Along or across front survey strategy? An operational example at an unstable front.

• Published in: Geophysical Research Letters
• Main Authors: Rixen, M., Allen, J.T., Alderson, S., Cornell, V., Crisp, N., Fielding, S., Mustard, A.T., Pollard, R.T., Popova, E.E., Smeed, D.A., Srokosz, M.A., Barth, A., Beckers, J-M
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2003
• Subjects: Faroes; Iceland
• Online Access: http://nora.nerc.ac.uk/id/eprint/100283/; https://doi.org/10.1029/2002GL015341

We present results of the optimization of near-real time on-board sampling strategy in the Iceland-Faroes oceanic frontal area, based on the outputs of a mesoscale 3D operational data assimilation forecasting experiment. By minimizing a root mean square error cost function, we show that in this example an along-front sampling strategy, i.e. with transects parallel to the front, produces smaller errors in temperature, salinity, nitrate, phytoplankton, and zooplankton fields, as a result of a combination of the direction of the sampling of the front and errors associated with the asynopticy of observations (Doppler effect). This is contrary to the classic across-front sampling strategies that are used in most field experiments reported in the literature, i.e. where transects are perpendicular to the front. A control model shows that at these spatio-temporal scales, the along front sampling strategy is optimal when the frontal instability has sufficiently developed.