PNNL

Abstract

The atmospheric response to the solar eclipse of 8 April 2024 in North America is investigated with a specific focus on the Marine Atmospheric Boundary Layer (MABL). Using data collected during the Third Wind Forecast Improvement Project (WFIP3), which deployed a variety of meteorological instruments, including Doppler lidars, sonic anemometers, and thermodynamic profilers, we examine changes induced by the eclipse on key meteorological parameters, such as temperature, wind speed, and turbulent fluxes. While the majority of the previous eclipse studies have been conducted over land, this study provides new observations for both coastal and marine environments, offering additional insight into eclipse-driven atmospheric variability in the MABL. The findings confirm a notable decrease in downwelling shortwave radiation, which results in rapid cooling of surface air. The temperature reduction ranges from 1.2 ?C and 1.4 ?C in coastal regions, and from 0.3 ?C and 0.5 ?C over the ocean. The analysis suggests that the MABL’s higher thermal inertia, compared to coastal regions, moderates the temperature decrease during the eclipse. Wind speed exhibits a more complex behavior, as it is influenced by both the MABL and pre-existing synoptic conditions. Although a reduction in wind speed is observable up to approximately 140 m above ground level (AGL) at coastal sites, at other locations closer to the ocean, this reduction is constrained to the lowest 100 m AGL. Turbulence parameters retrieved from sonic anemometers, such as turbulence kinetic energy, sensible heat flux, and friction velocity, show a decrease due to the eclipse in coastal regions, while minimal variability is observed in open ocean locations.