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Temporal and meridional variability of Satellite-estimates of surface chlorophyll concentration241Table I. Characteristics of the four ocean color sensors that can provide information on the Brazilian Continental Shelfon chlorophyll concentration. Note operating periods.Spectral Bands (only visible and near infrared only)Sensor Central wavelength (nm) Spectral Spatial resolution Operating datesresolution (nm) (m)CZCS 1 443; 520; 550; 67020825 24/10/1978 -750OCTS 2 412; 443; 490; 520565; 670765; 865SeaWiFS 3 412; 443; 490; 510555; 690765; 865MODIS 4 /Aqua531443; 488; 551667; 678; 936412; 748; 869469; 555; 1240858905; 137594064510020204020204051010152025304050700110010001000100010005002501000100025022/6/198603/9/1996 -29/6/199729/8/1997 -present04/07/2002 -presentObs: 1 Coastal Zone Color Scanner; 2 Ocean Color Temperature Sensor, 3 Sea-viewing Wide Field-of-view Sensor,4 Moderate Resolution Imaging Spectroradiometercomparison with the open ocean, within also a morecomplex physical dynamics (Longhurst 2006). Thus,we stress that the patterns presented here formeridional and seasonal Chl are a result from anumber of processes yet to be quantified, so theyneither translate directly into primary production norexportation rates for phytoplankton carbon.Remote Sensing Chlorophyll Observed in theBCSThe meridional and seasonal distributions ofChl over the large and heterogeneous BCS (Fig. 1)can be related to the equally diverse dominantphysical influences (Castro & Miranda 1998). Whendata from the four ocean color sensors are compared,similar general statistical distributions for Chl (Fig.2) emerged, especially for SeaWiFS andMODIS/Aqua sensors, which result from almost adecade of their simultaneous data acquisition (TableII). The OCTS sensor operated for less than a year,and there are only about 30 8-Day images availablefor the BSC. Lacks in data acquisition (Table II)represent besides instrument problems, cloudcoverage and algorithm failures.The highest degree of Chl variability wasfound in the latitudinal extremes of BCS (Areas 1and 7) while Chl was remarkable constant in Area 2.The highest and lowest mean Chl values were foundin Areas 7 and 3, respectively (Fig. 2) differingabout an order of magnitude from each other(e.g., ~1.0 versus ~0.1 mg.m -3 ). Meridional 8-Daymedian Chl variability as a function of time and theChl statistical distribution (Figs. 2 and 3) suggest theimportance of the distinct degrees of seasonality inthe different areas, but as indicated by some recentstudies on physical processes (e.g., Dotori & Castro2009) we also expect a significant contribution ofinterannual variability may also be expected.Data coverage by the distinct sensors alsoshowed important seasonal patterns (Fig. 4) that willbe assessed below, but we found no significantstatistical relationships between data coverage andChl for a given Area or sensor. For instance, bothSeaWiFS and MODIS/Aqua coverage wereremarkable poor in Area 1 during the summermonths, period when Chl was also low, while Areas3 and 7 showed good data coverage year round, anda clear seasonal Chl pattern. Figures 3 and 4 pointout the discontinuity for CZCS data coverage in theBSC (see also Table II), which is a result of NASA’sstrategy of turning off the sensor when it was outsidethe main interest areas due to limited on-boardstorage data and to preserve the sensor (Mcclain,2009). Indeed, CZCS had its life expectancyexpanded for several years, but unfortunately, thelow data coverage over the BSC prevent studiesto integrate its data with those acquired by thecurrent operational sensors (e.g., SeaWiFs andMODIS/Aqua - but see also www.ioccg.org/sensors/current.html) in order to produce longertime-series. Recent literature show, for areas whereCZCS data is available, detectable trends in Chlwith time that suggested alterations in the marinebiota (e.g., Antoine et al. 2005). Studies like thesePan-American Journal of Aquatic Sciences (2010), 5(2): 236-253