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The role of NAO in Western Europe climate variability during the Late Glacial and Holocene based on Iberian and Azores Island lake cores and climate instrumental data (CGL2010-15767).

This research project is funded by the Spanish Ministry of Science and Innovation through its Research and Development and Innovation (R & D & I) National Plan.


The North Atlantic Oscillation (NAO) and the El Niño - Southern Oscillation (ENSO) are two of the main climate modes that rule the globe natural climate variability on interannual and longer time scales.

At multiannual scale, NAO oscillations accounts for more of the 50 % of the winter rainfall variance in northwestern Iberian meteorological stations. This climate mode also rules other climatic and enviromental variables that have a direct impact on the terrestrial ecosystems like the plant growing season, the plant flowering period length, the tree ring growth and the location and development of many invertebrate, amphibian and bird species. NAO also has a strong and direct influence on lacustrine ecosystems through many ways, such as on lake water temperature, hydrological balance, and nutrient input and hence over the phytoplankton and zooplankton and therefore the whole food web.

Despite the importance of this climate phenomenon for Europe, only some historical reconstructions based on documentary evidences and tree rings covering the last 1,500 years and few long-term (millennial scale) reconstructions using terrestrial sedimentary records of the NAO fluctuations have been carried out. Surprisingly, few multiproxy reconstructions of the NAO evolution have been conducted in the Azores islands, albeit being located in one end of the dipole. These NAO millennial-scale studies using terrestrial sedimentary archives are almost absent for the Iberian Peninsula though first attempts are currently in progress.




The objective of this research project is to achieve a high-resolution spatial and temporal reconstruction of the North Atlantic Oscillation (NAO) climatic phenomenon at multiannual-decadal resolution for the last 1,000 years and at millennial time-scale for the last 15,000 years in the southwestern Europe and Azores islands from the multiproxy characterization of lacustrine sediments.

This objective includes the following milestones:

  • Development of long and high-quality instrumental climate (temperature and precipitation) records (both regional and single sites timeseries) and compilation of the NAO Indices (NAOi).
  • Assessments of intraannual, interannual, decadal and interdecadal relationships between NAO and the surface climate of Central Iberia and Azores.
  • Characterization of the NAO climate signal transmission from the atmosphere to the sediments for the last 1,000 years.
  • Geomorphological characterization of the catchments from Cimera and Peñalara Lakes (Central Mountains, Spain) and from a number of lakes in São Miguel island (Açores Islands, Portugal).
  • Multiproxy high-resolution characterization of the sedimentary cores taken from the selected lake systems.
  • Paleolimnological and paleoclimate reconstruction at two temporal scale windows: last 1,000 years, and Lateglacial and Holocene periods.
  • Identification and isolation of the NAO climate signal from the other signals in each temporal scale window and studied locality.
  • Exploratory analysis between multiproxies from the sedimentary lacustrine cores and Central Iberia and Azores instrumental climate timeseries.
  • Comparison of the reconstructed NAO climate signals in order to characterize the spatial-temporal evolution of this climate phenomenon.