Ice‐nucleating particle emissions from biomass combustion and the potential importance of soot aerosol

Abstract

Ice‐nucleating particles (INPs) are required for initial ice crystal formation in clouds at temperatures warmer than about −36°C and thus play a crucial role in cloud and precipitation formation. Biomass burning has been found to be a source of INPs in previous studies and is also a major contributor to atmospheric black carbon (BC) concentrations. This study focuses on isolating the BC contribution to the INP population associated with biomass combustion. Emissions of condensation mode INPs from a number of globally relevant biomass fuels were measured at −30°C and above water saturation as fires progressed from ignition to extinguishment in a laboratory setting. Number emissions of INPs were found to be highest during intense flaming combustion (modified combustion efficiency > 0.95). Overall, combustion emissions from 13 of 22 different biomass fuel types produced measurable INP concentrations for at least one replicate experiment. On average, all burns that produced measureable INPs had higher combustion efficiency, which is associated with higher BC emissions, than those that did not produce measureable INPs. Across all burns that produced measureable INPs, concentrations ranged from 0.1 to 10 cm−3, and the median emission factor was about 2 × 107 INPs per kilogram of fuel burned. For a subset of the burns, the contribution of refractory black carbon (rBC) to INP concentrations was determined by removing rBC via laser‐induced incandescence. Reductions in INPs of 0–70% were observed, indicating an important contribution of rBC particles to INP concentrations for some burns, especially marsh grasses.

Characteristics of Ice Nucleating Particles in and Around California Winter Storms

“…Another potential INP source is local soil particles (Hill et al, ) lofted by increased winds associated with the landfalling storm. While some combustion sources, such as biomass burning, could also contribute to the INP population (Levin et al, ; McCluskey et al, ; Petters et al, ), Schill et al () found no emission of INPs from diesel combustion. Other anthropogenic emissions, such as sulfate and nitrate aerosol, while likely accounting for the majority of aerosol number in this region are not expected to contribute to the heterogeneous INP budget.…”

Ice-nucleating particle concentrations unaffected by urban air pollution in Beijing, China

“…Observation of abundant BC in ice particle residuals in field experiments suggested that some BC-containing particles may preferentially act as INP (Cozic et al, 2008). In the experiments conducted by Levin et al (2016), emissions of different types of biomass fuel produced measurable concentrations of INP (0.1-10 cm −3 ) associated with higher BC concentration accounting for about 0-70 %. Determination of ice-nucleating properties of physically and chemically aged soot particles suggests that the heterogeneous ice nucleation activity of freshly emitted diesel soot particles is sensitive to some of the aging processes (Kulkarni et al, 2016).…”

“…Schill et al (2016) showed that neither fresh nor aged emissions from diesel engines contributed appreciably to atmospheric INP concentrations. However, some studies considered BC-containing particles as possible INP (Cozic et al, 2008;Levin et al, 2016;Cozic et al, 2007). Observation of abundant BC in ice particle residuals in field experiments suggested that some BC-containing particles may preferentially act as INP (Cozic et al, 2008).…”

Using depolarization to quantify ice nucleating particle concentrations: a new method

“…Measurements suggest that K-feldspar, a common component of soil dust aerosol, may account for a large fraction of Earth's INPs (Atkinson et al, 2013;YakobiHancock et al, 2013). Recent investigations of other aerosols have identified aromatic pollutant aerosols, secondary organic aerosols, marine aerosols, and aerosols produced from biomass burning as effective INPs DeMott et al, 2016;McCluskey et al, 2014McCluskey et al, , 2016Levin et al, 2016;Collier and Brooks, 2016).…”