Site-Based Observations of a Saharan Dust Storm's Impact on Evapotranspiration in North-Central Florida

Saharan dust storms serve an important role in the western Atlantic’s climate, affecting the radiation budget, modulating sea surface temperatures (SSTs), fertilizing ecosystems, and modifying cloud and precipitation patterns (Yuan et al. 2020). However, Saharan dust storms are expected to become less frequent as SSTs continue to rise. Predicting the climate response to this change requires a keen understanding of how the presence of these storms affect the radiation budget and evapotranspiration (ET). This study utilizes site-based observational datas from an AmeriFlux tower near Gainesville, FL (i.d. US-xSB) taken during a large dust storm in late June 2020. The storm’s progression was documented using satellite imagery. Aerosol optical depth (AOD) measurements from an Aerosol Robotic Network (AERONET) station, located at the AmeriFlux site, confirmed the presence of dust. Net radiation (NETRAD), air temperature (TA), latent energy flux (LE), sensible heat flux (SH), photosynthetic photon flux density (PPFD), vapor pressure deficit (VPD), and other factors known to affect or indicate ET were analyzed. FAny findings were validated using comparisons to reanalysis data products from the Global Land Data Assimilation System (GLDAS) model. Both model simulations and on-site observations support that ET decreased during the days dust concentrations were heaviest and increased after the dust passed. Cloud cover data, adopted from meteorological aerodrome reports (METARs) via an Automated Surface Observing System (ASOS) located in Gainesville (i.d. KGVN), showed that the effect of clouds on ET were not as great as that of dust. The results of this study show that dust aerosols significantly reduce surface ET, an essential piece towards predicting the climate response to a potential decrease in these storms. Further research is necessary to determine if changes from Saharan dust storms are significant enough to alter the climate.