An Unstructured Grid, Finite-Volume Coastal Ocean Model (FVCOM), Global-Regional-Coastal-Estuarine Applications

Robert C. Beardsley, Changsheng Chen and Geoffrey Cowles

http://fvcom.smast.umassd.edu

Outline

1. Introduction to FVCOM 2. Multiscale applications3. Northeastern Regional Association of Coastal

Ocean Observing Systems (NERACOOS) - Northeast Coastal Ocean Forecast System (NECOFS) - Inundation Pilot Study (with NWS) (Scituate, MA; Saco, ME) - Water Quality (DO) (Long Island Sound) - Observing system design experiments4. Recent FVCOM developments5. NECOFS needs6. Summary

Critical Issues in Coastal Ocean Modeling

Irregular geometry

Intertidal wetlands

Steep topography

Mass Conservation ?

FEM

AreaCdyfdxdyx

f*

FVM

0)ˆ

(

Cx

fwl

fx

C

Finite-Difference, Finite-Element and Finite-Volume Methods (FDM, FEM, FVM)

FDM

Cx

ff

x

f ii

1

i+1

i

x

Difference Variation Integration

FVCOM: Unstructured-grid, Finite-Volume Coastal Ocean Model (Chen, C. R. H. Liu and R. C. Beardsley, JAOT, 2003)

• All variables are computed in the integral form of the equations, which provides a better representation of the conservative laws of mass, momentum and heat in the coastal region with complex geometry.

•The numerical computational domain consists of non-overlapping unstructured cells.

• Combines the best from the finite-element method for the geometric flexibility and finite difference method for the simplest discrete computation.

• Both current and tracer remain the second-order accuracy.

u,v

u,v

u,v

u,v

u,v

u,vF

FF

F

F F

F

etcKKHSTF hm ,,,,,,,:

y

u,v

u,v u,v

u,v

Upgrading: non-hydrostatic version and semi-implicit version

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Pan-Arctic Ocean FVCOM

In the region where the mean water is deeper or equal to 100 m, 10 same thickness layers in the upper 30 m (with a layer thickness from 2 to 5 m) and 5 same thickness layers in the lower 25 m above the bottom.

Driven by the OMIP-Forcing-the sixth version and the model starts run at January 1 with the wintertime fields of water temperature and salinity.

The water temperature and salinity data were from polar science center Hydrographic Climatology (PHC) version 3.0.

The region north of 65oN is covered by the ice with a thickness of 2.5 m everywhere at initial

•Horizontal resolution: 0.3-1.0 km in the coastal region;•Generalized terrain-following coordinates: 46 layers: 10 uniform layers in the surface and bottom boundary layers, respectively.•1500 m cutoff off Georges Bank•Capable to nest to the coasta-estuarine model with a horizontal resolution of ~10 -500 m;

Penobscot Bay

Boston harbor area

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Northeast Coastal Ocean Forecast System (NECOFS)

Group Model Source Nesting Output Output Online

Stony Brook U WRF-ARW1

32-km NAM 1-deg

NOGAPS1-deg CMC0.5

deg GFS

32-km12-km (R)

4-km (NAM member)

2-day@ 1-hr

1.5-day for 4-km

Basic, ASF, RF

Y

Stony Brook U MM5 Same as WRF-ARW

32-km12-km (R)

4-km (NAM member)

2-day@ 1-hr

1.5-day for 4-km

Basic, ASF, RF

Y

UMassD MM5 32-km NAM 30 km10-km (R)

3-day@3-hr

Basic, ASF, RF

Y

UMassD WRF-ARW1

same 32-km9-km (R)3-km (L)

3-day@3-hr

Basic, ASF, RF

Y

UNH-AER ARW-WRF1

32-km NAM 27-km9-km (R)3-km (L)

2-day @6-hr

Basic, ASF, RF

Y3

UMaine - 12-km NAM - 2-day@6-hr

Basic, ASF2 Y

URLs:Stony Brook U: http://atmos.msrc.sunysb.edu/mm5rtStony Brook U: http://chaos.msrc.sunysb.edu/NEUS/nwp_graphics.htmlUMassD: http://fvcom.smast.umassd.edu/research_projects/GB/mm5/index.htmlUMassD: http://fvcom.smast.umassd.edu/research_projects/GB/WRF/index.htmlUNH-AER: http://www.jcoot.unh.edu/forecasts/forecasts.htmlUMaine: - http://www.gomoos.org/

