Program
 
Special Session 5: Ocean-atmosphere interaction, multi-scale climate variability and their implication for biogeochemical processes
 

 
 
1150
Characteristics of upwelling in the Alaskan Beaufort Sea based on 6 years of mooring data
Wednesday 11th @ 1150-1210
Room 1
Peigen Lin* , Xiamen University; Woods Hole Oceanographic Institution
Robert Pickart, Woods Hole Oceanographic Institution
Jianyu Hu, Xiamen University
Presenter Email: plinocean@stu.xmu.edu.cn
Based on 6-year mooring data, including a mooring array in September 2002–August 2004 and a single mooring in September 2008–August 2012, together with meteorological and atmospheric data, we identify the general characteristics of upwelling in the Alaskan Beaufort sea, distinguish the upwelling types and reveal their seasonal variation. Wind-driven upwelling event is defined as the period with positive potential density anomaly while under easterly wind forcing on average. The periods of the identified 131 upwelling events in 6-year record are normalized into 0 – 1. The composites of wind, hydrographic and velocity fields in the normalized event revealed the general characteristics of upwelling: delay effect of wind forcing, uplifted isopycnals with intensified stratification, revised along-isobath current and onshore cross-isobath flow in the bottom layer. Based on the uplifted watermass during each event, Atlantic water (AW) or Pacific water (PW), we distinguished AW-type and PW-type upwelling. The upwelling events were AW-type when the PW-AW boundary depth was shallower than 162 m, which suggested that the watermass boundary depth decide the upwelling types. The AW-type and PW-type upwelling usually occur in winter and summer, respectively. It is associated with the seasonal variation of the watermass boundary depth, shallower in winter and deeper in summer, which was due to the wind stress curl field. These variations were eventually controlled by the action of the two atmospheric centers, the Aleutian Low and Beaufort High.