September 11, 2013

From Zhijin Li and Peggy Li

Oceanic conditions for today

1. Nowcast, Surface Temperature, salinity, velocity and heights

The nowcast from the ROMS data assimilation is presented in Fig. 1.

1. The SST is slightly lower than the September climatology, while its spatial pattern is close to the climatology (Fig. 2). In contrast, last September enjoyed abnormally warmer SSTs, 2C higher than the climatology.
2. The SSS continue to be 0.1-0.2 PSU higher than the climatology, but overall it is 0.1 psu lower this year than last year. The high salinity significantly extends eastward in comparison with the climatology.
3. A number of eddies occur, and their spatial expansion is mostly smaller than 100 km.

Figure 1. SST, SSS, surface velocities, and SSH, September 11, 2013.

Figure 2. September climatological SST and SSS from WOA09.

Figure 3. SST, SSS, surface velocities, and SSH, September 11, 2012.

2 Diagnostic SSS features from Nowcast

Associated with small eddies, there are no dominant SSS frontal features. A warner and fresher filament intrudes from south to the SPURS mooring, and this filament seems real according to drifter SSS observations.

Figure 4. SSS fronts, SSS, maximum salinity depth and maximum salinity derived from the nowcast, September 11, 2013.

3. Atmospheric Conditions

The subtropical high-pressure system will weaken in the days to come. Hurricane Humberto,  is churning southeast of the SPURS region, and it will likely sweep over the SPURS region before Endeavor arrives.

Figure 5. Three-day forecast of surface winds from the NCEP Global Forecasting System (GFS). Hurricane, Humberto, is approaching the SPURS area. 

4. Oceanic Waves

The wave heights have picked up slightly, and the waves associated with Humberto. Humberto may cause waves as high as 8-10 m in days to come.

Figure 6. Two-day forecast of wave heights.