The outflow of Asian biomass burning carbonaceous aerosol into the upper troposphere and lower stratosphere in spring: radiative effects seen in a global model

Abstract

Abstract. Biomass burning (BB) over Asia is a strong source of carbonaceous aerosols during spring. From ECHAM6–HAMMOZ model simulations and satellite observations, we show that there is an outflow of Asian BB carbonaceous aerosols into the upper troposphere and lower stratosphere (UTLS) (black carbon: 0.1 to 6 ng m−3 and organic carbon: 0.2 to 10 ng m−3) during the spring season. The model simulations show that the greatest transport of BB carbonaceous aerosols into the UTLS occurs from the Indochina and East Asia region by deep convection over the Malay Peninsula and Indonesia. The increase in BB carbonaceous aerosols enhances atmospheric heating by 0.001 to 0.02 K d−1 in the UTLS. The aerosol-induced heating and circulation changes increase the water vapor mixing ratios in the upper troposphere (by 20–80 ppmv) and in the lowermost stratosphere (by 0.02–0.3 ppmv) over the tropics. Once in the lower stratosphere, water vapor is further transported to the South Pole by the lowermost branch of the Brewer–Dobson circulation. These aerosols enhance the in-atmosphere radiative forcing (0.68±0.25 to 5.30±0.37 W m−2), exacerbating atmospheric warming, but produce a cooling effect on climate (top of the atmosphere – TOA: -2.38±0.12 to -7.08±0.72 W m−2). The model simulations also show that Asian carbonaceous aerosols are transported to the Arctic in the troposphere. The maximum enhancement in aerosol extinction is seen at 400 hPa (by 0.0093 km−1) and associated heating rates at 300 hPa (by 0.032 K d−1) in the Arctic.

Variability of Aerosols and Clouds Over North Indian and Myanmar During the COVID-19 Lockdown Period

“…This confirms that the observed increase in AOD Myanmar and central Indian regions has been caused by large amounts of fires. A past study shows that fires emit smoke/carbonaceous aerosols peak in spring over the Myanmar region (Chavan et al, 2021). It will be interesting to observe the vertical structure of fire-emitted smoke.…”

Can Forest Fires Be an Important Factor in the Reduction in Solar Power Production in India?

“…India has suffered massive forest fires each year due to natural and anthropogenic causes, with the main concentration in the hilly terrains of the western/central Himalayas and the northeastern states. A large number of forest fires from November 2020 to June 2021 were reported in Odisha (51,968), Madhya Pradesh (47,795), Chhattisgarh (38,106), Maharashtra (34,025), Jharkhand (21,713), Uttarakhand (21,497), Andhra Pradesh (19,328), Telangana (18,237), Mizoram (12,864), Assam (10,718), and Manipur (10,475) [67]. Approximately 1300 hectares of forest area burned due to massive forest fires in 2021 in Uttarakhand state [68].…”

“…Wildfires and biomass burning are among the major important sources of carbonaceous aerosols, greenhouse gases, ozone precursors, trace gases, and particulate pollutant emissions in several regions, including Asia [3][4][5][6][7][8][9][10][11][12][13]. The impacts of forest fires and biomass burning on aerosols, air pollution, and radiative forcing over northern India were well documented in several earlier papers [3,9,[14][15][16][17][18][19][20][21][22][23], and are hence not repeated here.…”

Tropospheric warming over the northern Indian Ocean caused by South Asian anthropogenic aerosols: possible impact on the upper troposphere and lower stratosphere

“…1d), with increases for BC of 0 %-3 %, OC of 0 %-8.7 %, and sulfate of 0 %-0.2 %, compared to annual means. This peak in emissions in spring is to a large extent driven by springtime agricultural crop burning and biomass burning activity (Chavan et al, 2021).…”

“…Airborne observations during winter and spring, e.g., the Civil Aircraft for Regular Investigation of the Atmosphere based on an Instrument Container (CARIBIC) in March 1999and January 2001(Papaspiropoulos et al, 2002 and the Indian Ocean Experiment (INDOEX) in February-March 1999, show elevated aerosol amounts near 8-12 km over the Indian Ocean and South Asia (De Reus et al, 2001). Recently, using a set of model simulations, Chavan et al (2021) reported the transport of biomass burning aerosols to the upper troposphere by convection in spring 2013.…”