Atmospheric response to North Pacific SST The role of model resolution and synoptic SST variability Guidi Zhou, Mojib Latif, Wonsun Park*, Richard Greatbatch GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany *presenting Frontal-scale Air-sea Interaction Workshop Boulder, CO, USA August 6, 2013
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Atmospheric response to North Pacific SST The role of model resolution and synoptic SST variability Guidi Zhou, Mojib Latif, Wonsun Park*, Richard Greatbatch.
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Atmospheric response to North Pacific SST
The role of model resolution and synoptic SST variability
Guidi Zhou, Mojib Latif, Wonsun Park*, Richard Greatbatch
GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany*presenting
Accelerated jet stream Deep convection Deep diabatic heating Enhanced storm-track
Convergence of eddy vorticity flux is balanced by divergence in circulation, resulting in ascent at mid-levels and low-level convergence. The vortex stretching associated produces the surface low.
Convergence of eddy momentum flux reinforces the jet.
Consistent with Kushnir et al. 2002...
High vs. low resolutions
T31- response
Geopotential height (m) Geopotential height (m)
T213- response
Influence of synoptic SST variability
Snapshot, Jan 01, 1982.Fine spatial/temporal structures on T213Synoptic SST variability only in NP
ctrl, NP SSTa experimentsClimatological state, Jan 01 Smoothed spatial/temporal structures on T213
ctrl, NP SSTa experiments
Sea surface temperature (K)
Observed daily varying SST vs. climatological
SST as backgroundT213-daily varying
North Pacific background SST
T213-climatological background
SST
no significant responsesignificant eddy-mediated response
North Pacific atmosphere response to underlying SST anomalies in observations
This can be simulated only with higher resolution of AGCM, e.g. T213
Temporal resolution is also important in this aspect The response is eddy-mediated
Summary
In order to obtain a realistic response to midlatitude SST anomalies one needs to resolve the synoptic SST variability. This requires employing sufficiently high horizontal resolution.