
Anoop Sharad MahajanIndian Institute of Tropical Meteorology | IITM · Centre for Climate Change Research
Anoop Sharad Mahajan
PhD
About
175
Publications
32,971
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
5,460
Citations
Introduction
Anoop Sharad Mahajan currently works at the Centre for Climate Change Research, Indian Institute of Tropical Meteorology. Anoop does research in Atmospheric Chemistry.
Additional affiliations
January 2017 - present
November 2009 - November 2012
December 2012 - present
Education
September 2005 - July 2009
September 2004 - September 2005
August 2000 - August 2003
Publications
Publications (175)
Mercury (Hg) is a global pollutant with substantial risks to human and ecosystem health. By upward transport in tropical regions, mercury enters into the stratosphere, but the contribution of the stratosphere to global mercury dispersion and deposition remains unknown. We find that between 5 and 50% (passing through the 400-kelvin isentropic surfac...
Ocean-emitted dimethyl sulfide (DMS) is a major source of climate-cooling aerosols. However, most of the marine biogenic sulfur cycling is not routed to DMS but to methanethiol (MeSH), another volatile whose reactivity has hitherto hampered measurements. Therefore, the global emissions and climate impact of MeSH remain unexplored. We compiled a dat...
Dimethyl sulfide (DMS) significantly contributes to cloud condensation nuclei formation and can impact the Earth's radiative budget and climate. Our study analyzes differences in estimating seawater DMS concentrations using an observation-based interpolation method (H22) and proxy-based parameterization methods (G18 and W20) that rely on environmen...
Dimethyl sulfide (DMS) is a naturally emitted trace gas that can affect the Earth's radiative budget by changing cloud albedo. Most atmospheric models that represent aerosol processes depend on regional or global distributions of seawater DMS concentrations and sea–air flux parameterizations to estimate its emissions. In this study, we analyse the...
Dimethyl sulfide (DMS) contributes to cloud condensation nuclei (CCN) formation in the marine environment. DMS is ventilated from the ocean to the atmosphere, and, in most models, this flux is calculated using seawater DMS concentrations and a sea–air flux parameterization. Here, climatological seawater DMS concentrations from interpolation and par...
This study presents an innovative approach to creating a dynamic, AI based emission inventory system for use with the Weather Research and Forecasting model coupled with Chemistry (WRF Chem), designed to simulate vehicular and other anthropogenic emissions at satellite detectable resolution. The methodology leverages state of the art deep learning...
While the dominant role of halogens in Arctic ozone loss during spring has been widely studied in the last decades, the impact of sea-ice halogens on surface ozone abundance over the northern hemisphere (NH) mid-latitudes remains unquantified. Here, we use a state-of-the-art global chemistry-climate model including polar halogens (Cl, Br, and I), w...
Methane (CH4) is the second most abundant greenhouse gas and affects the Earth's radiative balance. In some regions, the methane burden and budget are still not well understood due to the lack of in situ observations, especially vertical profile observations. Here, we present the first high‐resolution aircraft‐based tropospheric vertical profiles o...
Mercury (Hg) is a contaminant of global concern, and an accurate understanding of its atmospheric fate is needed to assess its risks to humans and ecosystem health. Atmospheric oxidation of Hg is key to the deposition of this toxic metal to the Earth’s surface. Short-lived halogens (SLHs) can provide halogen radicals to directly oxidize Hg and pert...
Tropospheric reactive bromine is important for atmospheric chemistry, regional air pollution, and global climate. Previous studies have reported measurements of atmospheric reactive bromine species in different environments, and proposed their main sources, e.g. sea-salt aerosol (SSA), oceanic biogenic activity, polar snow/ice, and volcanoes. Typho...
Dimethyl sulfide (DMS) significantly contributes to cloud condensation nuclei (CCN) formation in the marine environment. DMS is ventilated from the ocean to the atmosphere, and in most models, this flux is calculated using seawater DMS concentrations and a sea-air flux parameterization. Here, climatological seawater DMS concentrations from interpol...
Dimethyl sulfide (DMS) is a naturally emitted trace gas that can affect the Earth's radiative budget by changing cloud albedo. Most models depend on regional or global distributions of seawater DMS concentrations and sea-air flux parameterizations to estimate its emissions. In this study, we analyze the differences between three estimations of seaw...
In this study, we present ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of aerosols from two urban locations (Delhi and Pune) and one high-altitude rural location (Mahabaleshwar) in India. We utilized a profile retrieval algorithm to estimate the vertical profiles and vertical column densities of aeros...
Nitrate comprises the largest fraction of fine particulate matter in China during severe haze. Consequently, strict control of nitrogen oxides (NOx) emissions has been regarded as an effective measure to combat air pollution. However, this notion is challenged by the persistent severe haze pollution observed during the COVID-19 lockdown when NOx le...
Ocean biogeochemistry involves the production and consumption of an array of organic compounds and halogenated trace gases that influence the composition and reactivity of the atmosphere, air quality, and the climate system. Some of these molecules affect tropospheric ozone and secondary aerosol formation and impact the atmospheric oxidation capaci...
