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Composite Reflectivity


The High-Resolution Rapid Refresh (HRRR)

The HRRR is a 3-km resolution, hourly updated, cloud-resolving atmospheric model, initialized by DFI-fields from the 13km radar-enhanced Rapid Update Cycle (RUC) run at NOAA/ESRL/GSD. (soon to be initialized similarly by the 13km radar-assimilating Rapid Refresh ).

    The HRRR uses
  • a configuration of the WRF model, similar to that used for the Rapid Refresh (ARW core, Thompson microphysics, RUC-Smirnova land-surface model, etc., as defined here ), but without any convective parameterization.
  • initialized with latest 3-d radar reflectivity via 13km backup RUC at ESRL/GSD, which includes radar reflectivity assimilation via its radar-DFI (digital filter initialization) technique.
  • 9 October 2009 - HRRR domain expanded again to full CONUS coverage. Products available at http://rapidrefresh.noaa.gov/hrrrconus .
  • 25 March 2009 - now runs over a domain covering approximately the eastern 2/3 of the lower 48 US, about 2.4x larger than the previous NE Corridor domain. NE Corridor HRRR products are now subset from the larger HRRR runs. Advantages of larger domain:
    • Coverage for hourly HRRR forecasts extended through midwest and southern U.S.
    • Boundary transition zones extended far from key aviation hubs, including ORD, MSP, ATL, and others.
  • no separate data assimilation, relying instead on radar-assimilating RUC.
  • 1-way nest inside RUC (including cloud hydrometeors specified on lateral boundaries)
    An interactive-chemistry version of the HRRR is now being run every 6h over the western US with real-time fire information (GOES ABBA) to provide air quality guidance (as of Aug08),
  • Same radar-enhanced RUC-DFI grids as atmospheric initial conditions, same as hourly eastern 2/3 CONUS HRRR.
  • Cycled chemistry variables, including 3-d ozone, PM 10 aerosol, PM 2.5 aerosol.
  • Adding WRF-chem to other parameterizations used in NE Corridor HRRR
The HRRR is the only hourly updated, radar-initialized, storm-resolving model running at this time over the US (or internationally), to our best knowledge.
    As a higher-resolution nest inside the hourly-updated Rapid Refresh (and current RUC), the HRRR is designed to
  • provide rapidly updated model guidance on convective storms for
    • air traffic management
    • severe weather forecasting
    • NOAA National Weather Service Warn-On Forecast
  • eventually provide improved background fields for NWS Real-Time Mesoscale Analysis
  • provide improved basis for other aviation hazard forecasts (e.g., wake vortex, ceiling, visibility, turbulence, inflight icing, terminal forecasts)
  • The HRRR is fully dependent on the hourly-updated Rapid Refresh and currently, the radar-enhanced Rapid Update Cycle (RUC) , as shown in daily comparisons of 3km model runs with and without the 13km radar-reflectivity assimilation in the RUC/RR.