Action period: 22/10/2013 - 21/10/2017

The main objective of the Action was to co-ordinate the operation of the many ceilometers (WG1),Doppler lidars (WG2) and microwave radiometers (WG3) installed across Europe, so they can be networked and provide quality controlled observations (WG4) to National Meteorological and Hydrological Services (NMHSs) in near real time.TOPROF has successfully implemented procedures so that observations from three previously under-exploited instruments are now suitable for use by European NMHSs to validate their new generation of high resolution numerical weather prediction (NWP) models. Ultimately the aim was to assimilate the data into the NWP model to improve forecasts of hazardous weather. TOPROF has developed the algorithms to convert the new observations into variables used in the NWP models and tested routines to ensure that the data are calibrated, in a standard format, and quality controlled.

• Automatic Lidar Ceilometers (ALC) measure aerosol and cloud backscatter profiles. The WG1 has developed the routines for identifying aerosols, volcanic ash, fog, cloud phase, depth and density from the ALC profiles. Volcanic dust and fog can cause major transport disruption. On-going trials of ALCs fog forecasting at Paris, Munich and Vienna airports are organised by WG1.
• Doppler Wind Lidars (DWL) sense the movement of aerosol particles and so measure wind and turbulence. The WG2 has developed DWL algorithms for characterising boundary layer winds, low level jets, turbulence, wind gustiness, and distorted airflow around isolated islands.
• Microwave radiometers (MWR) provide temperature and humidity profiles together with column integrated liquid cloud water. Two TOPROF measurement campaigns allowed WG3 to draft and distribute recommendations for common calibration and uncertainty characterization. Common data exchange formats were defined and implemented. A fast forward model and a one-dimensional variational retrieval code were developed to allow data assimilation into NWP.
• WG4 has investigated the impact of these new observations on improving weather forecast. Preliminary studies have been made at ECMWF of assimilating ALC data on smoke from Canadian forest fires. Ananalysis of MWR observations has shown a potential impact in improving the forecasts of heavy rainfall events in the Mediterranean.

Our team was mostly involved with the activities of WG 1. More specifically, in the developement of a forward stepwise screening algorithm (PARAFOG) to help prediction of radiation fog formation at airports. Our team was also involved in the monitoring of smoke clouds by the ALC observations. Q. Laffineur was a 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.

Action period: 17/05/2013 - 16/05/2017

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 addressed 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) was 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 promoted 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 team clearly was 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 was 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.

Action period: 29/04/2013 - 30/07/2017

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.