# Presentation: 274556

## WRF and the coastalmarine environment

- Kate LaCasse
- SOO/SPoRT Workshop
- 11 July 2006

## Operational SPoRT WRF

**12 km SE US nest**
**48 h forecasts initialized at 00 and 12 UTC**
**Complements NAM output because of different dynamics, physics, and observations**
**Available within AWIPS at Huntsville, Mobile, and Morristown WFOs**

## SPoRT Center coastal modeling

**Determine the impact of NASA observations**
**Conduct case studies based on feedback from the NWS offices about the operational SPoRT WRF**
**Focus on the marine boundary layer, sea breeze circulation, and associated clouds and precipitation**

## SST products used operationally

**Real-Time Global SST:**
**0.5 degree spatial ****resolution**
**Used in NAM, GFS, and RUC**** **

**MODIS SST composite:**
**1 km**** resolution**
**Used in SPoRT WRF**** **

**MODIS SST composite has more structure, especially east of Florida**

## Experiment design

**2 km horizontal resolution with 51 levels**
**24 h simulations run daily for May 2004**
**Parallel runs with either the RTG SSTs or the MODIS SST composite**

**Expect that differences between the simulations will be greatest near the SST gradient**

**40 km**

**RTG**

**MODIS**

**SST (K)**

## Results

**Compared to the control run, the simulations with MODIS SST composites over the Gulf Stream:**
**Increased sensible and latent heat fluxes**
**Higher PBL height**
***Increased up to 10% the 10 m wind speed***
**Changes in wind speed led to regions of enhanced convergence/divergence**

**10 m wind speed difference (MODIS – RTG; 10****-1****ms****-1****)**
**Nighttime, westerly cases**

## Case Study:  25 March 2006

**Mobile WFO provided feedback about a poor forecast by the SPoRT WRF as well as the NAM  and GFS**
**Case synopsis:**
**Runoff from heavy precipitation earlier in the week cooled SSTs near the Alabama coast**
**Models forecasted cool temperatures with northerly flow for the daytime on 25 March 2006**
**Warmer temperatures with southerly flow was observed, in conjunction with a sea breeze circulation**

## Review of SPoRT WRF and MODIS SSTs

**On this day, SPoRT WRF ran with the RTG SSTs instead of the MODIS SSTs**
**Cool MODIS SSTs were not adequately captured with the current compositing technique**

**22 March 2006 MODIS SST Composite**

**25 March 2006 Enhanced Composite**

## Determine sensitivity to model resolution and SSTs

**Possible ways to improve forecast:**
**Include a higher resolution (2.4 km) nest**
**Make an improved MODIS SST composite, which retains more recent MODIS SST data**
**Re-run forecasts initialized at both 00 and 12 UTC 25 March 2006**

**SSTs valid 25 March 2006**

## Results

**Higher resolution runs forecasted a slightly further inland progression of the sea breeze**
**Addition of MODIS SSTs improved forecast in northern Mobile Bay**

**10 m wind (ms****-1****)**
**9 h forecast valid 21 UTC 25 March 2006**

## Summary

**The SPoRT Center transitions new products, such as the MODIS SST composite, into the SPoRT WRF**
**Are more accurate initial conditions, through the use of additional observations, required to improve local modeling?**
**What resolution does WRF need to adequately resolve coastal processes?**