The signature of mesoscale eddies on sea surface temperature and its associated heat transport
Author(s)
Hausmann, Ute
Type
Thesis
Abstract
This thesis aims at analysing the impact of oceanic turbulence and air-sea interactions
on the sea surface temperature (SST) of the extra-tropical oceans on spatial scales of
a few hundred kilometres (the so-called "mesoscale"). Using satellite-based measurements
of SST and sea level, as well as surface tracks of mesoscale oceanic cyclones
and anticyclones, it is shown that turbulence does not transport heat through systematic
motions of cold cyclones and warm anticyclones, as was previously thought in
regions of strong mean flows like the Gulf Stream. Rather, it is suggested that heat
is transported as a result of the slight phase shift between temperature and pressure fluctuations developing on the mean flow. In addition, tentative estimates of the rate
at which air-sea heat fluxes damp the SST signatures of cyclones and anticyclones are
provided. The weak values obtained ( 20 W/m2K) contrast sharply with theoretical
expectations, but are in agreement with the observed long-lived thermal heat content
anomalies associated with the cyclones and anticyclones. These observations provide
important benchmarks for high-resolution ocean models and may moreover guide the
parametrization of subgrid-scale heat transport in climate models.
on the sea surface temperature (SST) of the extra-tropical oceans on spatial scales of
a few hundred kilometres (the so-called "mesoscale"). Using satellite-based measurements
of SST and sea level, as well as surface tracks of mesoscale oceanic cyclones
and anticyclones, it is shown that turbulence does not transport heat through systematic
motions of cold cyclones and warm anticyclones, as was previously thought in
regions of strong mean flows like the Gulf Stream. Rather, it is suggested that heat
is transported as a result of the slight phase shift between temperature and pressure fluctuations developing on the mean flow. In addition, tentative estimates of the rate
at which air-sea heat fluxes damp the SST signatures of cyclones and anticyclones are
provided. The weak values obtained ( 20 W/m2K) contrast sharply with theoretical
expectations, but are in agreement with the observed long-lived thermal heat content
anomalies associated with the cyclones and anticyclones. These observations provide
important benchmarks for high-resolution ocean models and may moreover guide the
parametrization of subgrid-scale heat transport in climate models.
Date Issued
2013
Date Awarded
2013-05
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Czaja, Arnaud
Sponsor
Imperial College London
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)