Calibration A Spot

Inter-calibration

 

Calibration A Spot
Calibration A Spot

Inter-calibration methods compare a reference instrument, with well-known calibration characteristics, with collocated observations from another instrument, in order to derive calibration corrections for the latter. This ensures consistency between the products of the different instruments.

Last Updated

28 March 2023

Published on

29 September 2020

Satellite inter-calibration is beneficial for:

  • identifying problems and increasing the confidence in the operational calibration of individual satellites. Hence, inter-calibration can serve as a monitoring tool for the operational calibration;
  • providing the basis for a normalised calibration, which is a prerequisite for the derivation of global products from different satellites.

EUMETSAT has performed inter-calibration using instrument measurements from both geostationary Meteosat satellites and the polar-orbiting Metop and NOAA satellites. EUMETSAT’s inter-calibration activities are now coordinated through the Global Space-based Inter-Calibration System (GSICS).

Monitored Instrument Reference Instrument Status GSICS Product Documentation
Meteosat-11/
SEVIRI
Metop-A/IASI Operational Near-real-time correction
Re-analysis correction
Bias monitoring
User guide
ATBD
Uncertainty analysis
Meteosat-10/
SEVIRI
Metop-A/IASI Operational Near-real-time correction
Re-analysis correction
Bias monitoring
User guide
ATBD
Uncertainty analysis
Meteosat-9/
SEVIRI
Metop-A/IASI Operational Near-real-time correction
Re-analysis correction
Bias monitoring
User guide
ATBD
Uncertainty analysis
Meteosat-8/
SEVIRI
Metop-A/IASI Operational Near-real-time correction
Re-analysis correction
Bias monitoring
User guide
ATBD
Uncertainty analysis
Meteosat-8/
SEVIRI
Aqua/MODIS (DCC) Demo Near-real-time correction
Re-analysis correction
ATBD
Meteosat-11/
SEVIRI
Aqua/MODIS (DCC) Demo Near-real-time correction
Re-analysis correction
ATBD
Meteosat-10/
SEVIRI
Metop-A/IASI Demo Near-real-time correction
Re-analysis correction
Bias monitoring
NRTC ReadMe
RAC ReadMe
ATBD
Error budget
Meteosat-9/
SEVIRI
Metop-A/IASI Demo Near-real-timecorrection
Re-analysis correction
Bias monitoring
NRTC ReadMe
RAC ReadMe
ATBD
Error budget
Meteosat-8/
SEVIRI
Metop-A/IASI Demo Near-real-time correction
Re-analysis correction
Bias monitoring
NRTC ReadMe
RAC ReadMe
ATBD
Error budget
Meteosat-7/
MVIRI
Metop-A/IASI Demo Near-real-time correction
Re-analysis correction
NRTC ReadMe
RAC ReadMe
ATBD
Error budget
Metop-A/
HIRS
Metop-A/IASI Prototype Near-real-time correction
Re-analysis correction
Bias monitoring
 
Metop-B/
HIRS
Metop-B/IASI Prototype Near-real-time correction
Re-analysis correction
Bias monitoring
 

GSICS Inter-calibration products

GSICS satellites
Figure 1: Weather satellites inter-calibrated by GSICS

The range of GSICS products includes the GSICS correction and GSICS bias monitoring. GSICS corrections are functions users can apply to correct the calibration of operationally-generated datasets from the monitored instrument so they are consistent with those of the reference instrument. GSICS corrections are available for both near-real-time and re-Analysis applications, with different latencies.

GSICS bias monitoring allow users to visualise the relative biases between the monitored and reference instruments for standard radiances. These take the form of time series plots in which the latest results can be compared with recent trends.

The table (above) summarises the status of a number of different GSICS products being developed by EUMETSAT. Links are provided to the {link:GSICS}, where the coefficients of the GSICS correction can be downloaded in netCDF format, and to the GSICS bias monitoring tool, which allows users to evaluate and plot the results of the inter-calibrations as time series of brightness temperature biases.

GSICS data and products server

EUMETSAT has taken the lead in the design and development of the first operational GSICS data and product server. The purpose of this server is to provide the platform for developing calibration products and to facilitate data exchange related to GSICS activities.

Its purpose, operational concepts and data exchange format (netCDF) were presented to the GSICS partners, at the joint GSICS meeting in 2008, where its development was agreed and endorsed by the GSICS partners and, then, the executive panel.

The GSICS became operational on 1 April, 2009. It currently serves the GSICS community with EUMETSAT’s instruments’ source datasets — as well as pre-operational GSICS products undergoing validation, according to the GSICS product acceptance procedure.

Our GSICS partners are in the process of developing their operational GSICS Data and Product servers. Once this is realised, a network of collaboration data and production servers will share all GSICS data and products with each other, providing a reliable data distribution service to the user community.

In the future, developments in the area of metadata conventions will be further examined. Using established conventions, or adding to them, adds value to data as all users of the convention will understand what the data is and use the same units. Another major benefit, for the user community, of using conventions is tools implemented to understand these conventions can immediately work with the data.

Further information may be found in the GSICS data and products server user guide, EUMETSAT Data Centre Archive netCDF formats and a presentation on GSICS collaboration servers.