Overview

The pan-European research infrastructure ACTRIS (The Aerosol, Clouds and Trace Gases Research Infrastructure) is aiming to produce high-quality data and information on short-lived atmospheric constituents and on the processes leading to the variability of these constituents in natural and controlled atmospheres. (https://www.actris.eu)

As part of ACTRIS the Karlsruhe Low Cloud Exploratory Platform (KLOCX) serves as a fully mobile ground-based observation system. It is mainly aimed to investigate processes involved in the development and dissipation of low-level clouds and fog using in-situ and remote sensing instruments.

Low-level clouds and fog impact our climate system but also human life. They reflect sunlight back into space, but also trap the Earth's thermal radiation. Up until now, one of the big questions in climate research is how strong these effects actually are. For humans, low-level clouds mostly pose a severe threat for aviation, sea and road traffic due to reduced visibility and they can prolong weather conditions favorable for reduced air quality.

With KLOCX, it will be possible to efficiently bundle the instrumentation needed for process studies directed to understand low-cloud and fog formation, persistence, and dissipation. Besides providing data for such process studies, the data collected will be available as ground truth to further improve satellite-based detection schemes of low clouds and fog.

Campaigns

ACTRIS ECCINT cloud in-situ intercomparison I (2022)

KLOCX participated with its ground-based fog and aerosol spectrometer in the 1st ACTRIS ECCINT cloud in-situ intercomparison for liquid water content (LWC), at the Sonnblick Observatory, Austria. The goal of the intercomparison was to check and compare instrument performance for LWC and the impact of different setups and sampling techniques.

Setup of multiple analyzers at one of the measurement balconies. — Setup of multiple instruments at one of the measurement balconies at Sonnblick Observatory, Austria.

TeamX Observational Campaign (2024/2025)

Part of the KLOCX instrumentation was setup in the Inn Valley, Austria for the TEAMx Observation Campaign. TeamX aims at improving the understanding of exchange processes in the atmosphere over mountains. In this context, KLOCX measurements are dedicated at providing new insights into the life-cycle phases of fog and low-level clouds. The remote sensing instruments will measure until spring 2025 and will provide valuable insight into the Life-cycle phases of low-level stratiform clouds in the Inn valley.

KLOCX instrumentation setup at i-Box Kolsass measurement site, Inn valley, Austria.

Karlsruhe Low Cloud Exploratory Platform (KLOCX) participates in international research initiative TEAMx

The Karlsruhe research platform KLOCX (https://www.imk-asf.kit.edu/Projekte_4081.php) is participating with a variety of state-of-the-art measuring instruments in the international measurement campaign TEAMx (Multi-scale transport and exchange processes - programme and experiment in the atmosphere over mountains) (https://www.teamx-programme.org). The campaign, which focuses on exchange processes in the atmosphere over mountains, aims to improve our understanding of these processes and contribute to more accurate weather and climate models. Currently the first Extensive Observation Period (EOP) takes place from 20 January until 28 February 2025.

KLOCX in the TEAMx Winter Campaign

From 25 September 2024 to 9 April 2025, KLOCX will be part of the TEAMx winter campaign. The research focusses on the study of low-level stratiform clouds and fog. The main aim is to better understand the different life-cycle phases of these clouds to improve the prediction of formation and dissipation.

Innovative Measuring Instruments in Use

During the measurement campaign, KLOCX will deploy a range of specialized instruments, including:

Wind lidar – for measuring wind fields in the atmosphere
Microwave radiometer – for determining temperature and humidity profiles
Ceilometer – for detecting cloud base height
Visibility sensor – for measuring visibility and current weather conditions
Sun photometer – for analyzing aerosol particles in the atmosphere
Disdrometer – for studying precipitation characteristics

Research for More Accurate Predictions

The main objective of the measurements is to analyze the microphysical differences between the different life-cycle phases of low clouds and fog. This is crucial for improving satellite retrievals and the analysis of fog and low clouds. The data obtained will help refine forecasting models, enabling more precise weather predictions.

By participating in TEAMx, KLOCX makes an important contribution to atmospheric research and the development of meteorological models – a significant step towards more accurate weather and climate forecasts.