Role of midlatitude oceanic stochastic forcing in the atmospheric responses

What is it about?

The atmospheric response to the midlatitude North Pacific sea surface temperature (SST) anomalies are essential albeit weak for understanding the associated air‐sea interaction there, wherein storm track plays an important role. To adequately capture the storm tracks and large‐scale atmospheric structures as well, high‐resolution SST with detailed oceanic fronts and eddies are required in fine‐resolution atmospheric general circulation models. One of the important effects of high‐resolution SST is to enhance the atmospheric transient eddies by introducing more internal oceanic variabilities, which can be obtained by an alternative way in this study, that is, adding extra oceanic stochastic forcing in a coarse‐resolution atmospheric general circulation model. A set of ensemble experiments and dynamic diagnostics illustrate that oceanic stochastic forcing can generate many more atmospheric transient eddies through the increases of thermal activity and atmospheric baroclinicity, and further enhance large‐scale atmospheric response to the midlatitude North Pacific SST anomalies. Without increasing the amount of oceanic fronts and eddies and the capability of resolving the atmospheric transient eddies, this study illustrates that the oceanic stochastic forcing is important and nonnegligible for the understanding and theory of oceanic feedback to the atmosphere in the midlatitudes.

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Why is it important?

With extra oceanic stochastic forcing, the midlatitude SST anomalies can produce many more atmospheric transient eddies that are essential for both structure and amplitude of the midlatitude atmospheric responses. However, the influences of oceanic stochastic forcing were not considered in previous studies. To fully understand the oceanic feedback to the atmosphere in the midlatitudes and advance the theory of midlatitude air-sea interaction, oceanic stochastic forcing is important and nonnegiligible.

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