Investigation of Arctic and Antarctic spatial and depth patterns of sea water in CTD profiles using chemometric data analysis

Ewelina Kotwa*, Silvia Lacorte, Carlos Duarte, Roma Tauler

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


In this paper we examine 2- and 3-way chemometric methods for analysis of Arctic and Antarctic water samples. Standard CTD (conductivity-temperature-depth) sensor devices were used during two oceanographic expeditions (July 2007 in the Arctic; February 2009 in the Antarctic) covering a total of 174 locations. The output from these devices can be arranged in a 3-way data structure (according to sea water depth, measured variables, and geographical location). We used and compared 2- and 3-way statistical tools including PCA, PARAFAC, PLS, and N-PLS for exploratory analysis, spatial patterns discovery and calibration. Particular importance was given to the correlation and possible prediction of fluorescence from other physical variables. MATLAB's mapping toolbox was used for geo-referencing and visualization of the results. We conclude that: 1) PCA and PARAFAC models were able to describe data in a satisfactory way, but PARAFAC results were easier to interpret; 2) applying a 2-way model to 3-way data raises the risk of flattening the covariance structure of the data and losing information; 3) the distinction between Arctic and Antarctic seas was revealed mostly by PC1, relating to the physico-chemical properties of the water samples; and 4) we confirm the ability to predict fluorescence values from physical measurements when the 3-way data structure is used in N-way PLS regression.

Original languageEnglish (US)
Pages (from-to)242-254
Number of pages13
JournalPolar Science
Issue number3
StatePublished - Sep 2014
Externally publishedYes

Bibliographical note

Funding Information:
This research was part of the ATOS project, funded as part of the Spanish contribution to the International Polar Year (IPY) by the Spanish Ministry of Science and Innovation ( POL200600550/CTM ). We thank the ATOS participants, UTM and crew of R/V Hesprides for help with CTD sampling and logistics.


  • Arctic Antarctic
  • CTD
  • Fluorescence
  • Multi-way analysis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology
  • General Earth and Planetary Sciences


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