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Completed Actions

ES0604: Atmospheric Water Vapour in the Climate System (WaVaCS)

The Action brings together leading European scientists to address the issue of atmospheric water vapour and its impact on climate. This Action is needed to integrate research carried out in different areas, including: atmospheric monitoring, data analysis and modelling. It brings together expertise that is both unique and timely.

In order to make significant progress in the field of water vapour and climate, it is necessary to integrate knowledge acquired from research based on different methodologies. To achieve this, the Action is structured into 4 working groups which together aim to increase knowledge on observations, theory, and data assimilation in the context of water vapour and climate.

The objective is to offer to the scientific community and the broader Earth Observation community an integrative approach to understanding the processes controlling the atmospheric water vapour distribution, in particular those elements linking water vapour and climate. Beneficiaries of this Action include the meteorological services, space agencies, environmental agencies and policy makers. The specific task of this Action is to promote knowledge dissemination activities at various levels through scientific missions, thematic training schools, support toward conference participation, and special issues in world-class scientific journals.

In order to implement an interdisciplinary approach, the Action will promote and support four cross-cutting Working Groups. The first two activities aim at improving the knowledge on observation systems and processes. The third and fourth activities aim at integrating and structuring this knowledge.


R. Van Malderen was a member of the management committee and participated to several workshops and a summer school.

More information on this Action can be found on the Action's homepage, or on the Action's webpage on the COST website.


ES726: Long term changes and climatology of UV radiation over Europe

Since UV solar radiation plays an important role in many processes in the biosphere, including the influence on human organisms and may be very harmful if UV exposure exceeds "safe" limits, the knowledge of biologically effective UV radiation doses and their geographical distribution and climatology in Europe is crucial for the European population. The main objective of the Action was to advance the understanding of UV radiation distribution under various meteorological conditions in Europe in order to determine UV radiation climatology and assess UV changes over Europe.

To achieve its general objective, the Action had the following practical objectives:
1) to inventory available solar radiation data sets, including UV data, spectral and broadband, ancillary data (ozone, clouds, sunshine etc.) and available satellite data,
2) to advance the understanding of UV reconstruction models for the calculations of UV climatology and assessment of UV changes,
3) to advance the understanding of biological UV radiation climatology and changes in Europe,
4) to advance the understanding of UV influence on ecosystem, both on the basis of climatology and changes of selected effective UV radiation doses in Europe,
5) to use the advanced knowledge under the points above, in order to elaborate a comprehensive analysis and information basis, addressed to beneficiaries,
Additionally, special attention had to be paid to application of QC/QA procedures for the UV measurements with broadband instruments. To get homogeneity of the broadband data, an additional objective is:
6) to create an European reference group of broadband radiometers.

To achieve these objectives, four working groups were established:
WG1 - Data collection
WG2 - UV modelling
WG3 – Requirements for biological UV effects
WG4 - Quality Control

H. De Backer was the leader of WG1 and A. Cheymol was a member of WG2. They were both also part of the management committee.

More information on this Action can be found on the Action's homepage, or on the Action's webpage on the COST website.


ES1206: Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate (GNSS4SWEC)

Global Navigation Satellite Systems (GNSS) have revolutionised positioning, navigation, and timing, becoming a common part of our everyday life. Aside from these well-known civilian and commercial applications, GNSS is now an established atmospheric observing system which can accurately sense water vapour, the most abundant greenhouse gas, accounting for 60-70% of atmospheric warming. Severe weather forecasting is challenging, in part due to the high temporal and spatial variation of atmospheric water vapour. Water vapour is under-sampled in the current meteorological and climate observing systems, obtaining and exploiting more high-quality humidity observations is essential to weather forecasting and climate monitoring.

This Action addresses new and improved capabilities from concurrent developments in both the GNSS and meteorological communities. For the first time, the synergy of the three GNSS systems (GPS, GLONASS and Galileo) will be used to develop new, advanced tropospheric products, exploiting the full potential of multi-GNSS water vapour estimates on a wide range of temporal and spatial scales, from real-time monitoring and forecasting of severe weather, to climate research.

In addition the Action will promote the use of meteorological data in GNSS positioning, navigation, and timing services, and it will stimulate knowledge transfer and data sharing throughout Europe.

