Gangopadhyay, A., P.F.J. Lermusiaux, L. Rosenfeld, A.R. Robinson, L. Calado, H.S. Kim, W.G. Leslie and P.J. Haley, Jr., 2011. The California Current System: A Multiscale Overview and the Development of a Feature-Oriented Regional Modeling System (FORMS). Dynamics of Atmospheres and Oceans, 52, 131-169, doi:10.1016/j.dynatmoce.2011.04.003.
Over the past decade, the feature-oriented regional modeling
methodology has been developed and applied in several ocean
domains, including the western North Atlantic and tropical North
Atlantic. This methodology is model-independent and can be utilized
with or without satellite and/or in situ observations. Here we
develop new feature-oriented models for the eastern North Pacific
from 36 to 48? – essentially, most of the regional eastern boundary
current. This is the first time feature-modeling has been applied
to a complex eastern boundary current system. As a prerequisite to
feature modeling, prevalent features that comprise the multiscale
and complex circulation in the California Current system (CCS) are
first overviewed. This description is based on contemporary understanding
of the features and their dominant space and time scales of
variability. A synergistic configuration of circulation features interacting
with one another on multiple and sometimes overlapping
space and time scales as a meander-eddy-upwelling system is presented.
The second step is to define the feature-oriented regional
modeling system (FORMS). The major multiscale circulation features include the mean flow and southeastward meandering
jet(s) of the California Current (CC), the poleward flowing California
Undercurrent (CUC), and six upwelling regions along the coastline.
Next, the typical synoptic width, location, vertical extent, and
core characteristics of these features and their dominant scales of
variability are identified from past observational, theoretical and
modeling studies. The parameterized features are then melded with
the climatology, in situ and remotely sensed data, as available.
The methodology is exemplified here for initialization of primitiveequation
models. Dynamical simulations are run as nowcasts and
short-term (4-6 weeks) forecasts using these feature models (FM)
as initial fields and the Princeton Ocean Model (POM) for dynamics.
The set of simulations over a 40-day period illustrate the applicability
of FORMS to a transient eastern boundary current region such
as the CCS. Comparisons are made with simulations initialized from
climatology only. The FORMS approach increases skill in several factors,
including the: (i) maintenance of the low-salinity pool in the
core of the CC; (ii) representation of eddy activity inshore of the
coastal transition zone; (iii) realistic eddy kinetic energy evolution;
(iv) subsurface (intermediate depth) mesoscale feature evolution;
and (v) deep poleward flow evolution.