1. Introducing Me, GSICS, and the UV Sub-Group
Tim Hewison1
EUMETSAT
Chair of GSICS Research Working Group

2. Who am I? Tim Hewison EUMETSAT Calibration Group
Responsible for GEO imagers
Supporting LEO imagers
Supporting Reprocessing
My background - Microwave
Cosmic!
AMSU characterisation
Airborne radiometers
Ground-based instruments
Chair of GSICS Research WG

3. Global Space-based Inter-Calibration System
What is GSICS?
Global Space-based Inter-Calibration System
Initiative of CGMS and WMO
Effort to produce consistent, well-calibrated data from the international constellation of Earth Observing satellites
What are the basic strategies of GSICS?
Improve on-orbit calibration by developing an integrated inter-calibration system
Initially for GEO-LEO Inter-satellite calibration
Being extended to LEO-LEO
Using external references as necessary
Best practices for prelaunch characterisation (with CEOS WGCV)
This will allow us to:
Improve consistency between instruments
Reduce bias in Level 1 and 2 products
Provide traceability of measurements
Retrospectively re-calibrate archive data
Better specify future instruments
EUMETSAT
CNES
JMA
NOAA
CMA
KMA
ISRO
NASA
WMO
USGS
NIST
JAXA
ROSHYDROMET
IMD
ESA
Well, what is GSICS?
The Global Space-based Inter-Calibration System (GSICS) is an initiative of CGMS and WMO, which aims to ensure consistent calibration and inter-calibration of operational meteorological satellite instruments.
One of the basic strategies of GSICS is to develop an integrated on-orbit cal/val system - initially by LEO-GEO Inter-satellite/inter-sensor calibration.
This will then allow us to provide corrections to improve the consistency between instruments, produce less biased level 1, and therefore, level 2 data, and ultimately, retrospectively re-calibrate archive data, which is of great interest in the climate monitoring community

4. TRACEABILITY / UNBROKEN CHAINS OF COMPARISONS
GSICS Principles
Systematic generation of inter-calibration products
for Level 1 data from satellite sensors
to compare, monitor and correct the calibration of monitored instruments to community references
by generating calibration corrections
with specified uncertainties
through well-documented, peer-reviewed procedures
based on various techniques to ensure consistent and robust results
Delivery to users
Free and open access
Adopting community standards
To promote
Greater understanding of instruments’ absolute calibration, by analysing the root causes of biases
More accurate and more globally consistent retrieved L2 products
Inter-operability for more accurate environmental, climate and weather forecasting products
TRACEABILITY / UNBROKEN CHAINS OF COMPARISONS

5. GSICS Products GSICS Bias Monitoring GSICS Correction
Routine comparisons of satellite radiances against reference
GSICS Correction
Function to correct issued radiances
For consistent calibration with reference
GSICS Reports & Guidelines
Recommendations to modify practices
Design and Operation of future satellite instruments
For Operational Environmental Satellites
 Infra-red recalibration (GEO and LEO)  Pre-Operational & Demo status
(current operational satellites)  Near real-time and re-analysis
 Visible and near-infrared recalibration (GEO and LEO)  In development within GSICS
 Microwave – Conical & Cross-track Scanners (LEO)  In development with GPM XCAL
 Historic Instruments  In development at EUMETSAT…

6. GRWG Sub-Groups - Motivation
Issue: Increasing Expectations – Non-increasing Resource Support
Following our initial success with GEO-LEO infrared and users’ demand for further inter-calibration products,
GSICS is aiming to expand to cover other instruments and other parts of the spectrum.
This requires the development of multiple techniques appropriate for different spectral bands.
It is difficult for one person to keep abreast of all the developments in each of these areas, let alone guide the development of future products.
Concept:
Instead of vice-chairs, identify Chairs of Sub-Groups

7. Possible Sub-Groups
Possible Sub-Groups include, but are not limited to:
Microwave (covering imagers and sounders) Chair: Cheng-Zhi Zou (NOAA)
Visible/Near Infrared Chair: Dave Doelling (NASA)
Thermal Infrared Currently covered by GRWG Chair
Ultra-violet channels/instruments
Archive Re-Calibration of historic instruments (FCDR generation) ?
Use of Synthetic observations for inter-calibration (NWP/RAOB+RTM) ?

8. Scope of UV Sub-Group
Understanding users’ requirements for inter-calibration products for UV
Identifying existing products that could meet those requirements
Encouraging  the creators of those products to submit them to the GSICS Procedure for Product Acceptance (GPPA)
Reviewing these products to ensure they adhere to GSICS principles with other members of the Sub-Group and users.
Developing new inter-calibration products, based on GSICS principles.
Submitting these to the GPPA
Liaison with users as beta testers
Interaction with GSICS Data Working Group
To ensure products are made available to users
Adhering to GSICS standards
Coordination with other groups (such as CEOS/ACC) would also be required to generate standards and best practices for UV calibration.

9. Meetings of UV Sub-Group
Mostly web meetings
Max 2.5hr:
11:00-13:30 UTC in summer
11:30-14:00 UTC in winter
Session at Annual GSICS Working Group meeting?
Next: March EUMETSAT, Germany
Break-out session at Conference/Workshop?

10. EUMETSAT Headquarters, Darmstadt, Germany
2014 GRWG+GDWG Meeting
Next annual GRWG+GDWG meeting:
Dates: March 2014
Location: EUMETSAT
Format:
Mon: “Mini Conference”
Tues: Plenary – Reports & Briefs
Wed: GRWG+GDWG Breakouts
Thurs: GRWG+GDWG Breakouts
Fri am: Plenary – wrap-up
2014 GSICS Users’ Workshop:
Asia?
EUMETSAT Headquarters, Darmstadt, Germany
- in the sunshine!

11. Chairing Sub-Groups
GRWG chair invited applications to chair sub-groups,
outlining proposed scope and working plan
to develop GSICS products for a specific application or spectral band
and send that to the GRWG Chair
Proposals will be reviewed by GSICS Exec Panel
Exec Panel ruled:
The GRWG leads and subgroup leads should be officially GRWG members; they should thus be appointed to GRWG by one of the GSICS member agencies.
Proposed Term:
3 year with optional annual extensions

12. Role of UV Sub-Group Chair
I see the role of chair as being one of coordination, nurturing and leadership:
Identifying user requirements
Leading development of new inter-calibration products
Coordinating reviews
Liaison with other groups to generate standards and best practices for UV calibration
All this would require:
Organising and Chairing a few web meetings a year,
Monitoring actions related to the development of inter-calibration products in their field,
Sending out s (and reminders) and
Reporting to the Exec Panel and/or Research Working Group Chair
Chairing a session at the working group meetings (or elsewhere) ?
- if sufficient number of people are able to attend

13. Thank You