Die Bedeutung von All-Sky-Imagern für die Beobachtung der Wolkendecke 🇬🇧

During the ACTRIS Science Conference 2024, Reuniwatt had the opportunity to showcase the unique features their Sky InSight™ offers in terms of cloud observation, including cloud type classification, cloud optical depth, cloud-base height and improved circumsolar detection.

Improving cloud observation via sky cameras

Observing cloud formations from the ground using sky imagers offers several benefits, both for scientific research and practical applications. These advantages span across meteorology, climate science, environmental monitoring, and even aviation safety.

The ACTRIS Science Conference in Rennes provided Reuniwatt with the unique opportunity to install a Sky InSight™ within the Couvent des Jacobins and produce a live demo of its cloud observation performance. For three days, under both rainy and sunny conditions, our sky cam produced a thermal map of the sky every 30 seconds.

A decade after the first version of its Sky InSight™, Reuniwatt has shown that using infrared enables an unprecedented accuracy for day and night cloud detection. Unlike visible light sensors, which cannot operate in the dark, infrared sensors detect the thermal radiation emitted by clouds and the Earth’s surface. This capability is crucial for the continuous monitoring of cloud dynamics performed at observatories, ensuring that data is collected around the clock. 24/7 observations are essential for understanding the full lifecycle of clouds, from formation to dissipation, and for capturing rapid changes that may occur overnight. Different users worldwide, from atmospheric sciences to defence and space applications rely on our instrument’s measurements.

Another significant advantage of infrared imaging is its ability to penetrate cloud cover and reveal information about the structure and properties of clouds. Infrared radiation can pass through thin clouds and haze, providing clearer images of the underlying and embedded cloud layers. This is particularly useful in studying complex cloud systems, such as those involving multiple layers of clouds at different altitudes. By analysing infrared images, researchers can gain insights into the vertical distribution of cloud layers, their thickness, and their temperature profiles. The Sky InSight™ calculates the Cloud Optical Depth (COD) by retrieving from measured cloud infrared radiation and ground temperature, estimating liquid water content and effective water droplet sizes within clouds. The clear-sky water vapour contribution to cloud infrared radiation is then removed, and a model is optimised empirically using an instrument during the calibration period to deliver the COD.

Going further in cloud cover monitoring

This event also was an opportunity to present our latest publication from Ben Slama, M., Liandrat, O., Balmes, K., Hodges, G., Comparison of cloud cover measurement techniques, ACTRIS Science Conference 2024, 13-16 May 2024, Rennes, France, in cooperation with NOAA: National Oceanic & Atmospheric Administration.  Cloud cover observations are crucial in climate research, where they contribute to understanding the role of clouds in the Earth’s energy balance. Clouds have a complex influence on the climate, as they can both cool the planet by reflecting solar radiation and warm it by trapping infrared radiation. By measuring the infrared radiation emitted by clouds, scientists can study their radiative properties and quantify their impact on the Earth’s energy budget. This information is vital for refining climate models and improving predictions of future climate change scenarios.

Moreover, infrared imaging is instrumental in identifying and analysing cloud microphysical properties, such as particle size and phase (liquid or ice). Different types of cloud particles emit infrared radiation differently, allowing researchers to infer their characteristics based on the emitted wavelengths. Understanding these microphysical properties is essential for studying cloud formation processes, precipitation mechanisms, and the interactions between clouds and aerosols. As infrared technology continues to advance, its applications in cloud studies will likely expand, offering even deeper insights into the complexities of cloud formation and behaviour.

Understanding cloud dynamics is crucial as they play a significant role in the Earth’s weather patterns and climate systems, reasons for which the Sky InSight™ has proved being a reliable tool for ACTRIS’ atmospheric research works. Reuniwatt is proud to participate in the infrared imaging sector and is dedicated to investing resources in R&D to deliver more accurate sky observations.