Land-atmosphere responses to a total solar eclipse in three ecosystems with contrasting structure and physiology

Authors: WOOD, J - University Of Missouri; Sadler, Edward; FOX, N - University Of Missouri; GREER, S - University Of Missouri; GU, L - Oak Ridge National Laboratory; GUINAN, P - University Of Missouri; LUPO, A - University Of Missouri; MARKET, P - University Of Missouri; ROCHETTE, S - State University Of New York- College Of Environmental Science And Forestry; SPECK, A - University Of Missouri; WHITE, L - Jackson State University

Submitted to: Journal of Geophysical Research Atmospheres
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2018
Publication Date: 1/18/2019
Citation: Wood, J.D., Sadler, E.J., Fox, N.I., Greer, S.T., Gu, L., Guinan, P.E., Lupo, A.R., Market, P.S., Rochette, S.M., Speck, A., White, L.D. 2019. Land-atmosphere responses to a total solar eclipse in three ecosystems with contrasting structure and physiology. Journal of Geophysical Research Atmospheres. 124(2):530-543. https://doi.org/10.1029/2018JD029630.
DOI: https://doi.org/10.1029/2018JD029630

Interpretive Summary: Mid-Missouri experienced up to 2 minutes 40 seconds of totality at around noontime during the total eclipse of 2017. We conducted the Mid-Missouri Eclipse Meteorology Experiment (MMEME) to examine land-atmosphere interactions during the eclipse. Here, research examining the eclipse responses in three contrasting ecosystems (forest, prairie and soybeans) is described. There was variable cloudiness around at the beginning and end of the eclipse at the forest and prairie, however, skies cleared during the eclipse. Unfortunately, there was convective activity at the soybean site, which masked the eclipse effect and exposed the field to cold outflow. Turbulence and wind speeds decreased during the eclipse at all sites, however, there was amplified turbulent intensity at the soybean during the passage of a gust front. Evaporation and heating of the atmosphere by the land surface shut off during the eclipse, with the atmosphere actually supplying some heat to the surface at totality. Although the eclipse had a large effect on surface energy balances, the air temperature response was relatively muted due to the absence of topographic effects and the relatively moist land and atmosphere. Knowledge of these ecosystems responses to such an abrupt perturbation of the forces driving energy, water, and carbon through those systems can inform models that scientists use to forecast weather or evaluate probable effects of future climate.

Technical Abstract: Mid-Missouri experienced up to 2 min 40 s of totality at around solar noon during the total eclipse of 2017. We conducted the Mid-Missouri Eclipse Meteorology Experiment (MMEME) to examine land-atmosphere interactions during the eclipse. Here, research examining the eclipse responses in three contrasting ecosystems (forest, prairie and soybeans) is described. There was variable cloudiness around 1st and 4th contact at the forest and prairie, however, solar irradiance (K') signals during the eclipse were relatively clean. Unfortunately, the eclipse forcing at the soybean field was contaminated by convective activity, which decreased K' beginning about an hour before 1st contact and exposed the field to cold outflow ~30 min before 2nd contact. Turbulence was suppressed during the eclipse at all sites, however, there was also an amplified signal at the soybean during the passage of a gust front. The standard deviations of the horizontal and vertical wind velocities, and friction velocities decreased by ~75% at the forest (aerodynamically rough), and ~60% at the prairie (aerodynamically smooth). The eddy fluxes of energy were highly coherent with the solar forcing with the latent and sensible heat fluxes approaching 0 W m-2 and changing in direction, respectively. For the prairie site, we estimated a canopy scale time constant for the surface conductance light response of 10 min. Although the eclipse imparted large forcings on surface energy balances, the air temperature response was relatively muted (1.5–2.5 °C decrease) due to the absence of topographic effects and the relatively moist land and atmosphere.