1 st Workshop on space-based architecture for Climate, Geneva, January WMO Gap Analysis with respect to GCOS requirements Presented by B. Bizzarri on appointment by WMO This working paper addresses the gap analysis for the Essential Climate Variables (ECV) defined in the framework of the “Implementation Plan for the Global Observing System for Climate in support of the United Nations Framework Convention on Climate Change (UNFCCC)“ The analysis was performed upon request of the WMO Expert Team on Satellite Systems (ET-SAT) as a discussion paper for the “Workshop on Continuity and Architecture Requirements for Climate Monitoring”, Geneva January An advanced presentation was made at CGMS-38, New Delhi 8-12 Nov FIRST WORKSHOP ON SPACE-BASED ARCHITECTURE FOR CLIMATE Continuity and Architecture Requirements for Climate Monitoring

1 st Workshop on space-based architecture for Climate, Geneva, January INDEX 1.Introduction 2.Definition of the Essential Climate Variables 3.Identification of the measurements implied by the ECVs 4.Short-list: ECVs based on components observable from satellite 5.Gap analysis 6. Conclusion and important notice 6.1Requirements coverage 6.2Time coverage 6.3Systematic gaps 6.4Important warning Appendix 1 - Instruments/missions gap analysis in the period Appendix 2 - Acronyms and lists of satellites and instruments

1 st Workshop on space-based architecture for Climate, Geneva, January List of GCOS Essential Climate Variables (ECV) Number of ECVs: 43 consolidated 06 in the waiting list 11 further chemical species (two CFCs considered) Total: 60

1 st Workshop on space-based architecture for Climate, Geneva, January Steps for the gap analysis Each ECV actually implies a number of observable variables. The first step was to identify the variables that can be observed from Space: - 16 ECVs were disregarded because implying all variables not-for-satellites. - 4 ECVs were disregarded waiting for more detailed definition ECVs were carried forward because could draw benefit from satellites. Each geophysical variable observable from satellite serves more ECVs. The gap analysis for ECVs consists of the gap analysis of the observable variables possible to be measured from Space. The gap analysis for observables from Space has been imported from the GOS Dossier vol. III (Gap analysis), limited to the period The period has been covered by reviewing historical information, recorded to some extent in the GOS Dossier vol. I (Programmes).

1 st Workshop on space-based architecture for Climate, Geneva, January One example Continue…

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1 st Workshop on space-based architecture for Climate, Geneva, January Programmes for IR temperature/humidity sounding from LEO

1 st Workshop on space-based architecture for Climate, Geneva, January Requirements coverage 40 out of the 60 ECV’s can be supported by satellite observation, to a major or minor extent.

1 st Workshop on space-based architecture for Climate, Geneva, January Requirements not covered The following 16 out of the 60 ECV’s are unlikely to draw any support from satellites, at least as current technology enables. The following 4 out of the 60 ECV’s have not been considered, waiting for more specific definition:

1 st Workshop on space-based architecture for Climate, Geneva, January Major conclusions Requirements coverage: Out of the 60 ECV’s, 40 draw benefit from satellite observation, 16 draw no benefit or marginal benefit, 4 need to be better specified. Time coverage For many observations, data records exist since at least 1975, and long- term commitment to continuity are available till at least Systematic gaps: - limb sounding missions after the conclusion of the currently flown ones, that implies future gap of data on the middle and high stratosphere; and - measurements requiring large facilities uneasy to be accommodated on operational satellites. Important warning It is stressed that this gap analysis only refers to the availability of satellite observations. However, the existence of observational data sets does not imply that the product has being or will be effectively retrieved and archived. Thus, the identified contribution is only potential.

1 st Workshop on space-based architecture for Climate, Geneva, January Any action ? Some suggestions (in increasing order of difficulty): 1)To bring the detail of the gap analysis for period to the same level as for all the necessary information is in the GOS Dossier; two steps possible: - to just add mention of the past instruments and periods - to add the information on instrument performances - to evaluate and add the information on product performances (this is available in Dossier vol. IV for reference post-2020 instruments). 2)To re-edit the current document expanding the text of the analysis and of the conclusions for each ECV. [insert slide] [warning: current text is 80 pages !] 3)To compare existing previous gap analysis (there are several !) with the present one (probably the most systematic, with wider coverage). Preliminary questions: is this Gap analysis useful ? is it cost/effective to improve it ? Maybe the essential message is already in.

1 st Workshop on space-based architecture for Climate, Geneva, January