First Surface Measurement of Cloud Condensation Nuclei over Kanpur, IGP: Role of Long Range Transport

Abstract

INTRODUCTIONThe concentration of cloud condensation nuclei (CCN) can significantly affect cloud microphysical processes, and in turn, several aspects of weather and climate. The aerosol-cloud interactions and its impact on climate is the least understood and therefore is a subject of intense research in recent years. For more details pertaining to the effects of aerosols on climate and on cloud processes and precipitation, one can look into the excellent reviews by (Lohmann and Feichter 2005;Rosenfeld et al. 2008).Aerosols, by acting as CCN, can perturb clouds. Their effect on earth radiative balance is the largest source of uncertainty in anthropogenic climate change (Houghton et al. 2001). A strong positive correlation exists between cloud droplet number concentration and CCN concentration, implying an increase in CCN number results in increased droplet concentration that increases reflectivity leading to climate cooling . This has been confirmed by both modeling results and field observations in marine and continental environments . Therefore, simultaneous in-situ measurements of cloud condensation nuclei and aerosol properties are crucial for establishing a quantitative relationship between cloud microphysics and the microphysical (size) and chemical properties of aerosol (Rissman et al. 2006). Amongst several outstanding issues, the most important is the creation of seasonal 3-D maps of the global distribution of CCN, which is most relevant to warm cloud formation. Considerable efforts have been made in recent years to construct a global CCN climatology, e.g., Southern Ocean (Hudson et al. 1998

Real‐time measurements of ambient aerosols in a polluted Indian city: Sources, characteristics, and processing of organic aerosols during foggy and nonfoggy periods

“…After clustering, the PM 1 chemical compositions corresponding to the BTs in each cluster were averaged, which is also shown in Figure . The BT analysis confirmed that the air masses sampled in this study predominantly arrived from the northwest, as reported in a previously conducted wintertime study at this location [ Patidar et al ., ]. BT analysis also indicates that the site is primarily affected by surface emissions as evident from the trajectory heights (Figure S10).…”

Characterization of organic residues of size‐resolved fog droplets and their atmospheric implications

“…During real-time ambient sampling, the AMS also sampled submicron background interstitial ambient aerosols present at the site before or during a fog event, which were too small and/or Journal of Geophysical Research: Atmospheres 10.1002/2015JD024508 too hydrophobic to be activated into fog droplets. Generally, condensation nuclei for fog droplets are a fraction of the submicron aerosol population with activated fractions of <20-100%, depending on particle size [Frank et al, 1998;Patidar et al, 2012;Hammer et al, 2014]. Therefore, real-time ambient submicron AMS data and offline fog water AMS data can be compared to understand the extent of aqueous processing of organics inside fog droplets.…”

CCN closure study: Effects of aerosol chemical composition and mixing state

“…The major pollution sources in the winter season are vehicle emissions, industrial emissions, biomass burning, open area burning, coal power plants, and domestic cooking [Nair et al, 2007]. In addition, the site is also affected by long-range transported aerosols from the northwestern part of India, which experiences large numbers of forest fires [Patidar et al, 2012]. The estimated distance of the fire hot spots (shown in Figure 1) from the sampling location is approximately 700-1000 Km.…”

“…The AMS and CCN data averaging time is kept same as the SMPS scan time, i.e., 3 min, thus eliminating 2 and 4 min of CCN data at the start of lower (0.2%) and higher (0.4%-1.0%) SS values, respectively. A supersaturation depletion correction has been applied due to high CCN concentrations following the same approach as described in earlier studies [Lathem and Nenes, 2011;Patidar et al, 2012]. Hereafter, SS refers to depleted SS instead of measured SS.…”

“…Both ground-and aircraft-based closure studies have previously been performed at this location using filter-based chemical composition measurements [Patidar et al, 2012;Srivastava et al, 2013]. Additionally, the size-resolved CCN measurements have been performed over three different seasons to understand the effects of chemical composition on CCN activity [Bhattu and Tripathi, 2014].…”