Sea Ice Station Umeä, Winter 2005 
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Sea Ice Station Umeä, Winter 2005 
Matti Leppäranta*, Kunio Shirasawa + , Jari Uusikivi*, Keguang Wang*, 
Olli-Pekka Mattila* and Antti Kangas* # 
*Division of Geophysics, University of Helsinki, Finland, Emails matt.lepparanta@helsinki.fi. 
iah.uusikivi@helsinki.fi. keauana.wang@helsinki.fi. 
olli-pekka.mattila@helsinki.fi 
+ Hokkaido University, Sapporo, Japan, Email kunio@DOD.lowtem.hokudai.ac.ip 
Presently in Finnish Institute of Marine Research, Helsinki, Finland, Email 
antti.kanaas@fimr.fi 
Abstract 
In winter 2005 ice investigations were performed in the Northern Quark, Gulf of Bothnia. A float 
was deployed at the Umea Marine Sciences Centre in November 2004 for atmospheric surface 
layer, ice, and oceanographic measurements; this float then was destroyed in heavy storm in 
January 2005. In spring manual measurements were made at the station with ice sampling. 
The throughflow of ice in the Northern Quark was examined by mathematical modelling. The 
geometry of the strait, in particular the fast ice boundary, is critical for the dynamics of the ice 
there. 
Introduction 
In the Baltic Sea winter, near-coastal areas are covered by landfast ice while further out drift ice 
fields are found. The boundary between the fast ice and drift ice zone is on average at 10 m 
depth contour but if the ice is very thick the ice cover of a basin may become stationary 
(Lepparanta, 2004). The evolution of the location of the fast ice boundary is a challenging but 
very complicated question. 
Coastal zone ice investigations have been ongoing in the recent years as part of our snow and 
ice research programme. This zone covers the fast ice zone and normally also a section of the 
drift ice field. The first main site was Santala Bay in the Gulf of Finland (e.g., Kawamura et al., 
2001 ; Granskog et al., 2004) and the second one was at Perameri Research Station on the 
western shore of Hailuoto island, Bay of Bothnia. In winter 2004/2005 the sea area off Umea 
Marine Sceinces Centre was taken as the third main site. This paper presents the Umea 
experimental campaign together with the first results.