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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.


Change in chl a in the upper 100 m of the water column at locations 3 and 4 in 5–10 August2012 simulated by the 12 ENSE members forced by the reanalysis atmospheric forcing from the past 12 years (2000–2011) and by the CNTL run (2012). The dash line represents the average change of the 12 (2000–2011) ensemble simulations.
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fig14: Change in chl a in the upper 100 m of the water column at locations 3 and 4 in 5–10 August2012 simulated by the 12 ENSE members forced by the reanalysis atmospheric forcing from the past 12 years (2000–2011) and by the CNTL run (2012). The dash line represents the average change of the 12 (2000–2011) ensemble simulations.

Mentions: [26] To assess how unusual the storm-induced changes on the shelves are, we compare the CNTL-simulated changes in chl a during the storm (in 5–10 August 2012) with the ENSE simulation results for locations 3 and 4 (Figure 14). Because ENSE consists of 12-member ensemble simulations of 5 August 2012 onward using the reanalysis atmospheric forcing from the past 12 years (2000–2011), the changes in chl a during 5–10 August 2012 may be considered to represent the “normal” variability in the recent years without the cyclone effects. Figure 14 shows that chl a biomass would normally decrease at locations 3 and 4 during 5–10 August (also see Figures 13c and 13d). The average decrease over all the 12 ensemble members (2000–2011) is 17% at location 3 and 5% at location 4. However, with the cyclone effects, the CNTL-simulated decrease at location 3 is only 1%. Moreover, CNTL simulates an increase of 28% at location 4 (Figure 14). This suggests that the cyclone-induced changes in chl a biomass are quite different from normal variability in recent years.


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)

Change in chl a in the upper 100 m of the water column at locations 3 and 4 in 5–10 August2012 simulated by the 12 ENSE members forced by the reanalysis atmospheric forcing from the past 12 years (2000–2011) and by the CNTL run (2012). The dash line represents the average change of the 12 (2000–2011) ensemble simulations.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig14: Change in chl a in the upper 100 m of the water column at locations 3 and 4 in 5–10 August2012 simulated by the 12 ENSE members forced by the reanalysis atmospheric forcing from the past 12 years (2000–2011) and by the CNTL run (2012). The dash line represents the average change of the 12 (2000–2011) ensemble simulations.
Mentions: [26] To assess how unusual the storm-induced changes on the shelves are, we compare the CNTL-simulated changes in chl a during the storm (in 5–10 August 2012) with the ENSE simulation results for locations 3 and 4 (Figure 14). Because ENSE consists of 12-member ensemble simulations of 5 August 2012 onward using the reanalysis atmospheric forcing from the past 12 years (2000–2011), the changes in chl a during 5–10 August 2012 may be considered to represent the “normal” variability in the recent years without the cyclone effects. Figure 14 shows that chl a biomass would normally decrease at locations 3 and 4 during 5–10 August (also see Figures 13c and 13d). The average decrease over all the 12 ensemble members (2000–2011) is 17% at location 3 and 5% at location 4. However, with the cyclone effects, the CNTL-simulated decrease at location 3 is only 1%. Moreover, CNTL simulates an increase of 28% at location 4 (Figure 14). This suggests that the cyclone-induced changes in chl a biomass are quite different from normal variability in recent years.

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.