News Storage
News
Keops2: Plankton blooms modeled
The Keops-2 oceanographic cruise ended last November. The strategy developed at sea with a new regional altimetry product to help to predict the extension of the blooms has been successful.
The possibility of predicting the extension of a plume with altimetry data is very important for cruise campaigns, because ocean color data are not available in the presence of clouds. In that case, the position of a sampling station can only rely on altimetry data.
During the Keops2, a model of the plume extension ran in near-real time on board the Marion-Dufresne research vessel. The model was fed by the Ssalto/Duacs regional product and allowed to test a novel adaptive sampling strategy, by which the position of the sampling stations were adjusted day-by-day to the position of the plume.
This strategy allowed to monitor the development of the bloom and its biogeochemical dynamics with a unprecedented precision for more than one month with more than 300 biophysical operations. Such detailed observations will serve to better quantify the role of the Southern Ocean on the carbon cycle.
The nice fit between modeled and observed patterns highlights the key role of horizontal transport in structuring in space and time phytoplankton abundance and the possibility of studying this mechanism by satellite altimetry.
Although both altimetric products do a good job, the regional one is clearly better in predicting the southern flank of the bloom extension (see in particular the pattern centered in 79°E 51°S, highlighted by the black ellipses on the figures below). Note that a difference in the plume extension corresponds to differences in the regional primary production and carbon export.
|
(A-B) Ocean color image from MODIS / MERIS for the 11/11/2011. (A) shows the expected Chlorophyll concentration, |
Further information:
- Smetacek V. et al. (2012), Deep carbon export from a Southern Ocean iron-fertilized diatom bloom, Nature 487, pp 313-319
- Buesseler (2012), The great iron dump, Nature 487, p 305
- Centre d'Océanologie de Marseille website: Keops-2 Objectives
- IPEV website: Keops-2, des nouvelles du terrain (in french).
- Club des Argonautes: Prévoir la floraison planctonique (in french)
- Image of the month, April 2009: Cruise around Kerguelen Island
- Access to Ssalto/Duacs data delivered for Keops-2 : first subscribe by filling in the form.