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Using IS4DVAR Data Assimilation in the near coastal modeling system

Using IS4DVAR Data Assimilation in the near coastal modeling system. Ivica Janeković & Brian Powell. #ifdef LAYOUT. Region of interest, domain, bathymetry Forward model setup IS4DVAR setup TLM validation Problems on the way Results & discussion

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Using IS4DVAR Data Assimilation in the near coastal modeling system

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  1. Using IS4DVAR Data Assimilation in the near coastal modeling system Ivica Janeković & Brian Powell

  2. #ifdef LAYOUT • Region of interest, domain, bathymetry • Forward model setup • IS4DVAR setup • TLM validation • Problems on the way • Results & discussion • Preliminary results – still running, suggestions are welcome

  3. Domain • Hawaiian Islands -> challenge for model skill • Complex bathymetry, forcing, boundary… • Hawaiian Ridge – major barotropic to baroclinic tidal conversion site -> Kaena Ridge, Niihau-Maui • Coastal dynamics in shallow/slope region on high resolution model for transport study of ordnance • We used nested approach from 2 model grids above • 4 km Hawaiian Islands Grid • -> 1.2 km Oahu-Maui Grid • -> 200 - 900 m Western Oahu Grid • Our focus is Western Oahu region & DA • 5 ADCP observations at “nice position” (07/09-07/10) • SST data from MODIS T/A

  4. Kauai Kaena Ridge Niihau

  5. (59,35) 33 km 12 km ADCP West Oahu Grid

  6. Bathymetry transect ADCP

  7. Forward model setup • We used hi-res bathymetry + LP smoothing • variable rx0 smoothing, iterative way, many grids… • 20 vertical levels (on the edge with rx1(!)) • increased number of levels in surface zone -> Θ_s= 7, Θ _b= 0.1 • vtransform, vstretching = 2 • variable resolution, in region where we have ADCPs (~200m) while at boundary ~900m (outer grid 1.2km) • Spin-up from 2004 - 2009 using: • forcing with local MM5 (1.5km), WRF (1.5km) • boundary from HIOG (1.2km outer model), tides inside • Model setup using: • U3 for advection, GLS - gen, IS4DVAR, small diffusion and viscosity, clamped BC,… • Forward model is doing well with tides • dominantly tidally driven (barotropic/baroclinic) • we want to improve circulation & phase

  8. IS4DVAR setup • in the beginning 40, 30, 20 inner loops, 1 outer loop • time window of 3 days (based on init and MTLM) • clamped boundary conditions • adjust initial filed + atmo. forcing, NO BRY ADJUSTMENT • OBS: • ADCPs (1 2 3 4) • discarded at the bottom • model/obs depths doesn’t match, bottom layer?! • ADCP 2 out of phase • SSH (1 2 3 4) • de-mean, added model mean value, nr. 2 faulty • MODIS T/A SST • not many data, proximity to coast, small domain • small grid (tiles), short time step of 60s (ncpu?) • small de-correlation scale (patchy fields) • run experiments with: • using only ADCPs • using ADCPs + SSH • using ADCPs + SSH + MODIS SST

  9. NLM-TLM approximation • In order to check validity of TLM approx: • we made inside domain perturbation (“wrong” SST) • run MTLM (10 inner loops) • used 40 (Modified Gram-Schmidt ortho-normalized) perturbations in init field for all state variables • horizontal de-correlation scale set to 3 km • run TLM and NLM (40 members) • correlation (NLM,TLM) for all state variables • system is OK for 5 days, high correlation (>0.6) • mixing in the 1st time step for salt, unstable perturbs • mostly driven by atmo and boundary forcing

  10. Effect of init field inside NLM • we run NLM from day_0 (1st of Nov 2009) using: • real BC, atmo. forcing and initial field • -> state_0 • we run NLM as before but with: • initial field randomly picked (Jun 2009) and then only “changed” ocean_time = day_0 • -> state_1 • compute correlation btw state_0 & state_1 for all state variables in time • After 2-3 days information in init field is swept away by BC and atmo forcing, correlation is round 1. • This have us interval how frequent we should assimilate

  11. correlation (state_0, state_1)

  12. Results/disscusion • If only looking at the ADCPs locations • all seems perfect, high correlation (~0.7 - 0.8) • What is really happening? • We do have high dimensionality case with small number of obs -> constraint • We made experiments gradually adding obs to see how it affects solutions and constraints • Did we corrected/destroyed baroclinic tides? • What happened to density filed in whole domain?

