Cloud processes are important fields of scientific research because of their role in meteorology, climate change at the global scale, and climate variability at the regional scale. Additionally, clouds and cloud-related weather conditions can have significant impact on human activities (e.g. water resources, transport, renewable energies). Clouds as a major component of meteorology and climate, cannot be studied independently from boundary layer processes, atmospheric dynamics, including radiative, microphysical, thermodynamical, dynamical and turbulent processes.
Hence cloud studies require knowledge of essential variables :
Cloud water content
Cloud droplet radius
Surface energy budget
Scientific research questions and societal applications linked to cloud and boundary-layer processes are numerous. Detailed and high-quality observations of cloud properties, atmospheric thermodynamic and dynamic variables are essential for the following applications:
- Studies of cloud microphysical, radiative, dynamic and thermodynamic processes, including cloud-aerosol interactions
- Cal/Val activities to support satellite-based global-scale observations
- Numerical weather prediction, severe weather (model verification, data assimilation, development of new parametrizations)
- Climate and climate change studies and modelling (climate variability studies, model verification)
- Air quality and green-house gas modelling (boundary layer observation and prediction)
- Prediction of weather conditions (fog, clouds, precipitation) that impact human activities (e.g. airport traffic planning, renewable energy production)
- Improve the quality of operational data provision for applied services (e.g. Copernicus program),
- Support Instrument / Measurement industry (standard procedures, new technology)
Network-wide consistent parameters
Within ACTRIS, the primary objective is to obtain the vertical cloud structure within an atmospheric column, utilising the temporal dimension to yield the equivalent of a two-dimensional slice through the three-dimensional atmosphere. The resolution required to capture such highly variable entities necessitates the use of active remote sensing in the form Doppler millimetre-band radars, automatic low power lidars, microwave radiometers, Doppler lidars and Disdrometers.
These five instruments are necessary to derive vertical profiles of cloud macrophysical and microphysical properties and related atmospheric variables based on several synergetic algorithms. Each required instrument must be calibrated before the relevant cloud parameters can be derived. In a network all instruments should be calibrated in a consistent and traceable manner so that retrieved parameters can be derived on a comparable scale and with a known uncertainty. Common algorithms to be applied to all network measurements are also a must to generate network-wide consistent geophysical parameters.
The Centre for Cloud Remote Sensing offers support to ACTRIS Cloud Remote Sensing National Facilities network and external users. Critical issues relevant for cloud observations are instrument calibrations, continuous data quality monitoring as well as harmonized data processing. These points must be addressed to derive network-wide consistent atmospheric quantities, such as cloud classification, liquid water content profiles as well as temperature and humidity profiles.
CCRES's support relies on scientific state of the art research and techniques from publications.