Clark Rowley

Comparisons of upwelling and relaxation events in the Monterey Bay area

[1] 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.

Real-time ocean data assimilation and prediction with global NCOM

The Naval Research Laboratory (NRL) at Stennis Space Center has developed a global implementation of the Navy Coastal Ocean Model (NCOM). Global NCOM encompasses the open ocean to 5 m depth in a curvilinear global model grid with 1/8 degree grid spacing at 45/spl deg/N, extending from 80/spl deg/S to a complete Arctic cap with grid singularities mapped into Canada and Russia. The model employs 40 vertical sigma-z levels, with sigma in the upper ocean and coastal regions, and z in the deeper ocean. The real-time system uses Navy Operational Global Atmospheric Prediction System (NOGAPS) 3-hourly wind stresses and heat fluxes. Operationally available sea surface temperature (SST) and altimetry (SSH) data are incorporated into NAVOCEANO Modular Ocean Data Assimilation System (MODAS) and Navy Layered Ocean Model (NLOM) analyses and forecasts of SSH and SST. These in turn are combined with the MODAS synthetic database to yield three-dimensional fields of temperature and salinity for assimilation into global NCOM. We describe the analysis and forecast system, present selected evaluations of the model performance, and discuss planned upgrades to the model and data assimilation methods.

NFLUX Satellite-Based Surface Radiative Heat Fluxes. Part II: Gridded Products

AbstractThe Naval Research Laboratory (NRL) ocean surface flux (NFLUX) system provides near-real-time satellite-based gridded surface heat flux fields over the global ocean within hours of the observed satellite measurements. NFLUX can serve as an alternative to current numerical weather prediction models—in particular, the U. S. Navy Global Environmental Model (NAVGEM)—that provide surface forcing fields to operational ocean models. This study discusses the satellite-based shortwave and longwave global gridded analysis fields, which complete the full suite of NFLUX-provided ocean surface heat fluxes. A companion paper discusses the production of satellite swath-level surface shortwave radiation and longwave radiation estimates. The swath-level shortwave radiation estimates are converted into clearness-index values. Clearness index reduces the dependency on solar zenith angle, which allows for the assimilation of observations over a given time window. An automated quality-control process is applied to the...

NFLUX Satellite-Based Surface Radiative Heat Fluxes. Part I: Swath-Level Products

AbstractThe Naval Research Laboratory (NRL) ocean surface flux (NFLUX) system originally provided operational near-real-time satellite-based surface state parameter and turbulent heat flux fields over the global ocean. This study extends the NFLUX system to include the production of swath-level shortwave and longwave radiative heat fluxes at the ocean surface. A companion paper presents the production of the satellite-based global gridded radiative heat flux analysis fields. The swath-level radiative heat fluxes are produced using the Rapid Radiative Transfer Model for Global Circulation Models (RRTMG), with the primary inputs of satellite-derived atmospheric temperature and moisture profiles and cloud information retrieved from the Microwave Integrated Retrieval System (MIRS). This study uses MIRS data provided for six polar-orbiting satellite platforms. Additional inputs to the RRTMG include sea surface temperature, aerosol optical depths, atmospheric gas concentrations, ocean surface albedo, and ocean ...

Overview of U.S. Navy Operational Oceanographic Models in Support of Acoustic Applications

The Naval Oceanographic Office operational global 1/8° Navy Coastal Ocean Model assimilates satellite and in‐situ data to produce daily 72‐hr forecasts. Output includes 3D fields of temperature, salinity, u‐ and v‐components of ocean currents at standard depth levels, and these support derived fields including sound speed and sonic layer depth. The global model provides initial/boundary conditions for nested regional models, primarily relocatable NCOM. The relocatable NCOM modeling system can be set up quickly for areas of interest, includes river and tidal forcing, and is forced with a high‐resolution atmospheric mesoscale model. Local and remote observations are incorporated into the models through the Navy Coupled Ocean Data Assimilation system, which assimilates sea surface temperature data from satellite, ships and buoys, profile data from floats and gliders, xbts, CTDs, fixed and drifting buoys as well as altimeter‐derived sea surface heights and ice concentration. In this presentation we will dis...