GCM4: Daily weather generating tool

Objectives

1. Develop a “point-and-click” program to run in association with Google Earth, that allows the user to choose a location, a time slice between 2010 and 2100, one of several climate models, and one of the three AR4 emissions scenario, and generate a set of daily weather files in DSSAT format for that location, which can then be displayed and downloaded by the user.

2. Revise the FORTRAN module GCM4 to incorporate data for up to five additional AR4 climate models, and to revise average outputs to allow the mean of all GCM outputs to be downscaled. 

Background

MarkSim™ is a third-order Markov rainfall generator that is able to simulate the observed variance of rainfall by way of stochastic resampling of the relevant markov process parameters.  The model is fitted to a calibration data set of some 10,000 weather stations worldwide, clustered into some 700 climate clusters using monthly values of precipitation and maximum and minimum temperatures. MarkSim can be used as a climate downscaler, and the purpose of the work here is to develop a module that can be used to generate daily weather data that are to some extent characteristic of future climatologies as generated by global climate models. 

Activities

• Various FORTRAN routines were developed, and these were then incorporated into an application linked to Google Earth, mounted on the server at CIAT in Colombia.
• Other AR4 climate model data were obtained via University of Oxford and the UK Met Office, and these were combined in the core application (GCM4_module) to be added to the web application. 

Outputs

1  A web-based application for generating daily weather data that can be used to drive a wide variety of agricultural impact models.  Weather data files are ready for use with the DSSAT4 crop modelling system.  Weather data can be generated for a subset of the climate models and scenario runs carried out for 2007's Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).

2  A peer-reviewed paper on the software and the methods used is in preparation.

Links

• The application is available at http://gisweb.ciat.cgiar.org/MarkSimGCM/ 
• Downscaled data grids for time-slices centered on 2030, 2050 and 2080 are available at http://futureclim.info/
• Documentation on the methods used can be found in Jones et al., “Generating characteristic daily weather data using downscaled climate model data from the IPCC’s Fourth Assessment”

Partners

the International Center for Tropical Agriculture (CIAT)

Timeframe