First release of the CMEMS Global coastal OLCI 300 meters Chlorophyll-a Product

2021 ◽  
Author(s):  
Philippe Garnesson ◽  
Antoine Mangin ◽  
Julien Demaria ◽  
Marine Bretagnon ◽  
Odile Hembise Fanton d'Andon
Keyword(s):  
Chlorophyll A ◽  
Spatial Resolution ◽  
End User ◽  
Vicarious Calibration ◽  
Large Matrix ◽  
Merging Procedure ◽  
Level 3 ◽  
Marine Environment Monitoring ◽  
Monitoring Service ◽  
Level 2

<p>The Ocean Colour Instrument (OLCI) on-board the Sentinel-3A and 3B satellites with a 300 m spatial resolution has a major advantage compared to other satellite missions with a typical 1 km spatial resolution. The chlorophyll-a product derived from OLCI’s 300 m measurement facilitates many applications in marine and coastal ecology, from ecosystem modeling, to fisheries management, and monitoring of water quality. The OLCI 300 m chlorophyll-a swath data (Level-2) are operationally disseminated in NRT mode by the EUMETSAT agency. The Copernicus Marine Environment Monitoring Service (CMEMS) eases the usage of these Level-2 (swath data) by providing Level-3 (daily mapped gridded files) at global and regional level.</p><p>This study highlights the first release of a 300 m NRT global daily chlorophyll-a product based on the merging of OLCI S3A and S3B. It will be routinely disseminated in the frame of CMEMS in May 2021. Before this date, the resolution of the CMEMS Chlorophyll products was 4km at global level and 1km over some European regional seas This 300 m product will be based on the Copernicus-GlobColour processor already used by CMEMS for the Global chlorophyll-a product and the regional Atlantic daily interpolated product. The daily image will correspond to a large matrix of 32400x64800 pixels with chlorophyll-a data provided along the coastline (200 km). CMEMS provides to the end-user facilities to extract data on his area and period of interest.</p><p>This new product will take benefit of a new EUMETSAT’s Level-2 product baseline which should be switched operationally in NRT mode mid-February 2021. This new baseline improves mainly the System Vicarious Calibration (SVC) gains of both S3A and S3B and the associated quality flags. The Chlorophyll-a OC4ME algorithm has been also improved with the use of the Colour Index algorithm for clear water. The assessment of this new OC4ME chlorophyll-a product (based on tandem data) shows a very good correlation between S3A and S3B. A regression between a daily S3A and S3B global product provides a R2 of 0.98 with a respective slope and offset of 1.0 and 0.005. However, some limitations concerning the level-2 upstream products have been identified. Details about the merging procedure, inter-comparison with existing product and illustrations of results will be presented.</p>

scholarly journals The Mediterranean Ocean Colour Level 3 Operational Multi-Sensor Processing

2018 ◽  
Author(s):  
Gianluca Volpe ◽  
Simone Colella ◽  
Vittorio Brando ◽  
Vega Forneris ◽  
Flavio La Padula ◽  
...  
Keyword(s):  
Fine Tuning ◽  
Ocean Colour ◽  
Basin Scale ◽  
Sensor Processing ◽  
Level 3 ◽  
The Mediterranean ◽  
Set Up ◽  
Marine Environment Monitoring ◽  
Monitoring Service

Abstract. This work describes the main processing steps operationally performed to enable single ocean colour sensors to enter the multi-sensor chain for the Mediterranean Sea of Ocean Colour Thematic Assembling Centre. Here, the multi-sensor chain takes care of reducing the inter-sensor bias before data from different sensors are merged together. The basin-scale in situ bio-optical dataset is used both to fine-tuning the algorithms for the retrieval of phytoplankton chlorophyll and attenuation coefficient of light, Kd, and to assess the uncertainty associated with them. The satellite multi-sensor remote sensing Reflectance spectra better agree with the in situ observations than that of the single sensors, and are comparable with the ESA-OC-CCI multi-sensor product, highlighting the importance of reducing the inter-sensor bias. 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.

