Aging Species of Atmospheric Particles with Height: Implications to Cloud Microphysics
Abstract ID#: 36017
A. Ahlawat1, S. K. Mishra1*, C. Sharma1, Sukhvir Singh1, M V S N Prasad1, B. Gupta1
1CSIR-National Physical Laboratory, New Delhi, India-110012
ABSTRACT:
Atmospheric particles have great impacts on different scales spanning from regional to global climate change (Watson et al., 2002). Aerosol plays an important role as the cloud condensation nuclei based on their composition and complex mixing states. Most of the observations pertaining to aerosol physico-chemical characteristics are limited to ground level observations. The altitude variation of the same (balloon based) is extremely limited (Zhang et al., 2012; Hara et al., 2013). The aged aerosols show enhanced ability of serving as nuclei for droplet formation and finally affect the radiative properties of clouds (Moteki et al., 2007).
To the best of our knowledge, there is no detailed study of aerosol aging information with varying altitude over India. To study the physico-chemical properties of aerosols with varying altitude, a tethered balloon based field campaign have been organized in National Physical Laboratory campus (28° 38׳ 10׳׳N, 77° 10׳ 17׳׳E) from 21-27 Feb, 2014 (Mishra et al., 2014). TOF-SIMS (Time of Flight-Secondary Ion Mass Spectrometry) was used to study the aging chemicals of aerosols collected at various altitudes. Samples were collected from ground level to 700m (total six altitudes). At 200m altitude, the particles were found to be heavily aged with aliphatic hydrocarbons which are fragments of tails of aliphatic amide group. Peterson and Tyler (2003) have already shown that the aging of aerosol with aliphatic amides may be of critical importance for cloud droplet formation. Together with hydrocarbons, particles were also found to be aged with HSO4-, SO3- and Cl- at 200 m altitude. The strong temperature inversion and air parcel movement from IGP (Indo Gangetic Plain) are the probable reason for enhanced aging of aerosols at this altitude. Implications of the observed aging with varying altitude to the cloud microphysics will be discussed during presentation.
ACKNOWLEDGEMENTS
Authors acknowledge CSIR Network Project AIM_IGPHim (PSC-0112) for the financial support and TIFR Balloon Facility for the tethered hoisting.