Introduction: General

Introduction

Model Evaluation Tools (MET) is a highly configurable, state-of-the-art suite of verification tools designed for the verification and evaluation of numerical weather forecasts. Although MET was developed at the Developmental Testbed Center (DTC) to be used with the Weather Research and Forecasting (WRF) modeling system, the data formats and standards used allow MET to be run on the output of other modeling systems as well.

The current MET capabilities include traditional verification approaches for standard surface and upper air variables; confidence intervals for most verification measures; and spatial forecast verification methods. The MET package is designed to be modular and flexible. Each tool can be run individually without running the entire set of tools. New tools can easily be added to the MET package due to this modular design.

Future MET development will take into account the needs of the NWP community - including operational centers and the research and development community.

Software Requirements

The following are required to build and run MET:

• C, C++, and Fortran-77 compilers all from the same family (recommend GNU, PGI, Intel, or IBM compilers)
• The UNIX make (GNU make) utility
• NCEP's BUFRLIB for decoding point observations in PrepBufr format
• Unidata's NetCDF version 3 library
• The GNU Scientific Library (GSL)
• The F2C or G2C library (not necessary for some compilers)

Additional Recommended Software

Although none of the following utilities are required to run MET, they may be helpful in preparing data for use in MET:

• The WRF Post-Processor for users verifying WRF model data
• The copygb utility for regridding GRIB data

While earlier versions of MET required the use of the cwordsh utility with PrepBufr data, it is no longer required.

Program Flow

MET consists of a set of verification tools run from the command line. The current MET tools perform the following verification techniques:

• Compare a gridded forecast to point observations using the PB2NC and/or ASCII2NC tools and the Point-Stat tool.
• Compare a gridded forecast to a gridded analysis field using the Grid-Stat tool and, optionally, the PCP-Combine tool.
• Apply an object-based verification approach to a gridded forecast and gridded analysis field using the MODE tool and, optionally, the PCP-Combine tool.
• Apply an intensity-scale decomposition verification approach to a gridded forecast and gridded analysis field using the Wavelet-Stat tool and, optionally, the PCP-Combine tool.
• Aggregate results across many cases using the Stat-Analysis and MODE-Analysis tools.

Documentation

MET Users Documentation consists of a detailed user's guide, slides from previous tutorials, and related white papers. Users are strongly encouraged to download and read the MET Users Guide before they start using MET.

Throughout this tutorial, you will have to type several commands on the command line and edit settings in several files. Those commands are displayed in this tutorial in such a way that it is easy to copy and paste them directly from the webpage. You are encouraged to do so to avoid typing mistakes and speed your progress through the tutorial.