feature oriented regional modeling system -- forms: an overview avijit gangopadhyay university of...

Feature Oriented Regional Modeling System -- FORMS: An Overview

Avijit Gangopadhyay

University of Massachusetts Dartmouth

Email: avijit@umassd.edu

Funded by NASA and ONR

OUTLINE

• Feature Oriented Regional Modeling System (FORMS)

• Concept -- Initialization/Synthesis Methodology

• Applications to different regions

Gulf Stream Front and Ring Analysis

Features in Western North Atlantic

• Gulf Stream

• Warm Core Rings

• Cold Core Rings

• Southern Recirculation Gyre

• Northern Recirculation Gyre

• Deep Western Boundary Current

• Gangopadhyay et al., 3-part series in 1997: Journal of Atmospheric and Oceanic Tech. (14) 1314:1365

• Maine Coastal Current• NEC Inflow• GSC Outflow• Jordan Basin Gyre• Wilkinson Basin Gyre• Georges Basin Gyre• Georges Bank Gyre• Tidal Mixing Front• Gangopadhyay et al. 2002

(Continental Shelf Res. In Press)• Gangopadhyay and Robinson,

2002: DAO 36(2002) 201-232

Deep Sea region (GSMR) Coastal region (GOMGB)

Table I. List of GOMGB features and selected studies

Features Selected Studies

Maine Coastal Current(including Great South Channel Outflow)

Beardsley et al. (1985), Bisagni et al. (1996), Brooks(1987, 1990, 1994), Brooks and Townsend (1989),Chapman and Beardsley (1989), Holboke and Lynch(1995), Mavor and Huq (1996), Mountain and Manning(1994), Lynch et al. (1992, 1996, 1997), Lynch (1999),Naimie et al. (1994), Naimi (1995,1996), Smith (1989).

Gorges Bank Anticyclonic circulation,Tidal Fronts

Loder et al. (1992), Butman and Beardsley (1987),Butman et al. (1987), Bisagni et al. (1996), Flagg(1987), Houghton et al. (1982).

Jordan Basin Gyre Brooks (1987), Pettigrew et al. (1998), Wright et al.(1986), Beardsley et al. (1997).

Wilkinson Basin Circulation Brown and Beardsley (1978), Brown and Irish (1992,1993), Brown (1998a), Mountain and Jessen (1987).

Georges Basin Gyre Brooks, (1985), Wright et al. (1986), Beardsley et al.(1997), Pettigrew et al. (1998), Xue et al. (2000).

North East Channel Inflow Brooks (1987), Ramp et al. (1985), Bisagni and Smith(1998)

Abbreviations:GOMGB : Gulf of Maine and Georges Bank

MCC : Maine Coastal CurrentGSC : Great South ChannelTMF : Tidal (Mixing) FrontJBG : Jordan Basin GyreWBG : Wilkinson Basin GyreGBG : Georges Basin GyreNEC : North East Channel

T(x,y,z)=Ta(x,z)+(x,z)(y)where,Ta(x,z)={[T0(x)-Tb(x)](x,z)

+Tb}

U(x,y,z)=(y){[UT(x)-UB(x)](x,z)+ UB(x)}

Tss(x,y,Z) = Tsh + (Tsl – Tsh) m(,Z)

m(,Z) = ½ + ½ tanh[(-.Z)/]

=tan

Where, m is the melding function:

In general, a coastal current (CC), a front (SSF) and an eddy/gyre (E/G) are represented by:

CC: TM(x, η, z) =TMa(x, z)+ αM(x, z) M(η)

SSF: Tss(x, y, z) = Tsh (x, z) + (Tsl (x, z) – Tsh(x, z)) (, z)

E/G: T(r, z) = Tc (z) - [Tc (z) - Tk (z) ] {1-exp(-r/R)}

 where, TM

a(x, z), Tsh (x, z) and Tc (z) are axis, shelf and core

(η) = (0 W)

(, z) = ½ + ½ tanh[(-.Z)/] 

Strategy for GOMGB

MCC WBG JBG GBG GBAG TMF SSF Inflow/Outflow

FORMS Protocol

• Identify Circulation and Water mass features• Regional Synthesis -- Processes from a modeling

perspective• Synoptic Data sets -- in-situ and satellite• Regional Climatology (Background Circulation)• OA (Climatology + Feature Models)• Simulation -- Nowcasting/Forecasting

FORMS Applications in Different Oceans

• Western north Atlantic – Operational modeling in GOMGB – AFMIS-RFAC

• Strait of Sicily – Dynamical analysis• Monterey Bay real-time forecasting with ROMS –

