Absorbing Aerosols, Possible Implication to Crop Yield - A Comparison between IGB Stations

Abstract

The current study compares black carbon radiative effects at the densely populated plain station, Varanasi and the lesser populated plateau station Ranchi with large forest cover but with numerous open coal mines. While the measured average black carbon mass density (BC) reduces from February to March at Ranchi following an increase in convective mixing, it is observed to increase by 150% from February to March in Varanasi, as transport from northeast forest fires increases. It is observed that absorption due to black carbon of non-fossil fuel origin is prevalent throughout the day, in Varanasi, while this contribution is most significant during post sunset hours in Ranchi. Radiative forcing, estimated hourly using chemical model (to derive BC-aod) and radiative transfer model, indicates that at least 5% of the incoming radiation is always cutoff during any time of the day in Varanasi while this is about 4% in Ranchi. BC effectively causes an apparent delayed sunrise by reducing the incoming radiation on the plains of Indo Gangetic Basin (IGB) by up to 25% at the daybreak. An estimate of crop loss due to cut off in radiation, using an empirical formula for crop yield as a function of radiation, indicates a possible loss of more than a quintal per hectare considering anthesis (February) and maturity (March) periods for the winter wheat in both the IGB stations with consistently higher losses in Varanasi.

Development of a Regression Model for Estimating Daily Radiative Forcing Due to Atmospheric Aerosols from Moderate Resolution Imaging Spectrometers (MODIS) Data in the Indo Gangetic Plain (IGP)

“…A statistical model of historical rice harvest in India, coupled with a regional climate scenario, indicated that there has been a slowdown in the increase in production over the last two decades due to increased brown cloud and greenhouse gas [30]. Similarly, Latha et al [31] compared the radiative forcing of atmospheric black carbon at two locations in IGP, Varanasi and Ranchi by using Santa Barbara DISTORT Atmospheric Radiative Transfer (SBDART) model and concluded that the incoming radiation is reduced by about 5% due to black carbon (BC) during any time of day at Varanasi and 4% at Ranchi. This study also estimated the loss of wheat crop at Varanasi and Ranchi while using the empirical model that was developed by Ahmed and Hassen [32] as −149 kg/ha and −141 kg/ha, respectively, due to the reduction of solar radiation because of atmospheric black carbon.…”

“…Das et al [37] studied winter haze in the eastern Indo Gangetic Basin through ground measurements during December 2013 to February 2014 and the radiative effect of haze by using SBDART and found the radiative forcing at the BOA in Silguri, Kolkata and Sunderban was −39.3, −70.3 and −38 Wm −2 respectively. In addition, Latha et al [31] studied the radiative forcing of atmospheric black carbon at Varanasi and Ranchi using SBDART and concluded that the radiative forcing due to atmospheric black carbon is significantly increased from February to March (i.e., from −30 Wm −2 to −50 Wm −2 ) at Varanasi due to an increased BC concentration and mixing layer height. The radiative forcing due to atmospheric aerosols at IGP stations has been studied at the annual, seasonal, and in some cases, monthly time scale by using radiative transfer models [36,[38][39][40][41][42][43][44].…”

Recent Increase in Winter Hazy Days over Central India and the Arabian Sea

“…The winter season is characterized by a shallower boundary layer, lower wind speed and low precipitation, leading to the accumulation of aerosols near the surface 2,14,15 . Along with the obvious health impacts, studies have shown that the high aerosol loading in winter can reduce radiation reaching to the surface by about 25%, thereby decreasing crop yield 16–18 . Nonetheless, aerosols act as cloud condensation nuclei and affect cloud formation and rainfall 19 .…”

Assessment of Fractionated Aerosols at a Semiarid Region over the Indo‐Gangetic Basin

“…Wind from the west and northwest prevails over this region in November. In November, crop burning and harvesting are common practices in Punjab and Haryana; these practices exert a substantial effect on the study site . The calm and stable atmospheric conditions as well as the low boundary layer contribute to an increasing concentration of pollutants.…”

“…Agra supports the transport of dust from the long range over the north Indian region in November, leading to higher concentrations of PM 10 practices exert a substantial effect on the study site. [23,58] The calm and stable atmospheric conditions as well as the low boundary layer contribute to an increasing concentration of pollutants. These conditions retain the high loading of PM 10 and PM 2.5 in the ambient air for a long period.…”