Dr. Yanxin Wang, a postdoctoral researcher at the School of Oceanography, Shanghai Jiao Tong University, has recently published a research article in Geophysical Research Letters as the first author. The work, entitled "Nitrate Distribution in Pacific Winter Water Along the Northern Edge of the Chukchi Sea", was done at Shanghai Jiao Tong University in collaboration with the Woods Hole Oceanographic Institution. Dr. Peigen Lin is the corresponding author.

Pacific-origin Winter Water (PWW) is a primary source of nitrate for the western Arctic Ocean, fueling primary production at the base of the food web. This cold, nutrient-rich water exits the Chukchi shelf via Herald Canyon and Barrow Canyon, which feed the eastward-flowing Chukchi Shelfbreak Jet (CSJ) and the westward-flowing Chukchi Slope Current (CSC), respectively (Figure 1). These two oppositely flowing boundary currents dominate the circulation along the northern Chukchi margin and play a crucial role in redistributing nutrients.

Figure 1. Schematic circulation of the Chukchi Sea and geographic place names. The red arrows are the Chukchi Shelfbreak Jet and Chukchi Slope Current within the study region (yellow‐dashed box). 

Using an extensive historical dataset of nitrate, hydrography, and velocity measurements collected from 31 cruises between 2002 and 2023, the authors systematically characterized the spatial distribution of nitrate along the northern edge of the Chukchi Sea. Their analysis reveals that nitrate concentrations in PWW increase significantly from east to west (Figure 2). By documenting the nitrate sources in Herald Canyon and Barrow Canyon and following its downstream evolution in the two currents, they demonstrate that the westward increase in nitrate is significantly associated with the eastwardflowing CSJ.

Figure 2. Spatial variation of nitrate concentration along the Chukchi Slope and in Barrow Canyon and Herald Canyon. (a) Segment‐averaged nitrate concentration anomaly in potential density classes, relative to the mean nitrate value. (b) Nitrate concentrations in the PWW layer.

Composite vertical sections across the eastern and western slope regions further show that the elevated nitrate signal is carried by the bottomintensified CSJ (Figure 3). As the CSJ flows eastward, it gradually loses nitrate through mixing and eddy shedding, creating the observed westwardincreasing nitrate gradient. The CSC, by contrast, carries lowernitrate water from Barrow Canyon.

Figure 3. Composite vertical sections for the western slope region and eastern slope region. (a, b) Absolute geostrophic velocity overlain by potential density. (c, d) nitrate concentration overlain by potential density.

These results highlight the fundamental role of the Chukchi Sea boundary current system in distributing nitrate across the Arctic shelfslope region. The findings provide critical insight into the physical mechanisms that control nutrient availability, which in turn regulates phytoplankton productivity and carbon sequestration efficiency in the western Arctic Ocean.

Article information and related links

Wang, Y., Lin, P., & Pickart, R. S. (2026). Nitrate distribution in Pacific winter water along the northern edge of the Chukchi Sea. Geophysical Research Letters, 53, e2025GL120015.

http://doi.org/10.1029/2025GL120015

Dr.Wang and Dr.Lin were supported by the National Key R&D Program of China (2024YFC2813202), Shanghai Pujiang Program (23PJ1405800), National Natural Science Foundation of China (42306251 and 42476262), and the Fundamental Research Funds for the Central Universities. RP was supported by the US National Science Foundation Grant OPP‐2135537 and the US National Oceanic and Atmospheric Administration Grant NA19OAR4320074.