scholarly journals The CMEMS GlobColour <i>Chlorophyll-a</i> Product Based on Satellite Observation

2019 ◽  
Author(s):  
Philippe Garnesson ◽  
Antoine Mangin ◽  
Odile Fanton d'Andon ◽  
Julien Demaria ◽  
Marine Bretagnon
Keyword(s):  
Satellite Observation ◽  
Global Level ◽  
Marine Strategy Framework Directive ◽  
Spatial Coverage ◽  
Long Time ◽  
Level 3 ◽  
Monitoring Service ◽  
Marine Environmental ◽  
Level 2 ◽  
The Eu

Abstract. This work concerns the chlorophyll products based on Satellite Observation and disseminated in the frame of the Copernicus Marine Environmental Monitoring Service (CMEMS). This work highlights the main advantages provided by the Copernicus Globcolour processor which is used to serve the CMEMS with a long time series from 1997 to present with level 3 &amp; 4 products at Global level (4 km of spatial resolution) and for the Atlantic level 4 product (1 km). It discusses the different ways to merge data coming from different sensors and it is shown that the GlobColour processor approach provide a better flexibility. At present, it is the only one CMEMS processor able to ingest the OLCI-S3A in the merged product (OLCI-S3A data are ingested in the operational CMEMS products since the April 2018 release). Behind the merging, the flagging strategy to go from level 2 provided by spatial agencies to the level 3 CMEMS products is also discussed. A better spatial coverage is demonstrated, including the coastal area which is of particular interest for many users involved in the EU Water Framework and Marine Strategy Framework Directive.

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

Ocean Science ◽  
2019 ◽  
Vol 15 (3) ◽  
pp. 819-830 ◽  
Author(s):  
Philippe Garnesson ◽  
Antoine Mangin ◽  
Odile Fanton d'Andon ◽  
Julien Demaria ◽  
Marine Bretagnon
Keyword(s):  
Remote Sensing ◽  
Chlorophyll A ◽  
Spatial Resolution ◽  
Remote Sensing Data ◽  
Satellite Observation ◽  
Data Sets ◽  
In Situ Data ◽  
Long Time ◽  
The One ◽  
Monitoring Service

Abstract. This paper concerns the GlobColour-merged chlorophyll a products based on satellite observation (SeaWiFS, MERIS, MODIS, VIIRS and OLCI) and disseminated in the framework of the Copernicus Marine Environmental Monitoring Service (CMEMS). This work highlights the main advantages provided by the Copernicus GlobColour processor which is used to serve CMEMS with a long time series from 1997 to present at the global level (4 km spatial resolution) and for the Atlantic level 4 product (1 km spatial resolution). To compute the merged chlorophyll a product, two major topics are discussed: The first of these topics is the strategy for merging remote-sensing data, for which two options are considered. On the one hand, a merged chlorophyll a product computed from a prior merging of the remote-sensing reflectance of a set of sensors. On the other hand, a merged chlorophyll a product resulting from a combination of chlorophyll a products computed for each sensor. The second topic is the flagging strategy used to discard non-significant observations (e.g. clouds, high glint and so on). These topics are illustrated by comparing the CMEMS GlobColour products provided by ACRI-ST (Garnesson et al., 2019) with the OC-CCI/C3S project (Sathyendranath et al., 2018). While GlobColour merges chlorophyll a products with a specific flagging, the OC-CCI approach is based on a prior reflectance merging before chlorophyll a derivation and uses a more constrained flagging approach. Although this work addresses these two topics, it does not pretend to provide a full comparison of the two data sets, which will require a better characterisation and additional inter-comparison with in situ data.

scholarly journals Seasonal Spatial and Temporal Distribution of Chlorophyll-a Concentration over Kuwait and the Arabian Gulf using Satellite and In-Situ Data

