Reconstruction of three centuries of annual accumulation rates based on the record of stable isotopes of water from Lomonosovfonna, Svalbard

• We use the upper 81 m of the record of stable isotopes of water from a 122 m long ice core from Lomonosovfonna, central Spitsbergen, to construct an ice core chronology and the annual accumulation rates over the ice field. The isotope cycles are counted in the ice core record using a model that neglects short wavelength and low amplitude cycles. We find approximately the same number of ä18O cycles as years between known reference horizons, and assume these cycles represent annual cycles. Testing the validity of this assumption using cycles in äD shows that both records give similar numbers of cycles. Using the ä18O chronology, and de-compressing the accumulation records using the Nye flow model, we calculate the annual accumulation for the ice core site back to 1715 AD. We find that the average accumulation rate from 1715 to 1950 o was on average 0.30 m w.e. Accumulation rates increased ca. 25% during the later part of the 20th century to an average of 0.41 m w.e. for the period 1950 – 1997. The accumulation rates show highly significant 2.1 and 21 year periodicities, which gives credibility to our time scale.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Naturgeografi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Physical Geography (hsv//eng)

Nyckelord

Physical geography

Naturgeografi

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