Observational evidence shows the ubiquitous presence of ocean-emitted short-lived halogens in the global atmosphere1–3. Natural emissions of these chemical compounds have been anthropogenically amplified since pre-industrial times4–6, while, in addition, anthropogenic short-lived halocarbons are currently being emitted to the atmosphere7,8. Despite...
Dimethyl sulfide (DMS) is a major contributor towards cloud condensation nuclei
(CCN) formation in the marine environment. This volatile compound is present
in sea water in aqueous form and it is produced by phytoplankton. Some of this
DMS is ventilated to the atmosphere. The total flux to the atmosphere in models
is calculated using a seawater DMS...
Dimethylsulfide (DMS) emitted from the ocean makes a significant global contribution to natural marine aerosol and cloud condensation nuclei and, therefore, our planet's climate. Oceanic DMS concentrations show large spatiotemporal variability, but observations are sparse, so products describing global DMS distribution rely on interpolation or mode...
Near-surface mercury and ozone depletion events occur in the lowest part of the atmosphere during Arctic spring. Mercury depletion is the first step in a process that transforms long-lived elemental mercury to more reactive forms within the Arctic that are deposited to the cryosphere, ocean, and other surfaces, which can ultimately get integrated i...
Mercury is a pollutant of global concern, especially in the Arctic, where high levels are found in biota despite its remote location. Mercury is transported to the Arctic via atmospheric, oceanic and riverine long-range pathways, where it accumulates in aquatic and terrestrial ecosystems. While present-day mercury deposition in the Arctic from natu...
Polar environments are among the fastest changing regions on the planet. It is a crucial time to make significant improvements in our understanding of how ocean and ice biogeochemical processes are linked with the atmosphere. This is especially true over Antarctica and the Southern Ocean where observations are severely limited and the environment i...
Chlorine radicals are strong atmospheric oxidants known to play an important role in the depletion of surface ozone and the degradation of methane in the Arctic troposphere. Initial oxidation processes of chlorine produce chlorine oxides, and it has been speculated that the final oxidation steps lead to the formation of chloric (HClO3) and perchlor...
Dimethylsulfide (DMS) emitted from the ocean makes a significant global contribution to natural marine aerosol and cloud condensation nuclei, and therefore our planet’s climate. Oceanic DMS concentrations show large spatiotemporal variability, but observations are sparse, so products describing global DMS distribution rely on interpolation or model...
We present an updated estimation of the bottom-up global surface seawater dimethyl sulfide (DMS) climatology ‘DMS-Rev3’. The update includes a large input dataset of 873,539 observations and has significant improvements in the data unification, filtering, and an upgraded smoothing algorithm based on observed DMS variability length scales (VLS). Thi...
Unlike bromine, the effect of iodine chemistry on the Arctic surface ozone budget is poorly constrained. We present ship-based measurements of halogen oxides in the high Arctic boundary layer from the sunlit period of March to October 2020 and show that iodine enhances springtime tropospheric ozone depletion. We find that chemical reactions between...
A validation study of satellite retrieved ozone profiles (Hulswar et al., 2020) was carried out over Indian Antarctic station ‘Bharati’ which indicated that there was a significant positive bias in the measurements by Microwave Limb Sounder (MLS) instrument onboard Aura satellite. This has implications for the estimations of ozone recovery over Ant...
We updated estimation of the bottom-up global surface seawater dimethyl sulphide (DMS) climatology to ‘DMS-Rev3’ (Hulswar et al., 2022). It is third of its kind and includes five significant changes from the last climatology, ‘L11’ (Lana et al., 2011) that was released about a decade ago. The update includes a much larger input dataset and includes...
This paper presents an updated estimation of the bottom-up global surface seawater dimethyl sulfide (DMS) climatology. This update, called DMS-Rev3, is the third of its kind and includes five significant changes from the last climatology, L11 (Lana et al., 2011), that was released about a decade ago. The first change is the inclusion of new observa...
Mercury, a global contaminant, enters the stratosphere through convective uplift, but its chemical cycling in the stratosphere is unknown. We report the first model of stratospheric mercury chemistry based on a novel photosensitized oxidation mechanism. We find two very distinct Hg chemical regimes in the stratosphere: in the upper stratosphere, ab...
The Indian Ocean is coupled to atmospheric dynamics and chemical composition via several unique mechanisms, such as the seasonally varying monsoon circulation. During the winter monsoon season, high pollution levels are regularly observed over the entire northern Indian Ocean, while during the summer monsoon, clean air dominates the atmospheric com...
Loss of stratospheric ozone has occurred over the last half a century due to catalytic destruction by halogen-containing anthropogenic compounds. Saturated ozone loss events, when the ozone concentrations decreased to less than or equal to 1 mPa (>95% ozone loss), were studied across nine stations in Antarctica using the Microwave Limb Sounder (MLS...
This paper presents an updated estimation of the bottom-up global surface seawater dimethyl sulfide (DMS) climatology. This update, called DMS-Rev3, is the third of its kind and includes five significant changes from the last climatology, ‘L11’ (Lana et al., 2011) that was released about a decade ago. The first change is the inclusion of new observ...
