ISSI Working Group on
Atmospheric Water Vapour

Water vapour and its role in weather and climate

Water vapour in the atmosphere is the key trace gas controlling weather and climate. It also plays a central  role in atmospheric chemistry, influencing the heterogeneous chemical reactions that destroy stratospheric ozone. The effects of water vapour are large in the upper troposphere and lower stratosphere, but there are few measurements of water vapour concentrations and its long-term variation in this altitude region.

The importance of measurements on a continuous basis of water vapour has been recognized and data from a number of well validated instruments worldwide are made available to the scientific community through NDACC, the Network for the Detection of Atmospheric Composition Change.

Members of NDACC have recognized the need to carefully anaylze the different measuring and retrieval techniques for water vapour and have established a working group on water vapour that met in 2006 for the first time. With ISSI the working group has found the support to continue with an activity that has started successfully.