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
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.