Remedy 1: Synergy between water vapour Raman lidar and other measurement techniques.

Primary gap remedy type: 
Secondary gap remedy type: 
Proposed remedy description: 

The synergy of water vapour Raman lidar with other measurement techniques, like GPS/GNSS, optical and microwave radiometry, etc., provides complementary information on the water vapour structure to constrain, extend or simply improve the quality of the information provided by lidar. In particular, synergy with passive microwave radiometers provides an robust solution to obtaining a low resolution profile of atmospheric water vapour during daytime also above the atmospheric altitude covered by lidar enabling the characterization of the entire atmospheric column: This could partially address this gap but this synergetic solution requires the development of new and more accurate algorithms to fully exploit the potential of the combined datasets. It also requires the co-location of these synergistic measurement techniques in close enough geographical proximity to be usable in this manner.


Continuous measurements of water vapour observations with high spatial (vertical) and temporal resolution are needed to achieve a comprehensive understanding of the role of water vapour on climate at regional and global scales as well as to estimate its impact on OLR = outgoing long- wave radiation (OLR) at top of atmosphere. The availability of water vapour profiles in both cloud and clear sky conditions would largely enhance several activities related to the study of climate, to satellite retrievals, and radiative transfer modelling. Furthermore, the synergetic approach to improve water vapour measurement continuity is at present the only chance to improve daytime water vapour profiling capabilities.

Measurable outcome of success: 

Success of any kind of synergetic products or joint retrieval performed using Raman lidar and microwave radiometry (or other measurement techniques) shall be assessed by using the data in the input data stream of the mesoscale models or by validating the water vapour model output profiles. Alternatively, a comparison with radiosounding profiles from Reference networks (i.e. GRUAN) can represent another good way to assess the added values of this higher-level products though in this case the difference in the representativeness of the two different products (lidar+other vs radiosonde) must be quantified and taken in account.

Expected viability for the outcome of success: 
  • Medium
  • High
Scale of work: 
  • Individually
  • Single institution
Time bound to remedy: 
  • Less than 5 years
Indicative cost estimate (investment): 
  • Low cost (< 1 million)
Indicative cost estimate (exploitation): 
  • No
Potential actors: 
  • Academia, individual research institutes
  • SMEs/industry
  • National measurement institutes