We updated the estimation of the bottom-up global surface seawater dimethyl sulfide (DMS) with an updated, DMS-Rev3 climatology. It is the third of its kind and includes five significant changes from the last climatology, ‘L11’ (Lana et al., 2011) that was released about a decade ago. The first change is the inclusion of new observations that have...
Iodine plays a vital role in oxidation chemistry over Antarctica, with past observations showing highly elevated levels of iodine oxide (IO) leading to severe depletion of boundary layer ozone in West Antarctica. Here, we present MAX-DOAS-based (multi-axis differential absorption spectroscopy) observations of IO over three summers (2015–2017) at th...
Recent observations have shown the ubiquitous presence of iodine oxide (IO) in the Indian Ocean marine boundary layer (MBL). In this study, we use the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem version 3.7.1), including halogen (Br, Cl, and I) sources and chemistry, to quantify the impacts of the observed levels of iodi...
In situ ozonesonde observations across nine Antarctic stations were used to validate the vertical profiles retrieved by the satellite-based Microwave Limb Sounder (MLS) instrument from 2004 to 2019. Intra-annual variations in the ozone concentration, along with the shape of the vertical profiles are well reproduced by the MLS with differences in th...
An updated estimation of the bottom-up global surface seawater dimethyl sulphide (DMS) climatology, DMS-Rev3, is the third of its kind and includes five significant changes from the last climatology, ‘L11’ (Lana et al., 2011) that was released about a decade ago. The first change is the inclusion of new observations that have become available over...
Iodine is a critical trace element involved in many diverse and important processes in the Earth system. The importance of iodine for human health has been known for over a century, with low iodine in the diet being linked to goitre, cretinism and neonatal death. Research over the last few decades has shown that iodine has significant impacts on tr...
Ocean‐going ships supply products from one region to another and contribute to the world’s economy. Ship exhaust contains many air pollutants and results in significant changes in marine atmospheric composition. The role of reactive halogen species (RHS) in the troposphere has received increasing recognition and oceans are the largest contributors...
Year-long observations of nitrogen dioxide (NO2) and formaldehyde (HCHO) using the Multi-Axis Differential Absorption Spectroscopy (MAX-DOAS) technique are reported from Pune City, India. We studied the diurnal and seasonal variations, effect of biomass burning and the weekend effect on both species. NO2 diurnal profiles displayed a traffic induced...
The Indian Ocean is coupled to atmospheric dynamics, transport and chemical composition via several unique mechanisms, such as the seasonally varying monsoon circulation. During the winter monsoon season, high pollution levels are regularly observed over the entire northern Indian Ocean, while during the summer monsoon, clean air dominates the atmo...
Recent observations have shown the ubiquitous presence of iodine oxide (IO) in the Indian Ocean marine boundary layer (MBL). In this study, we use the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem version 3.7.1), including halogens (Br, Cl and I) sources and chemistry, to quantify the impacts of the observed levels of iodi...
Iodine plays a vital role in oxidation chemistry over Antarctica, with past observations showing highly elevated levels of iodine oxide (IO) leading to severe depletion of boundary layer ozone in West Antarctica. Here, we present multi axis differential absorption spectroscopy (MAX-DOAS) based observations of IO over three summers (2015–2017) at th...
Iodine chemistry has noteworthy impacts on the oxidising capacity of the marine boundary layer (MBL) through the depletion of ozone (O3) and changes to HOx (OH/HO2) and NOx (NO/NO2) ratios. Hitherto, studies have shown that the reaction of atmospheric O3 with surface seawater iodide (I-) contributes to the flux of iodine species into the MBL mainly...
The last bottom-up climatology of sea-surface dimethyl-sulphide (DMS) concentrations, L11, was revised using an updated surface DMS database. The algorithm for the creation of the climatology was also improved with the incorporation of dynamic Longhurst provinces for more realistic monthly and seasonal biogeochemical response. Additionally, observe...
Marine iodine speciation has emerged as a potential tracer of primary productivity, sedimentary inputs, and ocean oxygenation. The reaction of iodide with ozone at the sea surface has also been identified as the largest deposition sink for tropospheric ozone and the dominant source of iodine to the atmosphere. Accurate incorporation of these proces...
Ozonesonde data between February 2016 and July 2019 from the Indian Antarctic station ‘Bharati’ were used for validation of total ozone columns (TCOs) and vertical profiles from satellite-based Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) instruments. Bharati falls in and out of the ‘ozone hole’ over Antarctica due to the dyna...
Abstract. Iodine chemistry has noteworthysignificant impacts on the oxidising capacity of the marine boundary layer (MBL) through the depletion of ozone (O<sub>3</sub>) and changes to HO<sub>x</sub> (OH/HO<sub>2</sub>) and NO<sub>x</sub> (NO/NO<sub>2</sub>) ratios. Hitherto, studies have shown that the reaction of atmospheric O<sub>3</sub> with sur...
Ozonesonde data between February 2016 and July 2019 from the Indian Antarctic station ‘Bharati’ were used for validation of total ozone columns (TCOs) and vertical profiles from satellite-based Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) instruments. Bharati falls in and out of the ‘ozone hole’ over Antarctica due to the dyna...