NE Weather Models being used to drive ocean models

Regional Domain: 9 km Large domain: 27 km

Domain 1

Domain 2

Domain 2

Domain 3

Domain 3

Local domain: 3 km

Hindcast

NECOFS Model Flow Diagram: 1.0

Stage: 1 (midnight)Crontab starts NECOFS

wrf forecast data

wrf hindcast data

fvcom data (results)

river data

sst data

Day# -10 -5 -4 -3 -2 -1 0 1 2 3

Day 0 ~ now

Current Process1:2:3:

(Previous Hindcast)

(Previous Forecast)

NECOFS Model Flow Diagram: 1.0

Stage: 2 (midnight)Update River Data

wrf forecast data

wrf hindcast data

fvcom data (results)

river data

sst data (Previous Forecast)

Day# -10 -5 -4 -3 -2 -1 0 1 2 3

Current Process1: Download USGS data and update data file2:3:

(Previous Hindcast)

NECOFS Model Flow Diagram: 1.0

Stage: 3 (00:10)Update SST Data

wrf forecast data

wrf hindcast data

fvcom data (results)

river data

sst data

Day# -10 -5 -4 -3 -2 -1 0 1 2 3

Current Process1: Download JPL SST and update OI assim2:3:

S 2

(Previous Forecast)

(Previous Hindcast)

Latest available SST data is already several days old

NECOFS Model Flow Diagram: 1.0

Stage: 4 (00:15)Run WRF

wrf forecast data

wrf hindcast data

fvcom data (results)

river data

sst data

Day# -10 -5 -4 -3 -2 -1 0 1 2 3

Current Process1: WRF Forecast2: WRF Hindcast3:

S 2

S 3

Continuous WRF data archive is automatically updated with new results

(Previous Hindcast)

(Previous Forecast)

NECOFS Model Flow Diagram: 1.0

Stage: 5 (08:00)Start FVCOM hindcast

wrf forecast data

wrf hindcast data

fvcom data (results)

river data

sst data

Day# -10 -5 -4 -3 -2 -1 0 1 2 3

Current Process1: WRF Forecast2: FVCOM Hindcast3:

S 2

S 3

FVCOM overwrites old results updating time period of new WRF data.

S 4

(Still running)

(Previous Hindcast)

(Previous Forecast)

NECOFS Model Flow Diagram: 1.0

Stage: 6 (11:00)Start FVCOM Forecast

wrf forecast data

wrf hindcast data

fvcom data (results)

river data

sst data

Day# -10 -5 -4 -3 -2 -1 0 1 2 3

Current Process1: FVCOM Forecast2:3:

S 2

S 3

S 4

S 5

S 5

(Previous Hindcast)

(Previous Forecast)

FVCOM forecast runs till end of available WRF data

NECOFS Model Flow Diagram: 1.0

Stage: 7 (12:00)NECOFS Forecast Finished!

wrf forecast data

wrf hindcast data

fvcom data (results)

river data

sst data

Day# -10 -5 -4 -3 -2 -1 0 1 2 3

Current Process1:2:3:

S 2

S 3

S 4

S 5

S 5 S 6

New Results are Automatically posted to the web site!

(Previous Hindcast)

(Previous Forecast)

http://fvcom.smast.umassd.edu

Recent Developments 1. Unstructured-grid finite-volume version of CICE

model (CICE-ug) – (for Arctic Ocean applications)

2. Unstructured-grid finite-volume version of SWAN (ug-SWAN)

3. Non-hydrostatic version of FVCOM (NH-FVCOM) (uses parallelized scalable sparse matrix solver library (PETSc) and high performance pre-conditional HYPRE software library)

4. Semi-implicit version of FVCOM (significant speed-up factor of ~10-20)

NECOFS Needs

1. Surface atmospheric forcing:

- Basic: winds, Ta, RH, Pa, P, SST, SW & LW radiation, PAR

- Derived: wind stress, heat flux (Qsw,Qlw,Qsen,Qlat), P-E

[ARW; COARE3; AVHRR, ISCCP, FLASHFlux (?)]

2. Boundary conditions for regional coastal ocean model from basin/global models: surface waves [WAVEWATCH]; surface elevation, T,S, currents, …[…..]

3. Coastal boundary conditions: watershed flux of water and nutrients into coastal ocean via surface discharge and groundwater [USGS, UNH NE watershed model system]

Summary

1.Unstructured-grid finite-volume model (FVCOM) system provides a new community tool to nest global-regional-coastal-estuarine system together, suitable for ocean application, particularly for coastal environmental hindcast/forecast and ecosystem research.

2.NECOFS are in operation, for more information, visit FVCOM website:

http://fvcom.smast.umassd.edu