# Presentation: 200364

## Regional Modeling using

**Regional Modeling using**
**MODIS SST composites**
**Prepared for the Science Advisory Committee**
**November 21, 2005**
**Kate LaCasse**
**B. Lapenta, S. Dembek, S. Lazarus, M. Splitt**

## Motivation:

**Mesoscale features are often observed along SST gradients**
**Current operational models use the coarse resolution**
**   ****(~50 km) RTG SST product**
**Better 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 US**
**Simulations in the vicinity of Florida from May 2004**
**Hurricane forecasts**

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

## WRF Operational Forecasts

**12 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**

## Improved Coastal and Marine Forecasts

**NAM**

**WRF**

**Improved Coastal and Marine Forecasts**

**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***

**MODIS SST- RTG SST (K)**
**14 May 2004**

## Computing Capacity:  Project Columbia

**Computing Capacity:  Project Columbia**

## Bulk Verification of 2m Temperature

**Average of 15 days from May 2004**
_**# of observations used**_
**METARs:  ~50,000**
**Buoys:  ~10,000**

**Overall there is little difference**
**   ****between 2m temperature forecasts,**
**   ****as expected**
**Expect to see greater impact of**
**   ****MODIS SSTs locally**

## Impact over ocean

**Impact over ocean**

## Horizontal convective rolls

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

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

## Validation of MODIS forecast

**01 UTC 14 May 2004**

**Low level convergence from**
**   ****horizontal convective rolls**
**   ****provides forcing for clouds**

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

**Do the MODIS SSTs also impact precipitation?**

## Convection Along SST Gradient

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

**RTG**

**MODIS**

**Radar composite**

**SST Gradient**

**Convection Along SST Gradient**

## WRF Hurricane Forecasts

**WRF Hurricane Forecasts**
**In 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, LA**
**Radar Reflectivity**

**42h forecast of**
**3h accumulated precip (in)**

**Hurricane Katrina**
**06 UTC August 29, 2005**

## 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**