Season-dependent size distribution of aerosols over the tropical coastal environment of south-west India

• Published in: Journal of atmospheric and solar-terrestrial physics Vol. 167; pp. 219 - 232
• Main Authors: Aryasree, S., Nair, Prabha R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2018
• Subjects: Aerosols; Meteorology; Number size distribution; Size dependence; Aerosols; Size dependence; Number size distribution; Meteorology
• ISSN: 1364-6826; 1879-1824
• DOI: 10.1016/j.jastp.2017.12.012

This paper presents the results of a detailed study on the size characteristics of aerosols at the tropical coastal site Thiruvananthapuram based on the in-situ measurements of size resolved aerosol number density using an aerosol spectrometer, covering a period of 28 months from September 2011 to December 2013. The diurnal pattern of aerosol number density is characterized by day time low and a two-fold increase during nighttime and these changes are closely associated with the strong mesoscale features namely the sea breeze and land breeze prevailing at the site. Aerosol Number Size Distribution (NSD) depicts a multi-modal nature with two prominent modes, one ≤0.1 μm and other ∼1 μm. Two other less pronounced modes are also observed in the NSD, one ∼0.3–0.5 μm and other ∼5–8 μm. The NSDs also exhibited strong seasonal changes linked with the synoptic meteorological feature of this region namely the South Asian monsoon. The seasonal NSDs were parameterized and analyzed. In addition to this, the effects of meteorological parameters temperature, relative humidity, and wind speed and airflow patterns on aerosol number density as revealed by partial correlation analysis were found to be aerosol size dependent. •Aerosol number density exhibits day time low and night time high.•Number density size distribution of aerosols shows season-dependent multimodal structure.•Fine particle mode is pronounced in winter and large particle mode in monsoon/pre-monsoon.•Meteorological effects on aerosol number density are size-dependent.