Hydrographic variations of the Pacific Waters in the Canadian Basin

Hydrographic variations of the Pacific Waters in the Canadian Basin are investigated using available CTD and XCTD data sets, SSMI ice concentration, and climatological data (EWG Arctic Ocean Atlas series). Here we focus on the variation of water mass properties of Pacific origin. Pacific Summer Water (PSW), Pacific Winter Water (PWW) and Atlantic Water (AW) are centered at S=31.3psu, 33.1psu respectively. After 1990, temperature of the Pacific Summer Water has been increased about 1.0 degree Celsius per decade. On the other hand the temperature of PWW has been dropped about 0.15 degree Celsius per decade. This negative correlation between PSW and PWW suggested that some dynamical mechanism controls the coherent variability. The variations of PSW and PWW well correlate with the time series of wintertime Arctic Oscillation (AO) index. Positive (negative) AO index corresponds to strengthening (weakening) of Beaufort High (BH). Strong BH enhances the oceanic Beaufort Gyre and leads the increase of northward advection of PSW in the western Canada Basin (Chukchi Borderland: CBL). Consequently large amount of PSW spreads from CBL into the central Canada Basin. Strong easterly associated with strong BH blows the sea ice along the Alaskan Coast in the Chukchi Sea, and activates the formation of coastal polynya between the Point Barrow and Cape Lisburne. Pacific Winter Water via the Alaskan Coast into the Canada Basin is cooled and salinized in the coastal polynya. Consequently, the temperature of PWW in the Canada Basin decreases and the salinity of PWW increases. The salinization in the Canada Basin due to PWW variation causes a deepening of isohaline, suggesting enhancement of baroclinic component of oceanic Beaufort Gyre.