A Weather Generator for Hydrological, Ecological, and Agricultural Applications
In an effort to create a tool that would provide input data to hydrology models, a weather generator was developed at the Ralph M. Parsons Laboratory, Massachusetts Institute of Technology. The generator allows simulation of hourly hydrometeorological variables representative of a given geographic location: precipitation, total cloud cover, incoming shortwave radiation, air temperature, humidity, and wind speed. The approach captures the essential relationships among the quantities of interest, while modeling the diurnal variation of weather conditions at the hourly scale. Precipitation is considered to be the key driver of simulated hydrometeorological conditions, which leads to a consistent co-variation of the weather variables. While a specific storm arrival model is assumed, in principle, any rainfall generation routine, e.g., accounting for intra-storm/diurnal variability of the precipitation process, can be used as the driver of the simulated hydrometeorological series. The weather generator can also be forced using real rainfall observations, which are more commonly available.
The generator was calibrated and validated with data from three meteorological stations located in New Mexico, Arizona, and Oklahoma. The set of variables reproduced by the weather generator can serve as input to a number of models of environmental systems, involving hydrological, ecological, water resources, and agricultural applications. The model is also suitable for creating scenarios of climate regimes (e.g., dry vs. wet climates) useful in sensitivity studies. The source code of the weather generator is publicly available. The manual and examples of test applications are also available.
The model is based on the doctoral dissertation of Dr. David Curtis (1982), who was supervised by Prof. Peter S. Eagleson. The work was continued in thesis of Dr. Valeriy Ivanov (2006), who introduced several modifications, which lead to a better or more efficient representation of the simulated statistics.
The technical information on the weather generator, the source code of the parameter estimation routine, and a brief manual can be downloaded here.
Relevant References
[1] Ivanov, V.Y., Bras, R.L., and Curtis, D.C. (2007). A Weather Generator for Hydrological, Ecological, and Agricultural Applications, accepted for publication in Water Resources Research.
[2] Curtis, D.C., and Eagleson, P.S. (1982). Constrained Stochastic Climate Simulation. Technical Report 274, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, Ralph M. Parsons Laboratory, Cambridge, MA, USA.