Effects of the 20 March 2015 solar eclipse in Strasbourg, France

Abstract

On 20 March 2015 a partial solar eclipse occurred at Strasbourg, France, with an obscuration of 72.4%. The consequences of this event were observed under optimal weather conditions with micrometeorological instruments. Among these, the global radiation deficit can be estimated to be of 1.724MJ per horizontal square meter. A modification of the solar spectrum with a greater proportion of photosynthetically active radiation was also observed. The extinction of the solar radiation resulted in a reduction of the net radiation, a sharp decrease in the surface temperatures and a change in all surface heat fluxes.

Ensemble-Averaging Resolves Rapid Atmospheric Response to the 2017 Total Solar Eclipse

“…Rapid changes in land-atmospheric interactions, including the components of the surface energy budget, also accompany a solar eclipse. Sensible and latent heat fluxes are attenuated because the available energy from incoming solar radiation decreases (Antonia et al, 1979;Eaton et al, 1997;Foken et al, 2001;Kastendeuch et al, 2016). The sensible heat flux diminishes dramatically and may reverse signs (Raman et al, 1990;Foken et al, 2001;Schulz et al, 2017;Turner et al, 2018).…”

Contrasting behavior of slow and fast photoreactive gases during the August 21, 2017, solar eclipse

“…The drop in temperature (respectively the stalling of the typical morning temperature increase) observed at the Boulder Reservoir (Figure 3b) was on the order of 3 o C, which is at the upper end of the range of cooling observed during other eclipses (Founda et al, 2007;Mauder et al, 2007;Chung et al, 2010;Subrahamanyam et al, 2011;Girach et al, 2012;Hanna et al, 2015). The drop in solar irradiance and surface heating has also been noted to result in increased stabilization of the surface layer, a drop in surface winds, weaker turbulent and convective mixing, and suppressed mixed boundary layer growth (Founda et al, 2007;Mauder et al, 2007;Tzanis et al, 2008;Nymphas et al, 2009;Subrahamanyam et al, 2011;Hanna et al, 2015;Kastendeuch et al, 2016). At a site in Oklahoma during the 21 August 2017 eclipse, turbulent fluxes of heat and momentum responded quickly to the decline in solar radiation, resulting in a large decrease of turbulent mixing in the boundary layer and in stable atmospheric conditions, similar to a nighttime stable boundary layer, near the surface.…”

The thermal effects noticed at Heathrow Airport during the partial solar eclipse of 20 March 2015

“…Although at Heathrow we do not have the complexity of observation equipment to which Kastendeuch et al . () had access while producing their article, it is still gratifying that some of the findings made are replicated in these more modest results.…”

“…As was discussed by Kastendeuch et al . (), surface temperatures do not seem to react immediately. First contact in London was 0825 utc , but for a further 25min the grass and concrete surface temperatures continued to rise, only starting to fall between 0850 and 0855 utc .…”

“…I thought it might be interesting to contrast the effects experienced at Heathrow with those reported in Kastendeuch et al . (). At Heathrow the partial solar eclipse was 85%, which was rather greater than at Strasbourg (72.4%).…”