Sverdrup revisited: Critical depths, maximum chlorophyll levels, and the control of Southern Ocean productivity by the irradiance-mixing regime

Journal Article · Sun Dec 01 04:00:00 EST 1991 · Limnology and Oceanography; (United States)

DOI:https://doi.org/10.4319/lo.1991.36.8.1650· OSTI ID:7222224

Nelson, D M ^[1]; Smith, Jr, W O ^[2]

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1. Oregon State Univ., Corvallis (United States)
2. Univ. of Tennessee, Knoxville (United States)

A reformulation of Sverdrup's critical-depth calculation, using recent optical and physiological information, is developed and applied to data from the Southern Ocean. Comparisons between calculated critical depths (Z{sub c}) and mixed-layer depths (Z{sub m}) indicate that both the marginal ice zone and the open waters of the antarctic Circumpolar Current provide favorable irradiance-mixing regimes for the initiation and early development of phytoplankton blooms in summer (i.e.) Z{sub c} > Z{sub m} when phytoplankton biomass is low and the water clear; that when ice-edge blooms develop, Z{sub c} shoals to depths about equal to Z{sub m}, implying the phytoplankton standing stocks in ice-edge blooms may be self-limiting as a result of reduced penetration of irradiance; and that the highest chlorophyll levels that can be sustained in summer in open waters not stabilized by meltwater are {approximately}1.0 {mu}g liter{sup {minus}1} in the Weddell and Scotia Seas and may be less in areas that experience stronger winds.

• OSTI ID: 7222224
• Journal Information: Limnology and Oceanography; (United States), Journal Name: Limnology and Oceanography; (United States) Vol. 36:8; ISSN LIOCA; ISSN 0024-3590
• Country of Publication: United States
• Language: English

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