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Title: The impact of equilibrating hemispheric albedos on tropical performance in the HadGEM2-ES coupled climate model

The Earth's hemispheric reflectances are equivalent to within ± 0.2 Wm–2, even though the Northern Hemisphere contains a greater proportion of higher reflectance land areas, because of greater cloud cover in the Southern Hemisphere. This equivalence is unlikely to be by chance, but the reasons are open to debate. Here we show that equilibrating hemispheric albedos in the Hadley Centre Global Environment Model version 2-Earth System coupled climate model significantly improves what have been considered longstanding and apparently intractable model biases. Monsoon precipitation biases over all continental land areas, the penetration of monsoon rainfall across the Sahel, the West African monsoon “jump”, and indicators of hurricane frequency are all significantly improved. Mechanistically, equilibrating hemispheric albedos improves the atmospheric cross-equatorial energy transport and increases the supply of tropical atmospheric moisture to the Hadley cell. Furthermore, we conclude that an accurate representation of the cross-equatorial energy transport appears to be critical if tropical performance is to be improved.
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Met Office Hadley Centre, Exeter (United Kingdom); Univ. of Exeter, Exeter (United Kingdom)
  2. Met Office Hadley Centre, Exeter (United Kingdom)
  3. Univ. of Exeter, Exeter (United Kingdom)
  4. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  5. Canadian Centre for Climate Modeling and Analysis, Toronto, ON (Canada)
  6. Japan Agency for Marine-Earth Science and Technology, Yokohama (Japan)
  7. JPL, Pasadena, CA (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
NE/M017214/1; GA01101; AC05-76RL01830
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 43; Journal Issue: 1; Journal ID: ISSN 0094-8276
American Geophysical Union
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States