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Air/Ocean Coupled Prediction Systems at NRL MRY

Air/Ocean Coupled Prediction Systems at NRL MRY. Richard M. Hodur Naval Research Laboratory Monterey, CA 8th HYCOM Workshop 19-21 August 2003 Camp Springs, MD. Air/Ocean Coupled Prediction Systems at NRL MRY Outline. Global Air/Ocean Coupled Modeling: NOGAPS/POP

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Air/Ocean Coupled Prediction Systems at NRL MRY

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  1. Air/Ocean Coupled Prediction Systems at NRL MRY Richard M. Hodur Naval Research Laboratory Monterey, CA 8th HYCOM Workshop 19-21 August 2003 Camp Springs, MD

  2. Air/Ocean Coupled Prediction Systems at NRL MRY Outline • Global Air/Ocean Coupled Modeling: • NOGAPS/POP • Validation of one-way coupled system • Development of two-way coupled system • Mesoscale Air/Ocean Coupled Modeling: • COAMPS/NCOM • Focus on Mediterranean: • Adriatic Circulation Experiment • Real-Time Testbed • Summary/Plans

  3. NOGAPS Navy Operational Global Atmospheric Prediction System • Complex Data Quality Control • Atmospheric Analysis: • Multivariate Optimum Interpolation Analysis (MVOI) of Winds and Heights • Univariate Analysis of Moisture • Ocean Analysis: • 2D Optimum Interpolation Analysis of SST • 3D Ocean MVOI of T, S, SSH, Sea Ice, and Currents • Nonlinear, Normal Mode Initialization • Hydrostatic, Spectral Atmospheric Model: • Cumulus Parameterization (Emanuel, MWR 1999) • Shallow Cumulus Parameterization (Tiedtke, ECMWF Report 1984) • PBL Parameterization (Louis, BLM 1982) • Radiation Parameterization (Harshvardhan et. al., JGR 1987) • Convective and Stratiform Cloud Parameterization (Teixeira and Hogan, JC 2002) • Gravity Wave Drag (Palmer et. al., QJRMS 1986) • Parallel Ocean Program (POP) Ocean Model • Features: • Over 16,000 Operational Forecasts run at FNMOC • 6 Hour Incremental Data Assimilation Cycle • Current Operational Resolution: T239 (~55 km), 30 Vertical Levels • Approximately 11 minutes/forecast day wall time using 120 O3K processors • Track Forecasts for all Tropical Cyclones w/max wind > 50 knots • Supplies Boundary Conditions to Mesoscale and Wave Models

  4. T, q, v NAVDAS NOGAPS Fluxes, Stresses SST T, S, v Ocean MVOI Ocean Model (POP) Fully Coupled NOGAPSAir-Ocean with Data Assimilation/Forecast Cycle MVOI: Multivariate Optimum Interpolation Analysis POP: Parallel Ocean Prediction Model

  5. Analysis-only produces significant errors in coastal boundary currents Reduced errors demonstrate importance of model to data assimilation NOGAPS/POP Coupled Modeling Comparison of Average 5 m Temperature Analysis Error Correction (Top) with Forecast Model Correction (Bottom) for August 2000

  6. SST RMS Forecast Statistics for CY 2002 NOGAPS/POP Coupled Modeling NOGAPS/MVOI/POP Results: SST RMS Errors, Forecast vs Persistence POP: 1/2 degree, 75S-75N, NOGAPS T159 Forcing

  7. Plots are for calendar year 2002 POP model run without assimilating SSH POP model was able to simulate SSH variability in many regions. Direct assimilation of SSH is expected to improve results. NOGAPS/Coupled Models Transition Status Comparison of Modeled (Top) and Observed (Bottom) SSH Variability

  8. Coupled Mesoscale Modeling of the Atmosphere and Ocean • Approach • Utilize existing mesoscale atmosphere and ocean data assimilation systems: • Atmospheric data assimilation system in the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS™) • 3-dimensional ocean multivariate optimum interpolation analysis (3D OMVOI) • NRL Coastal Ocean Model (NCOM) • Initial tests of the coupled system: Focus on the Mediterranean Sea • Active meteorologically and oceanographically • Navy relevance • Minimizes need for lateral boundary conditions for ocean model COAMPSTM is a trademark of the Naval Research Laboratory

