GRWG Web Meeting 2013-10-15

GSICS Web Meeting on Scoring Scheme to Select Reference Instrument

Agenda

1. Tim Hewison (EUMETSAT) – Introduction - A statement of the Problem
2. Dave Smith (RAL) - Thoughts on Selecting a Reference Instrument - in absentia
3. Bertrand Fougnie (CNES) - A Vision of How to Select the Reference - in absentia
4. Manik Bali (NOAA) - Is it "Good enough"?
5. Tim Hewison (EUMETSAT) – A Proposed Scoring Scheme
6. Group Discussion

Attendees

CMA: Yong Zhang

CNES: Denis Jouglet

EUMETSAT: Tim Hewison (Chair), Sebastien Wagner, Viju John, Bartolomeo Viticchie

JMA: Keita Hosaka, Masay Takahashi

KMA: Dohyeong Kim

NOAA: Fangfang Yu, Manik Bali

WMO: Jerome Lafeuille

Summary

The proposed scoring scheme can be summarised by the definition of the following for each class of GSICS product:

1. Variables describing required performance of Reference
2. Minimum thresholds for each variable required for inter-calibration to be useful for useful
3. Maximum thresholds (optimal values) for each variable above which no further improvement will be realised
4. Weighting for each variable (to align with contributions to overall uncertainty)

It was agreed that defining the first two of these for each class of GSICS product would be a useful exercise. Specifically, it was felt that defining the uncertainty introduced by the Spectral Band Adjustment Factor was a more useful variable than spectral resolution for inter-calibration products using non-hyperspectral reference instruments.

A sensitivity analysis should then be performed to establish each variable's contribution to the overall uncertainty of the inter-calibration product (where possible).

It was also agreed that it is difficult to quantify some of the variables, which are nevertheless critical to certain GSICS products (e.g. traceability). It may, however, be possible to list the requirements in terms of levels of characterisation and define these on a sliding scale.

Because of this and the assignment of the weightings, there will inevitably be an element of subjectivity in the selection of an inter-calibration reference. However, it was suggested that different GRWG members each propose a set of weightings for one class of GSICS product, with the intention of agreeing a definitive set by community agreement.

Action:

Tim Hewison to circulate a proposed list of variables for the GEO-LEO hyperspectral IR case in time for discussion at the next annual GRWG meeting.