Though the accumulated precipitation in the defoliated simulation was larger along a narrow corridor paralleling and downwind of the hurricane track, neither simulation satisfactorily replicated post-Michael precipitation patterns as recorded by NCEP Stage IV QPE, casting doubt as to whether the downwind enhancement was exclusively due to the defoliation scar. Meanwhile, the simulations produce changes to the sensible and latent heat fluxes of +8.3 W m ⁻² and −13.9 W m ⁻², respectively, while average relative humidity decreased from 73% to 70.1%. In the month following the foliage reduction, WRF resolves a 0.7☌ 2-m temperature increase with the greatest changes occurring at night. In this sensitivity study, two Weather Research and Forecasting (WRF) model simulations, a normal-landscape and a post-TC scenario, are compared to determine how a defoliation scar placed along Michael’s path alters surface heat fluxes, temperature, relative humidity, and precipitation near the storm’s track. This study seeks to understand potential spatial and temporal changes in defoliation-driven meteorological conditions using Hurricane Michael (2018) as a testbed. Changes to near-track vegetation can modify evapotranspiration for months after tropical cyclone passage, thereby altering boundary layer moisture and energy fluxes that drive the local water cycle. Additional field work and image analyses are required to further detail the impact of Hurricane Maria to Puerto Rico forests.ĭespite prompting persistent meteorological changes, severe defoliation following a tropical cyclone (TC) landfall has received relatively little attention and is largely overlooked within hurricane preparedness and recovery planning. An initial order-of-magnitude impact estimate based on previous work indicated that Hurricane Maria may have caused mortality and severe damage to 23-31 million trees. A ΔNPV map for only the forested pixels illustrated significant spatial variability in disturbance, with patterns that associated with factors such as slope, aspect and elevation. Dramatic changes in forest structure across the entire island were evident from pre- and post-Maria composited Landsat 8 images. Hurricane simulations were also conducted using the Weather Research and Forecasting (WRF) regional climate model to estimate wind speeds associated with forest disturbance. Spectral mixture analysis (SMA) using image-derived endmembers was carried out on both composites to calculate the change in the non-photosynthetic vegetation (ΔNPV) spectral response, a metric that quantifies the increased fraction of exposed wood and surface litter associated with tree mortality and crown damage from the storm. Calibrated and corrected Landsat 8 image composites for the entire island were generated using Google Earth Engine for a comparable pre-Maria and post-Maria time period that accounted for phenology.
This study focused on a rapid assessment of Hurricane Maria’s impact to Puerto Rico’s forests. The powerful storm traversed the island in a northwesterly direction causing widespread destruction. Hurricane Maria made landfall as a strong Category 4 storm in southeast Puerto Rico on September 20th, 2018.
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