Secondary sulphate aerosols and cirrus clouds detection with SEVIRI during Nabro volcano eruption

ABSTRACT

Secondary sulphate aerosols (SSAs) and cirrus clouds in the upper troposphere–lower stratosphere (UTLS) are two key atmospheric constituents that can modulate the Earth’s radiative balance. In this article, we present a new preliminary detection algorithm for UTLS SSAs with the Spinning Enhanced Visible and Infrared Imager (SEVIRI) geostationary instrument. This algorithm is used in combination with a well-established existing clouds classification algorithm, to provide, in perspective, a combined tool to better characterize the aerosol–cirrus interactions at the regional scale and at very high temporal resolution, thus potentially contributing to the understanding of the SSAs’ direct–indirect impact on the Earth’s radiative balance. This new combined tool is tested on the Nabro volcano eruption of June–July 2011, which is known to have emitted a great amount of SSA gaseous precursors in the UTLS and to have interacted with the peculiar Asian monsoon dynamics during summer 2011. Although volcanic aerosol–cirrus interactions are not analysed in details at this stage, this work demonstrates that this can be carried out with SEVIRI by introducing a new dedicated SSA product. First results of the new SSA detection algorithm are encouraging towards the use of this combined product.

Acknowledgements

The optical parameters of sulphate aerosol layers used in this work were obtained with the IDL Mie scattering routines developed by the Earth Observation Data Group of the Department of Physics of Oxford University, and available via the following website: http://eodg.atm.ox.ac.uk/MIE/. NOVELTIS and Alain Chédin are gratefully acknowledged for the support with the 4A/OP model.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This project was partially supported by the EU 7th Framework Program under grant 603557 (StratoClim).