Near-source dispersion and coagulation parameterization: Application to biomass burning emissions

Aerosol size distributions near biomass-burning sources undergo rapid evolution, primarily due to coagulation, which significantly alters the particle number size distribution. Existing long-range aerosol transport and climate prediction models often overlook near-source dynamics involving simultaneous coagulation and dispersion. To bridge this gap, the present study introduces a coagulation-dispersion model and provides semi-analytical solutions for the effective size distribution parameters. The precise solution for a diffusion-less coagulating plume with spatially varying particle concentration supports the conceptual accuracy of the semi-analytical parameterization for dispersion-coagulation model. These solutions form the basis for a parameterization scheme that considers input parameters such as source dimensions, particle mass flux, particle size, and atmospheric conditions. Utilizing this parameterization for case-specific biomass burning emissions shows a decrease in number emission rate by approximately a factor of 600, while the count median diameter of the initial size distribution increases by around 7 times. Additionally, we estimate the optical properties of aerosols both before and after the introduction of the near-source parameterization scheme. Results indicate an increase by a factor of 4 in the aerosol extinction coefficient and by a factor of ∼20 in the scattering coefficient, which will significantly influence the calculation of aerosol optical properties in global models. These changes in optical properties primarily stem from modifications in aerosol size distribution resulting from near-source aerosol dynamics. The results are further discussed

Heating and lighting: understanding overlooked energy-consumption activities in the Indian residential sector

Understanding the climate impact of residential emissions starts with determining the fuel consumption of various household activities. While cooking emissions have been widely studied, non-cooking energy-consumption activities in the residential sector such as heating and lighting, have been overlooked owing to the unavailability of data at national levels. The present study uses data from the Carbonaceous Aerosol Emissions, Source Apportionment and Climate Impacts (COALESCE) project, which consists of residential surveys over 6000 households across 49 districts of India, to understand the energy consumed by non-cooking residential activities. Regression models are developed to estimate information in non-surveyed districts using demographic, housing, and meteorological data as predictors. Energy demand is further quantified and distributed nationally at a 4 × 4 km resolution. Results show that the annual energy consumption from non-cooking activities is 1106 [201] PJ, which is equal to one-fourth of the cooking energy demand. Freely available biomass is widely used to heat water on traditional stoves, even in the warmer regions of western and southern India across all seasons. Space heating (51%) and water heating (42%) dominate non-cooking energy consumption. In comparison, nighttime heating for security personnel (5%), partly-residential personal heating by guards, dominant in urban centers and kerosene lighting (2%) utilize minimal energy. Biomass fuels account for over 90% of the non-cooking consumption, while charcoal and kerosene make up the rest. Half of the energy consumption occurs during winter months (DJF), while 10% of the consumption occurs during monsoon, when kerosene lighting is the highest. Firewood is the most heavily used fuel source in western India, charcoal in the northern hilly regions, agricultural residues and dung cake in the Indo-Gangetic plains, and kerosene in eastern India. The study shows that ∼20% of residential energy consumption is on account of biomass-based heating and kerosene lighting activities