| ABSTRACT | A new stochastic weather generator (WG) , which is able to produce realistic synthetic multi-variate multi-site (gridded or irregularly distributed in space) daily (or monthly, or annual) weather series representing both present and future climate conditions, is now being developed. The generator, whose model is based on the Wilks' (1999) multi-site extension of the parametric (Richardson’s type) single site M&Rfi WG, may be run in two modes: In the first mode, it is run as a classical generator, which is calibrated in the first step using weather data from a number of sites distributed either regularly (grids) or irregularly (stations) in space, and only then it may produce arbitrarily long synthetic time series mimicking the spatial and temporal structure of the calibration weather data. To generate the weather series representing the future climate, the WG parameters are modified according to the climate change scenario derived from GCM or RCM simulation. In the second mode, the user provides only basic information (not necessarily to be realistic) on the temporal and spatial auto-correlation structure of the surface weather variables and their mean annual cycle; the generator itself derives the parameters of the underlying autoregressive model, which produces the multi-site weather series. In the latter mode of operation, the user is allowed to prescribe the spatially varying trend, which is superimposed to the values produced by the generator; this feature has been implemented for use in developing the methodology for assessing significance of trends in multi-site weather series. While the WG's second mode is a subject of another conference contribution (EMS-2016 in Trieste), this contribution will focus on the first (classical) mode. The poster will (a) introduce the model of the generator, and (b) present sample results obtained by applying the WG on selected Mediterranean regions. In this experiment, the generator will be calibrated using the E-OBS gridded daily weather data and modified by climate change scenarios derived from the RCM simulation (taken from the CORDEX database). The focus will be put on the WG's ability to reproduce the spatial variability of surface weather characteristics (WG validation), and on assessing its future changes. |