The mists over the national capital and northwestern India seen during the winters not only cause people's problems on the ground but also influence the weather. A new study by an international group of researchers has found that the composition of a class of aerosols that carry carbon into the fog changes as it travels over the Earth mass to the oceans.
The absorption capacity of brown carbon lamp, a key component of fog, is reduced during transportation, but its average life is 3.6 days, compared to 9 to 15 hours in other regions. This means that brown carbon stays in the atmosphere of South Asia for more time and, therefore, can contribute to the warming of the region, researchers say.
The fog, also called the atmospheric brown cloud (ABC), contains several types of particles that come from vehicular contamination, biomass burning and other sources. This layer of contaminated air plays a critical role in the regional climate, as it absorbs and disperses the incoming sun radiation.
Two important components of ABC light absorption are carbon black and brown carbon. While black carbon mainly comes from sources such as diesel combustion, brown coal is a result of combustion of biomass. The new study focused on brown coal when its ability to absorb light was known when traveling on the oceans.
The researchers measured air samples in Delhi, located in the middle of the India-Gangetic Plains; Bhola in the south of Bangladesh, which is on the brink of the IGP; and at the Maldivian climate observatory in Hanimaadhoo, where the cloud goes brown after a long-range shipping.
It was found that the chemical composition of aerosols changed between places and over time. The water-soluble brown carbon concentrations were the highest in Delhi, lowered to the Bangladesh site and the lowest in the Maldives. The measurements of water-soluble extracts of brown coal show notable differences in the lighting absorption characteristics between the three sites, with brown carbon molecules that lose their heating capacity during the transport, according to the study published in the Science Advancements magazine on Thursday.
"Through measurements in three places, we were able to determine the ability of brown coal to absorb sunlight (and thus heat the surrounding atmosphere) and the speed with which this capacity diminished due to oxidation Photochemistry: a process that we call bleaching, "explained Prof. Örjan Gustafsson (Department of Environmental Sciences and Analytical Chemistry, Stockholm University), a senior member of the research team, in an interview with L & # 39; India Science Wire.
Since brown coal in southern Asia seems to have a longer average bleaching life, it has consequences for warming in the region. "From now on, we can not comment on the" true "ability to warming brown carbon. However, we can say that previous world modeling studies that are based on" fixed "values of # 39 Lightweight carbon absorption may have incorrectly estimated the effect of warming, "said Sanjeev Dasari, Ph.D. a student at the Stockholm University and the first author of the study, while talking to India Science Wire.
"This study is for winter months, but it still has crucial information given that the leading hypothesis for the reduction of monsoon in recent decades has been the solar attenuation of aerosols. It is clear that both Forecasting and climate projection models need to understand the impacts of a drastic transformation of the carbon-brown properties, "said Raghu Murtugudde, Professor of Atmospheric and Oceanic Sciences and Earth System Science at University of Maryland and visiting professor at IIT of Mumbai. I was not associated with the study.
The research team included Sanjeev Dasari, August Andersson, Srinivas Bikkina, Henry Holmstrand, Krishnakant Budhavan, Örjan Gustafsson (University of Stockholm); Sreedharan Sathees (Indian Institute of Science, Bangalore); Eija Asmi, Jutta Kesti, John Backman (Finnish Meteorological Institute); Abdus Salam (University of Dhaka); Deewan Singh Bisht, Suresh Tiwari (center of Delhi of the Indian Institute of Tropical Meteorology); and Zahid Hameed (Maldives Meteorological Service).