ISSI Working Group on
Atmospheric Water Vapour

First Workshop of the ISSI Working Group
11 – 14 February 2008, ISSI, Bern, Switzerland


The aim of the first workshop was to obtain an overview and to get a kind of an inventory of the different techniques as used to measure water vapor from the ground throughout the whole atmosphere up to the mesopause. Almost twenty scientists participated in this first workshop and presented different measurement techniques from in situ to active and passive remote sensing methods. The presentations of the individual participants can be downloaded. Ample time was devoted to discussions.

It has been realized that the field of users of water vapor data is vast and that the outcome of the ISSI workshop can serve the Global Earth Observation System of Systems (from presentation of J.C.Lambert) and users:

In particular the outcome might serve the following aspects:

The discussion showed clearly that water vapor is the core of climate monitoring, research, weather forecast and used for validation techniques but in order to get to this core several tools are needed as illustrated in Figure 1 from K. Hocke's presentation.

It has been realized that so-called fact sheets about each technique and then in particular for every specific instrument should be established. The content of these fact sheets shall be:

Technique description

Instrument Fact Sheet

The magic circles around H2O

Figure 1: The magic circles around H2O


The first workshop on water vapor was a success bringing together scientists and experts covering a wide area of measuring techniques of water vapor over the whole atmosphere. The knowledge about the techniques certainly is of great value for the scientific community and will serve as very helpful for many aspects. Improving the quality and quantity of water vapor measurements should have a pole position in climate monitoring. In situ and remote sensing techniques have made great progress and data from satellites may permit global trend studies of water vapor. But is has also been realized that the team is lacking some members from the theory side, scientists who are competent enough to highlight the science needs in all spheres of the atmosphere. Until the next workshop that is planned in November 2008 it is planned to put together a first draft of collected material about the different measuring techniques to be published in the frame of ISSI books. The following chapters have been identified:

  1. In situ measurements
    1. Cryogenic frost point technique (H.Vömel)
    2. FLASH (A.Yushkov)
    3. MOZAIC (H.Smit)
    4. Vaisala sensors (E.Kyrö)
  2. FTIR (R.Sussman, J.Notholt, M.Schneider)
  3. LIDAR (Th. Trickl, Th. Leblanc)
  4. Microwave (G.Nedoluha, N.Kämpfer)
  5. Satellites (J.Urban)
  6. CEOS, GEOS (J.C. Lambert)
  7. Validation achieved so far and published, cross references (K.Hocke)

The second workshop will take place at ISSI, 3 – 6 November 2008