Title of article :
Variability in specific-absorption properties and their use in a semi-analytical ocean colour algorithm for MERIS in North Sea and Western English Channel Coastal Waters
Author/Authors :
Tilstone، نويسنده , , Gavin H. and Peters، نويسنده , , Steef W.M. and van der Woerd، نويسنده , , Hendrik Jan and Eleveld، نويسنده , , Marieke A. and Ruddick، نويسنده , , Kevin and Schِnfeld، نويسنده , , Wolfgang and Krasemann، نويسنده , , Hajo and Martinez-Vicente، نويسنده , , Victor and Blondeau-Patissier، نويسنده , , David and Rِttgers، نويسنده , , Rüdiger and Sّrensen، نويسنده , , Kai and Jّrgensen، نويسنده , , Peter V. and Shutler، نويسنده , , Jamie D.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2012
Pages :
19
From page :
320
To page :
338
Abstract :
Coastal areas of the North Sea are commercially important for fishing and tourism, and are subject to the increasingly adverse effects of harmful algal blooms, eutrophication and climate change. Monitoring phytoplankton in these areas using Ocean Colour Remote Sensing is hampered by the high spatial and temporal variations in absorption and scattering properties. In this paper we demonstrate a clustering method based on specific-absorption properties that gives accurate water quality products from the Medium Resolution Imaging Spectrometer (MERIS). A total of 468 measurements of Chlorophyll a (Chla), Total Suspended Material (TSM), specific- (sIOP) and inherent optical properties (IOP) were measured in the North Sea between April 1999 and September 2004. Chla varied from 0.2 to 35 mg m− 3, TSM from 0.2 to 75 g m− 3 and absorption properties of coloured dissolved organic material at 442 nm (aCDOM(442)) was 0.02 to 0.26 m− 1. The variation in absorption properties of phytoplankton (aph) and non-algal particles (aNAP) were an order of magnitude greater than that for aph normalized to Chla (aph*) and aNAP normalized to TSM (aNAP*). Hierarchical cluster analysis on aph*, aNAP* and aCDOM reduced this large data set to three groups of high aNAP*–aCDOM, low aph* situated close to the coast, medium values further offshore and low aNAP*–aCDOM, high aph* in open ocean and Dutch coastal waters. The median sIOP of each cluster were used to parameterize a semi-analytical algorithm to retrieve concentrations of Chla, TSM and aCDOM(442) from MERIS data. A further 60 measurements of normalized water leaving radiance (nLw), Chla, TSM, aCDOM(442) and aNAP(442) collected between 2003 and 2006 were used to assess the accuracy of the satellite products. The regionalized MERIS algorithm showed improved performance in Chla and aCDOM(442) estimates with relative percentage differences of 29 and 8% compared to 34 and 134% for standard MERIS Chla and adg(442) products, and similar retrieval for TSM at concentrations > 1 g− 3.
Keywords :
Case 2 waters , Ocean colour remote sensing , North Sea , Inherent optical properties , Western English Channel , phytoplankton
Journal title :
Remote Sensing of Environment
Serial Year :
2012
Journal title :
Remote Sensing of Environment
Record number :
1631685
Link To Document :
بازگشت