Sea Level Change and Variability in the subtropical South Pacific
Abstract
Observational altimetry data and data of phase 5 of the Coupled Model Intercomparison Project (CMIP5) are investigated to analyze sea level change and variability for the subtropical South Pacific. The altimetry data covers the period 1993 to 2017 and is characterized by a non-uniform spatial trend pattern with trends higher than the global mean in the western part and trends lower than the global mean in the southern Ocean. An Empirical Orthogonal Function (EOF) analysis of the Region 20°S to 60°S is performed in order to analyze sea level variablility in the subtropics. The tropical region has been omitted in order to avoid the strong El Niño Southern Oscillation (ENSO) signal masking other subtropical variability in the analysis. The results show a clear pattern in the first EOF with a North-South dipole explaining 30% of the variance. The second EOF shows an East-West tripole explaining 13% of the variance; both on a decadal time scale. Two CMIP5 models (MPI-ESM-LR and CCSM4) have been selected to compare whether the models are able to reflect the observed results. Pattern correlations of the model and altimetry results show relatively low values, indicating that the subtropical variability is not well explained in the models. Remarkable is the difference between the two models, when analyzing the entire South Pacific, including the tropical region, where the CCSM4 shows high correlations, while the MPI-ESM-LR is still showing low correlation values, indicating that this model does not reflect well the tropical ENSO-related variability either. Related variables as sea surface temperature (SST) and wind are considered and their connection to sea level variabilty analyzed. First results show that the two models seem to better represent the observed SST variability than the sea level variability in the subtropical South Pacific.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A23P3057A
- Keywords:
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- 3319 General circulation;
- ATMOSPHERIC PROCESSES;
- 3364 Synoptic-scale meteorology;
- ATMOSPHERIC PROCESSES;
- 4504 Air/sea interactions;
- OCEANOGRAPHY: PHYSICAL;
- 4522 ENSO;
- OCEANOGRAPHY: PHYSICAL