Author(s): Annu Oikkonen; Matti Lepparanta; Kunio Shirasawa
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Keywords: No Keywords
Abstract: This study bases on the ice drift observation made with drifting ice buoys in the Sea of Okhotsk during winters 2004 and 2005, and with the ship moored into the drifting ice floe in the Baltic Sea in March 2009. Ice drift was compared with wind observations in both sea areas. In the Sea of Okhotsk also sea level measurements and the tidal component of sea level variations were used to study the importance of tidal forcing. During the Baltic Sea ice drift experiment data collected in three drifting ice stations represented three very different drifting conditions. During the first ice station (S1) wind was mild and ice field was very compact. In the second ice station (S2) stronger wind caused faster drift, but also a lot of ice deformations. Fastest ice drift (22 cm/s) was observed in the third ice station (S3), where ice drift was very close to free drift. In S1 and S2 power spectrums of wind and ice drift correspond well over the whole frequency span, while in S2 correspondence in higher frequencies is clear ly weaker. In the Sea of Okhotsk ice was drifting genera lly much faster than in the Baltic Sea. Although the ice drift power spectrums do not show very clear tidal peaks, cross wavelet and wavelet coherence analyses show the importance of tides. In the cross wavelet transforms of ice drift and sea level variations there is significant common power in tidal bands of about 12 h and 24 h, and the common power varies with varying maximum tide amplitude.
Year: 2010