Using the WRF Model to Investigate Climate Change Influence on the Track and Intensity of Hurricane Sandy

Location: National Center for Atmospheric Research, Boulder, Foothills Lab Building 2, Room 1001
Gary M. Lackmann, Department of Marine, Earth, and Atmospheric Sciences North Carolina State University

Hurricane Sandy was associated with historic societal impacts when it made landfall along the New Jersey shore in late October 2012. The event generated vigorous discussions as to whether the severity, or perhaps occurrence, of the event was tied to anthropogenic climate change. Two related questions are (i) whether the frequency of this type of event is altered by anthropogenic climate change, and (ii) if the synoptic pattern accompanying Hurricane Sandy had taken place in 100 years ago (or 100 years in the future), how would the track, intensity, and impacts have differed? Here, we investigate question (ii) using a simplified approach that is designed to quantify the storm-scale changes attributable to large-scale thermodynamic changes. First, hypotheses are presented as to how and why we would expect climate change to alter Sandy’s track and intensity. An ensemble of WRF model simulations, in conjunction with GCMderived large-scale thermodynamic changes, is used to analyze changes between current,past, and future versions of Sandy.

The impact of climate change on the synoptic steering features suggests offsetting processes. Warming and increased precipitation/condensational heating would strengthen the downstream ridge to the north of Sandy, resulting in stronger westward motion. Diabatic weakening of an upper-level trough to the south of Sandy would have the opposite effect. Increased upper-level westerly flow would lead to more progressive synoptic features, suggesting a more eastward track with warming. Numerical experiments are required to determine which effect, if any, dominates. For this presentation, I will explore some of the WRF features that enable skillful simulations of the storm. Results indicate that climate warming to date had limited effect on the observed Sandy, but that projected future warming would result in a significantly stronger storm with a more northward landfall location. Research to date has not directly addressed the question of climate-change influences on Sandy’s genesis or early track evolution.