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High atmospheric horizontal resolution eliminates the wind‐driven coastal warm bias in the southeastern tropical Atlantic
Author(s) -
Milinski Sebastian,
Bader Jürgen,
Haak Helmuth,
Siongco Angela Cheska,
Jungclaus Johann H.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl070530
Subject(s) - upwelling , tropical atlantic , orography , climatology , sea surface temperature , wind stress , environmental science , geology , oceanography , atmospheric sciences , atmosphere (unit) , meteorology , geography , precipitation
We investigate the strong warm bias in sea surface temperatures (SST) of the southeastern tropical Atlantic that occurs in most of the current global climate models. We analyze this bias in the Max Planck Institute Earth System Model at different horizontal resolutions ranging from 0.1° to 0.4° in the ocean and 0.5° to 1.8° in the atmosphere. High atmospheric horizontal resolution eliminates the SST bias close to the African coast, due to an improved representation of surface wind stress near the coast. This improvement affects coastal upwelling and horizontal ocean circulation, as confirmed with dedicated sensitivity experiments. The wind stress improvements are partly caused by the better represented orography at higher horizontal resolution in the spectral atmospheric model. The reductions of the coastal SST bias obtained through higher horizontal resolution do not, however, translate to a reduction of the large‐scale bias extending westward from the African coast into the southeastern tropical Atlantic.