A QUASIGLOBAL CONFIGURATION OF ROMS OR TOWARDS GOMS

A QUASI-GLOBAL CONFIGURATION OF ROMS (OR, TOWARDS GOMS? ) 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 etopo 2. ●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).

Organization 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 Nino 3. 4 Planned applications

Scaling 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~ Ah 0 (dx/dx 0)**3 cos(φ)cos(φ0) (3) where the subindex 0 marks the latitude, and viscosity of the largest grid size in the domain (dx 0). In practice: Obtain Ah 0 from (2) (i. e. , for the largest grid size), and then obtain the rest using (3).

Minimum Viscosity Coeff. (visc 2) vs. Latitude Ah=Ah(φ, dx)

MODEL's TOTAL KINETIC ENERGY vs. TIME

Gulf Stream, Antilles Curr. , Loop Current & Labrador Curr. ROMS MGSVA

Kuroshio, Oyashio, Liman, Tsuchiya & Tsugaru Currents

Malvinas-Brasil Confluence Area summer winter from MGSVA

TROPICAL PACIFIC CURRENTS AND SST

Tropical Instability Waves

Across-equator zonal velocity profiles (152°W – Hawaii-Tahiti transect) From Johnson & Luther (1994) current meter data ROMS

150 m Winter Flows off California Surface

STRAIT OF GIBRALTAR Mean speed from ROMS Mean speed from obs (ADCP)

Guinea, Equatorial and Angola Currents MGVSA

TRANSPORT THROUGH DRAKE PASSAGE Malvinas Whitworth & Peterson (1985)(*)=134 13 Sv Various ACDP estimates from the Univ. of Southampton=94 Sv-155 Sv ROMS: 128 Sv

ANTARCTIC CIRCUMPOLAR CURRENT

(from L. Talley, SIO) Global ROMS Global Salinity Minimum

SEA LEVEL COMPARISON AT SAN FRANCISCO

CLIMATIC INDEXES FROM 56 -y RUN: PDO and NIÑO 3. 4 Corr=0. 67; Coherence for 25 y harmonic: 0. 91 (10° phase) Corr=0. 73; Coherence for 4 y harmonic=0. 78 (ampl=0. 7 & phase =7°)

Planned 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. , Nino 3. 4 index). Include sea-ice. (*) underway