GATNDOR Conference Call Notes – 12 January 2012

Participants: Fabio Madonna, Tom Gardiner, Alessandro Fasso, June Wang, Dave Whiteman, Greg Bodeker, Peter Thorne, Dian Seidel

1. Note-taker volunteer

Dian volunteered.

2. Progress report from GATNDOR topic and results for ICM-4 (Alessandro, Fabio, June)

Topic 1 – Tool box for characterizing uncertainties

Alessandro summarized statistical models to characterize radiosonde errors in temperature profiles in a four-page draft report which he has shared with GATNDOR.  He intends to begin data analysis of data in January 2012 based on these models.  There will be an upcoming seminar by Fabio when he visits Alessandro at Bergamo in January to get this effort started.  The initial work will focus on 2-D modeling. Alessandro is hoping to have preliminary results on spatial-temporal uncertainty, at fixed-pressure levels, for consideration at ICM-4.   Some discussion followed of funding, both to support Alessandro’s travel to ICM-4 and to support extension of this work to 3-D (including vertical dimension).

Topic 2 – Management of change

Fabio reminded the group of the goals for ICM-4 – quantitative analysis and a manuscript.  June reported discussions with Greg Bodeker on development of guidelines for management of change in the GRUAN manual.  In February June will be analyzing Tateno dual-sonde sampling and overlap.  She raised the question of what the requirement is for accuracy and precision; Greg responded that the GRUAN requirements still stand.  Peter mentioned the GCOS-112 long-term stability requirement and suggested that the analysis address how to achieve those requirements.  June is considering raising the issue of a paper on management of change at ICM-4.  Some discussion ensued of the value of a paper in a technical journal vs a more general paper in, e.g., the Bulletin of the AMS.  Dian suggested that GATNDOR should strive for publications in technical journals, both to document GATNDOR work in the peer-reviewed literature and to set an example for the wider GRUAN community; Fabio agreed.

Topic 3 – Complementary observations

Fabio summarized the status of this effort. The goal is to develop optimal observation strategies and equipment lists for GRUAN Phases I and II, and a related manuscript.  He is working on two aspects, using singular value decomposition of redundant measurements: (1) analysis of redundant measurements of the same variable by different instruments to determine the added value of redundancy, and (2) how to combine such measurement to reduce overall uncertainty.  The overall goal is to determine optimal combinations of measurements.  This is in collaboration with Belay Demoz and Nico Cimini using data from Beltsville and Potenza.  Fabio intends to focus on this in February after his visit with Alessandro. Tom raised a question about the connection to the scheduling of measurements to anchor satellite observations.

3. TT3 progress report (Dave, Tom)

Tom reported that the team is working with Greg’s draft material on scheduling, to fill in gaps in the existing draft. Members of TT3 are taking responsibility for parts of this.  The plan is to have a revised version for ICM-4.  Dave reported that his analysis of upper-tropospheric water vapor trends in models suggested a few soundings per week could capture trends.  Extending this work to lower stratospheric water vapor, using Boulder observations and Microwave Limb Sounder observations suggests similar frequency of observation as had been recommended for the upper troposphere.  Tom mentioned the trade-offs between accuracy and precision vis-à-vis sampling frequency.    Dave raised the issue of using models as a basis for analysis of possible trends, and Dian responded that reliance on modeled trends might be overly limiting and could be misleading, so she suggested bracketing results using a range of trend assumptions.

4. ICM-4 agenda (GATNDOR contribution and side meeting(?)) (all)

Fabio noted the agenda includes time for presentation and discussion of GATNDOR results.  He questioned the structure of the agenda, with parallel sessions.  Peter responded that this approach was devised to accommodate all the topics requiring discussion and suggested that smaller parallel discussions encourage more participation.  Fabio asked about side meetings, and Peter responded that there was time for side meetings.  June also expressed concern about parallel sessions.  Greg proposed polling the working group to shorten parallel sessions to allow longer plenary session. Fabio asked if GATNDOR wanted to have a side meeting in the evening or lunch time, given that there is no dedicated Task Team or GATNDOR meeting time.  The group decided to meet, perhaps Wednesday lunchtime, at ICM-4.

5. AOB

Tom raised the issue of the upcoming ITS9 (International Temperature Symposium) in California, where there will be a GRUAN session.  Peter Thorne, Tom Gardiner, Franz Immler, and John Dykema are scheduled to give presentations.  Tom asked for information about GATNDOR to summarize for the science, and participants agreed to provide it.

6. Next telecon (mid-May 2012?)

No specific date set, but we will shoot for mid-May.

Fabio thanked the group for their participation and looked forward to seeing most at ICM-4 in Tokyo in March.

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