03.31.11: Relationship between FSLE, BVF and SST gradient

I give here the animation linking the FSLE, the 10-m BVF as well as the time series of upper 75-m BVF at the WHOTS location in the regional HYCOM simulation

Several comments can be made:

1. There are fast (about 1 day) and large-scale change in BVF that are not associated with horizontal gradient of SST and high FSLE. One illustration is for Dec. 12-16 2010 (Figs. 1 to 6), that shows the passage within days of a southwest-northeast band of high BVF across the domain.
2. The increase in stratification in the upper-ocean at the end of March 2010 –the first of such Spring event in the BVF time series– is associated with large SST gradient and FSLE and thus is likely to be due to a surface mixed layer instability (SMLI; Figs. 7 and 8),
3. But not all such Spring events are due to SMLI: the second one, at the beginning of May 2010 is not (Figs. 9 and 10).

Figure 1: (upper) FSLE and 10-m BVF on Dec. 12, 2010 and (lower) time series of BVF at the WHOTS location (red dot in the upper panel).

Figure 2: Gradient of SST and 10-m BVF on Dec. 12, 2010. The WHOTS location is shown by the white dot.

Figure 3: Same as Fig. 1 but 2 days later.

Figure 4: Same as Fig. 2 but 2 days later

Figure 5: Same as Fig. 1 but 4 days later.

Figure 6: Same as Fig. 2 but 4 days later.

Figure 7: Same as Fig. 1 but on Mar. 29, 2010.

Figure 8: Same as Fig. 2 but on Mar. 29, 2010.

Figure 9: Same as Fig. 1 but on May 8, 2010.

Figure 10: Same as Fig. 2 but on May 8, 2010.

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computed with anim_FSLE_near_surf_BVF.m in RESEARCH/PROJECTS/MARINE_BIOLOGY/SUBMESOSCALE_PROCESSES/FSLE/analysis/HYCOM/anim_FSLE_near_surf_BVF on the central disk.