Climatological time series for the KfC project High-Quality Climate Projections (Theme 6 WP3)

After the publication of the KNMI’06 climate change scenarios for the Netherlands (Van den Hurk et al. 2006), it took several years before the impacts of these KNMI’06 scenarios were estimated. One of the reasons for this was the lack of climatological time series that could be used directly in models to simulate, for instance, hydrological, ecological and agricultural impacts. The data requirements vary with sector and case study and tailoring of the climatological data appears necessary. For instance, river management is typically interested in basin-scale extreme precipitation and agriculture in local extreme rainfall during certain periods of the growing season. Yet, there are also many similarities between the hydrological, agricultural and ecological data requirements: They need information, directly or indirectly, on rainfall (extremes and drought), temperature (mean, minimum and maximum), wind, humidity and radiation (directly or for the estimation of evapotranspiration), often on a daily time resolution.

Climate change itself is not of most interest to society, but the impacts in several sectors are. Therefore, in the Knowledge for Climate (KfC) project "High-Quality Climate Projections" (Theme 6) a Work Package (WP3) was included on "Scenario development for climate change impact". The central research question of this WP3 was: "How to couple climate projections to impact assessment models and how can uncertainty in the impact assessment be incorporated in such a way that it can effectively be used by the adaptation climate community?"

This report presents a set of time series that largely match the KNMI’14 climate change scenarios (KNMI 2014; van den Hurk et al. 2014), constructed to enable early impact assessments before the official publication of the KNMI’14 climate scenarios. In this way, the time between the publication of the climate scenarios and estimates of related impacts can be reduced and at the same time this may promote the coherence in data use between different sectors.

The data requirements were discussed with the partners in WP3 (climate variables, spatial and temporal resolution, area to be covered, etc.) and are discussed in chapter 2. After determining the requirements for the common dataset, methods were developed to generate the dataset. The future time series are obtained by transformation (chapter 3) of the reference time series. This is often referred to as perturbation or delta method. Some climate variables are derived with the help of the other transformed time series (e.g. potential evapotranspiration, relative humidity)