Validation of MODIS-Aqua bio-optical algorithms for phytoplankton absorption coefficient measurement in optically complex waters of El Rincón (Argentina)

The color of EPEA: Variability in the in situ bio-optical properties in the period 2000 - 2017

“…Phy (443), and [a Phy (443)/a Phy (676)] at low irradiances, and vice versa). These effects, which respond to the principle of 'packaging effect' (Duyens 1956;Sathyendranath et al 1987;Bricaud et al 1995), have been reported for different places of the world ocean (Ciotti et al 2002;Babin et al 2003;Lutz et al 2003) and the Argentine Sea (Ferreira et al 2009;Segura et al 2013;Williams et al 2018;Delgado et al 2019).…”

Evaluation of MODIS-Aqua and OLCI Chlorophyll-a products in contrasting waters of the Southwestern Atlantic Ocean

“…gsfc.nasa.gov) and were processed using SeaDAS 7.4 software to obtain L2 Chl-a product using the OC3M algorithm (O'Reilly et al, 2000) and a switching atmospheric correction (AC) algorithm that uses the near infrared (NIR) or the short-wave infrared (SWIR) bands (NIR/SWIR-OC3M). Following the good results obtained by Delgado et al (2019) in this study area, the NASA standard AC algorithm that uses NIR bands (Stumpf et al, 2003;Bailey et al, 2010) was applied to stations located offshore (> 10 km from the coast), while the alternative AC algorithm that uses SWIR bands was applied to pixels located less than 10 km from the coast (Wang and Shi, 2005). Given the presence of turbid waters in the region, the high total radiance mask (HILT) was not applied and the cloud-masking was performed using the Rayleigh-corrected reflectance (dimensionless) at 2130 nm with a threshold of 0.018.…”

“…Even though the slope is close to 1, large errors indicate a poor performance of the algorithm with high scatter (RMSE = 1.65, PE = 118 %) and a clear tendency to overestimate in situ data, as indicated by the bias (1.18). This result is expected as more than half of the samples were collected within the coastal zone (z < 15 m; N=23; R 2 = 0.21, red symbols in Figure 2A), characterized by turbid waters (Delgado et al, 2017;2019), where Chl-a empirical algorithms usually tend to fail (O´Reilly et al, 2000). Within this coastal zone (z < 15 m), SPM concentrations varied between 30-100 mgl -1 (Delgado et al 2019) and the composition of the phytoplankton community was highly variable.…”

“…This result is expected as more than half of the samples were collected within the coastal zone (z < 15 m; N=23; R 2 = 0.21, red symbols in Figure 2A), characterized by turbid waters (Delgado et al, 2017;2019), where Chl-a empirical algorithms usually tend to fail (O´Reilly et al, 2000). Within this coastal zone (z < 15 m), SPM concentrations varied between 30-100 mgl -1 (Delgado et al 2019) and the composition of the phytoplankton community was highly variable. It was dominated by large chain-forming diatoms (40-80 % of total abundance), with a relatively low specific absorption coefficient (mean 0.032 (m 2 mg Chl-a) -1 ) due to the packaging effect (Delgado et al, 2019).…”

“…The Bahia Blanca Estuary is a tidally dominated, turbid and mixed system that is a main source of fine sediment to the inner shelf (Menendez et al, 2016) towards the eastern coastline (Delgado et al, 2017). Phytoplankton is mainly dominated by diatoms, comprising more than the 50 % of the cell abundances and biomass, followed by dinoflagellates (Guinder et al, 2018) and coccolithophores, both also highly abundant (Guinder et al, 2018;Delgado et al, 2019).…”