Observational Analysis of Land Effect on Tropical Cyclone Wind Profiles Before Landfall

• Paige Burchell, Meteorology and Climatology, University of Delaware

• Shuai Wang, Geography and Spatial Sciences, University of Delaware

Each year, tropical cyclones cause catastrophic damage to coastal communities, with high wind speeds being a source of destruction in these storms. Currently, there exist skillful models in determining tropical cyclone horizontal wind profiles over the ocean. However, there is a knowledge gap for such a model as the storm moves over land. In this project, horizontal wind profiles from an observed tropical cyclone wind dataset—HWIND—are analyzed. Most of the observed wind profiles contain a positive reduction factor, defined as 1 minus the fraction of azimuthally averaged land wind speeds over ocean wind speeds. Across all observations, the mean reduction factor increases as the radius of the azimuth increases. Clustering analysis is performed on the observed profiles using K-Means, and the geographic locations of tropical cyclones from each cluster are qualitatively analyzed. It is hypothesized that the size and terrain of a landmass is the main factor that impacts a tropical cyclone’s change in wind speed at landfall, as additional statistical analysis using non-parametric tests found no significant differences for tropical cyclone size and intensity distributions among clusters. Further research can investigate the theoretical atmospheric dynamics that explain this impact. Additionally, model simulations may be performed to create idealized wind profiles, which can be compared to the HWIND observations.