High Temporal Resolution Observations and Modeling of the Planetary Boundary Layer during the 2024 Total Solar Eclipse

Total solar eclipses provide a unique opportunity to evaluate the response of the atmosphere and land-atmosphere interactions to a rapid change in solar forcing. The Space Science and Engineering Center (SSEC) Portable Atmospheric Research Center (SPARC), a mobile meteorological instrumentation laboratory, was deployed to Richmond, Indiana, where it experienced nearly four minutes of totality. Deployed instruments included an Atmospheric Emitted Radiance Interferometer (AERI), a ground-based spectral radiometer from which temperature and water vapor profiles of the lower troposphere can be obtained every 30 s; a Doppler lidar, which was used to monitor vertical velocities every second; and radiosondes launched at key moments in the evolution of the eclipse.

Collectively, these observations show typical growth and development of the planetary boundary layer (PBL) while the eclipse was ongoing, but a drastic decrease in turbulent kinetic energy (TKE) immediately before totality. This lack of turbulence continued for approximately 45 minutes after totality, at which point the PBL rapidly grew back to its pre-eclipse height. Radiosondes observed the formation of a small and shallow “nocturnal” inversion during totality that rapidly eroded with the return of solar heating. Large eddy simulation (LES) modeling of the TKE mirrors the observations. Implications of these results on the observation and simulation of the more common morning and evening transitions will be discussed, along with contemporaneous satellite imagery.