12.20.10: SSH, dynamic height and unresolved SSH in the 1/30th deg. OFES simulation

In this note, using the 1/30th deg. OFES simulation, we show

1. sea surface height (SSH) east of Hawaii can be deduced from the dynamic height (DH) calculated with the assumption of level of no motion at 2000 m
2. this DH-induced SSH contains the information on the submesoscale
3. the difference between the DH-induced SSH and an AVISO-like SSH contains the information for wavelength less than 2° ,
4. yet one cannot isolate the submesoscale features from the unresolved mesoscale features in that difference.

Fig. shows the various SSH and Fig. 2 the associated surface Rossby number, in index for submesoscale features.

Figure 1: SSH: (a) model output, (b) from DH, (c) AVISO-like SSH and (d) unresolved SSH, that is (b) minus (c). Dynamic height was computed with the assumption of level of no motion at 2000 m. AVISO-like SSH is the low-pass filtered (wavelengths larger than 2° ) version of SSH. See OFES_test_dynamic_heigth.m in RESEARCH/PROJECTS/MARINE_BIOLOGY/SUBMESOSCALE_PROCESSES/OFES/OFES_test_dynamic_height on ipu1.

Figure 2: Surface Rossby number R = ζ / f: (a) from model output SSH at 2.5 m depth, (b) from geostrophic flow, (c) from DH-induced SSH, (d) from unresolved SSH of Fig. 1d.