ACcloud

The AIDA Calibration Centre for Cloud Physics (ACcloud) uses the 84.5 m³ volume aluminium aerosol and cloud simulation chamber AIDA for calibration of hygrometers and ice nucleating particle (INP) instruments. The AIDA chamber can be operated at variable pressure (0.01 to 1000 hPa), temperature (+50°C to -90°C), and humidity conditions including supersaturations with respect to ice and liquid water. Its capabilities to simulate upper tropospheric/lower stratospheric conditions and to generate supersaturations and clouds in a large volume are unique in Europe. The AIDA facility is equipped with an extensive suite of state of the art and reference instruments, both commercial and custom built. 
Hygrometers can be mounted inside the AIDA chamber for calibration at both cloud-free and cloudy conditions or sample from the AIDA chamber for calibration in a wide range of water partial pressures. Dense clouds can be used as reference point with a relative humidity of close to 100%. The INP instrument calibration is offered for reference aerosols with known INP concentration determined by well-documented and validated series of AIDA cloud expansion experiments. During the INP calibration runs, the AIDA chamber will also serve as a stable and well-characterized aerosol reservoir.

The ACcloud offers calibration of atmospheric hygrometers and ice nucleating particle (INP) instruments.  

Calibration of atmospheric hygrometers and ice nucleating particle (INP) instruments using the AIDA have typically a duration of 5 days with 1-2 days for set up and 3-4  days for the calibration at different AIDA conditions.

Research groups from atmospheric science community make up the vast majority of the users. A few innovative companies use the AIDA chamber for instrument development, testing and comparison.