1. General Model Information

Name: Weather Generator

Acronym: WGEN

Main medium: air
Main subject: meteorology,hydrology
Organization level: landscape
Type of model: Markov chain, not specified
Main application:
Keywords: atmospheric, weather simulation, stochastic, first-order Markov-chain probabilities, gamma distribution


For the BASIC version: Clayton Hanson ARS-USDA NW Watershed Res. Center 800 Park Blvd. Plaza IV Suite 105 Boise ID 83712-7716


C.W. Richardson


WGEN (Weather Generator) is a weather simulation model developed by Richardson at the USDA-ARS Grassland, Soil and Water Research Laboratory (Richardson and Wright, 1984). It can be used to generate daily values of maximum and minimum temperatures, precipitation and solar radiation. The model can generate these values stochastically for time periods ranging from days to hundreds of years.

The model uses an input file that contains information about first-order Markov chain probabilities for successive daily precipitation on a monthly basis, and monthly gamma distribution shape and scale parameters. The user can run the model using precipitation information to generate the other three variables or generate all four variables.

Author of the abstract:


There is a newer version of WGEN, in the form of a model written in BASIC with a User Manual:

Hanson, C.L., K.A. Cumming, D.A. Woolhiser, and C.W. Richardson, "Microcomputer Program for Daily Weather Simulation in the Contiguous United States." USDA Agricultural Research Service, Publication ARS-114, July 1994, 38 pp.

II. Technical Information

II.1 Executables:

Operating System(s): The software is available from the address above. The cost is $(US) 50.

II.2 Source-code:

Programming Language(s): FORTRAN/BASIC

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References

Richardson, C.W., and D.A. Wright. 1984. WGEN: a model for generating daily weather variables. U.S. Department of Agriculture, Agricultural ResearchService, Washington, D.C., ARS-8, 88p.
Pickering et al. (1994) WeatherMan: A utility for managing and generating weather data", Agronomy Journal 86:332-337 for a description of a user-friendly version of WGEN and SIMMETEO.

V. Further information in the World-Wide-Web

WGen 1.0 HarnworldWeather Generator

VI. Additional remarks

Global change implications: This model can be used for global changeresearch to assess the impacts of changes in temperature, solar radiationand precipitation on vegetation and soils. Because of its simplistic constructionand fairly reliable estimates, it can be linked to other models, such asCERES-Maize or QB-Maize that require daily weather as driving variables.

Last review of this document by: T. Gabele: Tue Oct 7 1997
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:52 CEST 2002

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