Climate change in the Iberian Peninsula by weather types and temperature

Abstract

The main advantage of classifying weather types is its systematic use with pressure gridded values. In this paper, an extensive database covering 74 years was used to determine weather types and their temperature fields in the Iberian Peninsula. Moreover, two 37-year periods were compared to investigate climate change in this region. Lamb weather types were determined. The most frequent was the anticyclonic type (21%) followed by the unclassified type (16.5%), with the distribution of these weather types being nearly similar over time. The pressure field was quite uniform in the region and pressure increased 0.7 hPa between the two periods. Moreover, pressure of easterly flows was greater than the pressure of westerly flows, with their difference being around 7 hPa, and the centres of cyclonic types were closer to the Iberian Peninsula than the centres of the anticyclonic types. Isotherms follow geographic parallels, although the meridian gradient was greater over the continental surface than over the ocean. Northern Africa proved to be prominent, since temperatures were highest and specific flows might favour heat waves over the peninsula. The temperature increase between the two 37-year periods was 0.5 °C. In addition, the contrast between the meridian gradients in the east and west of the region evolved towards a lower contrast of these meridian gradients throughout the whole of the region.