shows evidence of active LHW formation, and a CHL is absent. Where it is much fresher LHW is capped by a stable pycnocline and a CHL is present. Our examination reveals that the winter mixed layer salinity in the mid-Eurasian Basin during SCICEX'95 was about 34, indicating the absence of a CHL. The SCICEX'93 data from the Amundsen Basin (not shown) are fresher by about 0.5, while the Oden'91 data (not shown) are fresher still. In fact, the Oden'91 data are generally about equal to the maximum salinity field recorded over the 40-year EWG climatology (not shown). The Amundsen Basin and Lomonosov Ridge winter mixed layers salinified over the 1990's by about 1 .0 over the 40-year maximum values.
We can also compare the 1990's data with the EWG 40-year mean and 40-year minimum fields, again averaged over 40-60 m depth. These comparisons (not shown) demonstrate that the western Eurasian Basin during Oden'91 was about equal to the 40-year mean, while much of the Canada Basin was fresher than the 40-year mean during the SCICEX cruises. In fact, the central Canada Basin exhibits a freshening of about 0.5 relative to the EWG minimum field. Thus the Canada Basin (and its outflow north of Greenland towards Fram Strait) freshened as the Eurasian Basin salinified during the 1990's.
We have also documented the advance of AW into the Arctic Ocean over the course of the 1990's, as well as changes in the extent of Pacific-influenced halocline types (Upper Halocline Water and Bering Sea Water). Further, we have used a simple one-dimensional mixing model, initialized with SCICEX'95 data, to estimate the ice-ocean heat fluxes during April of 1995. We predict maximum heat fluxes of about 1.3 W m-2, which are of course over and above those expected to accrue during summer heating.
What is causing these changes? We propose that the answer lies in climatological atmospheric wind shifts associated with surface air pressure patterns, such as those documented by Walsh et al. [1996]. In particuial, the strenghening of the Eurasian low pressure cell during the 1990's may have enhanced the eastward flow of fresh water from western Siberian shelves, causing the injection point into the deep Arctic basins to shift eastward as well. This would explain the solidification of the Eurasian Basin, and is illustrated in Figure 3. We further propose an "advective-convective" mechanism for the formation of the CHL, wheherein LHW forms in the Nansen Basin by both local convection and advection from the Barents Sea, while the CHL forms only where fresh shelf water from the Kara and Laptev Seas advects into the deep basin somewhere east of 90゜E longitude.
Acknowledgments. We thank Dr. J. Morison. This work was supported by ONR and NASA.
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