System vicarious calibration for ocean color climate change applications: Requirements for in situ data

Zibordi, Giuseppe; Mélin, Frédéric; Voss, Kenneth J.; Johnson, B. Carol; Franz, Bryan A.; Kwiatkowska, Ewa; Huot, J.P.; Wang, Menghua; Antoine, David

doi:10.1016/j.rse.2014.12.015

Cited by 76 publications

(50 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Some of the differences observed in the blue region between the DALEC R rs and the satellite R rs may be further reduced by using data processing methods based on spectrally variant ρ (e.g., Lee, Ahn, Mobley and Arnone [22]). This study did not include an investigation and quantification of each source of uncertainty in the estimate of the DALEC R rs , such analysis of the uncertainty budget would include the effects on uncertainty of the system calibration, the superstructure perturbations, viewing geometries, distance of the instrument footprint from the hull, estimate of W, ρ and , non-cosine response of E d and further environmental perturbation such as wave effects [4,6,12].…”

Section: Discussionmentioning

confidence: 99%

“…The observed bias dependence on sun zenith angles may be due to observation geometry with respect to the ship heading, sun elevation, and relative azimuth between radiometer and sun, leading to water volume bidirectional components in the DALEC R rs . Hence, in future work a bidirectional effect correction scheme should be implemented in the DALEC processing chain [4,6]. …”

Section: Sensitivity To Dalec Processing Parametersmentioning

confidence: 99%

“…The spectral remote sensing reflectance (R rs (sr´1)) determined from top-of-atmosphere radiance is the primary ocean color product used for the generation of all higher-level products. Calibration and validation of OCR observations is a necessary and on-going requirement, to produce consistent time series of data and to ensure that processing methods accurately account for atmospheric and other environmental effects [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…Permanent fixed platforms and moorings supported by dedicated calibration and maintenance regimes provide the best quality observations for long-term calibration data, but ships can provide a suitable platform to collect spatially diverse ocean color data for global and regional validation purposes [2,4,14]. Targeted voyages with manually operated above-water radiometers can provide comprehensive datasets of a region at a given time [10,[14][15][16], while autonomous above-water radiometers can provide more extensive spatial coverage if the near-surface effects such as sun glint, platform shadowing and spray are minimized by maintaining a suitable viewing geometry and by implementing adequate quality control and processing procedures [11,[17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Potential of Autonomous Ship-Borne Hyperspectral Radiometers for the Validation of Ocean Color Radiometry Data

et al. 2016

View full text Add to dashboard Cite

Calibration and validation of satellite observations are essential and on-going tasks to ensure compliance with mission accuracy requirements. An automated above water hyperspectral radiometer significantly augmented Australia's ability to contribute to global and regional ocean color validation and algorithm design activities. The hyperspectral data can be re-sampled for comparison with current and future sensor wavebands. The continuous spectral acquisition along the ship track enables spatial resampling to match satellite footprint. This study reports spectral comparisons of the radiometer data with Visible Infrared Imaging Radiometer Suite (VIIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua for contrasting water types in tropical waters off northern Australia based on the standard NIR atmospheric correction implemented in SeaDAS. Consistent match-ups are shown for transects of up to 50 km over a range of reflectance values. The MODIS and VIIRS satellite reflectance data consistently underestimated the in situ spectra in the blue with a bias relative to the "dynamic above water radiance and irradiance collector" (DALEC) at 443 nm ranging from 9.8ˆ10´4 to 3.1ˆ10´3 sr´1. Automated acquisition has produced good quality data under standard operating and maintenance procedures. A sensitivity analysis explored the effects of some assumptions in the data reduction methods, indicating the need for a comprehensive investigation and quantification of each source of uncertainty in the estimate of the DALEC reflectances. Deployment on a Research Vessel provides the potential for the radiometric data to be combined with other sampling and observational activities to contribute to algorithm development in the wider bio-optical research community.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Sensitivity To Dalec Processing Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Potential of Autonomous Ship-Borne Hyperspectral Radiometers for the Validation of Ocean Color Radiometry Data

