GATNDOR 6 October 2011 Conference Call Notes

GATNDOR held a conference call on 23 May 2011, to discuss progress on scientific topics currently under investigation.
The summary notes of the call are pasted below.

GATNDOR call notes

Date: Thursday, October 6, 2011

Time: 4:00 pm, Europe Summer Time (Berlin, GMT+02:00)

Participant:
Fabio, Alessandro, John, June, Peter, Dave, Dian

1. Note-taker volunteer

Peter volunteered. Notes here follow the meeting agenda.

2. Review of work progress

Collocation issue.

Alessandro – yesterday,
sent a pdf document about uncertainty of dislocated measurements. Idea is to assess the uncertainty in the distribution of dislocated measurements. Its based on a spatio-temporal model for each measurement which then permits understanding of the distribution  of differences.

Question:
Distinguishing between environmental component and measurement biases? This is the difficult component to model / understand.

Dian – Nice to  have formalism of a framework.

Next steps?
Write a section in Dian’s poster for WCRP – tomorrow.  Needs to be submitted to the printers.  Need to then consider possibility that measurement errors depend upon multiple factors related to environmental  conditions, etc.  This complicates the  assumptions. Again, distinguish measurement and environmental components. Need of realistic data.  Data from Potenza already available. Will continue to develop ideas.

Deadline is ICM4 to present some update. Would be good to get more in depth analysis by then.

Management of change

June – Not much to update. Focus is to contribute in this area to the GRUAN manual. Lindenberg data there is an issue with accessing directly their GPS-PW data. This has helped to show the validation of RS-92 at Lindenberg. Also highlights subtle issues such as sensor boom cover changes in 2005 and 2008. Shows how corrections change the diurnal cycle and confirm the correct phase. Tateno data already available but not yet analyzed this. Several manuscript plans were discussed but are in early phases.

Dave: Is the diurnal issue down to solar corrections? Yes, to first order.

Quantifying the value of complementary observations

Fabio – Working
with Belay mainly on lidar, MWR, raobs and GPS. Will compare a few GRUAN sites (Beltsville, ARM, Potenza, Payerne). Will look at the influence of different
instruments, and how to manage different instruments. A scheme for minimizing uncertainty. Total error and conditional error for profile estimation.  Team members have differing degree of engagement.

3. GRUAN TT on Scheduling Protocol

Dave – Not a lot  of activity. Manuscript to JGR on work highlighted at two ICMs ago for WV trend detection. Main conclusion is in Figure 3 of the manuscript. Uncertainty is due to very small natural atmospheric variability. Key is increasing number of measurements in this region rather than measurement precision.

June: This is specifically for Upper-Troposphere water vapor?

Dave: Lower stratosphere is now the work and here the measurement uncertainty dominates over sampling frequency. So there is a trade off.

June: Does this apply also to Integrated Water Vapor (IWV)?

Dave: Not considered yet, will discuss with collaborators.

June: we have much more frequent GNSS IWV results is this long enough to assess trends.

Dian: Relies on  climate model representation in the UTLS. Do we need to caveat accordingly?

Dave: Indeed, perhaps need to consider a broader range of potential future trends to cover all possibilities.

4. Connection between the GATNDOR and GRUAN TT5/NPROVS for Site Atmospheric State Best Estimate (SASBE)

Fabio received a  request from Tony regarding collaboration with task team on ancillary measurements on definition of site atmospheric state best estimate for
validation of satellite measurements. Fabio will provide some info in support of this effort. Update on progress regarding collocation and redundancy.

John: Work with Dave Tobin is being discussed. ITS9 conference talk. Will meet with Dave Tobin next week. How the error varies with different instrument mixes will be discussed. Test cases will be put together.

Fabio: What is the status currently?

John: Plan is to use the algorithm that Dave Tobin used but use different instrument mixes at real GRUAN sites.

Dave: Because comparisons were in radiance space did not use the corrected radiosondes using the Miloshevich corrections. Likely the original and not corrected will be used.

Dian: Is the work useful in considering expanding GRUAN / scheduling? Where data will be needed. Can this feed into the expansion workshop activity?

John: Likely to be useful regarding minimum requirements for retrieval products from satellites. Instrumentation and uncertainty characterization.

5. WCRP conference

Peter – No oral presentation due to abstract consideration mix up. 12 posters to my knowledge. There will be a meeting the Tuesday evening but Greg is having issues confirming the room.

Questions were  on timing of evening meeting (between the end of oral sessions and nominal supper) and whether posters together (yes)

6. AOB

No other business to discuss

7. Next call

The call will be in mid-January 2012, not week of AMS / CBS Expert Team meeting (January, 23)

ADJOURN

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