A Modeling Study on Flows in the Strait of Hormuz (SOH)

Transcription

1 A Modeling Study on Flows in the Strait of Hormuz (SOH) Peter C Chu & Travis Clem Naval Postgraduate School Monterey, CA 93943, USA IUGG 2007: PS005 Flows and Waves in Straits. July 5-6, Perugia, Italy

2 Geography

3 Current Systems in Arabian Gulf and Gulf of Oman

4 Climatological Winds

5 What are current systems in the Strait of Hormuz?

6 Model Components Atmosphere: Coupled Ocean/Atmosphere Mesoscale Prediction (COAMPS) Non-Hydrostatic 27 km inner nest within 81 km nest Ocean Shallow Water Analysis and Forecast System (SWAFS) Princeton Ocean Model (POM) 2 km resolution Model Integration Period (Six Months) 00UTC 01 Feb 18UTC 31 Jul, 2006

7 Seasonal Variation of Winds

8 SWAFS Based on Princeton Ocean Model Multiple nested domains, 120 processors, passing lateral boundary conditions Assimilates satellite (SSTs, SSHs), in situ (XBTs, CTDs, float CTD) Assimilates elevations from global tide model in deep water Selectively assimilates elevations from coastal tide stations Provides 3-D currents, tides, and T,S

9 SWAFS Computational Domains North World Host 1/4 degree 8km 7km 8km Operational: 95% chance model is adequate to provide product for a specific request Pre-Operational: 70% chance model is adequate to provide product for a specific request Developmental: 20% chance model is adequate to provide product for a specific request April 2003

10 SWAFS Nesting (MPI) North World (1/4 degree) 96 processors Indian Ocean Nest (7 km) 120 processors North Arabian Sea Nest (2km) 120 processors

11 SWAFS - 5-day trajectories Blue: 2 day forecast Red: 3 day hindcast

12 SWAFS Real-time Meteorological Forcing (read.met) Atmospheric Boundary Layer Model (lab12sub) Ice Formation (ice) Tidal Forcing (tides.mod) Temperature /Salinity Climatology Main (Pm3) Turbulent closure sub-model (profg, advg) Vertical Diffusion (proft, profg, profu, profv) Advection & Hor diffusion (advt., advg, advu, advv, advavc) River Flow Information Nesting Routines External mode mode (external.mode) Boundary Conditions (bcond) Heat Fluxes (evapor) MPI Routines Bathymetry IO routines -- Core POM Components Visualization Disspla GMT Vis5d MCSSTs Data Assimlation (mcsst.mod, profile.mod) Residuals convariances Tidal amplitude/ phases Model testing GOODS (drifters. bts, ctds) GOODS (BTs, CTDs, palace floats) Altimetry Synthetics Current Meters ADCP

13 Data Assimilation for SWAFS Circulation Model GAC, LAC SSTs MCSST Analysis (OI) Temp Profile Analysis (OI) Salinity Profile Analysis (OI) Near-Surface Assimilation relaxation relaxation Sub-Surface Assimilation Forecast Model (SWAFS) Tides BTs, CTDs (mostly ARGO) Synthetic CTDs (under altim tracks) Lateral Boundary Conditions Met Fluxes Altimetry SSTs, Climatology V-Regressions MODAS-3D SWAFS, G-NCOM NOGAPS- COAMPS Blend

14 SWAFS Assimilation of Observed and Synthetic T,S Profiles for 3 day run Yesterdays SWAFS Run First guess Today s SWAFS Run Relax obs Relax obs Age of Obs Relax obs Same Obs but different time correlations

15 Mean Currents (Feb-Jul, 2006) Multi-Eddy Structure 27.5 o N Mean Flow in SOH Feb Jul cm/s Vector Scale 27 o N 20 cm/s Latitude 26.5 o N 26 o N 25.5 o N 25 o N 55 o E 55.5 o E 56 o E 56.5 o E 57 o E Longitude

16 Monthly Mean Currents (Vector Scale 20 cm/s) 27.5 o N Feb Mean Flow in SOH Feb cm/s 27.5 o N Mar Mean Flow in SOH Mar cm/s 27.5 o N Apr Mean Flow in SOH Apr cm/s 27 o N 27 o N 27 o N Latitude 26.5 o N 26 o N Latitude 26.5 o N 26 o N Latitude 26.5 o N 26 o N 25.5 o N 25.5 o N 25.5 o N 25 o N 55 o E 55.5 o E 56 o E 56.5 o E 57 o E Longitude May 25 o N 55 o E 55.5 o E 56 o E 56.5 o E 57 o E Jun Longitude 25 o N 55 o E 55.5 o E 56 o E 56.5 o E 57 o E Jul Longitude Mean Flow in SOH May o N 20cm/s 27.5 o N Mean Flow in SOH Jun cm/s 27.5 o N Mean Flow in SOH Jul cm/s 27 o N 27 o N 27 o N Latitude 26.5 o N 26 o N Latitude 26.5 o N 26 o N Latitude 26.5 o N 26 o N 25.5 o N 25.5 o N 25.5 o N 25 o N 55 o E 55.5 o E 56 o E 56.5 o E 57 o E Longitude 25 o N 55 o E 55.5 o E 56 o E 56.5 o E 57 o E Longitude 25 o N 55 o E 55.5 o E 56 o E 56.5 o E 57 o E Longitude

17 Complex EOF Variance EOF Percentage of Variance Cumulative Percentage of Variance % 18.08% 10.56% 6.70% 36.11% 54.19% 64.75% 71.45%

18 EOF-1 Vector Scale: cm/s Maximum tidal current speed ~1.5 m/s EOF -1 is primarily tidal influence and includes semidiurnal, diurnal, as well as spring/neap tidal constituents.

19 EOF -2 is mostly diurnal and spring/neap influenced but does have some semidiurnal influence. EOF-2

20 EOF -3 is affected by the semidiurnal tidal cycle as well as the effects of the eddy from the GOO. EOF-3

21 EOF-4 is also affected by the semidiurnal tidal cycle and is related to the onset and retreat of the GOO eddy. EOF-4

22 Conclusions Multi-eddy structure exists in the Trait of Hormuz. Tidal currents dominate the Strait of Hormuz. This model is coupled to a chemical spill model