A multi-hazard assessment of climatological impacts on hurricanes affecting the northeast US: Wind and rain.

摘要

It is generally accepted in the scientific community that the climate is changing. The Fourth Assessment Report compiled by the International Panel on Climate Change (IPCC) states that warming of the climate system is unequivocal, and that this warming has likely influenced observed changes in many physical systems at the global scale. It is essential that current design codes and standards adapt to reflect global climate change and that accurate projections of extreme environmental event hazards (e.g., wind, rain) are developed. This would allow for a better understanding of the risk to our existing inventory of civil infrastructure and also ensure that target safety and performance levels are met when designing structures and infrastructure systems in the future. With the trend toward performance-based engineering, for US coastal regions, along the Atlantic Ocean and Gulf of Mexico, this means a quantitative assessment of climate change impact on hurricane hazard performance levels is needed.;This dissertation presents results of a study to assess the impact of possible future climate change on the joint hurricane wind and rain hazard along the northeast US coastline. A number of different postulated climate change models (IPCC scenarios) are considered, where each scenario suggested changes in sea surface temperature (SST), the driving parameter in most modern hurricane models. In order to characterize the wind hazard, the climate scenarios are coupled with hurricane genesis, wind field, tracking, central pressure, and decay models to examine possible changes in hurricane intensity (maximum wind speed) and hurricane size (radius of maximum winds). The evolution of hurricane genesis frequency, hurricane genesis location, and hurricane track behavior are examined, though no temporal trend is apparent in either. Probabilistic models of hurricane genesis frequency, hurricane genesis location, and hurricane track behavior conditioned on SST are then developed and considered both independently and jointly with hurricane intensification. A rainfall hazard model is then developed using recorded rainfall data associated with hurricane events and a probabilistic model relating wind and rain is developed.;The maximum wind speed (or rain-rate) distribution, as well as the joint distribution of maximum wind speed (or rain-rate) and storm size, under the current and future climate scenarios, are then compared. Finally, a joint wind, rain, and size hazard model is constructed that includes consideration of projected climate change impacts. The use of such a joint hazard model in performance-based engineering applications also is discussed. In addition, climatological effects on rainfall accumulation versus the occurrence of maximum wind speeds is explored and the applications of such an assessment are discussed. Ultimately, the hurricane wind and rain hazards are projected to increase under most considered climate scenarios, with the increases in the rain hazard being much more drastic. The radius of maximum winds (rain), is shown to decrease with increasing wind/rain hazards. Rainfall accumulation at the time of occurrence of maximum winds for a category 2 event are not projected to increase substantially between the current and future climate scenarios.