A 3-D mesoscale map of primary production at the Antarctic Polar Front: results of a diagnostic model

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Strass, Volker, Naveira Garabato, A. C., Bracher, Astrid, Pollard, R. T., Lucas, M. I.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2002
• Subjects: Antarctic; Austral; The Antarctic; Antarc*
• Online Access: https://epic.awi.de/id/eprint/3054/; https://doi.org/10.1016/S0967-0645(02)00112-1; https://hdl.handle.net/10013/epic.13638

Abstract - A diagnostic model is established to estimate synoptically the mesoscale distribution of primaryproduction at the Antarctic Polar Front (APF). The model domain is a three-dimensional box, centered at roughly50° S and 10° E, of about 1° latitude and 2° longitude horizontal extent, and of 300 m depth. The box wassurveyed in high resolution during austral summer 1995/1996 with a towed undulating vehicle and bycomplementary ship based measurements. Measurements of global solar radiation, of the underwater light field,and of the chlorophyll concentration from the survey are used as input variables for the model. The model isbased on photosynthesis-light relationships, with parameters taken from in vitro incubations performed duringthe survey. The model results show mesoscale patches of elevated primary production along a meander of theAPF, and lowest production in a cold cyclonic eddy south of the front. Production is confined to a shallower depthrange in the front than outside, due to self-shading effects from generally higher mixed-layer chlorophyllconcentrations. Self-shading effects account for variations of the percent light depths, and of the saturation lightdepth, by a factor of two within the survey area. Primary production at the surface varies horizontally between 7and 56 mg C m-3 d-1 with a mean of 26 mg C m-3 d-1, and vertically integrated production ranges from 295 to975 mg C m-2 d-1, with an areal mean of 585 mg C m-2 d-1. Changes by a factor of two in integrated productionoccur on horizontal scales as small as 10 km. Production rates also differ significantly between days as a resultof changes in global solar radiation.