2021 ◽  
Author(s):  
Jasem A. Albanai
Keyword(s):  
Spatial Resolution ◽  
Arabian Gulf ◽  
Temporal Distribution ◽  
Spatial And Temporal Distribution ◽  
Important Indicator ◽  
Near Surface ◽  
In Situ Data ◽  
Level 3 ◽  
Level 2

The concentration of chlorophyll-a (chlor-a) is an important indicator of marine water quality, as it is considered an indicator of the phytoplankton density in a specific area. Remote sensing techniques have been developed to measure the near-surface concentration of chlor-a in water across the correlation between spectral bands and in situ data. This algorithm applies to sensors of varying spatial, temporal and spectral resolutions. However, in this study, chlor-a level 2 and 3 products of SNPP &ndash; VIIRS spectrometer (Equation OC3) of NASA OceanColor suite was relied upon to study the spatial and temporal distribution of chlor-a concentration in the Arabian Gulf (also known as the Persian Gulf) and the State of Kuwait&rsquo;s water (located to the north-eastern part of the Arabian Gulf) from 2012 to 2019. Ground truthing points (n = 192) matched to the level 2 products have been used to build an empirical model and cross-validate it. The correlation was positive where was 0.79 and the validation RMSE was = &plusmn; 0.64 mg/m-3. The derived algorithm was then applied to chlor-a level 3 seasonal products. Additionally, the chlor-a concentration values of Kuwaiti waters have been enhanced using the IDW algorithm to increase the spatial resolution, as it is considered as a small area compared to the spatial resolution of level 3 chlor-a products. The model derived from IDW was tested using the Mann Whitney test (Sig = 0.948 p &gt; 0.01). However, the result showed that the chlor-a concentration is higher in Kuwait Bay compared to Kuwaiti water, and it is higher in Kuwaiti water compared to the Arabian Gulf. The coasts have higher concentrations too, when compared to the open water. Generally, the chlor-a increases in winter and makes a semi-regular cycle during the years of study; this cycle is more regular in the Gulf&rsquo;s waters than in Kuwait&rsquo;s.

scholarly journals Introducing the 4.4 km spatial resolution Multi-Angle Imaging SpectroRadiometer (MISR) aerosol product

2020 ◽  
Vol 13 (2) ◽  
pp. 593-628 ◽  
Author(s):  
Michael J. Garay ◽  
Marcin L. Witek ◽  
Ralph A. Kahn ◽  
Felix C. Seidel ◽  
James A. Limbacher ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Horizontal Resolution ◽  
Science Data ◽  
Data Set ◽  
Earth Observing System ◽  
Uncertainty Estimates ◽  
Level 3 ◽  
Land Surfaces ◽  
Langley Research Center ◽  
Level 2

Abstract. The Multi-angle Imaging SpectroRadiometer (MISR) instrument has been operational on the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) Terra satellite since early 2000, creating an extensive data set of global Earth observations. Here we introduce the latest version of the MISR aerosol products. The level 2 (swath) product, which is reported on a 4.4 km spatial grid, is designated as version 23 (V23) and contains retrieved aerosol optical depth (AOD) and aerosol particle property information derived from MISR's multi-angle observations over both land and water. The changes from the previous version of the algorithm (V22) have significant impacts on the data product and its interpretation. The V23 data set is created from two separate retrieval algorithms that are applied over dark water and land surfaces, respectively. Besides increasing the horizontal resolution to 4.4 km compared with the coarser 17.6 m resolution in V22 and streamlining the format and content, the V23 product has added geolocation information, pixel-level uncertainty estimates, and improved cloud screening. MISR data can be obtained from the NASA Langley Research Center Atmospheric Science Data Center at https://eosweb.larc.nasa.gov/project/misr/misr_table (last access: 11 October 2019). The version number for the V23 level 2 aerosol product is F13_0023. The level 3 (gridded) aerosol product is still reported at 0.5∘×0.5∘ spatial resolution with results aggregated from the higher-resolution level 2 data. The format and content at level 3 have also been updated to reflect the changes made at level 2. The level 3 product associated with the V23 level 2 product version is designated as F15_0032. Both the level 2 and level 3 products are now provided in NetCDF format.

