Mediterranean ocean colour Level 3 operational multi-sensor processing

Abstract

Abstract. The Mediterranean near-real-time multi-sensor processing chain has been set up and is operational in the framework of the Copernicus Marine Environment Monitoring Service (CMEMS). This work describes the main steps operationally performed to enable single ocean colour sensors to enter the multi-sensor processing applied to the Mediterranean Sea by the Ocean Colour Thematic Assembly Centre within CMEMS. Here, the multi-sensor chain takes care of reducing the inter-sensor bias before data from different sensors are merged together. A basin-scale in situ bio-optical dataset is used both to fine tune the algorithms for the retrieval of phytoplankton chlorophyll and the attenuation coefficient of light, Kd, and to assess the uncertainty associated with them. The satellite multi-sensor remote sensing reflectance spectra agree better with the in situ observations than those of the single sensors. Here, we demonstrate that the operational multi-sensor processing chain compares sufficiently well with the historical in situ datasets to also confidently be used for reprocessing the full data time series.

The CMEMS GlobColour chlorophyll <i>a</i> product based on satellite observation: multi-sensor merging and flagging strategies

“…This perspective has already been investigated to retrieve PFT (phytoplankton functional type) from OLCI (e.g. Xi et al, 2018).…”

“…The reflectance merging approach is used by OC-CCI to derive the global chlorophyll a OC-CCI time series and by the regional CMEMS products. As pointed out by Volpe et al (2019) for the regional Mediterranean products, the band merging approach has the advantage of providing a homogeneous data set of spectral reflectance from which the following environmental parameters (amongst others) can be derived, in full consistency for the long term: chlorophyll a products, light attenuation, Kd and suspended particulate matter.…”

Ecoregions in the Mediterranean Sea Through the Reanalysis of Phytoplankton Functional Types and Carbon Fluxes

“…The regionally tuned satellite PFT algorithms were applied to a Mediterranean multisensor (Medium‐Resolution Imaging Spectrometer(MERIS), Moderate Resolution Imaging Spectroradiometer‐Aqua(MODIS), and Sea‐viewing Wide Field‐of‐view Sensor(SeaWIFS) chlorophyll a satellite time series (from September 1997 to August 2015) available from Copernicus Marine Environment Monitoring Service (CMEMS, OCEANCOLOUR_MED_CHL_L3_REP_OBSERVATIONS_009_073 product). These chlorophyll data are produced by the CMEMS OC TAC (Ocean Color Thematic Assembling Centre) using an ad hoc configuration of the ESA OC‐CCI (European Space Agency‐Ocean Color Climate Change Initiative, http://www.esa-oceancolour-cci.org) processor at high resolution in the Italian National Research Council Mediterranean processing chain (Volpe et al, , ). The chlorophyll product used in Di Cicco et al () is a merged Case I–Case II product, in which the different optical properties of inshore and offshore waters are taken into account by applying two different regional algorithms: (i) the MedOC4 (Volpe et al, ) specialized for open ocean waters and (ii) the AD4 (D'Alimonte & Zibordi, ) for coastal complex water.…”

Retrieval of Particulate Backscattering Using Field and Satellite Radiometry: Assessment of the QAA Algorithm

“…Above-water downwelling irradiance (E s ) data were collected by a reference sensor, mounted at the top of the ship's deck. R rs was computed using the SERDA software developed at CNR [47]. All the R rs data were band-shifted to the CCI bands for consistency with the satellite R rs .…”