Abstract
AbstractA biophysical model shows that Beaufort Gyre (BG) intensification in 2004–2016 is followed by relaxation in 2017–2018, based on a BG variability index. BG intensification leads to enhanced downwelling in the central Canada Basin (CCB) and upwelling along the coast. In the CCB, enhanced downwelling reduces nutrients, thus lowering primary productivity (PP) and plankton biomass. Enhanced upwelling along the coast and in parts of the Chukchi shelf/slope increases nutrients, leading to elevated PP/biomass in the Pacific Arctic Ocean (PAO) outside of the CCB. The overall PAO PP/biomass is dominated by the shelf/slope response and thus increases during BG intensification. As the BG relaxes in 2017–2018, these processes largely reverse, with increasing PP/biomass in the CCB and decreasing PP/biomass in most of the shelf/slope regions. Because the shelf/slope regions are much more productive than the CCB, BG relaxation has the tendency to reduce the overall production in the PAO.
Highlights
Large‐scale circulation in the Pacific Arctic Ocean (PAO; see Figure 1a for definition) is closely associated with the anticyclonic Beaufort Gyre (BG) located over the Canada Basin
Observations and model results indicate that the BG intensified in recent years; this intensification is associated with increased ocean velocity and freshwater content (FWC) in much of the PAO because of enhanced Ekman transport convergence and downwelling in the Canada Basin (CB) and enhanced upwelling in the Chukchi and Beaufort shelf and slope region (e.g., Giles et al, 2012; Krishfield et al, 2014; McPhee, 2013; Proshutinsky et al, 2009; Regan et al, 2019; Yang, 2009)
The BG intensification results from more frequent occurrence of a strong Beaufort high‐pressure atmospheric cell driving a strengthened anticyclonic wind and ocean circulation, as reflected in mostly positive values of the BG variability (BGV) index constructed based on the depth of a isohaline (S = 31 psu) in the central CB
Summary
Large‐scale circulation in the Pacific Arctic Ocean (PAO; see Figure 1a for definition) is closely associated with the anticyclonic Beaufort Gyre (BG) located over the Canada Basin. Observations and model results indicate that the BG intensified in recent years; this intensification is associated with increased ocean velocity and freshwater content (FWC) in much of the PAO because of enhanced Ekman transport convergence and downwelling in the Canada Basin (CB) and enhanced upwelling in the Chukchi and Beaufort shelf and slope region (e.g., Giles et al, 2012; Krishfield et al, 2014; McPhee, 2013; Proshutinsky et al, 2009; Regan et al, 2019; Yang, 2009). The enhanced downwelling in the CB and upwelling in the Chukchi and Beaufort shelf and slope region likely have an impact on the planktonic ecosystem in the PAO. A pan‐Arctic biophysical model, the Biology‐Ice‐Ocean Modeling and Assimilation System (BIOMAS, Zhang et al, 2015), is used to examine changes in BG circulation and upper ocean physics during the period 1992–2018 and to assess how these changes affect the spatiotemporal variability of the planktonic ecosystem
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
