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The great 2012 Arctic Ocean summer cyclone enhanced biological productivity on the shelves.

Zhang J, Ashjian C, Campbell R, Hill V, Spitz YH, Steele M - J Geophys Res Oceans (2014)

Bottom Line: In the central PSA, however, model simulations indicate a decrease in PP and plankton biomass.The simulated biological gain on the shelves is greater than the loss in the central PSA, and therefore, the production on average over the entire PSA is increased by the cyclone.The generally positive impact of cyclones on the marine ecosystem in the Arctic, particularly on the shelves, is likely to grow with increasing summer cyclone activity if the Arctic continues to warm and the ice cover continues to shrink.

View Article: PubMed Central - PubMed

Affiliation: Applied Physics Laboratory, University of Washington Seattle, Washington, USA.

ABSTRACT

[1] A coupled biophysical model is used to examine the impact of the great Arctic cyclone of early August 2012 on the marine planktonic ecosystem in the Pacific sector of the Arctic Ocean (PSA). Model results indicate that the cyclone influences the marine planktonic ecosystem by enhancing productivity on the shelves of the Chukchi, East Siberian, and Laptev seas during the storm. Although the cyclone's passage in the PSA lasted only a few days, the simulated biological effects on the shelves last 1 month or longer. At some locations on the shelves, primary productivity (PP) increases by up to 90% and phytoplankton biomass by up to 40% in the wake of the cyclone. The increase in zooplankton biomass is up to 18% on 31 August and remains 10% on 15 September, more than 1 month after the storm. In the central PSA, however, model simulations indicate a decrease in PP and plankton biomass. The biological gain on the shelves and loss in the central PSA are linked to two factors. (1) The cyclone enhances mixing in the upper ocean, which increases nutrient availability in the surface waters of the shelves; enhanced mixing in the central PSA does not increase productivity because nutrients there are mostly depleted through summer draw down by the time of the cyclone's passage. (2) The cyclone also induces divergence, resulting from the cyclone's low-pressure system that drives cyclonic sea ice and upper ocean circulation, which transports more plankton biomass onto the shelves from the central PSA. The simulated biological gain on the shelves is greater than the loss in the central PSA, and therefore, the production on average over the entire PSA is increased by the cyclone. Because the gain on the shelves is offset by the loss in the central PSA, the average increase over the entire PSA is moderate and lasts only about 10 days. The generally positive impact of cyclones on the marine ecosystem in the Arctic, particularly on the shelves, is likely to grow with increasing summer cyclone activity if the Arctic continues to warm and the ice cover continues to shrink.

No MeSH data available.


Simulated surface ocean velocity (vector) and (a–d) speed (colors) and (e–h) mean vertical diffusivity in the upper 15 m of the Arctic Ocean over the period 5–11 August 2012. The white lines are NCEP/NCAR reanalysis sea level pressure (SLP) contours with contour interval of 10 hPa. One of every 100 surface ocean velocity vectors is plotted.
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fig08: Simulated surface ocean velocity (vector) and (a–d) speed (colors) and (e–h) mean vertical diffusivity in the upper 15 m of the Arctic Ocean over the period 5–11 August 2012. The white lines are NCEP/NCAR reanalysis sea level pressure (SLP) contours with contour interval of 10 hPa. One of every 100 surface ocean velocity vectors is plotted.

Mentions: [17] The simulated increase in PP on the shelves and in some areas in the deep basins in the PSA during the storm is due to an increase in the availability of nutrients in the upper 10 m in those areas (Figures 7a–7d). The simulated increase in the nitrate concentration generally occurs in the areas of strong winds (Figures 2b–2f) that strengthen sea ice speed [Zhang et al., 2013] and surface ocean circulation (Figures 8a–8c), enhancing vertical mixing in the upper ocean. The enhanced mixing is reflected in an increased vertical diffusivity in the upper 15 m of the ocean (Figures 8e–8g) at locations affected by the cyclone. Depending on the vertical turbulent fluxes of momentum, vertical diffusivity is calculated based on the KPP (K-profile parameterization) of oceanic boundary layer mixing [Large et al., 1994]. Strong winds and rapid ice movement tend to amplify the vertical momentum transfer, which leads to larger vertical diffusivity in the ocean surface mixed layer and hence stronger vertical mixing [Zhang et al., 2013].


