A multiproxy reconstruction of spring temperatures in south-west Finland since 1750

Jari Holopainen, Samuli Olavinpoika Helama, Juha M. Kajander, Johanna Korhonen, Jouko Launiainen, Heikki Nevanlinna, Anni Reissell, Veli-Pekka Salonen

    Research output: Contribution to journalArticleScientificpeer-review

    Abstract

    Spring temperatures were reconstructed by multiproxy database for south-west Finland since 1750. Proxy records used here were ice break-up in the Aurajoki River, the Baltic Sea ice extent, the plant phenological index and the annual varve thickness in the Pyhajarvi Lake. Records were integrated into one palaeoclimate model using time-scale dependent calibration techniques. Reconstruction was verified with statistics showing a high degree of validation between the reconstructed and observed temperatures in Turku, south-west Finland. Reconstruction demonstrates that the springs have become warmer and reveals a warming trend since 1850s. Except for the period from 1750 to around 1850, the springs have been characterized as having a larger low-frequency variability, as well as by having a smaller range of annual temperature variations. Analyses of decadal variations revealed that the coldest springtimes occurred in the 1840s and 1850s and the first decade of the 19th century. Reconstruction was compared with the available meteorological series of central England, Stockholm, St. Petersburg, Uppsala and the spring-temperature reconstruction from western Norway. The effect of global solar, volcanic, greenhouse gases and aerosol forcings were examined together with the North Atlantic Oscillation (NAO) indices at local scale over the reconstructed period. Reconstructed spring-temperature changes have been related to changes in the atmospheric circulation, as indicated by the NAO (February-June).
    Original languageEnglish
    JournalClimatic Change
    Volume92
    Pages (from-to)213-233
    Number of pages21
    ISSN0165-0009
    DOIs
    Publication statusPublished - 2009
    MoE publication typeA1 Journal article-refereed

    Fields of Science

    • NORTH-ATLANTIC OSCILLATION
    • SURFACE AIR-TEMPERATURE
    • PAST 1000 YEARS
    • CLIMATE-CHANGE
    • HEMISPHERE TEMPERATURES
    • VOLCANIC-ERUPTIONS
    • SUMMER TEMPERATURE
    • LAST MILLENNIUM
    • TREE-RINGS
    • VARIABILITY
    • 117 Geography, Environmental sciences

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