Examining the Sensitivity and Impact of Anthropogenic Climate Change on North Atlantic Major Hurricane Landfall Drought and Activity

North Atlantic projections of major hurricane landfall drought with increased anthropogenic forcing were derived from the Geophysical Fluid Dynamics laboratory (GFDL) High Resolution Global Dynamical Model (HiFLOR; 25-km grid) and an analysis of the recent 12-year major hurricane landfall drought (2006-2017) was completed. First, in order to effectively analyze the sensitivity of the major hurricanes to the coastline, 6 different “buffers” (0km-500km) were developed by utilizing QGIS software, extending the coastline by their respective distances. All simulations (observational and modeled) are performed with all buffer distances. Observational data is taken from 1900-2015, so all other simulations are taken in 116 year moving means. With regards to the HiFLOR model, a “control run” is completed with an 1860 simulation running for 1200 years that does not take anthropogenic climate forcing into account, while an additional 1990 simulation is completed running 300 years that that factors in post-industrialization. Frequency of major hurricane drought length is collected, and the 1860 “control” surpasses the 1990 simulation with a higher frequency of longer lengths of drought period, regardless of buffer distance. This demonstrates that anthropogenic forcing is not a factor with increased major hurricane drought length, and could potentially increase the frequency of MHL.

Additional analysis of major hurricane landfall activity yields that the important relationship between El Niño Southern Oscillation (ENSO) and landfall is largely dependent on Atlantic Multidecadel Oscillation (AMO). It was noted that during negative AMO phases, there is a clear negative correlation between ENSO and MHL frequency (r < -.6), whereas there is no noticeable correlation during positive AMO phases. This indicates that AMO can largely influence the empirical interannuel relation between ENSO and tropical cyclone landfall frequency. However, during AMO positive phases, the correlation between all storm landfall (ASL) and MHL remains strong (r > 0.6). This strong correlation illustrates that the physical mechanism controlling the relationship between ASL and AMO during positive phases is key to understand the variations in the MHL activity.

Because the most recent 12-year major hurricane landfall drought took place during an AMO positive phase, the MHL and ASL frequencies were compared to other notable AMO positive decades (1930-1940 and 1950-1960) to deem the landfall activity during this drought significant. The ASL and MHL frequencies were found statistically significant (p < 0.05 with a one tailed t- test). Current research is being conducted to compare the drought years to the active 2017 hurricane season and other AMO positive years. Conditions being examined include sea surface temperature, steering flow, and vertical wind shear.