Earth-Sun System Division National Aeronautics and Space Administration SPoRT SAC Nov 21-22, 2005 Regional Modeling using MODIS SST composites Prepared.

Earth-Sun System DivisionNational Aeronautics and Space Administration

SPoRT SAC Nov 21-22, 2005

Regional Modeling usingMODIS SST composites

Prepared for the Science Advisory CommitteeNovember 21, 2005

Kate LaCasseB. Lapenta, S. Dembek, S. Lazarus, M. Splitt



Motivation:Mesoscale features are often observed along SST gradientsCurrent operational models use the coarse resolution (~50 km) RTG SST productBetter specification of the SSTs, especially SST gradients, through the use of a high resolution (1 km) MODIS SST composite, should better resolve the forcing mechanisms which lead to some of the observed features

Current Activities:Operational forecasts over the southeastern USSimulations in the vicinity of Florida from May 2004Hurricane forecasts

All modeling is performed using the Weather Research and Forecasting (WRF) prediction system



WRF Operational Forecasts12 km resolution with 37 vertical levels

48h forecasts daily at 00 and 12 UTC

Dynamics and Physics•Eulerian mass core•Dudhia shortwave radiation•RRTM longwave radiation•YSU planetary boundary layer•Noah land surface model•Lin microphysics•Kain-Fritsch cumulus

Initialized with 40km NAM analyses

NAM 3h forecasts used for LBCs

SSTs are replaced with MODIS SSTs

Used by both the NWS Huntsville and Mobile offices within AWIPS



NAM WRF

Improved Coastal and Marine Forecasts

Radar Reflectivity

3h accumulated precipitation (in)24h forecast ending 00 UTC August 4,

2005



Impact of MODIS SSTs on Mesoscale Weather

Methodology:

2 km resolution with 51 levels

Physics differences from operational WRF:

•No cumulus parameterization•WSM 6-class microphysics scheme

24h simulations run daily for May 2004

Parallel runs for both the RTG SSTs and the MODIS SST composites

3h WRF simulation

24h WRF simulation

00 0021

ADAS ADAS

MODIS SST- RTG SST (K)14 May 2004



Computing Capacity: Project Columbia



Bulk Verification of 2m Temperature

Average of 15 days from May 2004

# of observations used

METARs: ~50,000Buoys: ~10,000

METARs BuoysMETARs Buoys

Overall there is little difference between 2m temperature forecasts, as expected

Expect to see greater impact of MODIS SSTs locally



MODIS - RTG SST (K)14 May 2004

MODISRTG

10m Wind Divergence (s-1*10-4)1h forecast valid 01 UTC 14 May 2004

Impact over ocean

RTG MODIS

Net Sensible Heat Flux (Wm-2*10)1h forecast valid 01 UTC 14 May 2004



Horizontal convective rolls

Upward Vertical Motion (ms-1*10-2)

RTG MODIS

~100 km

1000

900

950

850

1000

900

950

850

800

Wind Divergence (s-1*10-4)1h forecast valid 01 UTC 14 May 2004

RTG MODIS

~100 km

1000

900

950

850850

1000

900

950

850

800

SST differences of ~1.5 K have a significant impact on the boundary layer



Validation of MODIS forecast01 UTC 14 May 2004

Low level convergence from horizontal convective rolls provides forcing for clouds

Visible Satellite Image

MODIS

10m Wind Divergence (s-1*10-4)

Do the MODIS SSTs also impact precipitation?



Reflectivity (dBZ)18h forecast valid at 18 UTC 01 May 2004

RTG MODIS

Radar composite

SST Gradient

Convection Along SST Gradient



WRF Hurricane ForecastsIn collaboration with Goddard Space Flight Center, run test cases to determine if WRF forecasts are sensitive to SSTs

Domain configured like May 2004 runs

24 – 48 h forecasts

Initialized with 40 km NAM analyses

NAM 3h forecasts used for LBCs

Parallel forecasts with either RTG SSTs or MODIS SST composite

New Orleans, LARadar Reflectivity

42h forecast of3h accumulated precip (in)

Hurricane Katrina06 UTC August 29, 2005



Hurricane Katrina Maximum 10m Wind Speed

60

80

100

120

140

160

180

200

12

Z 2

7th

15

Z

18

Z

21

Z

00

Z 2

8th

03

Z

06

Z

09

Z

12

Z

15

Z

18

Z

21

Z

00

Z 2

9th

03

Z

06

Z

09

Z

12

Z

Forecast Date

Sp

eed

(m

ph

)

RTG

MODIS

Observed

Initial cases indicate that WRF hurricane forecasts are sensitive to SSTs.



Summary:Use of MODIS SST composites is currently ongoing in operational WRF forecasts

May 2004 simulations and hurricane forecasts provide the opportunity to determine the impact of MODIS SSTs on regional forecasts

Preliminary work suggests that the WRF model appears to respond appropriately to high-resolution SST data

Greatest impact of MODIS SSTs is seen in the marine boundary layer

Earth-Sun System Division National Aeronautics and Space Administration SPoRT SAC Nov 21-22, 2005 Regional Modeling using MODIS SST composites Prepared.

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