Hobart

Seminar Abstract

Monday 20 July 2009, 11.30am (Tas time)
CSIRO Auditorium, Hobart

Felix W Landerer
Jet Propulsion Laboratory
California Institute of Technology
Pasadena, USA

The pattern of projected regional sea level changes: magnitudes, mechanisms and uncertainties

The uncertainties of projected changes in global mean and regional sea level for the twenty-first century are currently at the meter level. This is partly due to the lack of truly global long-term observations, partly due to a lack of understanding of the time-scales of ice sheet response to global warming, and also partly due to a large spread in the projected pattern of regional sea level changes across a spectrum of coupled climate models. For many regions, this regional sea level change is on the same order of magnitude as the global mean change from thermal expansion. It is evidently important to understand the mechanisms behind these regional changes, with the ultimate goal to reduce the current uncertainty of this pattern.

In this talk, I present results of simulations with coupled climate models (as used for the IPCC report), and I will discuss some of the mechanisms that are associated with regional dynamic sea level changes. One particular focus is on the North Atlantic region. Here, changes in the sinking branch of the Atlantic meridional overturning circulation might have a direct effect on the regional sea surface height pattern. While there is some conceptual merit to this idea, the pattern of simulated sea level changes in this region is rather complex on interannual to decadal timescales, and is not suitable as an indicator of the overturning circulation. Additionally, I will discuss the projected changes of temperature and salinity changes and their contribution to the density-related (steric) sea level changes. An unexpected finding from this analysis is that steric sea level changes are associated with a distinct pattern of horizontal mass redistribution, which leads to changes in the Earth orientation vector.

In light of the short observational period, coupled climate models can also help to assess global and regional sea level changes in terms of natural climate variability. On interannual to decadal time scales, one dominant mode of variability is the El Nino-Southern Oscillation (ENSO). I will discuss the response of regional and global mean sea level to ENSO variability, and assess the hydrological balance between the oceans, atmosphere and continents.

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Clothilde Langlais, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5399
Natalie Kelly, (Biology/Modelling seminars) CSIRO Marine and Atmospheric Research 0438 452 483
Jillian Enraght-Moony, (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5320
Communications Manager, Antarctic Climate and Ecosystems CRC (03) 6226 2265
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 8/12/09