Near Real-Time SSTs in Mesoscale Prediction Dr. Steven M. Lazarus, Corey Calvert, & Mike Splitt

1. Near Real-Time SSTs in Mesoscale Prediction Dr. Steven M. Lazarus, Corey Calvert, & Mike Splitt Florida Institute of Technology

2. Regional weather is impacted by air-sea interaction at varying scales…

3. Advancement of Coastal Science: • upwelling (e.g., event of summer 2003) • ocean mixing • land falling hurricanes • wind and waves (coastal erosion, marine forecasts, etc.) • riptides • estuarine & coastal ocean modeling • clouds (freezes) and precipitation (coastal showers, deep convection)

4. Relevant Science/Operational Questions and Issues… • How do we best blend SSTs from multiple platforms? • 2. Do we apply SSTs as only a boundary condition or do we nudge the boundary layer as well (i.e., are the surface fluxes in balance)? • 3.What are the impacts of high-resolution SSTs on short-term model forecasts, how do we best evaluate them, and do they match expectations (e.g., land vs. ocean)? • 4. Are short-term forecast improvements (e.g., precipitation) consistent with seasonal observations? • 5. What direction are we heading (e.g., coupled ocean/atmosphere)? • 6. Where can we get the most bang for our $? • 7. Is the future skin or bulk SSTs?

5. What we are doing now… • Focusing on producing a high-resolution SST products that can be “used” in real-time – we are trying to capture the best estimate (timely & accurate) of the bulk SST. • Evaluating whether or not the high-resolution SSTs enhance simulation of observed mesoscale and meso-gamma scale processes. • Where things are headed… • SST product development contingent on model evaluations. Retrievals vs. direct use of radiances (e.g., Li and Derber, NCEP). • Movement toward coupling hydrodynamic models with atmospheric models (e.g., NWS regional scale ARPS runs). • Regional coupled models may be well-suited to applications such as simulating hurricanes and short term predictions of mesoscale features.

6. Data assimilation/analysis from a coupled perspective… • Some of the relevant arguments are: • real world coupled thus initial conditions and forecasts should be performed in coupled mode. • ocean models need improved surface fluxes. • atmospheric models need improved SSTs. • forecast errors are coupled and should be minimized in the initial conditions. The hope is: • we expect more accurate field information (data)/analyses. • we get better initial conditions for forecasts/nowcasts. • improve coupled model simulations. • flux corrections are consistent in both components of the system

7. Does coupling matter at time scales on the order of a day, i.e. for short-term forecasts? Is the answer situationally dependent? • Timely SST products will be needed (e.g., see World Climate Research Program Observation and Assimilation Panel Report) regardless of the modeling paradigm (dynamic, static coupling…), but… • ocean community needs the SST profile in the water column. • Fundamental difficulties persist w.r.t. numerical models in simulating processes associated with ocean and atmosphere boundary layers

8. Evaluation…SSTs & WRF upper air WSR-88D QuikSCAT CloudSAT surface data RTG-SST (NCEP) ??? MODIS COMPOSITES WRF (24 h forecasts) SST ANALYSES ? BOUY CLIMO GOES smooth traditional/limited quality? How much # crunching is needed to assess impact of SSTs (e.g., seasonal modeling/forecast issues)?

9. Evaluation Efforts… Limitations of over-ocean data are problematic from both the direct evaluation and assimilation/modeling perspectives! sparseness multi-platform timeliness

10. Chelton and Wentz BAMS 2005 • SSTs (color) • wind stress (solid contours) ECMWF (top) and NCEP (bottom) surface stress w/ Reynolds SSTs ECMWF (top w/ RTG-SSTs) and NCEP (bottom) surface stress (w/ Reynolds).

11. MODIS impact on WRF simulations What is the impact on marine forecasts (i.e., Gulf stream convection, coastal showers, upwelling dynamics/feedback w.r.t SSTs, etc.)? WRF forecast differences (RTG – MODIS) for 1.) skin temperature (color contours w/ interval=0.4 K) and 2.) 10 m wind magnitude (solid contours, interval .2 ms-1). Also shown are the 10m winds from WRF (w/ MODIS SSTs, barbs in ms-1) valid at 08 UTC 14 May 2004.

12. MODIS impact on WRF simulations cooler cooler cooler cooler warmer warmer wind magnitude (ms-1) RED contours RH (%) boundary layer impacts (match expectations, amplitude?)

13. Use of NASA scatterometer data… WRF 10 h forecast valid 1 May 2004. 10 m winds (black barbs), QuikSCAT (red barbs), surface observations (ship, buoy, METAR).

14. FIT SST Analysis Cycle… ARPS Forecast Cycle at NWS Melbourne How best to match up the forecast cycle and SST analyses?

15. FIT SST Analyses RTG MODIS + = Analysis

16. Parting Comments… • Future Efforts • Near-term • FIT analyses (glint, diurnal adjustment and latency issues) • Composite & Analysis Evaluation (non-modeling) • Model Evaluation • Long-term • transition to operations • communicating results to users (e.g., what is important for a forecaster/user to know about the products?)