Abstract. The Lomonosov Ridge represents a major topographical feature in the Arctic
Ocean which has a large effect on the water circulation and the distribution
of water properties. This study presents detailed bathymetric survey data
along with hydrographic data at two deep passages across the ridge: a
southern passage (80–81∘ N), where the ridge crest meets the
Siberian continental slope, and a northern passage around 84.5∘ N.
The southern channel is characterized by smooth and flat bathymetry around
1600–1700 m with a sill depth slightly shallower than 1700 m. A
hydrographic section across the channel reveals an eastward flow with
Amundsen Basin properties in the southern part and a westward flow of Makarov
Basin properties in the northern part. The northern passage includes an
approximately 72 km long and 33 km wide trough which forms an intra-basin
in the Lomonosov Ridge morphology (the Oden Trough). The eastern side of the
Oden Trough is enclosed by a narrow and steep ridge rising 500–600 m above
a generally 1600 m deep trough bottom. The deepest passage (the sill) is
1470 m deep and located on this ridge. Hydrographic data show irregular
temperature and salinity profiles indicating that water exchange occurs as
midwater intrusions bringing water properties from each side of the ridge in
well-defined but irregular layers. There is also morphological evidence that
some rather energetic flows may occur in the vicinity of the sill. A well
expressed deepening near the sill may be the result of seabed erosion by
bottom currents.
