a quasi-global configuration of roms (or, towards goms ?) guillermo auad & art miller (crd/sio)
DESCRIPTION
A QUASI-GLOBAL CONFIGURATION OF ROMS (OR, TOWARDS GOMS ?) Guillermo Auad & Art Miller (CRD/SIO) Grid features : zonal resolution : 0.8 º (fixed); meridional resolution : 0.3 to 0.7º (slowing varying: ∆ resolution < 1.5% ); vertical resolution : 20 levels. - PowerPoint PPT PresentationTRANSCRIPT
A QUASI-GLOBAL CONFIGURATION OF ROMS (OR, TOWARDS A QUASI-GLOBAL CONFIGURATION OF ROMS (OR, TOWARDS GOMSGOMS?)?)
Guillermo Auad & Art Miller (CRD/SIO)Guillermo Auad & Art Miller (CRD/SIO)
Grid features:
●zonal resolution: 0.8º (fixed); meridional resolution: 0.3 to 0.7º (slowing varying: ∆resolution < 1.5%); vertical resolution: 20 levels.●Includes: fixed Iceshelf, topography from etopo2.●Zonal walls at 80º (N & S). ●E-W periodic condition used at longitude 180º.
Runs carried out so far:
1.- Spin up climatological run from rest and Levitus T-S. (60-year long) driven by NCEP/NCAR reanalysis wind stresses and heat fluxes. 2.- 56-year long hindcast run (i.e., climat. + anomalous winds and heat fluxes), from 1948 to 2003 (finished a few days ago).
OrganizationOrganization
A minor code adaptation
Spin up of the model's total kinetic energy
Model output: main ocean currents of the World
A tough test: coastal flows
A tougher test: representation of a water mass: NPIW
2 climatic indexes in the Pacific Ocean: PDO and Nino3.4
Planned applications
Scaling of horizontal viscosity coefficientScaling of horizontal viscosity coefficient
goal: for each grid cell to proportionally (to its grid size) contribute potential vorticity to western boundary layers.
ß ψx ~ Ah ψxxxx (1)
but since Ah needs to satisfy a minimum value in order to yield realistic solutions (Bryan, Manabe and Pacanowski, 1975):
Ah> 0.17 * ß* dx³ (2)
from (1) and (2) we can scale Ah as
Ah~ Ah0 (dx/dx0)**3 cos(φ)cos(φ0) (3)
where the subindex 0 marks the latitude, and viscosity of the largest grid size in the domain (dx0).
In practice: Obtain Ah0 from (2) (i.e., for the largest grid size), and then obtain the restusing (3).
Minimum Viscosity Coeff. (visc2) vs. LatitudeMinimum Viscosity Coeff. (visc2) vs. Latitude
Ah=Ah(φ,dx)
MODEL's TOTAL KINETIC ENERGY vs. TIMEMODEL's TOTAL KINETIC ENERGY vs. TIME
ROMSMGSVA
Gulf Stream, Antilles Curr.,Gulf Stream, Antilles Curr.,Loop Current & Labrador Curr.Loop Current & Labrador Curr.
Kuroshio, Oyashio, Liman, Tsuchiya & Tsugaru CurrentsKuroshio, Oyashio, Liman, Tsuchiya & Tsugaru Currents
from MGSVA
Malvinas-Brasil Confluence AreaMalvinas-Brasil Confluence Areasummer winter
TROPICAL PACIFIC CURRENTS AND SSTTROPICAL PACIFIC CURRENTS AND SST
Tropical Instability WavesTropical Instability Waves
Across-equator zonal velocity profilesAcross-equator zonal velocity profiles(152(152°W – Hawaii-Tahiti transect)°W – Hawaii-Tahiti transect)
From Johnson & Luther (1994) -current meter data
ROMS
150 m
Surface
Winter Flows Winter Flows off Californiaoff California
STRAIT OF GIBRALTARSTRAIT OF GIBRALTAR
Mean speed from ROMS
Mean speed fromobs (ADCP)
Guinea, Equatorial and Angola CurrentsGuinea, Equatorial and Angola Currents
MGVSA
TRANSPORT THROUGH DRAKE PASSAGETRANSPORT THROUGH DRAKE PASSAGE
Malvinas
Whitworth & Peterson (1985)(*)=134 13Sv
Various ACDP estimates from theUniv. of Southampton=94Sv-155Sv
ROMS: 128 Sv
ANTARCTIC CIRCUMPOLAR CURRENTANTARCTIC CIRCUMPOLAR CURRENT
(from L. Talley, SIO)
Global Salinity Minimum
Global ROMS
SEA LEVEL COMPARISON AT SAN FRANCISCOSEA LEVEL COMPARISON AT SAN FRANCISCO
CLIMATIC INDEXES FROM 56-y RUN:CLIMATIC INDEXES FROM 56-y RUN:PDO and NIPDO and NIÑO3.4ÑO3.4
Corr=0.67; Coherence for 25y harmonic: 0.91 (10° phase)
Corr=0.73; Coherence for 4y harmonic=0.78 (ampl=0.7 & phase =7°)
Planned Applications of the Global ROMSPlanned Applications of the Global ROMS
Couple “GOMS” to an atmospheric model (ECPC fcsts) Use its output (climat & hincdast) as OBCs in regional models (a few latin
american scientists are interested in this)Sea level (*)& climatic studies. Studies on water mass formation (NPIW and Ross Sea area)
Future runs/planned improvements: Filter forcing with Killworth's matrix to obtain more realistic amplitudes (*)
(e.g., Nino3.4 index). Include sea-ice.
(*) underway