The snow physical parameters are closely related to the sizes, shapes, and chemical composition of light-absorbing particles (LAPs). By utilizing a computer-controlled scanning electron microscope software called IntelliSEM-EPAS (TM), we first report the measured size-resolved concentration of soot, dust, and fly ash particles in fresh (wet) and aged (dry deposition) snow samples collected at an industrial city in China during and after a snowfall at intervals of 6-8 days. Due to wet scavenging by seasonal snow, soot and dust particles in snow are absorbed by 69.7% and 30.3% at wavelengths of 550 nm, lowering snow albedo by 0.0089 and 0.0039, respectively. Soot particle size increases slightly during dry deposition, whereas size-resolved mineral dust does not undergo a significant shift in particle size. These results indicate the essentiality to involve the effects of accurate size and composition of in-snow LAPs for a better assessment of snow light absorption and reflectance. Plain Language Summary A field survey was undertaken to collect freshly fallen (1) and aged surface (15) snow samples at 1-day intervals in the center of Changchun city, China, which is surrounded by heavy industrial emission sources. We used an advanced computer-controlled scanning electron microscope to determine particle size and number distributions of three major light-absorbing particle types with diameters of 0.2-10 mu m in seasonal snow, namely soot, dust, and fly ash. Soot and dust particles deposited in various ice-grain sizes via wet and dry deposition were also examined in terms of their contributions to light absorption and snow albedo reduction. We report here a first attempt to detect a combination of log-normal soot, dust, and fly ash in seasonal snow, as well as their potential effects on the reduction of snow albedo.

[1] Aerosol sources, transport, and sinks are simulated, and aerosol direct radiative effects are assessed over the Indian Ocean for the Indian Ocean Experiment (INDOEX) Intensive Field Phase during January to March 1999 using the Laboratoire de Meteorologie Dynamique (LMDZT) general circulation model. The model reproduces the latitudinal gradient in aerosol mass concentration and optical depth (AOD). The model-predicted aerosol concentrations and AODs agree reasonably well with measurements but are systematically underestimated during high-pollution episodes, especially in the month of March. The largest aerosol loads are found over southwestern China, the Bay of Bengal, and the Indian subcontinent. Aerosol emissions from the Indian subcontinent are transported into the Indian Ocean through either the west coast or the east coast of India. Over the INDOEX region, carbonaceous aerosols are the largest contributor to the estimated AOD, followed by sulfate, dust, sea salt, and fly ash. During the northeast winter monsoon, natural and anthropogenic aerosols reduce the solar flux reaching the surface by 25 W m(-2), leading to 10 - 15% less insolation at the surface. A doubling of black carbon (BC) emissions from Asia results in an aerosol single-scattering albedo that is much smaller than in situ measurements, reflecting the fact that BC emissions are not underestimated in proportion to other ( mostly scattering) aerosol types. South Asia is the dominant contributor to sulfate aerosols over the INDOEX region and accounts for 60 - 70% of the AOD by sulfate. It is also an important but not the dominant contributor to carbonaceous aerosols over the INDOEX region with a contribution of less than 40% to the AOD by this aerosol species. The presence of elevated plumes brings significant quantities of aerosols to the Indian Ocean that are generated over Africa and Southeast and east Asia.