Errors and uncertainties in ocean colour remote sensing (2)
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Abstract
One of the main questions you will be asked as a remote sensing expert is: how reliable and good is
information, which we derive from remotely sensed ocean colour data? Can we trust them?
What is the error or uncertainty range of these data?
In this section of the IOCCG training course, which consists of 3 lectures and exercises, we will look into
this problem.
Lectures
The first lecture will be dedicated to the sources of uncertainties. We have to consider that our
observations are the reflectivity in a number of spectral bands, which are measured at the top of
atmosphere (TOA) or, in case of an aircraft platform, in a certain height above the water. We try
nothing less than to isolate, retrieve and quantify a small effect on these spectra, which is caused by
absorption and scattering of e.g. of phytoplankton, from a large number of other effects, of which in
particular the atmosphere dominates the TOA spectrum. Problems of this kind may induce large
uncertainties. In some cases it might be even impossible to retrieve reliable information of the ocean
from remotely sensed reflectance spectra. Thus, one important area of ocean colour research is to
analyze sources of uncertainties, to develop methods to quantify uncertainties and finally to find way
to reduce uncertainties.
In this lecture we will consider
- Natural factors, which determine uncertainties, and their variability
- Uncertainties, which are induced by reducing the manifold of factors to a few dominant wavelength (nm)
- Radiance (Wm‐2 sr‐1 μm‐1) air molecules different aerosols thin clouds
- Sky reflectance Sun glint foam floating material chlorophyll
- Suspended particles different phytoplankton species dissolved organic matter
- Vertical distribution Bottom reflection contrails
- Errors caused by spaceborne or airborne instruments: calibration, ageing, noise
- Errors caused by in situ measurements, sampling and procedures
- Problem of comparing in situ with space borne
- How to quantify uncertainties: scatter, bias, robustness, stability
- Validation procedures and strategies
- Testing of algorithms
- Round robin exercises
- Sensitivity studies
- Determination of uncertainties on a pixel by pixel bases
- flagging
- Detection of spectra / pixels, which are out of scope of the algorithm
- Masking of clouds and cloud shadows
- Use of additional information
- Pre‐classification of water types and use of dedicated algorithms
- How to produce maps from satellite data, which include information about uncertainties.
Curriculum
Bibliography
Speaker(s) : Roland Doerffer, Helmholtz Center Geesthacht /Brockman Consultants, Germany
Public : All
Date : Tuesday 10 july 2012
Place : Villefranche-sur-Mer

- Ocean Colour Algorithms (1)
- Inherent optical properties of ocean waters
- Ocean Colour Algorithms (2)
- Inversion of inherent optical properties from remote sensing
- Hyperspectral remote sensing of optically shallow waters
- Atmospheric correction issues unique to shallow waters
- Iop applications
- Techniques used for inverting atmospherically corrected rrs spectra
- Improved ocean ecosystem predictions through improved light calculations
- Ecosystem predictions using accurate radiative transfer models
- Above and in water radiometry: methods and calibration requirements
- Uncertainty analysis and application of in situ radiometric products
- In Situ Measurements (1)
- Errors and uncertainties in ocean colour remote sensing (1)
- In Situ Measurements (2)
- Errors and uncertainties in ocean colour remote sensing (2)
- High-resolution hyperspectral oc rs in coastal areas (1)
- High-resolution hyperspectral oc rs in coastal areas (2)
- Atmospheric correction of ocean colour rs observations (1)
- Use and importance of oc remote sensing in global coupled bgc models
- Atmospheric correction of ocean colour rs observations (2)
- Ocean colour remote sensing in turbid coastal waters (1)
- Using the oc time series to address climate change
- Atmospheric correction of ocean colour rs observations (3)
- Ocean colour remote sensing in turbid coastal waters (2)
- Harmful algal blooms: the contrast with other algal blooms (1)
- Ocean colour remote sensing in high latitude environments (1)
- Harmful algal blooms: the contrast with other algal blooms (2)
- Phytoplankton fluorescence: theory and interpretation from oc remote sensing (2)
- Ocean colour remote sensing in high latitude environments (2)
- Phytoplankton fluorescence: theory and interpretation from oc remote sensing (1) Detailed list
Contents
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