  13. Exp 1: ADCPs only

  14. Exp 1: ADCPs only

  15. Exp 1: ADCPs only

  16. Exp 1: ADCPs only ADCP 1 Correlation/STD depth U0 UA V0 VA -53.4 0.68/0.17 0.72/0.15 -0.60/0.15 -0.57/0.15 -45.4 0.70/0.18 0.75/0.16 -0.49/0.12 -0.44/0.12 -37.4 0.70/0.19 0.76/0.16 -0.38/0.11 -0.27/0.11 -29.4 0.71/0.19 0.77/0.16 -0.32/0.11 -0.18/0.10 -21.4 0.72/0.19 0.78/0.16 -0.31/0.10 -0.17/0.10 -13.4 0.71/0.20 0.77/0.17 -0.25/0.11 -0.21/0.11 ADCP 3 Correlation/STD depth U0 UA V0 VA -9.9 0.70/0.16 0.78/0.13 0.27/0.04 0.26/0.04 -8.4 0.71/0.16 0.78/0.13 0.27/0.04 0.26/0.04 -6.9 0.71/0.16 0.79/0.13 0.25/0.04 0.25/0.04 -5.4 0.70/0.16 0.79/0.13 0.23/0.04 0.23/0.05 -4.2 0.70/0.16 0.78/0.13 0.21/0.04 0.22/0.05 ADCP 4 Correlation/STD depth U0 UA V0 VA -5.9 0.56/0.21 0.64/0.18 -0.18/0.07 -0.14/0.08 -3.2 0.56/0.21 0.64/0.19 -0.09/0.08 -0.12/0.09

  17. Exp 2: ADCPs + SSH

  18. Exp 2: ADCPs + SSH

  19. Exp 2: ADCPs + SSH

  20. Exp 2: ADCPs + SSH ADCP 1 Correlation/STD depth U0 UA V0 VA -53.4 0.68/0.17 0.72/0.15 -0.60/0.15 -0.58/0.15 -45.4 0.69/0.18 0.75/0.16 -0.49/0.12 -0.46/0.13 -37.4 0.70/0.19 0.76/0.16 -0.36/0.11 -0.30/0.11 -29.4 0.71/0.19 0.77/0.16 -0.30/0.11 -0.20/0.10 -21.4 0.71/0.19 0.77/0.16 -0.29/0.10 -0.16/0.10 -13.4 0.71/0.20 0.77/0.17 -0.25/0.11 -0.13/0.10 ADCP 3 Correlation/STD depth U0 UA V0 VA -9.9 0.71/0.16 0.77/0.14 0.27/0.04 0.27/0.04 -8.4 0.71/0.16 0.78/0.13 0.26/0.04 0.25/0.04 -6.9 0.71/0.16 0.78/0.13 0.24/0.04 0.24/0.04 -5.4 0.71/0.16 0.78/0.13 0.23/0.04 0.23/0.05 -4.2 0.70/0.16 0.78/0.14 0.21/0.04 0.22/0.05 ADCP 4 Correlation/STD depth U0 UA V0 VA -5.9 0.56/0.21 0.64/0.18 -0.19/0.07 -0.17/0.08 -3.2 0.56/0.21 0.64/0.19 -0.09/0.08 -0.15/0.09

  21. Exp 3: ADCPs + SSH + SST

  22. Exp 3: ADCPs + SSH + SST

  23. Exp 3: ADCPs + SSH + SST

  24. Exp 3: ADCPs + SSH + SST

  25. Exp 3: ADCPs + SSH + SST

  26. Exp 3: ADCPs + SSH + SST ADCP 1 Correlation/STD depth U0 UA V0 VA -53.4 0.68/0.17 0.71/0.16 -0.61/0.14 -0.58/0.15 -45.4 0.69/0.18 0.74/0.16 -0.50/0.12 -0.45/0.12 -37.4 0.69/0.19 0.75/0.16 -0.39/0.11 -0.29/0.11 -29.4 0.70/0.20 0.76/0.16 -0.33/0.10 -0.19/0.10 -21.4 0.71/0.20 0.77/0.17 -0.32/0.10 -0.18/0.10 -13.4 0.70/0.20 0.76/0.17 -0.27/0.11 -0.17/0.10 ADCP 3 Correlation/STD depth U0 UA V0 VA -9.9 0.70/0.16 0.78/0.13 0.28/0.04 0.31/0.04 -8.4 0.71/0.16 0.78/0.13 0.29/0.04 0.30/0.04 -6.9 0.71/0.16 0.78/0.14 0.27/0.04 0.29/0.04 -5.4 0.70/0.16 0.78/0.14 0.25/0.04 0.26/0.04 -4.2 0.70/0.16 0.78/0.14 0.23/0.04 0.24/0.05 ADCP 4 Correlation/STD depth U0 UA V0 VA -5.9 0.55/0.21 0.63/0.18 -0.20/0.07 -0.15/0.08 -3.2 0.55/0.22 0.63/0.19 -0.11/0.08 -0.13/0.09 Corr(ssh_obs,ssh_nlm_0)=0.75 Corr(ssh_obs,ssh_nlm_0)=0.75 Corr(SST_obs,SST_nlm_0)=0.69 Corr(SST_obs,SST_nlm_1)=0.70

  27. Still work in progress • All indicates that the key is to fix outer model as much as possible (use DA) in order to get right BC • Right now we are only adjusting atmo+initial • We do need to perform observation sensitivity • How sensitive is our system to ADCP obs? • Ek vs Ep inside model • Impact studies • Overlapping could help to avoid shocks • Would W4DVAR help?

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