Questions to answer

• The SQG should work only below the Ekman layer and above the thermocline –within a mixed layer where the stratification is weak. Around Hawaii, the SQG might thus be valid only within the upper 100 m, which might be deep enough to be used as a tool to diagnose nutrient upwelling in observations.

• I am still not confident with my calculation of vertical velocity w from eSQG. To test this, I should use the OFES 1/10th deg. model. Mahadevan and Archer (2000) have shown that 1/10th deg. resolution should be enough to start have submesoscale features such as those produced by frontogenesis for the region around Hawaii. As a start, I should use a region in the North Atltantic where eSQG have shown to work well (Isern-Fontanet et al. 2008). If the routines works then I could start to learn the depth at which eSQG theory is valid around Hawaii. Now it is possible that eSQG theory might not work and a more general theory such as SQG may be more appropriate. Another way would be to compute κ, the quantity introduced by Chavanne et al. (2010), around dipole of vorticity. If κ is -1, then SQG is not applicable –SQG predicts -1/2 (see Cedric’s emails).

• Study how phytoplankton and nutrient appears in the oligotrophic ocean around Hawaii in the OFES 1/10th deg. model. Try to quantify how much is being produced locally by upwelling of nutrients, and how much is being advected horizontally from the nutrient-enriched regions to the north and south. McGillicuddy et al. (2003) found in a 1/10-th deg. model that eddy pumps the missing amount of nutrients necessary for the observed primary production. The critic from Klein et al. (2009) is

  “Nutrient isolines below the euphotic zone mostly follow the isopycnals either because of the low resolution [1/3th deg. in Oschlies & Garcon (1998)] or because of a first-order relaxation using a reference nutrient-density relationship and the modeled density such as that in the 1/10th deg. degree resolution study of McGillicuddy et al. (2003).”

• Float observations:

  • Are the contours of constant density always follow the isopycnals? No, there are nutrient anomalies. What is the relationship between density and nutrient expected during frontogenesis?
  • Any correlation between upwelling events and FSLE? If yes, perform a statistical test.
  • Estimate w from SQG theory. Any correlation as well?
  • Look at the behavior of nutrient, density and w in the OFES model.
  • Dowload the most recent float observations –there are now two floats– @ http://www.mbari.org/chemsensor/FloatList.html.

• Glider observations: high horizontal resolution.

• Learn how to see the submesoscale features in surface chlorophyll as observed by satellite. Do we see these around Hawaii or not?

• In the seasonal cycle of Chl as observed by satellite, do we have the same asymmetry as for the EKE -the increase is more rapid and shorter than the decrease? If yes, what does this mean? Also, what does the local maxima of SSH std mean? Why SSH would be correlated with Chl –is this what we would obtain if Chl appears mostly within mesoscale eddies, with high Chl corresponding to low SSH?