  9. COAMPS™ Coupled Ocean/Atmosphere Mesoscale Prediction System • Complex Data Quality Control • Analysis: • Atmosphere: MVOI of u, v, and Heights; Univariate of T, q • Ocean: 2D SST; 3D MVOI of T, S, SSH, Sea Ice, and Currents • Initialization: • Atmosphere: Hydrostatic Constraint on Analysis Increments, or Digital Filter • Ocean: Stability check • Model: • Atmosphere: • Numerics: Nonhydrostatic, Scheme C, Nested Grids, Sigma-z, Flexible Lateral BCs • Parameterizations: PBL, Convection, Explicit Moist Physics, Radiation, Surface Layer • Ocean:Navy Coastal Ocean Model (NCOM) • Numerics: Hydrostatic, Scheme C, Nested Grids, Hybrid Sigma/z • Parameterizations: Mellor-Yamada 2.5 • Features: • Globally Relocatable (5 Map Projections) • User-Defined Grid Resolutions, Dimensions, and Number of Nested/Parent Grids • Incremental Data Assimilation; Atmosphere - 6 or 12 hours; Ocean - 12 or 24 hours • Applicable for Idealized or Real-Time Applications • Single Configuration Managed System for All Applications • Operations (Atmospheric Components plus 2D SST Analysis): • FNMOC: 8 Areas, 4 runs/day, grid spacing as low as 6 km, forecasts to 72 hours • Navy Regional Centers: 2 runs/day, grid spacing as low as 3 km, forecasts to 48 hours COAMPS is a registered trademark of the Naval Research Laboratory

  10. Preprocessing and MVOI Analysis Initialization and Forecast QC Atmosphere Preprocessing and OMVOI Analysis Initialization and Forecast QC Ocean Existing Future COAMPS™ Coupled Ocean/Atmosphere Mesoscale Prediction System COAMPS is a registered trademark of the Naval Research Laboratory

  11. NOGAPS Fields Observations Observations Observations Analysis NOGAPS BC’s COAMPS 24 h Forecast COAMPS 24 h Forecast COAMPS 24 h Forecast 12h fcst Analysis NOGAPS BC’s 12h fcst NOGAPS BC’s Analysis 12h fcst Atmospheric Reanalyses Purpose: Generate high-resolution fields for forcing NCOM • Cold start at first analysis time • 12 h incremental data assimilation cycle • Hourly output from forecast model • Analysis include SST analysis for each grid Result: Hourly surface forcing fields for extended time periods

  12. Atmospheric Reanalyses Average 10 m winds for Oct 98 using Data Assimilation and Cold Starts with 27 km Resolution Hours 0-11 of all forecasts used Results indicate that horizontal resolution is important to capture gap flow and other surface-forced events correctly 10 81 km Wind Speed (m/s) 5 0 27 km

  13. Atmospheric Reanalyses Average 10 m winds for Oct 98 using hourly output from 27 km grid Hours 0-11 of all forecasts used Results indicate that data assimilation reduces model spin-up as evidenced by stronger winds in gap flow regions and along coastlines 10 Data Assimilation Wind Speed (m/s) 5 0 Cold Start

  14. Atmosphere: • Bora: Strong, localized northeasterly winds around Istrian peninsula • Scirocco: Strong, warm southeast winds • Ocean: • Cyclonic cells in the central and southern regions • River runoff and strong winds create large variability in the northern Adriatic Po River Bora Ocean-Atmosphere Nested Modeling of the Adriatic Sea during Winter and Spring 2001 Meteorology and Oceanography in the Adriatic

  15. Momentum, Heat fluxes Momentum, Heat fluxes Ocean-Atmosphere Nested Modeling of the Adriatic Sea during Winter and Spring 2001 Design of Experiment • Objectives • Simulate Adriatic atmospheric and oceanic circulation at high resolution • Document and understand response of the shallow northern Adriatic waters to forcing by the Bora and Po river run-off • Quantify the effects of coupling (e.g., one-way, two-way, frequency, resolution) on atmosphere and ocean forecasts • Aid in planning and interpreting Adriatic Circulation Experiment (ACE) observations 1. Generate 27 km atmospheric forcing fields over the Med 2. Generate 6 km, 2-year spin-up of the Med using forcing from #1, then 12-hour data assimilation for October 1999 3. Generate 4 km atmospheric forcing fields over the Adriatic Sea 4. Generate 2 km Adriatic forecasts using initial conditions and inflow from #2, and atmospheric forcing from #3, 1/28/01-6/4/01 81 km COAMPSTM 36 km COAMPSTM 27 km 12 km 4 km 1 4 3 2 Initial conditions and lateral boundary forcing 6 km NCOM 2 km NCOM

  16. Results (1) 4 km and 36 km winds have similar correlation to observations (2) Ocean model performs better with 4 km winds Atmosphere (1) Ocean (2) Comparison of observed 10 m winds to observations and 25 m ocean current to observations Comparison of 36 km and 4 km atmospheric winds Results suggest that the consideration of the effects on an ocean model should be a metricin the validation of atmospheric models and that high-resolution forcing fields improve ocean forecasts