AOSN-II in summer 2003 -- Upwelling• Brazil Current Meander-eddy-Upwelling System• Persian Gulf, Arabian Sea – Rapid response• Chilean Waters – Northern Humboldt Current –

Biophysical modeling

Feature oriented methodology is applicable to ALL different

Numerical Models • MOM (Modular Ocean Model)

• POP (Parallel Ocean Program)

• ROMS (Regional Ocean Model System)

• POM (Princeton Ocean Model)

• MIT GCM

• HOPS (Harvard Ocean Prediction System)

• Finite Element / Finite Volume modelsIt is an Initialization and Assimilation Methodology

Strait of Sicily Feature Oriented Regional Modeling Set Up

The Brazil Current System

Meander-eddy-Upwelling System

The Brazil Current Structure

The Hardest Work of All!!

SEC

IWBC

Dynamical Features in BCS• Brazil Current (Surface (0-150m) – 2 branches• Bifurcating SEC around the Abrolhos Bank and

Vitoria ridge – Pycnocline (150-500m))• IWBC + NADW (DWBC)• Cabo Sao Tome eddy• Cabo Frio eddy• Vitoria eddy• Upwelling regions• Instability-generated Vortex dipoles in Santos

Bight• Fresh water influx in the shelf between the coast

and the Brazil Current

Southern CaliforniaCoastalregion

The California Current System

The Pacific basin-scale ROMS configuration at 50-km spatial resolutions will provide the required boundary conditions for the regional ROMS off the U.S. West coast.

Sea surface temperature simulated by ROMS. The 3-level ROMS domains are displayed.

Snapshot of sea surface temperature (left) and surface current (right) simulated by the 1.5-km ROMS. Model 500m, 1000m, 1500m, and 2000m isobaths are displayed (left).

Humboldt Current System

The Peru-Chile Current System

Shallow water feature models

• Use of ‘intelligent observations’ that are important to resolve the scales and represent the underlying dynamical processes

• Not only temperature-salinity structure, but include first-order dynamics

• Process-oriented feature models

Upwelling

• Wind speed and direction at highest available resolution from QuikScat

• Mixed-layer depth estimate from MODIS• Infer the Ekman Current in the Upper Mixed layer• Additional baroclinic currents may be added for

coastally trapped waves or alongshore currents• Monterey Bay in Summer 2003, Vietnamese shelf

in summer 2003, Brazil Current - Cape Frio upwelling region in austral summer 2003.

Transient feature models

• Coastal filaments, jets, squirts and eddies• Automated gradient-detection algorithm (Cayula

and Cornillon, 1995)• Small scales (1-100 km) and short-life (20-40

days)• Spatial and temporal dependence of FM

parameters• Low vs. high chlorophyll regions (Chan, 1999)

CONCLUSIONS

• Developing FORMS is a pre-requisite for Synoptic modeling system

• FORMS is unique for each region

• Shallow water FORMS are very important for accurate prediction of bio-physically active systems

• FORMS is independent of the numerical modeling system (POM, ROMS, MOM, POP, HOPS etc.)

OBJECTIVELY BASED FEATURE MODEL

• Wilkinson basin water masses

• Brooks June 1982 data

• Cluster model of water masses

• EOF vertical analysis

• Feature model of vertical temperature and salinity

Brooks 1982 June survey in Wilkinson Basin

T,S Diagram

CLUSTER MODEL

Distance function

222nnnD dSTF

dcnScnTcn ddSSTT /,/,/ where

Water mass Ellipsoids

Explained Percent Variance

No. of Modes Included

The 1997 PRIMER IV

Field experiment

To-be-analyzed via Cluster-EOF analysis with NRL-Stennis team

Feature tracking in shallow coastal regions

• MODIS instrument on Terra and Aqua

• Resolution ~ 250 meters (1-km globally)

• Temperature precision – 0.3-0.5K

• Navigational accuracy – 50 meters per pixel

• Moving mesh algorithm (Rowley and Ginis, 1999) ; Wavelet approach (Liu et al., 2002)

• Monterey Bay application – PCCS?

MODIS chlorophyll on July 23, 2002 for southern California from Terra (left) at 1815 GMT, and the same field from Aqua (right) at 2115 GMT. A feature-tracking algorithm that uses the chlorophyll field as tracer will deduce the surface currents, which can be assimilated in the Navy’s modeling system. [Courtesy:Ron Vogel, http://www.modis-ocean.gsfc.nasa.gov/whatsnew.html]