International Cooperative for Aerosol Prediction (ICAP)

ICAP is an international forum for aerosol forecast centers, remote sensing data providers, and lead systems developers to share best practices and discuss pressing issues facing the operational aerosol community. While the dynamical meteorology community has well-developed protocols and near real-time observing systems to support forecasting, the aerosol community is only beginning to organize. Infrastructure and data protocols need to be developed between operational centers in order to fully support this emerging field.

Observing Aerosols: New perspectives and implications for global modeling

June 10-12, 2026 • Bonn, Germany

In 2024, HARP2 and SPEXone instruments were launched on the PACE satellite, and in 2025 Metop-SG successfully made it into orbit with the 3MI instrument onboard. These instruments are all polarimeters, capable of observing the polarization state of light scattered by the atmosphere and surface, and providing detailed information about aerosols and cloud particles. Polarimeters have been used in space before, but the higher polarimetric accuracy, spectral range, number of viewing angles, and improved spatial resolution mean that these new instruments are more accurately able to observe particle size, absorption properties, refractive index, and aerosol type.

Polarimeters are not the only recently launched instruments to offer a new perspective on aerosols. EarthCARE has been providing operational observations since early 2025 that give a more accurate and updated understanding of the vertical structure of aerosols in the atmosphere. The potential of fundamentally changing the way aerosol observations are used in models has also started to be investigated, with research into all-sky visible reflectance and lidar extinction assimilation to jointly inform on aerosols and clouds.

In this 16th meeting of the International Cooperative for Aerosol Prediction (ICAP), the focus is on how these new observations or methodologies can be used to add value to global aerosol models. In particular, how the additional information on particle size, absorption, type, and vertical structure can be utilized by models that rely on different aerosol and cloud assumptions than retrievals or direct observations.

Past Meetings