Contributions of atmospheric forcing and chaotic ocean variability to global and regional sea level changes over 1993-2015
Event: 2019 Ocean Surface Topography Science Team Meeting
Session: Science I: Climate data records for understanding the causes of global and regional sea level variability and change
Presentation type: Type Oral
Sea level rise is one of the most important consequences of the actual global warming. Since the early 1990s, satellite altimetry has become the main observing system for continuously measuring the sea level variations. Satellite altimetry data have revealed a global mean sea level rise of 3.1 mm/yr since 1993. This rise is not uniform and presents large deviation around its global average. Since 2005 and because of the high accuracy of the complementary observing systems, we are now able to close the sea level budget within the uncertainties by combining satellite altimetry data, ocean mass change from GRACE and in situ measurements of temperature and salinity (T/S) based on Argo floats. Ocean model simulations, in particular in the eddying regime, revealed the existence of chaotic imprints in regional sea level trends. These chaotic fluctuations may leave random imprints on decadal regional sea level trends. A global ¼°ocean/sea‐ice 50‐member ensemble simulation is analyzed to disentangle the imprints of the atmospheric forcing and the chaotic ocean variability on sea level change and its causes over the satellite altimetry period. We first present the respective contributions of atmospherically-forced and chaotic variability to sea level change and its causes as resolved by the ensemble model simulations. We refine our analysis by investigating these variability imprints as resolved by the different observing systems. Thus, we subsample the ensemble model outputs to the observations, we interpolate the synthetic data set on a regular grid to quantify the chaotic imprints of sea level change and its causes at global and regional scales over 1993-2015.