Three different working groups have been set up to reach these goals:

  • Advanced GNSS processing techniques (WG1)
  • Use of GNSS tropospheric products for high-resolution, rapid-update NWP and severe weather forecasting (WG2)
  • Use of GNSS tropospheric products for climate monitoring (WG3)

The interest of our group clearly lies in the topics discussed in WG3. In particular, R. Van Malderen has been assigned as the leader of the work package WP3.3 "Set up a high quality GNSS Integrated Water Vapour (IWV) dataset" with objectives: (1) to evaluate the uncertainty of GNSS IWV in a comprehensive way and (2) to set up a GNSS IWV dataset suitable for climate applications. R. Van Malderen is also a substitute member of the management committee.

The Action's homepage can be found here, and more information is also available from the Action's webpage on the COST website.


ES1207: A European Brewer Network (EUBREWNET)

This action coordinates Brewer spectrophotometer measurements of ozone, spectral UV and aerosol optical depth (AOD) in the UV within Europe. It unites the ozone, UV and AOD communities through a formally managed European Brewer Network capable of delivering a consistent, spatially homogeneous European data resource, significant for the World Meteorological Organisation (WMO), the World Ozone and UV data centre (WOUDC), the International Ozone Commission (IO3C), the Intergovernmental Panel on Climate Change (IPCC), Global Monitoring for Environment and Security (GMES) and the ozone trend assessment panels.

Around 50 Brewer spectrophotometers are deployed in Europe, independently funded by national agencies, each duplicating effort to achieve seperately best practice and accuracy. This COST action is the ideal mechanism to remove this disparity, to establish knowledge exchange and training and to open up a route to links with international agencies and other networks globally.

Four different working groups will work together to establish a coherent European Brewer spectrophotometer network:

  • WG 1: Instrument characterisation and calibration
  • WG 2: Algorithm development
  • WG 3: Network governance and data management
  • WG 4: Users, public outreach and applications

Our team was mostly involved with the activities of WG 3. More specifically, V. De Bock was the leader of WG 3 and a member of the Management Committee. A. Mangold was also a member of the Management Committee and R. Van Malderen was a substitute member.

The Action's homepage can be found here and more information is also available from the Action's webpage on the COST website.


ES1303: Towards operational ground based profiling with ceilometers, doppler lidars and microwave radiometers for improving weather forecasts (TOPROF)

The new generation of high-resolution (1km) weather forecast models now operational over Europe promises to revolutionise predictions of severe weather and poor air quality. To realise this promise, a dense observing network is required, focusing especially on the lowest few km of the atmosphere, so that forecast models have the most realistic state of the atmosphere for initialisation, continuous assimilation and verification. This Action will focus on developing three instruments available throughout Europe:

  • Several hundreds of ceilometers providing backscatter profiles of aerosol and cloud properties with 30m vertical resolution every minute,
  • more than 20 Doppler lidars, a new technology, providing vertical and horizontal winds in the lower atmosphere with a resolution of 30m every 5 minutes, and
  • about 30 microwave profilers giving profiles of temperature and humidity in the lowest few km every 10 minutes.


The aim of the Action is to co-ordinate the operation of these instruments across Europe, so that they can be networked and provide quality controlled and calibrated observations of winds, temperature, humidity, clouds and aerosols in the lowest few km of the atmosphere to National Meteorological and Hydrology Services in near real time. There are four Working Groups in this Action. The first three Working Groups deal with the three instruments: ceilometers (WG1), Doppler lidars (WG2) and microwave radiometers (WG3). The fourth Working Group deals with the use the new data in Numerical Weather Prediction (WG4).

Our team is mostly involved with the activities of WG 1. More specifically, Q. Laffineur has been assigned as the leader of the Task 6 of the WG1 "Use of Automatic LIDAR ceilometers for fog diagnostic and nowcasting" The main objective of the task 6 is to devellop a forward stepwise screening algorithm to help prediction of radiation fog formation and transitions between stratus and fog based on the hydroscopic growth function of aerosol scattering coefficient coupled with the standard surface weather observations. Q. Laffineur is also a member of the Management Committee of TOPROF.

The Action's homepage can be found here, and more information is also available from the Action's webpage on the COST website.