3MI Cloud Algorithm Development Support

About 3MI Cloud Algorithm Development Support.

The 3MI design and heritage comes from the POLDER/PARASOL missions. Algorithms exist in the community for retrieval of cloud optical properties from POLDER/PARASOL which could, in principle, be applied to 3MI data. However, 3MI has additional spectral channels (specifically in the ultraviolet and the short-wave infrared) and more polarised channels than its predecessors and has stringent requirements on its final product quality. In addition, 3MI presents a particular challenge due to the need to provide near real-time data products (~120 minutes after sensing) combined with an increase in spatial resolution which increases the data rate and, therefore, computational cost of product generation.

As 3MI will fly on EPS-SG alongside METimage, which can be expected to produce superior cloud products due to the higher spatial resolution and additional measurements in the infrared spectral region, it is important that any cloud algorithm development should focus on the unique characteristics of 3MI, namely the multi-angular viewing and the measurement of polarisation.

Therefore, support is required for the definition of algorithms for 3MI cloud products which will capitalise on these unique characteristics of 3MI, and be sufficiently fast to be able to be run in near real-time, and sufficiently accurate to satisfy the product quality requirements.

Data Resources
Study Meetings



The aim of this study is to provide support to the development of cloud property retrieval algorithms from the 3MI instrument on EUMETSAT Polar System – Second Generation (EPS-SG), in particular those which take advantage of the unique characteristics of 3MI as compared to METimage, namely the multi-angular viewing and the measurement of polarisation.


This support will comprise:

  • Review and comparison of the currently proposed METimage and baseline 3MI cloud products.
  • Proposal for unique and complementary cloud products from 3MI, taking advantage of the multi-view and polarisation information to be documented in an Algorithm Theoretical Baseline Document (ATBD).
  • Preparation of a prototype software implementation of the algorithm.
  • Demonstration of the performance of the proposed algorithms using test data to be proposed and prepared by the Contractor.

The contractor is required to base its cloud properties retrieval on multi-spectral, multi-polarisation, multi-angle acquisitions, up to 14 acquisitions or 'views (See Figure 1). These are co-registered to a regular, equal area, fixed geophysical grid with configurable grid spacing, close to the instrument footprint spatial resolution (Level 1c data), which are parallax corrected using a digital elevation model of sufficient resolution, and cover the full instrument swath.

The co-registration is done separately for SWIR and VNIR channels with a maximum of 14 acquisitions for both. Since the along-track dimension of the SWIR detector is half the size of the VNIR its viewing angle range along-track is restricted to half of the VNIR detector and, therefore, the detectors share only seven out of 14 viewing angles which are identical to the VNIR angles.

Figure 1
Figure 1: The 3MI concept, multi-view, multi-spectral, and multi-polarisation sampling


Phase Details
Kick-Off 06/12/2016
Duration 18 months
Status Ongoing
WP1 Review of METimage and baseline 3MI Cloud Products
Completed: 04/05/2017
WP2 Proposal for Innovative Cloud Algorithms from 3MI
Completed: 28/07/2017
WP3 Preparation of Test Data and Definition of Validation methods
Completed: 06/12/2017
WP4 Development of Prototype Code and Demonstration of Performance of Innovative Algorithms
Ends: August 2018
WP5 Documentation and Final Report
Ends: September 2018

Data Resources

For data inquiries, please contact Bertrand Fourgnie.

Study Meetings

Phase Date and location
KO 05/12/2016, EUMETSAT
PM1 04/05/2017, EUMETSAT
PM2 28/07/2017, EUMETSAT
PM3 06/12/2017, LOA, Lille, France
PM4 Planned July 2018, LOA, Lille, France
FAR Planned early Sept 2018, EUMETSAT


EUMETSAT Project Manager
Dr Rosemary Munro
Competence Area Manager
Remote Sensing and Products Division
Prof. Jérôme Riedi
Laboratoire d’Optique Atmosphérique, Université de Lille, France
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