Understanding the Role of Ocean Dynamics in Midlatitude Sea Surface Temperature Variability Using a Simple Stochastic Climate Model

In a recent paper, we argued that ocean dynamics increase the variability of midlatitude sea surface temperatures (SSTs) on monthly to interannual time scales, but act to damp lower-frequency SST variability over broad midlatitude regions. Here, we use two configurations of a simple stochastic clima...

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Vydáno v:Journal of climate Ročník 35; číslo 11; s. 3313 - 3333
Hlavní autoři: Patrizio, Casey R., Thompson, David W. J.
Médium: Journal Article
Jazyk:angličtina
Vydáno: Boston American Meteorological Society 01.06.2022
Témata:
Active damping
Atmospheric models
Boundary currents
Climate
Climate models
Climate variability
Configurations
Damping
Dynamics
Energy spectra
Heat flux
Heat transfer
Modelling
Ocean currents
Ocean dynamics
Ocean models
Oceans
Power spectra
Sea surface
Sea surface temperature
Sea surface temperature variability
Spectra
Surface temperature
Temperature variability
Time
Variability
Western boundary currents
ISSN:0894-8755, 1520-0442
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Shrnutí:In a recent paper, we argued that ocean dynamics increase the variability of midlatitude sea surface temperatures (SSTs) on monthly to interannual time scales, but act to damp lower-frequency SST variability over broad midlatitude regions. Here, we use two configurations of a simple stochastic climate model to provide new insights into this important aspect of climate variability. The simplest configuration includes the forcing and damping of SST variability by observed surface heat fluxes only, and the more complex configuration includes forcing and damping by ocean processes, which are estimated indirectly from monthly observations. It is found that the simple model driven only by the observed surface heat fluxes generally produces midlatitude SST power spectra that are too red compared to observations. Including ocean processes in the model reduces this discrepancy by whitening the midlatitude SST spectra. In particular, ocean processes generally increase the SST variance on <2-yr time scales and decrease it on >2-yr time scales. This happens because oceanic forcing increases the midlatitude SST variance across many time scales, but oceanic damping outweighs oceanic forcing on >2-yr time scales, particularly away from the western boundary currents. The whitening of midlatitude SST variability by ocean processes also operates in NCAR’s Community Earth System Model (CESM). That is, midlatitude SST spectra are generally redder when the same atmospheric model is coupled to a slab rather than dynamically active ocean model. Overall, the results suggest that forcing and damping by ocean processes play essential roles in driving midlatitude SST variability.
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ISSN:0894-8755
1520-0442
DOI:10.1175/JCLI-D-21-0184.1