Ulrika Willén, researcher at the SMHI Rossby Centre, describes the usefulness of cloud radars:
"Cloud radars reveal the vertical structure of clouds and can be used to derive cloud water, crucial features for understanding the impact of clouds on weather and climate. A cloud radar data can be used to validate clouds in satellite retrievals and models."
"Basically, it works the same way as a more familiar operational radar for weather monitoring or a military radar. It sends electromagnetic signals at radio frequency and uses their returns to identify targets of interest," Leonardo Porcacchia, researcher at SMHI, explains.
The extraordinary feature of a cloud radar is that it operates at higher frequencies to detect clouds and atmospheric particles, which makes it smaller in dimensions and lighter in costs (than a rain radar). In particular, the newly deployed cloud radar monitors constantly the atmosphere and provides measurements at uniquely high vertical resolution.
In addition, the cloud radar can bring the model and observational communities together. The SMHI research department have used Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS)/Cloudnet data to evaluate climate and weather forecast models.
"Now with the new Swedish cloud radar to be part of the ACTRIS/Cloudnet network and with cloud data from satellites, we are looking forward to get more insight into cloud vertical structure, cloud phase and the impact on weather forecasts and climate modelling," says Ulrika Willén.
Deployment part of ESA-funded project
The radar deployment at Norunda represents the first phase of the ESA-funded FRM4Radar project, which aims at producing Fiducial Reference Measurements (FRM) within continental Europe to evaluate observations from the Earth Cloud Aerosol and Radiation Explorer (EarthCARE) satellite mission scheduled to launch in 2021. SMHI picked Norunda to be part of the mini-network of FRM sites that includes the University of Cologne, Germany, and the National Institute of Research and development in Optoelectronic (INOE), Romania.
The project is the outcome of an Arctic, mid latitude workshop (APVE) organised by the European Space Agency (ESA), SMHI and Canadian partners in Norrköping 2015, with the goal of identifying Space-based Earth observation validation needs. The recommendation of the organising committee, was to establish an observational ground-based network of cloud radars (Cloudnet) for validation, verification and calibration of satellite cloud data, and to add two cloud radars to Cloudnet in Sweden and Romania to fill the network gaps in northern and eastern Europe, respectively.
In summary, the newly deployed cloud radar, together with other instruments to be deployed in Norunda in the near future, offers great opportunities for novel research in air dynamics, cloud physics, precipitation, and model evaluation, and will foster collaboration within the European ACTRIS community.