1. Regional Air-Sea Interactions in Eastern Pacific 6th International RSM Workshop Palisades, New York July 11-15, 2005 6th International RSM Workshop Palisades, New York July 11-15, 2005 Hyodae Seo Scripps Institution of Oceanography Hyodae Seo Scripps Institution of Oceanography

2. Outline 1. Regional Ocean Atmosphere Coupled Model 2. Research 1. Gap-Induced Low-Level Winds and Air-Sea Interaction in Central America 2. Atmospheric Boundary Layer Adjustment to Tropical Instability Waves (TIWs) in Eastern Tropical Pacific 3. Summary 1. Regional Ocean Atmosphere Coupled Model 2. Research 1. Gap-Induced Low-Level Winds and Air-Sea Interaction in Central America 2. Atmospheric Boundary Layer Adjustment to Tropical Instability Waves (TIWs) in Eastern Tropical Pacific 3. Summary

3. Regional Ocean-Atmosphere Coupled Model

4. 1. Model and Coupler Description IC and Lateral BC: NCEP/DOE Reanalysis SST Boundary Layer Variables Ocean Atmosphere COARE Bulk Formula Plus Winds relative to ocean currents Regional Spectral Model (RSM) Lateral BC: Ocean Data Assimilation Product (JPL) Regional Ocean Modeling System (ROMS) Sequential Coupling Coupling Frequency  3 hourly coupling  Daily coupling Bulk Formula in BL Regional Ocean-Atmosphere Coupled Model Winds Relative to Ocean

5. Gap-Induced Low-level Winds and Air-Sea Interaction in Central America Tehuantepec Papagayo Panama OBSERVATION: Xie et al., 2005 Jan-Mar SST and Windstress Climatology

6. 2.1. Gap Winds and Air-Sea Interaction 1999-2003 Model Climatology Ekman Pumping Velocity (10^- 6 m/s) Sea Surface Temperature (C) Dry Hole Costa Rica Dome Cold SST Winter Summer Upwelling by Papagayo Jet Tehuantepec Papagayo Panama Precipitation (mm/day) Winter

7. Atmospheric Boundary Layer Response to Tropical Instability Waves (TIWs) in Eastern Tropical Pacific Tropical Instability Waves (TIWs) Global SST Image from microwave satellites Aug 25-27, 1999 (Wentz et al.)

8. 2.2 Atmospheric BL Adjustment to SSTs a. Winds and SST OBSERVED SSTs Chelton et al., 2001 MODEL SST MODEL Wind Stress 3 month average of wind-stress and SST Similar gross patterns of winds and SST during TIWs season June 21 – October 20 1999 OBSERVED Wind Stress

9. 2.2 Atmospheric BL Adjustment to SSTs b. Temporal/Spatial Associations Wind Stress Wind-Divergence MODEL: 1999 - 2003 along 2N SSTStressDiv June 2003 June 2002 June 2001 June 2000 June 1999 Jun - Dec. 1999 Tropical Instability Waves (TIWs) and Winds SST

10. 2.2 Atmospheric BL Adjustment to SSTs c. Stability of Atmospheric BL Due to SSTs September 2 - 4, 1999 V-Wind U-Wind Specific Humidity Vir. Pot. Temp. September 2 - 18, 1999 Atmospheric Temp Ocean Temp Warm Phase: 173, Cold Phase: 217 Typical TIWs and Winds STABL E UNSTABL E STABL E UNSTABL E

11. 2.2 Atmospheric BL Adjustment to SSTs d. Isotherms and Wind Vectors: Dynamic Feedback Chelton, 2005 Chelton, 2001 Wind Stress Divergence Wind Stress Curl Wind Stress Divergence Wind Stress Curl Typical Patterns of Winds and SST Implication of DYNAMIC FEEDBACK OBSERVATION MODEL

12. 2.2 Atmospheric BL Adjustment to SSTs e. Thermodynamic Feedback Latent Heat Flux Sensible Heat Flux MODEL SIMULATION Latent and Sensible Heat Flux damp the SST anomaly; Turbulent flux provides NEGATIVE FEEDBACK To SST by TIWs. Less Cooling More Cooling

13. 3. Summary High-resolution ocean-atmosphere coupled model has been developed to study air-sea interactions in various parts of the World Ocean. Mesoscale SST induces atmospheric boundary layer adjustment, which may feed back onto ocean. Central American gap winds force upper ocean thermocline topography, which in turn affects atmospheric deep convection and precipitation. High-resolution ocean-atmosphere coupled model has been developed to study air-sea interactions in various parts of the World Ocean. Mesoscale SST induces atmospheric boundary layer adjustment, which may feed back onto ocean. Central American gap winds force upper ocean thermocline topography, which in turn affects atmospheric deep convection and precipitation.

14. Thanks!

15. Model Domain

16. Wind Stress CurlLatent Heat FluxWind Stress Div Wind Stress Curl SST & Wind Stress Over Warm Eddies: ~ 100km Southern California Coast Additional Example of relations between wind stress vector and isotherms in southern California coastal ocean

17. OBSERVATIONMODEL 1999-2000 Mean Low-level Cloud Longitude Month Model Bias: Low-level Cloudiness Eastern Pacific OBSERVATIONMODEL 1999-2003 Mean SST Month Longitude Stratus/Stratocumulus are overestimated over south east Pacific (because of colder SSTs in model?) Longitude