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.