WG 1 Workshop on Water Vapor Measurements with Lidar: Calibration and Validation, July 13, 2004

• Goal of the workshop
• List of participants
• Workshop minutes

Meeting place and time

Goal of the workshop

Some efforts have been deployed to develop the water vapor using Raman lidar. This technique is very promising to probe the upper troposphere and the tropopause region. This type of instrument will allow to insure a monitoring of the upper troposphere, validate the coming satellite experiments, and to perform specific case studies on regional scales in UTLS. However this new technique suffers from strong calibration requirements.

Some works have already be done to collect information, however at this step a formal meeting is required. A workshop have been decided to be held during the ILRC conference. The goal of this workshop is to bring the main teams involved on water vapor Raman lidars and to discuss the main issues. It has been decided to use the opportunity of the next Aura statellite as a geographical transfer to compare the measurements of the different existing or emerging lidars. The meeting will not include formal presentation from the participants as most of the warok will be presented at the ILRC conference during the previous days. During this meeting 3 topics will be discussed:

1. format issue
2. validation issue using Aura
3. validation strategy including mobile systems
4. Update status and financial supports

At the end of the meeting a report about our strategic approach will be available for individual national agency.

List of participants

Geraint Vaughan (UK)
Valentin Simeonov (Switzerland)
Paola d'Aulerio (Italy)
Arnoud Apituley (Neederland)
Franz Immler (Germany)
Ina Mattis (Germany)
Christoph Ritter (Germany)
Laurent Robert (France)
Philippe Keckhut (France)
Gelsomina Pappalardo (Italy)
Fernando Congeduti (Italy)
Vincenzo Rizzi (Italy)
Rene udHoff (Nederland)
Thierry Lablanc (US)
Tom McGee (US)
David Whiteman (US)
Richard Ferrare (US)
Tomohiro Nagai (Japan)
LeeChooHee (South Korea)

Workshop minutes

The workshop was hosted by Gelsomina Pappalardo, chaired by Philippe Keckhut.

Philippe Keckhut has presented the framework of the meeting, referring to the NDSC and COST and about the need for a collective effort on the water vapor. Philippe Keckhut has also reported about review work about the lidar status and capabilities that participants have already send to him (11 instruments). It appears that most of the systems are still under development. This is mainly true regarding the calibration methodology that uses exclusively collocated radiosondes. The different stages of maturity render difficult a collective work at the present stage based on data exchange.

The Aura validation was then discussed. It has been proposed to use it as a geographical transfer for comparing all the lidar to the same reference. Aura has just being launched with two experiments measuring water vapor in the upper troposphere (MLS, HIRDLS) and one measuring the total column (TES). There was a debate about the potential conclusions that can be draw from Aura-Lidar comparisons. Several participants argued about the antagonist objectives of validating Aura and using a new experiment as Aura as a geographical transfer reference. As there are 4 mobile instruments, it was decided that the same approach, than NDSC has used in the past on other types of instruments, will be performed. Mobile systems will be compared during a campaign on a site where other instruments and measurements are available. Then those instruments can be used for comparisons with instruments that can not be moved. In the same time, calibration methodology can be compared and tested. The site as well as the funding for such exercises, need to be found.

After discussions, it appears valuable to participate collectively at the Aura validation. The Aura validation will be used as a common task. A proposal will be send to NASA in August on the basis of no-cost because all the participants can not claim for support at the same agencies. So this will be done on an individual basis but can refers to this collective proposal.

Finally we have discussed the format issue. It needs to be performed in conjunction with the NDSC efforts to get a uniform format and the transfer from AMES to HDF format. However it has been decided to work on the information that is required to appear on the water vapor data files. A first proposal will be done by Philippe Keckhut on September.