GRWG Web Meeting 2014-05-27

GSICS Web Meeting on Delta Corrections - Reference Migration, Archive Re-Calibration & Diurnal Cycles

Agenda

1. Viju John (EUMETSAT) - Update on EUMETSAT Plans to Re-Calibration of Meteosat Archive
2. Fangfang Yu (NOAA) – Characterising Diurnal Calibration Variations using Double-Differences
3. Ryoko Yoshino (JMA) - Double Differences of MTSAT2-IASIA/B (revised in 28 May)
4. Tim Hewison (EUMETSAT) – Delta Corrections - What will they be used for?
5. All - Discussion

Attendees

Chair: Tim Hewison

CMA: Xu Na

EUMETSAT: Tim Hewison, Sebastien Wagner, Bartolomeo Viticchie, Rob Roebeling, Viju John

JMA: Ryoko Yoshino, Masaya Takahashi, Arata Okuyama, Masayuki Sasaki, Keita Hosaka

KMA: Minjin Choi, Hyesook Lee

NOAA: Fangfang Yu, Manik Bali

Summary

An approach was agreed to characterise the diurnal calibration variations based on the double differencing wrt AIRS and IASI, and that this should be included in the netCDF format for the current RAC and NRTC GEO-LEO IR products before progressing to operational status. However, it was also agreed that these coefficients do not need to be updated dynamincally if an analysis shoes them to be predictable, in which case including a static evaluation would be sufficient initially.

It was agreed that double differences from multiple references should be generated for the whole period they are available and analysed to characterise their relative biases and their uncertainties.

In the future the use of blended references should be addressed prior to generating Archive Recalibration Corrections/Coefficients. An alternative approach to the delta corrections was also outlined: instead of correcting the relative biases of the reference instruments, we could consider expanding their specified uncertainties to ensure their data are consistent and can be combined into a merged reference. This is also something that could be addressed using synthetic datasets in preparation for generating ARC products.

Outcome

Action: Fangfang Yu (NOAA) to prepare netCDF format to include characterisation of diurnal calibration variations for current GEO-LEO IR RAC and NRTC.

Action: Tim Hewison (EUMETSAT) to implement delta corrections based on integer years of overlap period in netCDF for current GEO-LEO IR RAC and NRTC and draft ATBD to describe their generation.