The PECAN field campaign assembled a rich array of observations from lower-tropospheric profiling systems, mobile radars and mesonets, and aircraft over the Great Plains during June-July 2015 to better understand nocturnal mesoscale convective systems and their relationship with the stable boundary layer, the low-level jet, and atmospheric bores.

[1] Northern Hemisphere sea ice areal extent, and perhaps thickness, have shown a detectable reduction over the past several decades. This situation is particularly apparent in the southern Beaufort Sea. The region encompassing the Mackenzie Shelf, the Cape Bathurst Polynya, and the Canada Basin mobile pack ice all occur in a region referred to here as the Canadian Arctic Shelf Exchange study area (CASES). In this paper we present results from an analysis of atmosphere, sea ice, and ocean coupling over the period 1979 to 2000 as a means of setting a physical science context for the CASES research network (operating over the period [2001][2002][2003][2004][2005]. Results show that the Cape Bathurst Polynya complex can be considered as a recurrent polynya; particularly the flaw leads associated with the early opening of the polynya. The Polynya appears to be a consequence of the Beaufort Sea Gyre acting like an ice bridge and a series of flaw leads creating conditions conducive to oceanic upwelling. The sea ice average areal extent has been decreasing in this region over the period 1979 to 2000. Large regional reductions are found (1) north of the Yukon and Alaska Coasts in the region between the Canada Basin pack ice and the landfast sea ice and (2) at the eastern limit of the Cape Bathurst Polynya in Amundsen Gulf. The meteorological forcing of sea ice anomalies occurs through a full range of timescales and space scales. At hemispheric scales a statistical cross-correlation analysis between weekly sea ice concentration anomalies and the Arctic Oscillation accounts for a maximum of about 25 percent of the explained variance and show a surprising spatial coherence in correlation magnitudes both within the study area and northward along the Canadian Archipelago coast. At local scales, positive and negative concentration anomaly periods can be explained through local-scale advective processes associated with regional-scale sea level pressure, 500 hPa geopotential heights, and surface temperature anomalies.

In this paper we provide an overview of the meteorological and sea-ice conditions within the northern portion of Baffin Bay and the region of the North Water (NOW) Polynya between Ellesmere Island and Greenland. Our results indicate an east-west temperature gradient across the NOW and Baffin Bay regions with colder temperatures on the Ellesmere Island coast (-14°C) and warmer temperatures on the Greenland coast (-9°C Nos résultats révèlent l'existence d'un gradient de température est-ouest à travers les régions de la polynie des eaux du Nord et de la baie de Baffin, les températures les plus froides se trouvant sur la côte de l'île d'Ellesmere (-14 °C) et les plus chaudes sur la côte du Groenland (-9 °C). Ce gradient est dû à l'advection d'air chaud (à haute altitude et dans la couche limite) résultant des courants atmosphériques dominants. La configuration de la pression au niveau de la mer (PNM) montre un creux inversé marqué dans la

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