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12.20.10: some conclusions relative to the anomalous events in density in mixed layerΒΆ

These results concern the subtropical gyre, east of Hawaii:

  1. short-period events of intrusion of deep water into the mixed layer are observed in a) the two years available of the WHOTS data and b) in the HYCOM numerical model, in Winter-Spring
  2. suggesting that the weak stratification during that period allows submesoscale processes with large vertical velocity to occur.

Furthermore, the analysis of the 1/30th deg. OFES simulation suggests that 3. Lateral eddy stirring is the dominant cause for the anomalous density in the mixed layer (see Fig. 1 in this note and Fig. 3a in this note). 4. Mixed layer instabilities with large vertical velocities do occur but they are confined to the mixed layer (z>-80 m) so that in most cases they have little impact on the nitrate (the nutricline is around 150 m; see Fig. 6 in this note). 5. There is no measure deduced from the density field that correlate well with either the lateral stirring or the submesoscale instabilities (see this note). In the same note, we show that even the submesoscale instabilities do not correlate well with the Rossby number, considered as an index of filamentation.

Are these results useful? What else would I need to do make them more appealing?

  1. Look at over years of the WHOTS dataset
  2. Analyze the HYCOM model: study the annual cycle, if more (and or stronger) events occur in Spring-Winter and if those are related submesoscales instabilities or not.
  3. Use high-resolution SST and link it to the density anomaly observed at WHOTS; if there is a link, study if more events occur in Spring-Winter.