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Conversely, the objective of P equal to 0.5 would require bias values of approximately 2%. Considering uncertainties on chl-a in situ data (Claustre et al 2004), results of algorithms evaluations (Brewin et al 2015), chl-a satellite products validation analyses (Gregg and Casey 2004;Mélin, Zibordi, and Berthon 2007) or inter-comparison Mélin 2010, and Figure 2(a)), uncertainties associated with the satellite-derived remote-sensing reflectance (Mélin and Franz 2014), and limitations inherent to the calibration of radiometers in space (Zibordi et al 2015), it is unlikely that, in the current state of technology and algorithm development, these levels of biases will be achieved by merely applying a fully consistent processing chain for the various missions (even though this is highly desirable). This study suggests that bias correction methods should become an integral part of the strategy to create ocean colour multi-mission CDRs.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Impact of inter-mission differences and drifts on chlorophyll-atrend estimates

Mélin

2016

International Journal of Remote Sensing

View full text Add to dashboard Cite

The chlorophyll-a (chl-a) concentration is an Essential Climate Variable, and the study of its variability at global scale requires a succession of satellite ocean colour missions to cover a period suitable for climate research. In the context of a multi-mission data record, inter-mission differences can introduce artefacts affecting trend evaluations, and the impact of the bias between the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS) chl-a products is shown to be significant in a substantial part of the ocean. The assessment of trends can also be directly impacted by a drift in the chl-a time series resulting from sensor functions. These issues are addressed by a sensitivity analysis that compares slopes of linear regression obtained for varying levels of intermission bias and drift with respect to a 15-year reference series built with SeaWiFS and MODIS data. The relationship, constructed for a representative set of ocean provinces, between bias and the level of significance associated with the comparison of slopes shows that a bias on the order of ±5-6% generally induces a slope that is significantly different from the reference case, while a threshold on bias values not exceeding 2% largely alleviates this effect. Moreover, the study suggests that a drift larger than 2% per decade on the chl-a series can result in misleading conclusions from a trend analysis. All results have a clear regional dependence that needs to be taken into account in bias-correction and merging efforts. Low chl-a regions, such as the oligotrophic subtropical gyres, appear particularly sensitive to perturbations and require still higher levels of consistency and stability.ARTICLE HISTORY

show abstract

Single dual mode (continuous and cast) instrumentation package for inherent optical property measurements: Characterization of the bucket for backscattering observation

Volpe

Dionisi

Brando

et al. 2021

Limnology & Ocean Methods

View full text Add to dashboard Cite

This work describes a continuous sampling system that has been designed, implemented, and tested for the acquisition of Inherent Optical Properties (IOPs) during field campaigns. The major challenge of the work was to design and build a flow-through housing accounting for the complex sensing geometry of the ECO-VSF3, a backscattering meter, i.e., three sensor heads each of which measures the VSF at three angles. A detailed characterization of the ECO-VSF3 housing in terms of impact of the boundaries and overall system inertia is reported.A key feature of the system design is the possibility to easily detach the IOP package from the flow-through hydraulic circuit and use it in cast mode at fixed stations. This, to the best of authors' knowledge, is the first time the ECO-VSF3 is used in an underway system. Results from the comparison of continuous (Co) and cast (Ca) b b measurements show excellent agreement, with differences not exceeding 7%, thus proving the system to be reliable and highlighting the feasibility for increasing the spatio-temporal sampling of surface observations.

show abstract

System vicarious calibration for ocean color climate change applications: Requirements for in situ data

Cited by 76 publications

References 26 publications

The Potential of Autonomous Ship-Borne Hyperspectral Radiometers for the Validation of Ocean Color Radiometry Data

The Potential of Autonomous Ship-Borne Hyperspectral Radiometers for the Validation of Ocean Color Radiometry Data

Impact of inter-mission differences and drifts on chlorophyll-atrend estimates

Single dual mode (continuous and cast) instrumentation package for inherent optical property measurements: Characterization of the bucket for backscattering observation

Contact Info

Product

Resources

About