Investigating the chlorophyll-a variability in the Gulf of Taranto (North-western Ionian Sea) by a multi-temporal analysis of MODIS-Aqua Level 3/Level 2 data

2018 ◽  
Vol 155 ◽  
pp. 34-44 ◽  
Author(s):  
Emanuele Ciancia ◽  
Irina Coviello ◽  
Carmine Di Polito ◽  
Teodosio Lacava ◽  
Nicola Pergola ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Temporal Analysis ◽  
Ionian Sea ◽  
Multi Temporal ◽  
Level 3 ◽  
Level 2 ◽  
North Western

scholarly journals Assessment of the Level-3 MODIS daily aerosol optical depth in the context of surface solar radiation and numerical weather modeling

2012 ◽  
Vol 12 (9) ◽  
pp. 23219-23260 ◽  
Author(s):  
J. A. Ruiz-Arias ◽  
J. Dudhia ◽  
C. A. Gueymard ◽  
D. Pozo-Vázquez
Keyword(s):  
Solar Radiation ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Spatial Resolution ◽  
Surface Solar Radiation ◽  
Numerical Weather ◽  
Level 3 ◽  
Weather Modeling ◽  
The Mean ◽  
Level 2

Abstract. The Level-3 MODIS aerosol optical depth (AOD) product offers interesting features for surface solar radiation and numerical weather modeling applications. Remarkably, the Collection 5.1 dataset extends over more than a decade, and provides daily values of AOD over a global regular grid of 1°×1° spatial resolution. However, most of the validation efforts so far have focused on Level-2 products (10-km, at original resolution) and only rarely on Level-3 (at aggregated spatial resolution of 1°×1°). In this contribution, we compare the Level-3 Collection 5.1 MODIS AOD dataset available since 2000 against observed daily AOD values at 550 nm from more than 500 AERONET ground stations around the globe. One aim of this study is to check the advisability of this MODIS dataset for surface shortwave solar radiation calculations using numerical weather models. Overall, the mean error of the dataset is 0.03 (17%, relative to the mean ground-observed AOD), with a root mean square error of 0.14 (73%, relative to the same), albeit these values are found highly dependent on geographical region. For AOD values below about 0.3 the expected error is found very similar to that of the Level-2 product. However, for larger AOD values, higher errors are found. Consequently, we propose new functions for the expected error of the Level-3 AOD, as well as for both its mean error and its standard deviation. Additionally, we investigate the role of pixel count vis-à-vis the reliability of the AOD estimates. Our results show that a higher pixel count does not necessarily turn into a more reliable AOD estimate. Therefore, we recommend to verify this assumption in the dataset at hand if the pixel count is meant to be used. We also explore to what extent the spatial aggregation from Level-2 to Level-3 influences the total uncertainty in the Level-3 AOD. In particular, we found that, roughly, half of the error might be attributable to Level-3 AOD sub-pixel variability. Finally, we use a~radiative transfer model to investigate how the Level-3 AOD uncertainty propagates into the calculated direct normal (DNI) and global horizontal (GHI) irradiances. Overall, results indicate that, for Level-3 AODs smaller than 0.5, the induced uncertainty in DNI due to the AOD uncertainty alone is below 15% on average, and below 5% for GHI (for a solar zenith angle of 30°. However, the uncertainty in AOD is highly spatially variable, and so is that in irradiance.

scholarly journals ROSACE: A Proposed European Design for the Copernicus Ocean Colour System Vicarious Calibration Infrastructure

