WHOI PO
Carl Wunsch, MIT - Interpreting the Multi-decadal-average Ocean Circulation
| Date |
Time |
Location |
| July 1st, 2025 |
3:05pm-4:05pm |
Clark 507 |
Title: Interpreting the multi-decadal-average ocean circulation
Abstract: The combination of modern global observing systems and general circulation models has made it possible to estimate the global ocean circulation and its variability over several decades. An estimate (from the ECCO project), produced from a nonlinear least-squares fit with Lagrange multipliers of the MITgcm and several billion observed, weighted, data points permits calculation of the time average of the temperature, salinity, velocity, etc. over 26 years. One motivation was to ask the question of whether such a time-average is significantly simplified as compared e.g., to a snapshot or annual average? The short answer is "no" -- an intense regionality in the circulation remains and which in turn raises numerous further interesting questions, such as whether an average of arbitrarily-long duration would indeed simplify? Has the ocean ever been in equilibrium? The quantitative nature of the estimated variability is extremely spatially heterogeneous, implying that the interpretation of even such simple concepts as global averages and global average trends, requires great care -- and is at the edge of statistical knowledge.