1. TOPC Report
Wolfgang Wagner

2. TOPC XIX Meeting at TU Wien on 5–7 April 2017
Change in Panel Membership
Panel membership is expected to rotate: 3 years + one extension, exceptions possible but need good justification

3. Panel and Experts

4. Proposal for Evaporation/Latent Heat Flux as ECV
Presentation by Han Dolman
There is a high need for λE data but is it technically and economically feasible for systematic observation?
λE cannot be measured directly from space, requires multiple observations
Solar radiation, humidity, air temperature, wind speed, soil moisture, vegetation cover, stress and phenology
Several successful intercomparison exercises
Michel et al. (2016) TheWACMOS-ET project–Part 1: Tower-scale evaluation of four remote-sensing-based evapotranspiration algorithms, HESS 20.2,
Summary of 24 stations average R2 for 3-hourly and daily tower forcing. EC denotes the model agreement with the evapotranspiration reference from eddy-covariance measurements, and ER is the model agreement with the evapotranspiration reference based on the in situ energy residual.

5. Some Thoughts on the Monitoring of ECVs
Our current approach to “monitoring of the adequacy ECVs” currently relies on expert judgements
Expert judgement is much more encompassing than a single benchmark
Yet, are there more objective and quantitative ways?
Overall scientific “usefulness”
Uptake by the user community
Nowadays the impact of publications is well documented. What about data and the software used for producing it?
How may one benefit from and interact with emerging initiatives/ organisation/technologies?
DataCite (
Depsy for software citations (
Using GitHub ( to store, publish, and collaborate on open, machine-readable datasets
Etc.

6. Some Results of Brainstorming
There is a need to better connect to the scientific community
Focus on concrete activities (and do not get lost in transgression …)
Seek continuous feedback on GCOS Action Plan
Enable critical review of ECV requirements by writing down
their current definition
Invite groups to showcase their climate indicators

7. ECV Requirements Definition: Example from ECV Glaciers
Many thanks to Michael Zemp for always responding
promptly!
ECV Requirements Definition: Example from ECV Glaciers
Glacier area is the map-projected size of a glacier in km2. Typically, a minimum size of 0.01 or 0.02 km2 is applied, as a glacier must flow by definition and ice patches smaller than this are likely stagnant. The frequency “Annual” means that each year the availability of satellite (or aerial) images should be checked to not miss the year with the best snow conditions (i.e. snow is only found on glaciers and not hiding their perimeter). The horizontal resolution of m refers to typically used satellite sensors (Landsat and ASTER) to map glaciers. At coarser resolution the quality of the derived outlines rapidly degrades. Spatial resolutions better than 15 m (e.g. the 10 m from Sentinel 2) are preferable as typical characteristics of glacier flow (e.g. crevasses) only become visible at this resolution (Paul et al. 2016). The measurement uncertainty refers to the accuracy of the glacier area. For clean ice this value can be reached using automated methods, for debris-covered glaciers manual editing is required to have a product accuracy better than this (Paul et al. 2013).

8. TOPC Discussion Forum

9. Soil Moisture Workshop 2017
Over 100 participants from 22 countries
GCOS was one of the co-sponsors
Two discussion topic:
Feedback on GCOS requirements  ok but need for a best practices guidance
Identification of observational gaps  Need for an L-band radiometry continuity mission

10. Open Questions
Conflict of TOPC Discussion Forum with GCOS Open review of the ECV requirements?
How can we make the various GCOS tables more stable and less prone for errors?
How to tame Oscar?