Time-Space Variability of Chlorophyll-a and Associated Physical Variables within the Region off Central-Southern Chile

Abstract

Time-space fluctuations of chlorophyll-a (Chl-a) within the region off central-southern Chile (33-42°S), and their association with meteorological-oceanographic conditions, were analyzed using satellite time series data (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012). The mean distribution of moderate values of Chl-a (~0.5 mg•m −3 ) in the northern section (33-38°S) extended out to ~200 km of the coast whereas they were restricted to a narrower band in the southern section (38-42°S). Mean wind stress and wind stress curl were upwelling favorable for most part of the year in the northern section whereas upwelling-downwelling periods were distinct in the southern section. The dominant frequency of Chl-a variability in the coastal zone and the coastal transition zone was annual, as it was for the rest of the variables, except in a transitional band between these zones and where a semi-permanent jet is located. At the annual frequency, the alongshore distribution of coastal Chl-a presented strong discontinuities, with minimum values around upwelling centers (~37 and 40°S) and higher values (> 2 mg•m −3 ) in between. Also at the annual frequency, correlation analyses suggest that Ekman transport and Ekman pumping might act synchronously to extend the offshore distribution of the highest Chl-a values during the spring-summer period whereas mesoscale activity appears to contribute to Chl-a increases in the coastal transition zone. Sea surface temperature does not appear to be associated with the annual cycle of Chl-a in the coastal zone and in the coastal transition zone it might be linked to Chl-a variability through the effects of internal waves. OPEN ACCESSRemote Sens. 2013, 5 5551

Temporal Variability in Net Primary Production in an Upwelling Area off Central Chile (36°S)

“…Nevertheless, central Chile is characterized by its intricate geometry, with gulfs, bays, islands and peninsulas generating high time-space NPP variability. A NPP spatial pattern was observed by Testa (2017) and found by Morales et al (2013) to coincide with Chl-a distribution. Each upwelling system is therefore considered unique in terms of its productivity.…”

Phytoplankton Size Structure in Association with Mesoscale Eddies off Central-Southern Chile: The Satellite Application of a Phytoplankton Size-Class Model

“…Coastal upwelling and solar radiation promote the generation of an upwelling front in this region. Variations in the coastline orientation, bathymetry, general circulation, and mesoscale activity also influence front and eddy generation [56][57][58]. In the area off Point Lavapié, several cyclonic and surface/subsurface anticyclonic eddies are persistently generated in association with higher levels of eddy kinetic energy, and these features move seaward through the CTZ at a relatively low speed (~1.7 km d −1 ) [15,30,32,59].…”

Performance Analysis of MODIS 500-m Spatial Resolution Products for Estimating Chlorophyll-a Concentrations in Oligo- to Meso-Trophic Waters Case Study: Itumbiara Reservoir, Brazil

“…Remote sensing techniques have been extensively used for monitoring chl-a in aquatic systems [4,[8][9][10]. The advantages of using remote sensing techniques to monitor chl-a are: (1) the geographical coverage of satellite images, which provide information about the entire aquatic system; (2) remote sensing, which allows us to obtain information from inaccessible places; and (3) historical satellite images, which allow the inference of water quality information from the past records [11].…”

“…Several methods for estimating chl-a concentration in different turbid waters (Case 2) with remote sensing have been investigated [4][5][6][7][8][9][10][11][12]. Many studies have suggested that remote spectroscopic measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) should be used to estimate chl-a concentrations in Case 2 waters through empirical and semi-empirical algorithms [4,15,16].…”