University of manchester University of Oxford University of Leeds
National Centre for Atmospheric Science Natural Environment Research Council

Project Aims

The Global Aerosol Synthesis and Science Project (GASSP) is a research project designed to improve our understanding of global aerosol effects on climate.

The project has two themes:

  1. The creation of a very large global dataset of aerosol measurements designed to allow easier evaluation and calibration of global aerosol models.  The creation of this dataset is motivated by the fact that only a small fraction of the community’s enormous investment in atmospheric aerosol measurements is ultimately used to test and improve models.
  2. Use of this large dataset to constrain global aerosol models in order to reduce the uncertainty in the effect of aerosols on climate as much as possible.

GASSP was initially funded for 3 years by the National Environmental Research Council (between 2012 to 2106), but it is an ongoing effort, with work continuing through multiple subsequent projects.  The GASSP database of aerosol observations is still growing, and we welcome contributions or collaborations with the observational community.  Please contact if you have observations that you would like to include in the GASSP database. 

Key findings from GASSP (and subsequent projects) are summarised here.

GASSP Dataset

Through GASSP, we have created a very large data set of in-situ aerosol observations, including observations of aerosol number, size, composition and the cloud composition nuclei concentration.

Understanding the global variation of these physical aerosol properties is an essential step if we want to understand how aerosol affects cloud properties on a global scale.  But these physical aerosol properties cannot be measured by satellite, so to get a large-scale picture of these physical aerosol properties, and an understanding of how they vary across the globe, we need in-situ observations from ship, aircraft and station data from a wide range of locations.  Thankfully the number of these observations is increasing each year, but for modelling groups to use these observations to get a global picture of the aerosol, the data needs first needs to be collated from multiple sources and processed to a single format, which can be time consuming and requires multiple groups to duplicate effort.

The GASSP data set has been complied to address this; by synthesising multiple in-situ aerosol observations in a single data set with a single format, we have created a resource the community can easily use to test, evaluate and improve their models, resulting in improved understanding and prediction of the effects of aerosols on climate.

More information about the measurements held in GASSP dataset.

Constraint and Uncertainty Reduction

The second theme of the GASSP project is to use this extensive observational database to improve the processes in the model and work to develop the best possible computer model of global aerosol.  This “process-based” approach to model development can be done using novel statistical techniques that provide insight into not just the level of uncertainty in the prediction, but where that uncertainties comes from.

The GASSP project was the first time that novel statistical emulation techniques were applied to a global aerosol model.  Since this time it has become a important tool for researchers working to develop models of the atmosphere and climate (publications).

More information about the constraint and uncertainty work.