The CIAO Atmospheric Observatory (CNR-IMAA Atmospheric Observatory), active since 2000, hosts a set of remote sensing instruments that provide important climatological observations of optical, microphysical, and geometrical properties of aerosols and clouds. 
CIAO is the largest permanent observation site in the Mediterranean basin and one of the first sites in Europe for atmospheric measurements. 

Scientific Objectives: 
The main scientific objective of the observatory is to enhance the understanding of atmospheric processes and their role in meteorological phenomena, climate change, and air quality. Given the global coverage and relevance of the studied processes, key aspects of the activities and approaches adopted include the development of internationally recognized Standard Operating Procedures, open data policy, and full sharing of methodologies and know-how. 

Six main objectives are identified: 

• Advancing the knowledge of interactions between different atmospheric constituents and parameters through synergistic approaches based on multi-sensor and multi-platform observations. 
• Improving the quality of observations through the development of methodologies and procedures for measuring atmospheric variables and for the analysis, quality assurance, and quality check of provided data. 
• Advancing the understanding of processes and interactions involving different atmospheric constituents and parameters (aerosols, clouds, trace gases, humidity, temperature, and precipitation) through synergistic approaches based on multi-platform remote sensing and in situ measurements of relevant atmospheric variables. 
• Expanding the sharing of knowledge in the atmospheric domain through the development and implementation of open data and FAIR data management policies within research infrastructures. 
• Promoting knowledge in the atmospheric domain through the development and implementation of policies for access to European research infrastructures. 

Research activities at the CIAO observatory are conducted in collaboration with major ground-based observation networks (ACTRIS, ICOS, EARLINET, CloudNet, AERONET, NDACC, GRUAN, GALION, BSRN), with the main objective of providing long-term observational data relevant to climate and air quality research, in support of satellite missions (NASA, ESA, JAXA) and in collaboration with the modeling community (ECMWF, AEROCOM, etc.). 
The data quality also adheres to the protocols developed within the international networks where instrumentation is operational.