Near Real-Time SSTs in Near Real-Time SSTs in Mesoscale PredictionMesoscale Prediction

Dr. Steven M. Lazarus, Corey Calvert, & Mike SplittDr. Steven M. Lazarus, Corey Calvert, & Mike Splitt

Florida Institute of TechnologyFlorida Institute of Technology

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

Advancement of Coastal Science: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)

1. 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?

Relevant Science/Operational Questions and Issues…Relevant Science/Operational Questions and Issues…

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…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.

What we are doing now…What we are doing now…

Data assimilation/analysis from a coupled perspective…Data assimilation/analysis from a coupled perspective…

Some of the relevant arguments are: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: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

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

MODIS COMPOSITESMODIS COMPOSITES

SST ANALYSESSST ANALYSES

WRF (24 h forecasts)WRF (24 h forecasts)??????

BOUYBOUY GOESGOES CLIMOCLIMO

Evaluation…SSTs & WRFEvaluation…SSTs & WRF

traditional/limited quality? smooth

RTG-SST (NCEP)RTG-SST (NCEP)

??

upper air WSR-88DQuikSCAT CloudSATsurface data

How much # crunching is needed to assess impact of SSTs (e.g., seasonalHow much # crunching is needed to assess impact of SSTs (e.g., seasonalmodeling/forecast issues)?modeling/forecast issues)?

Evaluation Efforts…Evaluation Efforts…

Limitations of over-ocean data are problematic from both the direct evaluation and assimilation/modeling perspectives!

sparseness

timeliness

multi-platform

Chelton and Wentz BAMS 2005Chelton 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).

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.

What is the impact on marine forecasts (i.e., Gulf stream convection, coastal showers, upwelling dynamics/feedback w.r.t SSTs, etc.)?

MODIS impact on WRF simulationsMODIS impact on WRF simulations

cooler coolerwarmer cooler coolerwarmer

wind magnitude (ms-1) RH (%)RED contours

MODIS impact on WRF simulationsMODIS impact on WRF simulations

boundary layer impacts (match expectations, amplitude?)

Use of NASA scatterometer data…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).

ARPS Forecast Cycle at NWS MelbourneARPS Forecast Cycle at NWS Melbourne

FIT SST Analysis Cycle…FIT SST Analysis Cycle…

How best to match up the forecast cycle and SST analyses?

++

==

RTGRTG MODISMODIS

AnalysisAnalysis

FIT SST AnalysesFIT SST Analyses

Parting Comments…Parting Comments…

Future Efforts

Near-termNear-term

FIT analyses (glint, diurnal adjustment and latency issues)

Composite & Analysis Evaluation (non-modeling)

Model Evaluation

Long-termLong-term

transition to operations

communicating results to users (e.g., what is important for a forecaster/user to know about the products?)