The great 2012 Arctic Ocean summer cyclone enhanced biological productivity on the shelves.

Zhang J, Ashjian C, Campbell R, Hill V, Spitz YH, Steele M - J Geophys Res Oceans (2014)

Simulated surface ocean velocity (vector) and (a–d) speed (colors) and (e–h) mean vertical diffusivity in the upper 15 m of the Arctic Ocean over the period 5–11 August 2012. The white lines are NCEP/NCAR reanalysis sea level pressure (SLP) contours with contour interval of 10 hPa. One of every 100 surface ocean velocity vectors is plotted.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508965&req=5

fig08: Simulated surface ocean velocity (vector) and (a–d) speed (colors) and (e–h) mean vertical diffusivity in the upper 15 m of the Arctic Ocean over the period 5–11 August 2012. The white lines are NCEP/NCAR reanalysis sea level pressure (SLP) contours with contour interval of 10 hPa. One of every 100 surface ocean velocity vectors is plotted.
Mentions: [17] The simulated increase in PP on the shelves and in some areas in the deep basins in the PSA during the storm is due to an increase in the availability of nutrients in the upper 10 m in those areas (Figures 7a–7d). The simulated increase in the nitrate concentration generally occurs in the areas of strong winds (Figures 2b–2f) that strengthen sea ice speed [Zhang et al., 2013] and surface ocean circulation (Figures 8a–8c), enhancing vertical mixing in the upper ocean. The enhanced mixing is reflected in an increased vertical diffusivity in the upper 15 m of the ocean (Figures 8e–8g) at locations affected by the cyclone. Depending on the vertical turbulent fluxes of momentum, vertical diffusivity is calculated based on the KPP (K-profile parameterization) of oceanic boundary layer mixing [Large et al., 1994]. Strong winds and rapid ice movement tend to amplify the vertical momentum transfer, which leads to larger vertical diffusivity in the ocean surface mixed layer and hence stronger vertical mixing [Zhang et al., 2013].

Bottom Line: In the central PSA, however, model simulations indicate a decrease in PP and plankton biomass.The simulated biological gain on the shelves is greater than the loss in the central PSA, and therefore, the production on average over the entire PSA is increased by the cyclone.The generally positive impact of cyclones on the marine ecosystem in the Arctic, particularly on the shelves, is likely to grow with increasing summer cyclone activity if the Arctic continues to warm and the ice cover continues to shrink.

View Article: PubMed Central - PubMed

Affiliation: Applied Physics Laboratory, University of Washington Seattle, Washington, USA.

ABSTRACT

[1] A coupled biophysical model is used to examine the impact of the great Arctic cyclone of early August 2012 on the marine planktonic ecosystem in the Pacific sector of the Arctic Ocean (PSA). Model results indicate that the cyclone influences the marine planktonic ecosystem by enhancing productivity on the shelves of the Chukchi, East Siberian, and Laptev seas during the storm. Although the cyclone's passage in the PSA lasted only a few days, the simulated biological effects on the shelves last 1 month or longer. At some locations on the shelves, primary productivity (PP) increases by up to 90% and phytoplankton biomass by up to 40% in the wake of the cyclone. The increase in zooplankton biomass is up to 18% on 31 August and remains 10% on 15 September, more than 1 month after the storm. In the central PSA, however, model simulations indicate a decrease in PP and plankton biomass. The biological gain on the shelves and loss in the central PSA are linked to two factors. (1) The cyclone enhances mixing in the upper ocean, which increases nutrient availability in the surface waters of the shelves; enhanced mixing in the central PSA does not increase productivity because nutrients there are mostly depleted through summer draw down by the time of the cyclone's passage. (2) The cyclone also induces divergence, resulting from the cyclone's low-pressure system that drives cyclonic sea ice and upper ocean circulation, which transports more plankton biomass onto the shelves from the central PSA. The simulated biological gain on the shelves is greater than the loss in the central PSA, and therefore, the production on average over the entire PSA is increased by the cyclone. Because the gain on the shelves is offset by the loss in the central PSA, the average increase over the entire PSA is moderate and lasts only about 10 days. The generally positive impact of cyclones on the marine ecosystem in the Arctic, particularly on the shelves, is likely to grow with increasing summer cyclone activity if the Arctic continues to warm and the ice cover continues to shrink.

No MeSH data available.