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

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

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

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

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

11. 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 Analysis COAMPS 24 h Forecast Analysis COAMPS 24 h Forecast Analysis COAMPS 24 h Forecast Observations NOGAPS Fields NOGAPS BC’s 12h fcst 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 27 km 81 km 10 5 0 Wind Speed (m/s)

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 Data Assimilation Cold Start 10 5 0 Wind Speed (m/s)

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 Bora Po River Ocean-Atmosphere Nested Modeling of the Adriatic Sea during Winter and Spring 2001 Meteorology and Oceanography in the Adriatic

15. 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 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 6 km NCOM 27 km 81 km COAMPS TM 2 km NCOM 36 km 12 km COAMPS TM 1 3 2 4 4 km Momentum, Heat fluxes Initial conditions and lateral boundary forcing Momentum, Heat fluxes Ocean-Atmosphere Nested Modeling of the Adriatic Sea during Winter and Spring 2001 Design of Experiment

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

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

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

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

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

21. Real-Time Ocean Data Assimilation/Forecast Test-Bed Ocean Analysis/Model Components Real-time ocean data assimilation run on NRL SGI O2K MVOI, obs from GODAE Server NCOM (6 km) 72h forecast 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 Hourly Atmospheric Stresses and Fluxes (27 km) from FNMOC COAMPS™ forecast, Lateral Boundary Conditions From Global NCOM or POP 12h NCOM (6 km) 72h forecast MVOI, obs from GODAE Server SST to Atmospheric Model SST to Atmospheric Model Hourly Atmospheric Stresses and Fluxes (27 km) from FNMOC COAMPS™ forecast, Lateral Boundary Conditions From Global NCOM or POP

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 12 h frequency runs 1 h and 6 h frequency runs 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

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

27. 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 Air/Ocean Coupled Prediction Systems at NRL MRY Summary/Plans