SWAAMI contributed to the joint NERC-MoES programme: Drivers of Variability in the Asian Monsoon, through a detailed determination of aerosol physical and chemical properties across India in the advance of, and during, the Indian monsoon using UK and Indian research aircraft. The measurements delivered a chemical and physical characterisation of the aerosol that is considerably more detailed than any previous and enabled an assessment of aerosol composition and mixing state, provided source characterisation and deliver quantification of aerosol optical properties such as extinction, absorption and single scattering albedo. Such detailed characterisation allowed representations of aerosol properties in regional and global climate models. Aircraft measurements were combined with syntheses of long term data from across the continent and previous field studies to provide a data set that can challenge how well models represent aerosol across the region. Improving model representations of aerosol properties and testing the extent to which this improves model performance against data provided a framework for ensuring model aerosol schemes improve and in doing so allowed more reliable predictions of aerosols effects on the heat budget of the region and hence improve our knowledge of how aerosols may influence the Indian monsoon.

SWAAMI combined measurements of the properties of aerosols across northern India and the Bay of Bengal during the pre-monsoon in unprecedented detail with long term measurements from ground based networks and data from previous intensive campaigns in order to challenge model representations of aerosols over India and their effects on the monsoon.
Key objectives of SWAAMI were to:
*Assess the impact of mineral dust, black carbon aerosol and co-emitted organic and inorganic species on the radiation budget via the direct, semi-direct and indirect effects
*Assess the impact of the aerosol radiative forcing on the local energy budget, atmospheric dynamics and hydrological cycle over India
*Assess the impact of the forcings and feedbacks arising from aerosols over Indian region on regional and global climate.

Grant ref: NE/L013886/1