Semester of Graduation
Master of Oceanography and Coastal Sciences (SOCS)
Oceanography and Coastal Sciences
Tropical cyclones modify surface-atmosphere interactions in several ways, including the destruction of patches of tree canopy, increasing the direct and diffuse (shortwave) radiation reaching the surface. This addition of radiation at the surface impacts the sensible, latent, and substrate heat (energy) fluxes, generating heat anomalies along the hurricane’s track, which, among other effects, contributes to the higher post-hurricane surface air temperatures. This study consists of a case study on Hurricane Laura (2020) to examine hurricane defoliation impacts on heat stress metrics. Normalized difference vegetation index (NDVI) data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) identified the spatial extent of defoliation produced from Hurricane Laura (2020) in southwestern Louisiana. This defoliation extended for 135 km cross-track along the coastline with remnants of the modified landscape conditions persisting for one year following landfall. The Weather Research and Forecasting (WRF) model version 4.2 was utilized to examine the severity of heat metric changes associated with the defoliation through a post-Laura, defoliated numerical weather simulation and a control, normal foliage simulation. In Cameron, Louisiana, the site of Hurricane Laura’s landfall, at least 10 days exceed +1.0°C in daily average heat index change during the month following Hurricane Laura. Four additional WRF simulations were performed with altered landfall years of 2017 and 2018 to determine the sensitivity of Hurricane Laura-like defoliation on heat metrics to different synoptic conditions. Synoptic conditions modulated the overall magnitude of average change in heat metrics, but heat stress metrics experienced significant increases despite different synoptic conditions. The wetland dominated southwest coast of Louisiana did not show the greatest potential for warming, but coastal Louisiana still experienced an average warming of 0.95C° in nighttime heat index in Cameron, Louisiana, following Hurricane Laura. Overall, the greatest heat stress metrics change occurred during the nighttime from 0000 Coordinated Universal Time (UTC) to 0600 UTC when communities are most prone to heat mortality, with an average increase of 0.25C° in heat index at 0600 UTC across southwest Louisiana. Tropical cyclone-related heat events present a unique opportunity to investigate the severity of an often-times overlooked impact from tropical cyclones.
Reesman, Cade, "Changes in Heat Metrics Following a Major Hurricane and Implications on Heat Stress" (2022). LSU Master's Theses. 5580.
Miller, Paul W.