Collaborative Research: Air-Sea Fluxes at High Wind Speeds with Application to Tropical Cyclone Intensity Prediction

理论和数值试验表明，热带气旋的强度对风暴中心表面动量通量和热通量的相对重要性很敏感，但对极高风速下的这种通量却知之甚少。根据在中等风速下的观测得到的地面交换系数的泛函形式外推到大风，可以预测永远不会观测到大于名义热带风暴强度的风暴。假设这一悖论可以通过适当地解释在高风速下影响地表通量的物理过程来解决。解决这一问题需要一个多学科的理论、数值和实验室工作方案，以解决目前热带气旋模型中被忽视或处理不当的几个关键物理过程。因此，来自四个机构(伍兹霍尔海洋研究所、罗德岛大学、麻省理工学院和寒冷地区研究与工程实验室)的首席调查人员组成了一个研究小组进行这项研究。具体来说，首席调查员将：1.通过理论分析和实验室实验研究再入海雾对海气热交换的影响；2.进行一项理论和实验研究计划，旨在对气泡的海气热交换进行定量估计；以及3.更好地估计波浪对海-气动量交换的影响。这项研究应该会导致在非常高的风速下更好地计算地表通量。这些公式将应用于数值天气预报模式，以提高热带气旋强度预报的准确性。

Theory and numerical experiments demonstrate that the intensity achieved by tropical cyclones is sensitive to the relative importance of surface fluxes of momentum and enthalpy in the storm core, yet very little is known about such fluxes in extremely high wind speeds. Extrapolation to high winds of the functional form of surface exchange coefficients deduced from observations at moderate wind speeds leads to the prediction that storms of greater than nominal tropical storm strength should never be observed. It is hypothesized that this paradox can be resolved by a proper account of the physical processes affecting surface fluxes at high wind speeds. Attacking this problem requires a multi-disciplinary program of theoretical, numerical and laboratory work in order to address several crucial physical processes that are neglected or poorly handled in present tropical cyclone models. Accordingly, Principal Investigators from four institutions (Woods Hole Oceanographic Institution, University of Rhode Island, Massachusetts Institute of Technology and the Cold Regions Research and Engineering Laboratory) have formed a research team to perform this research. Specifically, the Principal Investigators will: 1. Investigate the effect of re-entrant sea spray on air-sea enthalpy exchange through theoretical analysis and laboratory experiments:2. Conduct a program of theoretical and experimental research designed to yield quantitative estimates of air-sea heat exchange by bubbles; and3. Produce better estimates of the effect of waves on air-sea momentum exchange.This research should lead to better formulations of surface fluxes in very high wind speeds. These formulations will be implemented in numerical weather prediction models to improve the accuracy of tropical cyclone intensity prediction.