Abstract:A solar eclipse provides a well-characterized reduction in solar radiation, of calculable amount and duration. This captivating natural astronomical phenomenon is ideally suited to science outreach activities, but the predictability of the change in solar radiation also provides unusual conditions for assessing the atmospheric response to a known stimulus. Modern automatic observing networks used for weather forecasting and atmospheric research have dense spatial coverage, so the quantitative meteorological re… Show more
“…In many ways, the L-A response as the Sun was obscured by the Moon was similar to the afternoonto-evening transition (e.g., Harrison & Hanna, 2017;Wingo & Knupp, 2015), albeit much faster. The decrease in solar flux resulted in a decrease in the sensible heat flux, which caused the Earth's surface to cool with the subsequent development of an SBL with a near-surface temperature inversion.…”
Section: Discussionmentioning
confidence: 89%
“…The August 2017 eclipse event over the United States provides an excellent opportunity to evaluate the accuracy of how L‐A interactions are represented in numerical models, as essentially the eclipse simulated a rapid sunset/sunrise event (Harrison & Hanna, ). This eclipse occurred near midday when the convective boundary layer (CBL) was already well developed and thus provides an opportunity to observe how quickly turbulent fluxes of heat and momentum decay and regenerate in response to throwing the “solar switch.” We will show that during this event, the developing CBL evolved into a stable boundary layer (SBL), which became unstable again after the recovery of solar radiation.…”
On 21 August 2017, a solar eclipse occurred over the continental United States resulting in a rapid reduction and subsequent increase of solar radiation over a large region of the country. The eclipse's effect on the land‐atmosphere system is documented in unprecedented detail using a unique array of sensors deployed at three sites in north‐central Oklahoma. The observations showed that turbulent fluxes of heat and momentum at the surface responded quickly to the change in solar radiation. The decrease in the sensible heat flux resulted in a decrease in the air temperature below 200 m, and a large decrease in turbulent motions throughout the boundary layer. Furthermore, the turbulent mixing in the boundary layer lagged behind the change in the surface fluxes, and this lag depended on the height above the surface. The turbulent motions increased and the convective boundary layer was reestablished as the sensible heat flux recovered.
“…In many ways, the L-A response as the Sun was obscured by the Moon was similar to the afternoonto-evening transition (e.g., Harrison & Hanna, 2017;Wingo & Knupp, 2015), albeit much faster. The decrease in solar flux resulted in a decrease in the sensible heat flux, which caused the Earth's surface to cool with the subsequent development of an SBL with a near-surface temperature inversion.…”
Section: Discussionmentioning
confidence: 89%
“…The August 2017 eclipse event over the United States provides an excellent opportunity to evaluate the accuracy of how L‐A interactions are represented in numerical models, as essentially the eclipse simulated a rapid sunset/sunrise event (Harrison & Hanna, ). This eclipse occurred near midday when the convective boundary layer (CBL) was already well developed and thus provides an opportunity to observe how quickly turbulent fluxes of heat and momentum decay and regenerate in response to throwing the “solar switch.” We will show that during this event, the developing CBL evolved into a stable boundary layer (SBL), which became unstable again after the recovery of solar radiation.…”
On 21 August 2017, a solar eclipse occurred over the continental United States resulting in a rapid reduction and subsequent increase of solar radiation over a large region of the country. The eclipse's effect on the land‐atmosphere system is documented in unprecedented detail using a unique array of sensors deployed at three sites in north‐central Oklahoma. The observations showed that turbulent fluxes of heat and momentum at the surface responded quickly to the change in solar radiation. The decrease in the sensible heat flux resulted in a decrease in the air temperature below 200 m, and a large decrease in turbulent motions throughout the boundary layer. Furthermore, the turbulent mixing in the boundary layer lagged behind the change in the surface fluxes, and this lag depended on the height above the surface. The turbulent motions increased and the convective boundary layer was reestablished as the sensible heat flux recovered.
“…To calculate the displacement perturbations from the radiosonde, the ascent speed and horizontal wind components are first smoothed to remove high-frequency instrumental noise. For this study, data spanning heights of 13–17 km are selected, as these were the heights at which maximum obscuration of the solar disc was observed by the radiosonde [24] and are above the nominal height of the tropopause in the mid-latitudes. Figure 1.( a ) Temperature, ( b ) u and v wind components and ( c ) vertical ascent speed from a Vaisala RS92 radiosonde ascent made from the Mesospheric, Stratospheric and Tropospheric Radar site at Aberystwyth, Wales, UK, on 3 March 2015.…”
Internal gravity waves are generated as adjustment radiation whenever a sudden change in forcing causes the atmosphere to depart from its large-scale balanced state. Such a forcing anomaly occurs during a solar eclipse, when the Moon’s shadow cools part of the Earth’s surface. The resulting atmospheric gravity waves are associated with pressure and temperature perturbations, which in principle are detectable both at the surface and aloft. In this study, surface pressure and temperature data from two UK sites at Reading and Lerwick are examined for eclipse-driven gravity wave perturbations during the 20 March 2015 solar eclipse over northwest Europe. Radiosonde wind data from the same two sites are also analysed using a moving parcel analysis method, to determine the periodicities of the waves aloft. On this occasion, the perturbations both at the surface and aloft are found not to be confidently attributable to eclipse-driven gravity waves. We conclude that the complex synoptic weather conditions over the UK at the time of this particular eclipse helped to mask any eclipse-driven gravity waves.This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’.
“…With recent developments in computer models used to produce weather forecasts and climate‐change predictions, solar eclipses are a useful opportunity as a ‘controlled experiment’ to gauge how the atmosphere responds when the incoming energy – which drives atmospheric circulation and all our weather systems – is temporarily reduced (Harrison and Hanna, ). Eclipses are also of interest given the important role of solar photovoltaic (PV) and wind‐turbine installations in the national and global portfolio of renewable energy sources.…”
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
