Context
Scientists at the Aryabhatta Research Institute of Observational Sciences (ARIES), in collaboration with scientists from the University of Delhi, IIT Kanpur and Space Physics Laboratory, ISRO have made extensive observations of black carbon and elemental carbon and estimated monthly and wavelength-dependent values of MAC over the central Himalayan region for the first time.
What is black carbon?
- Black carbon, or soot, is part of fine particulate air pollution (5) and contributes to climate change.
- It is formed by the incomplete combustion of fossil fuels, wood and other fuels.
- Complete combustion turns all carbon in the fuel into carbon dioxide (CO2), but combustion is never complete and CO2, carbon monoxide, volatile organic compounds, and organic carbon and black carbon particles are all formed in the process.
- The complex mixture of particulate matter resulting from incomplete combustion is often referred to as soot.
- Black carbon is a short-lived climate pollutant with a lifetime of only days to weeks after release in the atmosphere.
- During this short period of time, black carbon can have significant direct and indirect impacts on the climate, the cryosphere (snow and ice), agriculture and human health.
- Black Carbon (BC) has recently emerged as a major contributor to global climate change, possibly second only to CO2 as the main driver of change. BC particles strongly absorb sunlight and give soot its black color.
Key findings
- The calculated annual mean value of MAC has been found it to be significantly lower than the constant used earlier.
- These lower values are a result of transport of processed (not fresh) air pollution emissions at this otherwise clean site.
- The study also revealed that these estimated MAC values show significant seasonal variation.
- It is found that these changes are caused by the seasonal variability of biomass burning, air mass variation, and meteorological parameters.
Need for the study
- The accurate estimationof Black carbon will now be possible using optical instruments in the Himalayan region using mass absorption cross-section (MAC).
- The precise knowledge on BC at various wavelengths will help in source apportionment studies done to constrain the sources of BC emissions, an important information to form the mitigation policies.
- It will also improve the performance of numerical weather prediction and climate models.
MAC
- The mass absorption cross-section (MAC) of BC defines the characteristic link between its atmospheric concentrations and climate impacts.
- MAC is a spectral quantity relating the absorptive efficiency of a particle per unit mass.
- When multiplied by the path-integrated mass concentration of a particle, MAC yields the observed absorption at a specific wavelength of light.
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About ARIES
- ARIES (Aryabhatta Research Institute of Observational Sciences) is one of the leading research Institutes which specializes in observational Astronomy & Astrophysics and Atmospheric Sciences.
- It is an autonomous institute under the Department of Science & Technology (DST).
- The main research interests of Astronomy & Astrophysics division are in solar, planetary, stellar, galactic and extra-galactic astronomy including stellar variabilities, X-ray binaries, star clusters, nearby galaxies, quasars, and inherently transient events like supernovae and highly energetic Gamma Ray Bursts.
- Research focus in Atmospheric Sciences division is mainly in the lower part of the atmosphere and covers the studies on aerosols and trace gases.
