S5POC: Exploitation of Sentinel-5-P for Ocean Colour Products
The S5POC project is one of the seven themes of ESA's Sentinel-5p+ Innovation activity, which aims at developing innovative products for the TROPOMI instrument on the Sentinel-5 Precursor satellite which are not yet part of the operational processor. The Copernicus Sentinel-5P satellite was launched in October 2017 and provides operational data since July 2018. This mission is intended as a gap-filler between the time series of the former instruments GOME and SCIAMACHY, the still operating GOME-2 and OMI and the future Copernicus S5 instruments.
Hyperspectral satellite data provide measurements of the top of atmosphere radiance signal, which can be used for novel algorithms aimed for the observation of marine ecosystems and the light-lit surface ocean. Previous developments on the atmospheric satellite sensor SCanning Imaging Absorption Spectro-Meter for Atmospheric CHartographY (SCIAMACHY) have shown great potential to retrieve ocean colour (OC) information from hyperspectral atmospheric sensors, such as the chlorophyll-a concentration of various phytoplankton functional types (PFTs; Bracher et al. 2009, Sadeghi et al. 2012, Bracher et al. 2017), the sun-induced signal of marine chlorophyll-a red fluorescence (SIF-marine: Wolanin et al. 2015, Joiner et al. 2016) and underwater light availability (Dinter et al. 2015, Oelker et al. 2019).
By exploiting TROPOMI’s potential for OC products, especially with respect to PFT-CHL, SIF-marine and underwater spectral range resolved light availability (given by the apparent optical properties - AOP, Kd), a continuation of the time series of data, started with SCIAMACHY and the current satellite sensors OMI and GOME-2, will be possible. It sets the ground for the application of TROPOMI OC algorithms on the very similar UV/VIS/NIR (UVN) instruments on S4 and S5 and ensures a long-term future perspective of such data sets.
The S5POC project will explore the capacity of TROPOMI data to provide novel ocean colour products. The objectives of this S5P+ Innovation activity are to:
- develop a solid scientific basis for the application of S5P data within the context of novel scientific and operational OC products applications;
- assess existing algorithms which have been used for OC product retrievals from SCanning Imaging Absorption Spectro-Meter for Atmospheric CHartographY (SCIAMACHY), Ozone Monitoring Instrument (OMI) and Global Ozone Monitoring Experiment (GOME-2);
- develop novel OC products and retrieval methods that exploit the potential of the S5P mission’s capabilities beyond its primary objectives, in particular, the chlorophyll-a concentration (CHL) of important phytoplankton groups (PFT-CHL), the underwater light attenuation coefficients (Kd) for the ultraviolet (UV) and the blue spectral region separately (KdUV, KdBlue), and the sun-induced marine chlorophyll-a fluorescence signal (SIF-marine) from TROPOMI S5P level-1 data;
- explore the potential of the UV range of S5P for ocean biology;
- use complementary products from Sentinel-3 (S3) and S5P for exploring the UV measurements of TROPOMI for assessing sources of coloured dissolved organic matter and the amount of UV-absorbing pigments in the ocean;
- validate the innovative products with established reference in situ datasets and perform intercomparison to other satellite OC data;
- define strategic actions for fostering a transition of the methods from research to operational activities;
- maximize the scientific return and benefits from the S5P mission for surface ocean research and services (e.g. CMEMS) by assessing the synergies with other satellite sensors, in particular explore the synergistic use of S5P and S3.
Project duration: July 2019 to June 2021.
Funding: ESRIN/ESA within the Sentinel-5-P+Innovation project.
Bracher A. et al. (2009) Quantitative observation of cyanobacteria and diatoms from space using PhytoDOAS on SCIAMACHY data. Biogeosciences 6: 751-764.
Bracher A. et al. (2017) Global Monthly Mean Chlorophyll a Surface Conc. from August 2002 to April 2012 for Diatoms, Coccolithophores and Cyanobacteria from PhytoDOAS Algorithm Version 3.3 Applied to SCIAMACHY Data. PANGAEA. Doi: 10.1594/PANGAEA.870486.
Dinter T. et al. (2015) Retrieval of light availability in ocean waters utilizing signatures of vibrational Raman scattering in hyper-spectral satellite measurements. Ocean Science, 11: 373-389.
Joiner J., et al. (2016) New methods for the retrieval of chlorophyll red fluorescence from hyperspectral satellite instruments: simulations and application to GOME-2 and SCIAMACHY. Atmospheric Measurement Techniques, 9: 3939-3967.
Oelker J. et al. (2019) Global diffuse attenuation coefficient derived from vibrational Raman scattering detected in hyperspectral backscattered satellite spectra. Optics Express, 27 (12): A829-A855.
Sadeghi A. et al. (2012) Improvements to the PhytoDOAS method for identification of coccolithophores using hyper-spectral satellite data. Ocean Science, 8: 1055-1070.
Wolanin A. et al. (2015a) Global retrieval of marine and terrestrial chlorophyll fluorescence at its red peak using hyperspectral top of atmosphere radiance measurements: Feasibility study and first results. Remote Sensing of Environment, 166: 243-261.
Data Pool (internal access only)
AWI team (Prime)
Astrid Bracher (lead)
Andreas Richter (lead)
Vanda Brotas (lead)
Maycira Costa (lead)