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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L17702, doi:10.1029/2007GL030844, 2007

Long-term drought severity variations in Morocco

Jan Esper

Swiss Federal Research Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland


David Frank

Swiss Federal Research Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland


Ulf Büntgen

Swiss Federal Research Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland


Anne Verstege

Swiss Federal Research Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland


Jürg Luterbacher

National Centre of Competence in Research on Climate (NCCR) and Institute of Geography, University of Bern, Bern, Switzerland


Elena Xoplaki

National Centre of Competence in Research on Climate (NCCR) and Institute of Geography, University of Bern, Bern, Switzerland


Abstract

Cedrus atlantica ring width data are used to reconstruct long-term changes in the Palmer Drought Severity Index (PDSI) over the past 953 years in Morocco, NW Africa. The reconstruction captures the dry conditions since the 1980s well and places this extreme period within a millennium-long context. PDSI values were above average for most of the 1450–1980 period, which let recent drought appear exceptional. However, our results also indicate that this pluvial episode of the past millennium was preceded by generally drier conditions back to 1049. Comparison of PDSI estimates with large-scale pressure field reconstructions revealed steady synoptic patterns for drought conditions over the past 350 years. The long-term changes from initially dry to pluvial to recent dry conditions are similar to PDSI trends reported from N America, and we suggest that they are related to long-term temperature changes, potentially teleconnected with ENSO variability and forced by solar irradiance changes.

Received 30 May 2007; accepted 26 July 2007; published 5 September 2007.

Keywords: climate change; drought; Morocco.

Index Terms: 0473 Biogeosciences: Paleoclimatology and paleoceanography (3344, 4900); 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 1637 Global Change: Regional climate change; 9305 Geographic Location: Africa.

Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 574216 bytes)

Citation: Esper, J., D. Frank, U. Büntgen, A. Verstege, J. Luterbacher, and E. Xoplaki (2007), Long-term drought severity variations in Morocco, Geophys. Res. Lett., 34, L17702, doi:10.1029/2007GL030844.