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Climate variability and change can have important impacts for crop production. Therefore, the aim of this study is to investigate projections of the wheat yield in an increasingly warm climate. To address our objectives, we determined relationships between wheat yield in Spain and large-scale variables. Partial least squares regression was applied to determine the modes of the climate variables that drive wheat-yield variability, revealing a significant influence of surface solar radiation. Based on seasonal patterns of solar radiation, we determine models to estimate inter-annual wheat-yield variability. We find that the performance of the models based on solar radiation is better than that of earlier studies based on temperatures and precipitation variables. In this way, we use simulations of the Coupled Model Intercomparison Project Phase 5 (CMIP5) to project wheat-yield trend under warming climate by implementing direct statistical downscaling. The expected range of projected wheat yield trend for 21st century indicates decreases of about 6–8% across Spain. The suggested models could be applied for adaptation and planning.

The trends of precipitation over the Iberian Peninsula (IP) and the North Atlantic Oscillation (NAO) index from December to March are compared using observations and model simulations from the Coupled Model Intercomparison Project phase 3 (CMIP3). The evaluation is performed in two multi-models as derived by averaging simulations corresponding to two experiments: one represents climate in the 20th century (20C3M) and the other the scenario with medium forcing IPCC SRES A1B in the 21st century. The NAO index shows a trend to more positive phases and precipitation tends to decrease in the case of observations, with greater significance in the NAO than in precipitation. The simulations in the 20th century underestimate the trend both in the NAO and in precipitation compared to observations. The multi-model in the 21st century indicates a change in the NAO regimes to being more positive; this leads to a reduction of precipitation over the IP. To explain the precipitation trend changes we consider the response of precipitation to the NAO, the regression between sea level pressure (SLP) over the Euro-Atlantic area onto precipitation averaged over the IP and the composite of precipitation for years with greater and lower NAO. Copyright © 2009 Royal Meteorological Society

Observational series of winter precipitation in the eastern part of the Cantabrian coast in the northern Iberian Peninsula are studied. This rather small area shows a clearly different interannual variability to the rest of the Peninsula. Series of winter precipitation for the whole area are defined using principal component (PC) analysis and they reflect the variability that can be attributed to changes in atmospheric circulation around the area. This variability is physically explained on the basis of the structure of baroclinic activity and vertically integrated moisture transports over the area derived from the NCEP/NCAR Reanalysis project. According to them, the leading PC of winter precipitation represents the overall precipitation over the area. Wet phases of this PC are associated to an increase of baroclinic activity leaving the eastern part of the Atlantic storm track and entering the Mediterranean basin. Conversely, dry phases show a strong reduction of baroclinic activity over the region. The second PC is linked to meridional water vapour transports over the area, which are affected by the topography of the region. Copyright © 2001 Royal Meteorological Society