CHOPIN Campaign

Unravelling aerosol-cloud interactions through a synergy of in-situ observations, remote sensing and modeling

Hosted by NCSR Demokritos at the Helmos Hellenic Atmospheric Aerosol & Climate Change Station (a PANACEA, ACTRIS, GAW facility) and the FORTH/EPFL at the Kalavryta Ski Center.

Observation periods:

1 October 2024 – 30 November 2024 (all sites, remote sensing platforms, UAVs and Helikite)

1 December 2024 – 15 January 2025 (all sites, radar remote sensing platforms)

16 January 2024 – March 31 2025 (all sites, only in-situ sampling)

Goals

The Cleancloud Helmos OrograPhic sIte experimeNt (CHOPIN) campaign is one of the main observational activities of the CleanCloud project funded by the EC Horizon Europe Call “Improved knowledge in cloud-aerosol interaction” (HORIZON-CL5-2023-D1-01-04). CHOPIN is a Cluster 1 activity of CleanCloud and involves more than 10 partner institutions from Europe.

The main goal of the CHOPIN Campaign is to gain a better understanding of the processes involved in the formation and evolution of mixed-phase clouds and to improve & develop algorithms used for ground-based and spaceborne remote sensing of aerosols, clouds and their interactions. This is accomplished using an extensive array of in situ and remote sensing instrumentation located at a unique and optimal high-altitude location at Mt.Helmos for targeted studies of aerosol-cloud interactions.

The Greek mountain top is considered ideal for cloud and climate research. It sits at the crossroads of many different air streams and is in a “climate hotspot”, which like the Arctic, is changing much faster compared to the global average. This allows particles of almost any kind to interact with clouds, from wildfire smoke to pollution and highly processed particles from continental Europe, to sea salt from the Mediterranean and dust from Sahara, to pollen, bacteria and fungal spores transported from thousands of kilometres away or the forest below.

The CHOPIN researchers, with the extensive and detailed datasets collected, are expect to be able to directly observe how cloud properties change with the particles in the air – representative of a post-fossil future – and by that contribute to the understanding of future climate impacts of aerosol-cloud interactions. The dataset collected during CHOPIN will be used to develop parameterizations of aerosols, clouds and their interactions, and be used in the improved CleanCloud models and simulations.

CHOPIN also benefits from the synergy of other projects,including the Swiss National Science Foundation LipicAir and AAIDI projects and the ERC project PyroTRACH. Observations from CHOPIN will also be used to evaluate EarthCare aerosol and cloud retrievals, and will be used synergystically by the sister projects CERTAINTY and AirSENSE, funded by ERCEA and ESA.

Coordinated observations between CHOPIN and the high-altitude station at Monte Cimone, Italy during the October/November, 2024 intensive period is also being carried out. This will allow for understanding of the similarities/differences in the airmasses sampled by each site, as well as the study of the evolution of aerosol and their properties during periods where airmasses transport from one site to the other.

Campaign partners

CHOPIN locations and site characteristics

The Helmos Hellenic Atmospheric Aerosol & Climate Change station (or simply Helmos Mt) is operated by the National Center for Scientific research “Demokritos” (NCSR-Demokritos). The Aroania (or Helmos) mountainous region is a unique and optimal location for targeted studies of aerosol-cloud interactions. Aroania, situated in the Achaea Prefecture of Greece and is the 3rd highest mountain in the Peloponnese (summit at 2340 m amsl.) and hosts a NCSR-Demokritos monitoring station situated at 2314 m amsl. A unique characteristic of the Helmos High Altitude Monitoring Station (2314 m, 42°N 05′ 30”, 34°E 14′ 25”) is that it is a typical free tropospheric background site with very low influence from the surface polluted layers (Collaud Coen et al., ACP, 2018) and lies in a cross-road of different air masses (continental, Saharan, long-range biomass burning, volcanic, etc.). The site is about 8 km distance from the Kalavryta Ski Center, and another 15 km away from the village of Kalavryta.

CHOPIN sampling site locations (left: HAC2 and Ski Center; right: locations of sites at Kalavryta Ski Center)

Observations during CHOPIN take place at 6 sites: 5 located at the Kalavryta Ski Center where remote sensing (radar, wind lidar, sun photometery, lidars), UAVs, the Helikite platform, and in-situ observations at the “cabin low altitude station” are performed. Observations at the (HAC)2 are also carried out at the 6th site throughout the observation period.

Depending on the time of day and year, the (HAC)2 may reside in the free troposphere, boundary layer or at the interface between the two. Because of this, the airmasses sampled between the sites may be quite different – or linked. Free tropospheric air may contain influences of dust intrusions and biomass burning, while the boundary layer may contain bioaerosols emitted from the forest below. The vertical profiling instruments and observations at the (HAC)2 provide the necessary insights on the presence of PBL aerosol or not at (HAC)2 and the low altitude station.

More information about the airmass characteristics, statistics and aerosol sources can be found in the studies of Zografou et al. (2024), Foskinis et al. (2024a), Foskinis et al., (2024b) and Gao et al. (2024). The synergy between the remote and in-situ observations and modeling to unravel cloud processes and extreme events at the site can be found in Georgakaki et al., (2024).

A talk summarizing all the above, the CHOPIN campaign and its predecessor CALISHTO can be found on the CleanCloud video Channel (duration: 1 hour).

Instruments

Models (forecasts and later analysis)

Data quicklooks

Sponsors and projects

CHOPIN moments and its amazing team

Videos

News