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Comparison of MERIS (algal1 and algal2) and MODIS (OC3M) chlorophyll products and validation with HPLC in-situ data collected off the Western Iberian Peninsula.

Carolina Sá(1), José Da Silva(1), Paulo Oliveira(2) and Vanda Brotas(1)

(1) Institute of Oceanography - University of Lisbon, Rua Ernesto de Vasconcelos, 1749-016 Lisbon, Portugal
(2) IPIMAR, Av. Brasília, 1449-006 Lisbon, Portugal

Abstract

Ocean colour algorithms that are designed for use at global scales may be less accurate at local and regional scales and therefore it is important to understand the limitations of the different products in reference to specific areas. It is essential to validate the ocean-colour standard products with in-situ data in order to provide the quality requirements needed for monitoring purposes. Chlorophyll a (Chl a) is used as the main biomass proxy for phytoplankton and ocean colour sensors allow a synoptic and quasi-permanent following of this pigment concentration in surface waters. Water samples collected on board 6 cruises off the Portuguese coast during the period 2005 – 2007 were processed by reversed phase HPLC for pigment determination, and the Chl a concentration compared with MERIS and MODIS data. The performance of MERIS (algal1 and algal2) and OC3M MODIS products was evaluated using match up datasets constructed with different time and space windows. The results for bias, rms and flag performance are presented and discussed taking into account the distribution of different phytoplankton groups (determined by relative pigment abundance) and the oceanographic conditions observed during the cruises.

 

Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry