Low-latitude aurorae (LLA) were an uncommon phenomenon not well known or understood in 1780. During our historical manuscript research of high atmospheric phenomena, we came across a document reporting an observation made by the abbot Rozier in Beausejour, France, on 15/08/1780. Thanks to the accuracy of his report, we were able to confirm it was a white, two-band structure LLA. Due to the few existing geomagnetic and solar observations, this is useful new geomagnetic activity proxy data.

Drought events are of great importance in most Mediterranean climate regions, and the impacts caused on rainfed crops are particularly evident. In this study the impacts of drought on two representative rainfed crops in Spain (wheat and barley) are assessed by testing various worldwide drought indices and two datasets at different spatial resolution.

Drought is a major driver of vegetation activity in Spain. Here we used a high-resolution remote-sensing dataset spanning the period from 1981 to 2015 to assess the sensitivity of 23 vegetation types to drought across Spain. Results demonstrate that vegetation activity is controlled largely by the interannual variability of drought. Nevertheless, there are some considerable spatio-temporal variations, which can be linked to differences in land cover and aridity conditions.

We mapped – for the first time – the probability of occurrence of drought over Spain, with the overriding aim of improving current drought assessment, management and mitigation measures, and strategies across the region. Spatially, our estimations suggest a higher probability of extreme drought events in southern and central areas of Spain compared to northern and eastern regions. Nevertheless, there are strong differences among drought indices and drought timescales.

We analyzed changes in surface relative humidity (RH) at the global scale from 1979 to 2014 and compared the variability and trends in RH with those in land evapotranspiration and ocean evaporation in moisture source areas across a range of selected regions worldwide. Our results stress that the different hypotheses that may explain the decrease in RH under a global warming scenario could act together to explain recent RH trends.