Pavement Precipitation Accumulation

1
Pavement Precipitation Accumulation
Presenter Mark Askelson University of North
Dakota Department of Atmospheric
Sciences/RWIC/STWRC

• Improved Winter Precipitation Algorithm

2
Improved Winter Precipitation Algorithm

• Algorithm Design

Radar Alg. Output
Decoder
Clutter and AP Filter
Snow Accum. Algorithm
Radar Data
Blend Surface and Radar
Decoder
Surface Obs.
Radar Surface Output
Radar Surface Satellite Output
Train Satellite from Radar Surface
Fill Holes
Decoder
Satellite Data
Blending Algorithm
Analyses/Model
Final Output
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Improved Winter Precipitation Algorithm

• Radar Data
• Bureau of Reclamation snowfall accumulation
  algorithm
• Developed in late 1990s
• State-of-the-art radar algorithm
• Surface Data
• Adjust radar-based valuesbias correction
• Yes/no flags to refine snowfall area

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Improved Winter Precipitation Algorithm

• Satellite data
• Geostationary Orbiting Environmental Satellites
  (GOES) Cloud Top Pressure Data
• Estimates of atmospheric pressure at top of
  clouds
• Available every hour
• Idea cloud top pressure is related to snowfall
  rate. Deeper systems more likely to produce
  heavier snowfalls.
• Main function fill holes

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Improved Winter Precipitation Algorithm

• Concerns
• Create snowfall where it is not present.
• ? Must evaluate.
• ? Use surface data to prevent?
• Accuracy
• ? Same cloud tops will likely produce different
• snowfall rates in different systems.
• ? Will train using combined radar and surface
• observation data.

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Improved Winter Precipitation Algorithm

• First Generation (Complete)
• Based on level III radar data
• Second Generation
• Based on level II radar data
• Progress
• Many base level radar routines completed
• Level II data decoder
• Components of satellite processing software

Radar-based liquid water equivalent snowfall rate
(mm hr-1) at 6.a.m. on 25 January 2004. From
early version of PPAES.