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WRF Wharf Modeling System Overview

Aug 8, 2024

Notes on WRF Wharf Modeling System: Program Real

Overview

  • Presentation on version 4.2 of the WRF Wharf modeling system.
  • Focus on the real.exe program, which takes input from WPS and generates data for the WHARF model.
  • Assumes familiarity with WPS description and general functions.

Structure of Presentations

  • Grouped into categories:
    • Overview
    • General Descriptions (2 talks)
    • Setup and Run (2 talks)
  • This presentation covers description and functions of the real program.

Functions of the Real Program

  1. Definition and Purpose

    • Handles vertical interpolation of meteorological data.
    • Generates data suitable for WHARF model.
  2. Input Requirements

    • Standard Input Variables:
      • Mandatory: 3D/2D fields (e.g., horizontal winds, temperature, moisture).
      • Optional: Soil moisture, surface pressure, sea level pressure.
    • Source of Data:
      • Data comes from WPS and MEGRID.
    • Vertical Coordinate Handling:
      • Must be monotonic in pressure (increasing or decreasing).
  3. Base State Computation

    • The base state is computed and used in the WHARF model.
    • Impacts vertical coordinate and potential temperature definitions.
  4. Output Data

    • Produces output files for WHARF model:
      • WHARF input file (3D volume of atmospheric data).
      • WHARF boundary file (for coarse grid only).

Vertical Interpolation

  • Real program performs vertical interpolation, unlike WPS which handles horizontal interpolation.
  • Adjustments required when modifying options in the WHARF namelist.
  • Soil Level Interpolation: Initialization for physics; important for reruns when modifying options.

Computational Aspects

  • real.exe can run as a serial or parallel job.
  • Not computationally bound; performance benefit from distributed memory mainly for large domains.

Model Initialization

  • Supports idealized initialization (ideal.exe) and real data initialization (real.exe).
  • Emphasizes realistic static fields (e.g., topography, land use), not idealized.

Data Handling

  • Input Data:
    • From UNGRIB and METGRID; includes various meteorological fields.
    • The preprocessing transforms data for the WHARF model.

Runtime vs. Compile Time Options

  • Runtime Options:
    • Change simulation without recompiling the code (via input files).
    • Uses Fortran namelist files (e.g., namelist.input for REAL, namelist.wps for WPS).
  • Compile Time Options:
    • Require recompilation to activate; involve changes to source code.

Diagnostics and Data Consistency

  • Generates diagnostic fields and ensures consistency among input datasets.
  • Adjusts fields to be consistent to prevent issues in WHARF model.

User Considerations

  • Users should be cautious with vertical interpolation options; different options can impact results significantly.
  • Recommended to start with default settings and adjust as necessary.
  • Importance of keeping physics options consistent between REAL and WHARF model.

Conclusion

  • The real program is crucial for transitioning data from WPS to WHARF model.
  • For questions, contact the WHARF forum for support and additional resources.
  • Source codes for WHARF and WPS are available on GitHub.