2020 ◽  
Vol 12 (10) ◽  
pp. 1535
Author(s):  
David Antoine ◽  
Vincenzo Vellucci ◽  
Andrew C. Banks ◽  
Philippe Bardey ◽  
Marine Bretagnon ◽  
...  
Keyword(s):  
Western Mediterranean ◽  
National Metrology Institute ◽  
Ocean Colour ◽  
High Quality ◽  
Vicarious Calibration ◽  
Ground Segment ◽  
Colour System ◽  
Marine Environment Monitoring ◽  
Monitoring Service

The European Copernicus programme ensures long-term delivery of high-quality, global satellite ocean colour radiometry (OCR) observations from its Sentinel-3 (S3) satellite series carrying the ocean and land colour instrument (OLCI). In particular, the S3/OLCI provides marine water leaving reflectance and derived products to the Copernicus marine environment monitoring service, CMEMS, for which data quality is of paramount importance. This is why OCR system vicarious calibration (OC-SVC), which allows uncertainties of these products to stay within required specifications, is crucial. The European organisation for the exploitation of meteorological satellites (EUMETSAT) operates the S3/OLCI marine ground segment, and envisions having an SVC infrastructure deployed and operated for the long-term. This paper describes a design for such an SVC infrastructure, named radiometry for ocean colour satellites calibration and community engagement (ROSACE), which has been submitted to Copernicus by a consortium made of three European research institutions, a National Metrology Institute, and two small- to medium-sized enterprises (SMEs). ROSACE proposes a 2-site infrastructure deployed in the Eastern and Western Mediterranean Seas, capable of delivering up to about 80 high quality matchups per year for OC-SVC of the S3/OLCI missions.

scholarly journals On the resolutions of ocean altimetry maps

2019 ◽  
Author(s):  
Maxime Ballarotta ◽  
Clément Ubelmann ◽  
Marie-Isabelle Pujol ◽  
Guillaume Taburet ◽  
Florent Fournier ◽  
...  
Keyword(s):  
Sea Level ◽  
Spatial Resolution ◽  
Tide Gauge ◽  
Optimal Interpolation ◽  
Climate Forecasting ◽  
Ocean Altimetry ◽  
The Mean ◽  
Marine Environment Monitoring ◽  
Monitoring Service ◽  
Along Track

Abstract. The DUACS system produces sea level global and regional maps that serve oceanographic applications, climate forecasting centers, geophysics and biology communities. These maps are constructed from optimal interpolation of altimeter observations and are provided on a global 1/4° × 1/4° (longitude × latitude) and daily grid resolution framework (1/8° × 1/8° longitude × latitude grid for the regional products) through the Copernicus Marine Environment Monitoring Service (CMEMS). Yet, the dynamical content of these maps is not ensured to have a full 1/4° spatial and 1-day resolution, due to the filtering properties of the optimal interpolation. In the present study, we estimate the effective spatial and temporal resolutions of the newly reprocessed delayed-time DUACS maps (aka, DUACS-DT2018). Our approach is based on the spectral coherence between maps and independent datasets (along-track and tide gauge observations), which represents the correlation between two sea level signals as a function of wavelength. We found that the spatial resolution of the DUACS-DT2018 global maps based on sampling by three altimeters simultaneously ranges from ~ 100 km-wavelength at high latitude to ~ 800 km-wavelength in the Equatorial band and the mean temporal resolution is ~ 28 days period. The mean effective spatial resolution at mid-latitude is estimated to ~ 200 km. The mean effective spatial resolution is ~ 120 km for the regional Mediterranean Sea product and ~ 140 km for the regional Black Sea product. An inter-comparison with former DUACS reprocessing systems (aka, DUACS-DT2010 and DUACS-DT2014) highlights the progress of the system over the past 8 years, in particular a gain of resolution in highly turbulent regions. The same diagnostic applied to maps constructed with two altimeters and maps with three altimeters confirms a modest increase of resolving capabilities and accuracies in the DUACS maps with the number of missions.

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