旋形成的认识不足，妨碍了对个别热带气旋（TCs）进行5天以上预报的能力。此外，从低分辨率再分析产品和气候模式模拟推断TC特征的物理基础有限。此外，由于目前依赖有缺陷的数据集和粗糙的分辨率模型，科学家们无法在确定飓风和全球变暖之间的联系方面取得任何实质性进展。首席研究员（pi）正在通过理论分析、现有数据的综合分析、模型实验和预测方案开发来解决这些不确定性和缺陷。他们将使用观测数据集和模型的组合来调查：(i)成因热带气旋：他们将重新检查几十年前由Gray（1968）开发的成因标准，以评估其在改进的数据集、增加的理论认识和气候基本状态变化的背景下的效用和有效性。（ii） TC成因预测与预测：在建立一套新的TC成因因素的基础上，pi将构建一个动态-经验混合贝叶斯模型，用于预测7-30天的TC风险概率。（iii）暖化世界中的TC强度和频率：pi将使用ARW（高级研究天气研究与预报）和CMIP-3（气候变化气候模式相互比较程序）模拟来研究以下假设：*在暖化气候中，平均TC强度将增加，并且强度分布将向更多的4类和5类TC转移；*在气候变暖的情况下，北大西洋以外的温带气旋频率将大致保持不变，而北大西洋温带气旋的频率将略有增加；*即使冬季半球的海面温度足够温暖，夏季半球仍将继续以高温为主；*在目前的气候条件下，tc是跨越北纬30度向极地输送能量的重要贡献者，在气候变暖的情况下仍将如此；*在目前和较暖的气候中，tc都是大气中热量和水分垂直输送的重要贡献者。知识价值：这项研究将增进对热带气旋形成条件的了解。这一改进的认识将为改进在一系列时间尺度上和在一个变暖的世界上对热带气旋活动的预测奠定基础。更广泛的影响：改进热带气旋预报和评估下个世纪TC特征的社会经济影响是巨大的。这些机构非常积极地开展关于飓风和气候变化主题的公共宣传教育，并将继续与决策者、应急管理人员和私营部门互动。

Deficiencies in knowledge of tropical cyclogenesis hamper the ability to make forecasts of individual tropical cyclones (TCs) beyond about 5 days. Further, there is a limited physical basis for inferring TC characteristics from low-resolution reanalysis products and climate model simulations. Furthermore, scientists have been unable to make any substantive progress in determining a link between hurricane and global warming, owing to current reliance on flawed data sets and coarse resolution models. The Principal Investigators (PIs) are addressing these uncertainties and deficiencies through theoretical analysis, a comprehensive analysis of existing data, model experimentation and predictive scheme development. They will use a combination of observation data sets and models to investigate: (i) Genesis tropical cyclones: They will re-examine the genesis criteria developed by Gray (1968) a number of decades ago, to assess their utility and validity in the context of improved data sets, increased theoretical understanding, and changes in the base state of the climate. (ii) TC genesis predictability and predictions: Based on the development of a new set of TC genesis factors, the PIs will construct a hybrid dynamical-empirical Bayesian model for the forecasting the probabilities of TC risk in the 7-30 days forecast horizon. (iii) TC intensity and frequency in a warming world: The PIs will use the ARW (Advanced Research Weather Research and Forecasting) and CMIP-3 (Climate Change Climate Model Inter-comparison Program's) simulations to investigate the following hypotheses: * Average TC intensity will increase in the warmer climate, and there will be a shift in the intensity distribution towards more category 4 and 5 TCs; * The frequency of TCs outside the North Atlantic will remain roughly constant in a warmer climate, while the frequency of North Atlantic TCs will increase slightly; * TCs will continue to predominate in the summer hemisphere even if the winter hemisphere sea surface temperatures are sufficiently warm;* TCs are substantial contributors to the poleward energy transports across 30 degrees north in the present climate and will remain so in a warmer climate; * TCs are substantial contributors to the vertical transport of heat and moisture in the atmosphere, both in the present and warmer climate.Intellectual merit: This research will result in improved understanding of the conditions for the formation of tropical cyclones. This improved understanding will lay the foundation for improved projections of tropical cyclone activity over a range of time scales and in a warming world. Broader Impacts: The socioeconomic impact of improved tropical cyclone forecasts and assessments of TC characteristics for the next century are substantial. The PIs are very active in public outreach education on the topic of hurricanes and climate change, and will continue to interact with policy makers, emergency managers, and the private sector.