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An Evaluation of A Hybrid, Terrain-following Vertical Coordinate In The WRF-BASED RAP and HRRR Models

Abstract

A new hybrid, sigma-pressure vertical coordinate was recently added to the Weather Research and Forecasting (WRF) model in an effort to reduce numerical noise in the model equations near complex terrain. Testing of this hybrid, terrain-following coordinate was undertaken in the WRF-based Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) models to assess impacts on retrospective and real-time simulations. Initial cold-start simulations indicated that the majority of differences between the hybrid and traditional sigma coordinate were confined to regions downstream of mountainous terrain and focused in the upper levels. Week-long retrospective simulations generally resulted in small improvements for the RAP, and a neutral impact in the HRRR when the hybrid coordinate was used. However, one possibility is that the inclusion of data assimilation in the experiments may have minimized differences between the vertical coordinates. Finally, analysis of turbulence forecasts with the new hybrid coordinate indicate a significant reduction in spurious vertical motion over the full length of the Rocky Mountains. Overall, the results indicate a potential to improve forecast metrics through implementation of the hybrid coordinate, particularly at upper levels, and downstream of complex terrain.

Article / Publication Data
Active/Online
YES
Status
FINAL PRINT PUBLICATION
Volume
35
Available Metadata
Accepted On
March 30, 2020
DOI ↗
Fiscal Year
NOAA IR URL ↗
Peer Reviewed
YES
Publication Name
Weather and Forecasting
Published On
May 01, 2020
Final Online Publication On
May 01, 2020
Final Print Publication On
June 01, 2020
Publisher Name
American Meteorological Society
Print Volume
35
Print Number
3
Page Range
1081–1096
Issue
3
Submitted On
July 23, 2019
Project Type
LAB SUPPORTED
URL ↗

Institutions

Not available

Authors

Authors who have authored or contributed to this publication.

  • Jeffrey R. Beck - lead Gsl
    Cooperative Institute for Research in the Atmosphere, Colorado State University
    NOAA/Global Systems Laboratory
  • John M. Brown - second Gsl
    Federal
  • Jimy Dudhia - third Ncar
    National Center for Atmospheric Research
    1850 Table Mesa Drive, Boulder, Colorado
  • David O. Gill - fourth Ncar
    National Center for Atmospheric Research
    1850 Table Mesa Drive, Boulder, Colorado
  • Tracy Hertneky - fifth Ncar
    National Center for Atmospheric Research
    1850 Table Mesa Drive, Boulder, Colorado
  • Joseph Klemp - sixth Ncar
    National Center for Atmospheric Research
    1850 Table Mesa Drive, Boulder, Colorado
  • wei wang - seventh Ncar
    National Center for Atmospheric Research
    1850 Table Mesa Drive, Boulder, Colorado
  • Christopher Williams - eighth Ncar
    National Center for Atmospheric Research
    1850 Table Mesa Drive, Boulder, Colorado
  • Ming Hu - ninth Gsl
    Federal
  • Eric P. James - tenth Gsl
    Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder
    NOAA/Global Systems Laboratory
  • Jaymes S. Kenyon - eleventh Gsl
    Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder
    NOAA/Global Systems Laboratory
  • Tatiana (Tanya) R. Smirnova - twelveth Gsl
    Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder
    NOAA/Global Systems Laboratory
  • Jung-Hoon Kim - thirteenth Other
    Other