Aerosol particle behavior during Dust Storm and Diwali over an urban location in north western India

In this study, the aerosol behavior during two contradictory events, i.e., dust storm (DS) and Diwali (DW) has been studied over Jaipur. The aerosol particle number concentration shows distinct features between DS and DW events. The total ANC was found minimum during DS while maximum during DW. The 24 h mean of total ANC was 9.15 × 10⁴ (±7.71 × 10⁴) and 5.38 × 10⁵ (±3.73 × 10⁵ particles/l) during DS and DW, respectively. The total ANC increases from 7.78 × 10⁴ to 5.32 × 10⁵ and 3.52 × 10⁵ to 1.70 × 10⁶ particles/l in 24 h during DS and DW, respectively. In DS, the ANC in coarse mode (2 < particle diameter < 20 μm) is significantly high while in DW, the ANC in fine mode (0.3 < particle diameter < 2 μm) exhibits higher concentration. During dust episode, a significant change in ANC (3.0 × 10³ to 1.12 × 10⁵ particles/l) was observed for the particle of size range in 2.0–20 μm with a slight increase in particles number concentration (7.48 × 10⁴ to 4.20 × 10⁵ particles/l) in 0.3–2.0 μm range is also observed. During DS, the fine and coarse mode particles increased 4.61 and 36.44 times while during DW, it increased 3.83 and 0.95 times, respectively. The relatively high particle levels during DW are attributed for two reasons: local emissions due to burning of fire crackers and meteorological conditions, i.e., low wind speeds and low mixing-layer heights lead to relatively high particle concentrations.