RT Journal Article T1 Iberia in 1816, the year without a summer A1 Trigo, Ricardo M. A1 Vaquero, José M. A1 Alcoforado, María João A1 Barriendos, Mariano A1 Taborda, João A1 García Herrera, Ricardo Francisco A1 Luterbacher, Juerg AB The year 1816 was characterized by unusual weather conditions, in particular, by a cold and wet Summer season ('year without a summer') on both the European and North American continents. The eruption of Tambora, an active stratavolcano, on the Island of Sumbaya (Indonesia) in April 1815 has been identified as the main driving force for the strong 1816 temperature anomaly. This climate anomaly has been relatively well studied in central Europe, France, Scandinavia and the United Kingdom. The unusual unsettled weather and climate at mid-latitudes in 1816 and 1817 had major socioeconomic impacts. particularly in terms of a poor yield of agricultural production, malnutrition and consequentially an increased potential for diseases anti epidemics. The Iberian Peninsula was also affected by the intense climate anomalies during, those years. Documentary Sources describe the impact that the cold and wet summer of 1816 had on agriculture, namely the bad quality of fruits, delayed ripening of vineyards and cereals. It is within this context that we stress the relevance of recently recovered meteorological observed data, from 1816 onwards. for stations located in Portugal (Lisbon) and also for a longer period for the Spanish stations of Madrid, Barcelona and San Fernado-Cadiz. We have compared observed (station-based) and large-scale reconstructed seasonal temperature anomalies computed for the winter and summer seasons after the eruption (1816-1818). There is qualitative agreement between the two independent data sets, though some stations partly indicate stronger departures from the long-term averages for single years compared to neighbouring grid points. In particular. all available stations reveal a cold summer of 1816, mainly in July and August. In comparison to the 1871-1900 reference period, those two months were 2-3 degrees C cooler, close to what has been reported for central Europe. We also discuss the regional climate anomalies for those years (1816-1818) using independently reconstructed atmospheric circulation fields. PB John WiIley & Sons LTD SN 0899-8418 YR 2009 FD 2009-01 LK https://hdl.handle.net/20.500.14352/44813 UL https://hdl.handle.net/20.500.14352/44813 LA eng NO © 2008 Royal Meteorological Society. Ricardo Trigo and Ricardo García Herrera received support from the Portuguese-Spanish integrated action (E-27/2005) funded by CRUP and MCYT and the EU 6th Framework Program (CIRCE). José M. Vaquero acknowledges support from the Gulbenkiam Foundation-Biblioteca Nacional de Portugal, and the Programme 'José Castillejo' from the Spanish Science Ministry. Mariano Barriendos acknowledges the Research Programme 'Ramón y Cajal' and Research Group 'Paisatge i paleoambients a la muntanya mediterrania', University of Barcelona. Jurg Luterbacher is supported by the Swiss National Science Foundation through its National Centre of Excellence in Research on Climate (NCCR) and the EU 6th Framework Program (CIRCE). Some of the historical Portuguese material used in this work was consulted at the Biblioteca Nacional de Portugal (Lisbon, Portugal) and Biblioteca del Real Observatorio de la Marina (San Fernando, Spain). Long-term series of observed data were also obtained through the Portuguese project SIGN (Signatures of environmental chance in the observations of the Geophysical Institutes) under POCTI/CTA/47803/2002 project. The authors are indebted to Manola Brunet and Javier Sigro for providing data for Madrid. Finally the authors would like to thank both reviewers for their helpful and constructive comments that help in improving the manuscript. NO Unión Europea. FP6 NO Conselho de Reitores das Universidades Portuguesas (CRUP), Portugal NO Ministerio de Ciencia y Tecnología (MCYT), España NO Fundação Calouste Gulbenkian (Portugal) NO Ministerio de Educación y Ciencia (MEC), España NO Programa Ramón y Cajal NO Grupo de investigación ‘Paisatge i paleoambients a la muntanya mediterr`ania’ (Universidad de Barcelona) NO National Centre of Excellence in Research on Climate (NCCR), Suiza NO Project SIGN (Signatures of environmental change in the observations of the Geophysical Institutes), Portugal NO Programa CIRCE (UE) NO Biblioteca Nacional de Portugal (BNP) NO Programa José Castillejo (MEC), España DS Docta Complutense RD 8 jun 2025