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Rapid Refresh

Updated Aug 2017 - Rapid Refresh and HRRR specification of sea- and lake-surface temperature and snow/ice
RAP and HRRR both use the same external SST/ice data fields, but interpolated to higher resolution, of course, in the 3km HRRR.
    Water-surface temperature (ocean and lakes)
  • Other than lake-surface-temperature exceptions below starting in 2013-14, specified using RTG_SST_HR
    • Starting in summer 2017, RTG_SST_HR was used for all lake surface temperatures (as well as for all water surface temperatures).
    • Before this change (ESRL RAP/HRRR on 13 June 2017, NCEP-oper RAP/HRRR on 12 July 2017), NAM_SST was used for inland lakes other than Great Lakes, specified using N.American SST (NAM_SST) - 14km resolution . With improvements made to RTG_SST_HR in Nov 2016, it was found that it gave superior small lake temperatures than NAM_SST, which was far too cold in spring 2017. Grids available here: http://www.nco.ncep.noaa.gov/pmb/products/sst/
    • Great Salt Lake, Salton Sea, Lake Champlain - use monthly climatology - also introduced to RAP with RAPv2
    • Before these dates, RAP used RTG_SST_HR for LST for all lakes
  • Lake-surface-temperature exceptions implemented with RAPv2 implementation at NCEP - 25 Feb 2014, or starting late Sept 2013 for ESRL experimental RAP)
    Snow/ice cover
  • Snow geographic cover (and 2-layer snow water equivalent and snow temperature) is cycled in the Rapid Refresh on an ongoing basis, since 2011 at this point. The NESDIS IMS snow cover is used to horizontally trim and build snow cover, as described below.
  • Use NESDIS IMS snow cover
  • Applied to RAP at ~0z each day after new IMS snow data available.
  • Trim snow cover at all points where shown by IMS-snow field
  • Build snow cover (starting in 2013) (snow water equivalent based on snow at neighbor points or = 1mm if neighbors are snow-free) where needed.

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Prepared by Stan Benjamin stan.benjamin@noaa.gov, 303-497-6387 [an error occurred while processing this directive]