  17. 4 km 27 km Collaboration with Adriatic Circulation Experiment (ACE) COAMPS™ Fields: 5 October 1999 Resolution Comparison: Atmospheric Forcing

  18. 27 km forcing 4 km forcing Collaboration with Adriatic Circulation Experiment (ACE) 2 km NCOM Fields: 5 October 1999 Comparison of Ocean Model Results Using Atmospheric Fields with Different Resolutions

  19. Collaboration with Adriatic Circulation Experiment (ACE) Animation of 2 km Adriatic NCOM Simulation for Oct 1999

  20. S l o v e n i a Trieste LEGEND Venice Piran Center+NRL: ADCP 20 • • • 1 2 + WTG (+ Sal) 3 4 5 Adige Center: SEPTR 6 VR Line Rovinj IRB: ADCP or RCM Po IC IOF: ADCP C r o a t i a 6 KB Line EuroStratiform: ADCP 5 1 4 2 IRPEM: CM Mooring 3 x CP Line 10 2 IBM: C10 Mooring 1 9 ISDGM: Tower 8 Paguro Marine Park Cesenatico 2 OGS: Met + CM Buoy 7 SS Line 1 ND Line 6 50 x NIB: Met + CM Buoy 5 4 OGS: Wave Buoy 2 3 1 Max WERA range: 120 km Senigallia OGS and U. Hawaii: x WERA Radars (3) I t a l y Ancona Split OGS: Codars (3) 100 200 NRL, Perkins, 06 Oct 2002 Ocean-Atmosphere Nested Modeling of the Adriatic Sea during Winter and Spring 2001 Field Program (2002-2003): Current Measurements Hank Perkins, NRL SSC, Version of 06 Oct 2002

  21. Hourly Atmospheric Stresses and Fluxes (27 km) from FNMOC COAMPS™ forecast, Lateral Boundary Conditions From Global NCOM or POP Hourly Atmospheric Stresses and Fluxes (27 km) from FNMOC COAMPS™ forecast, Lateral Boundary Conditions From Global NCOM or POP SST to Atmospheric Model SST to Atmospheric Model NCOM (6 km) 72h forecast NCOM (6 km) 72h forecast 12h MVOI, obs from GODAE Server MVOI, obs from GODAE Server 12h Cold Start: • First-guess: GDEM, Global NCOM, or POP • QC observations/MODAS synthetics • MVOI (z-levels) • Initialization • 5-day spin-up Warm Start: • First-guess: NCOM 12 h forecast • QC observations • MVOI (z-levels) • Increments added to first-guess • Initialization Real-Time Ocean Data Assimilation/Forecast Test-Bed Ocean Analysis/Model Components Real-time ocean data assimilation run on NRL SGI O2K

  22. COAMPS™/NCOM Web Page

  23. NCOM Sea Surface Temperature 12-21 May 2003: Hours 1-12

  24. Sample Validation of SST Analysis Output from Ocean MVOI for Real-Time Mediterranean Run at 0000 UTC 6 March 2003 Similar statistics calculated at each analysis time for all variables at all analysis levels Statistics indicate that OMVOI/NCOM is performing better than climatology or persistence

  25. Preliminary results suggest that significant differences exist when forcing an ocean model with 12 h frequency as opposed to 1 h or 6 h frequency • Importance of Temporal Resolution of Ocean Forcing • Comparison of NCOM runs using 1 h, 6 h, and 12 h COAMPS™ forcing • Comparisons for Gulf of Lion during February 1999 12 h frequency runs 1 h and 6 h frequency runs

  26. SST: tau 0 Surface currents: tau 0 SST: tau 72 Surface currents: tau 72 Application of COAMPS™/NCOM in Eastern Pacific Cold Start Initial Fields and Lateral Boundary Conditions from Global NCOM

  27. Air/Ocean Coupled Prediction Systems at NRL MRY Summary/Plans • Global: • Testing NOGAPS/POP one-way coupled system • Starting two-way coupled tests • Transition to HYCOM for global ocean prediction • Mesoscale: • Atmospheric Reanalyses • Importance of horizontal resolution • Importance of data assimilation • Air-Ocean Coupling • Use unfiltered, native grid fields for ocean forcing • Collaboration with Adriatic Circulation Experiment (ACE) • New metric for model verification • Importance of horizontal resolution of ocean forcing • Importance of temporal resolution of ocean forcing • Real-time ocean data assimilation/Forecast test-bed • Build in HYCOM for Initial/Lateral Boundary Conditions • Two-way coupling

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