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Numerical simulations of the impact of the 20 March 2015 eclipse on UK weather.

Abstract

Short lead-time forecasts using the operational United Kingdom variable-resolution (UKV) configuration of the Met Office's numerical weather prediction model, with horizontal grid-length 1.5 km over the UK, with and without a representation of the 20 March 2015 eclipse, have been used to simulate the impact of the eclipse on UK weather. The major impact was surface-driven through changes to surface heat and moisture fluxes that changed the boundary-layer development. In cloud-free areas, the nocturnal stable boundary layer persisted or quickly re-established during the eclipse. Surface temperatures were reduced by 7-8°C, near-surface air temperature by 1-3°C, and near-surface winds were backed, typically by 20°. Impacts on wind speed were small and variable, and would have been very difficult to detect. Smaller impacts occurred beneath cloud. However, the impact was enhanced because most of the incoming radiation that reached the surface was driving surface sensible heat flux rather than moisture flux, and the near-surface air temperature impact (0.5-1°C) agrees reasonably well with observations. The modelled impact of the eclipse was substantially reduced in urban areas due to their large thermal inertia. Experience from other assessments of the model suggests that this lack of response may be exaggerated. Surface impacts propagated upwards and downstream with time, resulting in a complex pattern of response, though generally near-surface temperature differences persisted for many hours after the eclipse. The impact on atmospheric pressure fields was insufficient to account for any significant perturbations to the wind field when compared with the direct impacts of surface stress and boundary-layer mixing.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'.

Authors+Show Affiliations

Department of Meteorology, University of Reading, Reading RG6 6BB, UK p.clark@reading.ac.uk.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

27550770

Citation

Clark, P A.. "Numerical Simulations of the Impact of the 20 March 2015 Eclipse On UK Weather." Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences, vol. 374, no. 2077, 2016.
Clark PA. Numerical simulations of the impact of the 20 March 2015 eclipse on UK weather. Philos Trans A Math Phys Eng Sci. 2016;374(2077).
Clark, P. A. (2016). Numerical simulations of the impact of the 20 March 2015 eclipse on UK weather. Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences, 374(2077), doi:10.1098/rsta.2015.0218.
Clark PA. Numerical Simulations of the Impact of the 20 March 2015 Eclipse On UK Weather. Philos Trans A Math Phys Eng Sci. 2016 Sep 28;374(2077) PubMed PMID: 27550770.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Numerical simulations of the impact of the 20 March 2015 eclipse on UK weather. A1 - Clark,P A, PY - 2016/04/25/accepted PY - 2016/8/24/entrez PY - 2016/8/24/pubmed PY - 2016/8/24/medline KW - boundary layer KW - eclipse KW - forecast KW - numerical weather prediction JF - Philosophical transactions. Series A, Mathematical, physical, and engineering sciences JO - Philos Trans A Math Phys Eng Sci VL - 374 IS - 2077 N2 - Short lead-time forecasts using the operational United Kingdom variable-resolution (UKV) configuration of the Met Office's numerical weather prediction model, with horizontal grid-length 1.5 km over the UK, with and without a representation of the 20 March 2015 eclipse, have been used to simulate the impact of the eclipse on UK weather. The major impact was surface-driven through changes to surface heat and moisture fluxes that changed the boundary-layer development. In cloud-free areas, the nocturnal stable boundary layer persisted or quickly re-established during the eclipse. Surface temperatures were reduced by 7-8°C, near-surface air temperature by 1-3°C, and near-surface winds were backed, typically by 20°. Impacts on wind speed were small and variable, and would have been very difficult to detect. Smaller impacts occurred beneath cloud. However, the impact was enhanced because most of the incoming radiation that reached the surface was driving surface sensible heat flux rather than moisture flux, and the near-surface air temperature impact (0.5-1°C) agrees reasonably well with observations. The modelled impact of the eclipse was substantially reduced in urban areas due to their large thermal inertia. Experience from other assessments of the model suggests that this lack of response may be exaggerated. Surface impacts propagated upwards and downstream with time, resulting in a complex pattern of response, though generally near-surface temperature differences persisted for many hours after the eclipse. The impact on atmospheric pressure fields was insufficient to account for any significant perturbations to the wind field when compared with the direct impacts of surface stress and boundary-layer mixing.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'. SN - 1364-503X UR - https://www.unboundmedicine.com/medline/citation/27550770/Numerical_simulations_of_the_impact_of_the_20_March_2015_eclipse_on_UK_weather_ L2 - https://royalsocietypublishing.org/doi/full/10.1098/rsta.2015.0218?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -