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Improved key process in representing Arctic warming (D3.5)

Davy, Richard; Gao, Yongqi

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  "description": "<p><strong>Summary:</strong></p>\n\n<p>This Blue-Action task was focused on improving the representation of some of the most important<br>\nphysical processes which contribute to Arctic warming within the climate models used by the<br>\nconsortium. The two processes we addressed were the effect on the atmospheric state of the fracturing<br>\nof the sea ice cover and turbulence under strongly stable thermal stratification. The creation and<br>\ndevelopment of<br>\n<strong>The work done:</strong> We first analysed the results of previously performed large eddy simulations which<br>\nresolved the turbulence over leads to determine the effect leads have on sensible heat flux from open<br>\nwater. Because of the effect of three-dimensional structures in the turbulent mixing above leads, the<br>\nheat flux coming from leads can be amplified compared to the fluxes one would get from open water<br>\nunder the same air-sea temperature difference. The amplification effect strongly depends on the width<br>\nof the lead, with the largest effect occurring for leads of widths around 1.4 km. We assessed the<br>\nfunctional sensitivity of this amplification effect to key parameters used in the turbulence-resolving<br>\nmodel, including the length scale for the convective boundary layer, which reflects the background<br>\nstability in the atmosphere.<br>\nWe combined this relation between the amplification effect of heat fluxes as a function of lead width<br>\nwith observed distributions of lead widths. These were taken from the peer-reviewed literature where<br>\n<strong>The key findings: </strong>The presence of leads in sea ice dramatically alters the surface energy balance in the<br>\nArctic. There is a large seasonal cycle to the effect of the presence of leads, because the flux from the<br>\nleads depends strongly on the background stability in the atmosphere. In the winter when the<br>\natmosphere is often strongly stably stratified, the leads strongly amplify the surface sensible heat flux<br>\ncoming from open water. In the summer there is the opposite effect and the generally weaker<br>\natmospheric stability reduces the flux coming from leads.</p>", 
  "license": "", 
  "creator": [
      "affiliation": "Nansen Environmental and Remote Sensing Centre", 
      "@type": "Person", 
      "name": "Davy, Richard"
      "affiliation": "Nansen Environmental and Remote Sensing Centre", 
      "@type": "Person", 
      "name": "Gao, Yongqi"
  "url": "", 
  "datePublished": "2019-09-30", 
  "@context": "", 
  "identifier": "", 
  "@id": "", 
  "@type": "CreativeWork", 
  "name": "Improved key process in representing Arctic warming (D3.5)"
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