Giovedì 28 Aprile alle ore 14:30 presso il Dipartimento di Ingegneria Civile, Ambientale e Meccanica dell’ Università di Trento si terrà il seminario: “Understanding the Role of Midlatitude Ocean Dynamics in Climate Variability”.
Il seminario, tenuto da Casey Patrizio (CMCC), potrà essere seguito anche in streaming:
Meeting ID: 810 1831 2870
Abstract The ocean plays a key role in regulating Earth’s mean climate, both because of its massive heat capacity, but also its heat transport via its slow-moving overturning circulations and other dynamics. In principle, fluctuations in such ocean heat transport can influence the variability of the climate, first by impacting the sea-surface temperature (SST) variability and in turn the atmospheric variability through air-sea heat flux exchange. However, the role of ocean dynamics in driving climate variability is incompletely understood, particularly in the extratropics. In the first part of the seminar, the role of ocean dynamics in midlatitude SST variability is explored using two different configurations of Hasselmann’s stochastic climate model. It is shown that the model driven only by the observed surface heat fluxes generally produces midlatitude SST power spectra that are too red compared to observations. Including observed estimates of oceanic forcing and damping in the model reduces this discrepancy by whitening the midlatitude SST spectra. It is also shown that the whitening of midlatitude SST variability by ocean processes operates in NCAR's Community Earth System Model (CESM). In the second part, the atmospheric response to midlatitude ocean-forced SST anomalies is explored using the simple model developed in the first part. The model is first used to isolate the oceanic and atmospheric-forced components of the observed SST variability in the Kuroshio-Oyashio Extension (KOE) region. The associated atmospheric circulation anomalies are then diagnosed by lagged-regression of monthly sea-level pressure (SLP) anomalies onto the KOE- averaged SST anomalies, and their oceanic and atmospheric-forced components. It is shown that a large-scale SLP pattern is linked the oceanic-forced component of the SST variability, but not the atmospheric-forced component.