Foreword

This User’s Guide describes the Advanced Research WRF (ARW) Version 3.8 modeling system, released in April 2016. As the ARW is developed further, this document will be continuously enhanced and updated. Please send feedback to wrfhelp@ucar.edu.

This document is complementary to the ARW Tech Note (http://www2.mmm.ucar.edu/wrf/users/docs/arw_v3.pdf), which describes the equations, numerics, boundary conditions, and nesting etc. in greater detail.

Highlights of updates to WRFV3.8 include:

· WRF model:

Physics:

o New Kain-Fritsch cumulus potential scheme (contributed by PNNL);

o A new option for aerosol-radiation interaction (aer_opt = 3) (contributed by G. Thompson and T. Eidhammer of RAL/NCAR);

o Improvement to various physics options;

o Updated cloud fraction scheme (icloud =3);

o WRF-Hydro 4.0 (contributed by the WRF-Hydro group of RAL/NCAR)

Others:

o A flux-adjusting surface data nudging option;

o Improved vertical refinement (contributed K. Lundquist of LLNL);

o 30-seconds GMTED2010 topography dataset.

· WRF-DA updates:

o New observation type: AMSR-2 radiance (contributed by Xin Li, Jie Ming, Ming Xue, Yuan Wang, and Kun Zhao of Nanjing University, China)

o New dynamic constraint for 3DVAR and Hybrid DA (contributed by Syed Rizvi of NCAR and Chun Yang of Nanjing University of Information Science & Technology, China)

· WRF-Chemistry

o Dust scheme improvement (contributed by Martina Klose of Univ. of Cologne and New Mexico State Univ.).

For the latest version of this document, please visit the ARW Users’ Web site at http://www2.mmm.ucar.edu/wrf/users/.

Contributors to this guide:

Wei Wang, Cindy Bruyère, Michael Duda, Jimy Dudhia, Dave Gill, Michael Kavulich, Kelly Keene, Ming Chen, Hui-Chuan Lin, John Michalakes, Syed Rizvi, Xin Zhang, Judith Berner, Soyoung Ha and Kate Fossell

Contributors to WRF-Fire chapter:

Jonathan D. Beezley, Janice L. Coen, and Jan Mandel

Contributors to UPP section:

Hui-Ya Chuang, Nicole McKee, Tricia Slovacek, Jamie Wolff, and Kate Fossell

Special Acknowledgment:

We gratefully acknowledge the late Dr. Thomas T. Warner for his years of research, development, instruction, leadership, and motivation in the field of NWP modeling.