Do we need photonic-based instruments to characterize multiscale processes in marine environments?

Abstract

Ocean Optics XXI, 8-12 October 2012, Glasgow, Scotland, United KingdomTime- or space-series analysis is the one of the essential methods for marine science to understand the dynamics of ocean processes. It not only helps to identify the phenomenon represented by sequences of observations, but also helps to forecast events by feeding models. One of the first questions to address regarding the sampling strategy to obtain a time/space data series is the sampling frequency and the number of samples to measure. In many cases the answers to these questions are based mainly on logistic or operational restrictions (maximum number of samples that it is possible to process, instrumental capabilities, etc.). However, it is important to take into account the principles of Information Theory in order to avoid potential artefacts derived from improper sampling design. Furthermore, in those cases where the processes are not stationary (a common situation in marine environments) the sampling frequency and the number of samples play an important role in determining the time-frequency resolution required to characterize their dynamical properties. To address these problems of scale, two data sets are used as examples: (a) the analysis of a time series measured 3 samples/hr by the Imaging FlowCytobot (IFCB) installed at the entrance to the Mission-Aransas estuary (Port Aransas, TX, USA) during 2008 and (b) the high resolution spatial series of fluorescence data obtained 1 sample/m with an autonomous underwater vehicle (AUV) in Alfacs Bay (Ebro delta, Spain) during 2011. The final results indicate the need for measurements with sampling rates much higher than those commonly used in conventional methods (such as those relying on manual microscopy or pigment analysis) even in those cases in which the main goal is to characterize the dynamics at large spatial (order of km) or temporal (order of month-year) scales. These results reinforce the idea that the regular use of photonic-based instruments (optical, imaging or holographic systems) is necessary to characterize multiscale processes in marine environments due to the fact that, at present time, these are the only technologies capable of sampling at the required ratesPeer Reviewe