Getting beyond cold starts improving wrf forecasts with rapid refresh initializations
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Getting Beyond Cold Starts: Improving WRF Forecasts with Rapid Refresh Initializations. Cliff Mass and David Ovens University of Washington Seattle, Washington. Is there an easy way to get beyond cold starts?. For many WRF applications, users take either of two routes:

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Getting Beyond Cold Starts: Improving WRF Forecasts with Rapid Refresh Initializations

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Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

Getting Beyond Cold Starts:Improving WRF Forecasts with Rapid Refresh Initializations

Cliff Mass and David Ovens

University of Washington

Seattle, Washington


Is there an easy way to get beyond cold starts

Is there an easy way to get beyond cold starts?

  • For many WRF applications, users take either of two routes:

    • Cold start using GFS, ECMWF, or other operational model grids

    • High-resolution data assimilation using local data assets using WRFDA, DART EnKF, or something else.

  • Today, there is potentially another possibility over much of North America: high-resolution initialization using NOAA Rapid Refresh grids.


Mesoscale data assimilation why not let someone else do the hard work

Mesoscale Data Assimilation: Why not let someone else do the hard work?

  • The NOAA/NWS runs the Rapid Refresh (RR) and High Resolution Rapid Refresh (HRRR) systems hourly, completing analyses and short-term forecasts.

    • RR: 13 km grid spacing, 18 hr forecast

    • HRRR, 3-km grid spacing, 15 hr forecast

  • Both make use a wide variety of mesoscale data sources, including radar, satellite, mesonets, soundings, aircraft data, and more.


Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

Rapid

Refresh


Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

HRRR


Rapid refresh for wrf initialization

Rapid Refresh for WRF Initialization

  • My perception is that Rapid Refresh has become substantially more realistic and skillful during the last few years.

  • But one is hard pressed to prove this from stats on their web site!

  • The 3-D grids are available.

  • So why not try using RR grids for initialization of WRF?


June 3 2014 21 utc

June 3, 2014 21 UTC

A test: Can mesoscale initialization from RR help with coastal stratus, major problem for the Northwest real-time WRF?


Three runs

Three Runs

  • UW Real-time WRF initialized with GFS using YSU PBL, Thompson Microphysics, NOAA LSM, SAS Cumulus Param. ,RRTM radiation

  • UW Real-Time WRF with same physics, but initialized with Rapid Refresh grids

  • WRF with RUC physics and Rapid Refresh initialization (RUC LSM, MYNN PBL, Grell CU, Thompson Micro)


Gfs initialization

GFS Initialization


Using rapid refresh initialization

Using Rapid Refresh Initialization


Using rapid refresh initialization and rapid refresh physics

Using Rapid Refresh Initialization and Rapid Refresh Physics


Observed sounding at quillayute on the washington coast 6 4 13 at 12utc

Observed Sounding at Quillayute on the Washington Coast: 6/4/13 at 12UTC


Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

900


Getting beyond cold starts improving wrf forecasts with rapid refresh initializations

925


May 20 th 18 utc

May 20th, 18 UTC


What about the next morning 12 utc 21 may 2014

What about the next morning? 12 UTC 21 May 2014


Real time gfs forced

Real-Time GFS-forced

925


Forced by rr

Forced by RR

925


Rr init and rr physics

RR Init and RR Physics

925


Long term tests april may

Long-Term TestsApril-May


Temperature mae 12 hr forecast

Temperature MAE, 12 hr forecast

GFS Init

RR Init

RR Init and RR Physics


Dew point mae

Dew Point MAE


Wind direction mae

Wind Direction MAE


Wsp mae

WSP MAE


Conclusions

Conclusions

  • Initialization with NOAA Rapid Refresh grids does help in initializing shallow low clouds and maintaining them early in the forecasts.

  • Rapid Refresh (RUC) physics package contributes to establishment and maintenance of shallow, stable features.

  • Overall verification for the entire domain (NW U.S. and adjacent waters) for an extended does not suggest much overall improvement.


Conclusions1

Conclusions

  • The effects of initialization fades over the first day of the forecast, but physics effects remain substantial.

  • Will verify impacts on other seasons before deciding to go with this approach in the operational system.


The end

The End


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