INTRODUCTION

The subarctic Pacific is one of the most productive regions of the world’s oceans and an important sink for atmospheric CO2. Like most high-latitude ocean basins, the subarctic Pacific exhibits strong seasonal to interannual variations in ocean biology and CO2 uptake that appear to be tightly coupled to changes in its physical environment. Unlike the North Atlantic, precipitation is in excess of evaporation in the subarctic Pacific. As a consequence, there is a surface layer of low salinity that resides over a permanent halocline at 100-150m, which constrains winter mixing and renewal of mixed layer nutrients in winter. A unique feature of the subarctic Pacific however, is the development of the Aleutian Low Pressure System (ALPS, 50^oN, 170^oW), under the influence of which the region experiences strong climate-modulated variations in meteorological and physical oceanographic conditions that have a profound effect on biological production in the region. Although the intensification of the ALPS is a regular feature in winter, it is particularly severe following the onset of El-Niño, when it strengthens and moves in a southeastward direction causing large disturbances in the pressure gradient between Siberia and the Aleutian Low. As a result during winters that follow El Niño events, the entire western half of the subarctic comes under the influence of highly intensified East Asian Monsoonal winds which have a profound impact on oceanographic conditions in the region.