Comparisons of upwelling and relaxation events in the Monterey Bay area

Abstract

Observations show significant differences in circulation patterns of upwelling and relaxation events that occurred in the Monterey Bay during two Autonomous Ocean Sampling Network field experiments in August 2003 and 2006. During the 2003 experiment, circulation exhibited more typical patterns associated with upwelling/relaxation: the development of the southward flowing jet and pair of cyclonic (inside of the bay) and anticyclonic (outside of the bay) circulations during upwelling and the development of the northward flow along the coast during relaxation of winds. During the upwelling event of 2006, the southward flow was weaker and shallower than in 2003. The second relaxation event of 2006 was significantly different from the first relaxation event of 2006 and the relaxation event of 2003: a southward flow was present along the entrance to the bay and this southward flow penetrated into the subsurface up to around 50 m at the mooring location. Two reasons for the observed differences in upwelling and relaxation events of 2003 and 2006 are identified in the paper: weaker winds in August 2006 than in August 2003 and strong positive sea surface height anomalies propagating poleward along the coast during 2006. The 2003 field program included an extensive sampling of the bay and surrounding areas with a fleet of underwater gliders, while during 2006 program, the extensive sampling was conducted in the area of upwelling center to the north of the Monterey Bay. During the 2003 field program, the Monterey Bay model was able to reproduce observed surface and subsurface features with assimilation of glider observations. However, during the 2006 field program, the assimilation of glider data from the upwelling center to the north of the Monterey Bay had minimal impact on model simulations of observed features to the south of the upwelling center.

Oceanographic and atmospheric conditions on the continental shelf north of the Monterey Bay during August 2006

“…12). Both models and the observations show that the SSH anomalies during August 2006 were larger than normal and much larger than during AOSN-II in summer 2003 Shulman et al, 2010). Both models also show that these SSH anomalies were propagating poleward at 1-3 m s −1 , as can be seen by the slope of the maxima (red region) in the latitude vs. time plots (Fig.…”

“…The models were run in near-real time to provide knowledge input to the adaptive sampling decision tree. The three models used were the Harvard Ocean Prediction System (HOPS) (Robinson, 1999;Haley et al, 2009;Haley and Lermusiaux, 2010), the Jet Propulsion Laboratory implementation of the Regional Ocean Modeling System (JPL/ROMS) (Schepetkin and Williams, 2004;Chao et al, 2009;Wang et al, 2009), and the Navy Coastal Ocean Model/Innovative Coastal-Ocean Observing Network (NCOM/ICON) model (Shulman et al, , 2010. Two versions of the HOPS model were examined: HOPS solo (hereafter HOPSs) which had 1.5 km horizontal resolution, and HOPS nested (hereafter HOPSn) which was nested within HOPSs and had 0.5 km horizontal resolution (Fig.…”

Coastal Trapped Waves, Alongshore Pressure Gradients, and the California Undercurrent*

“…NCOM-CCS (Shulman et al 2007) is a primitive equation, 3D, hydrostatic model with a horizontal resolution of ;9 km. The model domain covers the region 308-498N, 1358-1158W (Figs.…”

Persistent ocean monitoring with underwater gliders: Adapting sampling resolution

“…Model outputs contain a 24 hour hindcast, 24 hour nowcast and 24 hour forecast each day. For more details on this model, please see (Shulman et al, 2009) and (Shulman et al, 2010).…”