About
172
Publications
58,917
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Introduction
Additional affiliations
July 2016 - present
July 2006 - September 2011
October 2011 - July 2016
Position
- Professor (Assistant) and Head Max Planck Partner Group at IIT Madras
Description
- I am currently heading a research group with primary research interest in Aerosol impact interaction climate and human health. The techniques we apply include field measurement campaign, laboratory studies, and numerical model stimulations.
Education
June 2002 - July 2006
Indian Institute of Tropical Meteorology (Pune University)
Field of study
- Atmospheric Chemistry and Physics, Meteorology
Publications
Publications (172)
Plain Language Summary
Air pollution from human activities and biomass burning is a significant issue in India. To understand the efficacy of current efforts, a computer model is used to study the projected levels of carbonaceous aerosols (measured as optical depth) from 2000 to 2100. The results suggest that emissions are expected to decrease afte...
The central Arctic cryosphere is influenced by the Arctic amplification (AA) and is warming faster than the lower latitudes. AA affects the formation, loss, and transport of aerosols. Efforts to assess the underlying processes determining aerosol variability are currently limited due to the lack of ground-based and space-borne aerosol observations...
The Arctic is currently warming rapidly, at a rate four times higher than the global average. This warming has significant consequences, leading to increased precipitation in the Arctic. Aerosols play a crucial role in cloud formation, cloud condensation nuclei (CCNs) and ice-nucleating particles (INPs), influencing rain and snowfall. However, unce...
Anthropogenic mercury emissions pose significant risks to both human health and ecosystems, particularly when transformed into methylmercury. India stands as the second-largest contributor to mercury emissions, estimated at 144.7 tonnes of Hg/year, with uncertainties ranging from 75 to 330 Mg/year. India ratified the Minamata Convention in 2018, co...
Understanding the complex interactions between atmospheric aerosols and water vapor in subsaturated regions of the atmosphere is crucial for modeling and predicting aerosol–cloud–radiation–climate interactions. However, the microphysical mechanisms of these interactions for ambient aerosols remain poorly understood. For this study, size-resolved sa...
Air pollution caused by various anthropogenic activities and biomass burning continues to be a major problem in India. To assess the effectiveness of current air pollution mitigation measures, we used a 3D global chemical transport model to analyze the projected optical depth of carbonaceous aerosol (AOD) in India under representative concentration...
The central Arctic cryosphere is influenced by the Arctic Amplification (AA) and is warming faster than the lower latitudes. AA affects the formation, loss and transport of aerosols. Efforts to assess the underlying processes determining aerosol variability are currently limited due to the lack of ground-based and space-borne aerosol observations w...
This study proposes the relationship between fungal bioaerosols and biotic stress on crops using a case study on wheat leaf rust reported from northern India. We sampled and quantified the size-resolved fungal bioaerosols using the next-generation sequencing technique from a wheat crop field during winter. Puccinia recondita, the fungal pathogen th...
The climate in the Arctic has warmed much more quickly in the last 2 to 3 decades than at the mid-latitudes, i.e., during the Arctic amplification (AA) period. Radiative forcing in the Arctic is influenced both directly and indirectly by aerosols. However, their observation from ground or airborne instruments is challenging, and thus measurements a...
Tropospheric chlorine chemistry can strongly impact the atmospheric oxidation capacity and composition, especially in urban environments. To account for these reactions, the gas- and aqueous-phase Cl chemistry of the community atmospheric chemistry box model Chemistry As A Boxmodel Application/Module Efficiently Calculating the Chemistry of the Atm...
Comprehending the intricate interplay between atmospheric aerosols and water vapour in subsaturated regions is vital for accurate modelling of aerosol–cloud–radiation–climate dynamics. But the microphysical mechanisms governing these interactions with ambient aerosols remain inadequately understood. Here we report results from high-altitude, relati...
Microplastics (MPs) in the atmosphere can undergo long-range transport from emission regions to pristine terrestrial and oceanic ecosystems. Due to their inherent toxic and hazardous characteristics, MPs pose serious risks to both human well-being and the equilibrium of ecosystem. The present study outlines the comprehensive characterization, spann...
Indian subcontinent witnessed a rise in surface air temperature (SAT) in recent decades, during the summer months of March, April and May. The monsoon core region (MCR) of India experiences a hot and humid climate, with temperatures typically highest in May and June before the onset of the monsoon. Global climate model (GCM) simulations of SAT are...
The climate effects of atmospheric aerosol particles serving as cloud condensation nuclei (CCN) depend on chemical composition and hygroscopicity, which are highly variable on spatial and temporal scales. Here we present global CCN measurements, covering diverse environments from pristine to highly polluted conditions. We show that the effective ae...
The COVID lockdown presented an interesting opportunity to study the anthropogenic emissions from different sectors under relatively cleaner conditions in India. The complex interplays of power production, industry, and transport could be dissected due to the significantly reduced influence of the latter two emission sources. Here, based on measure...
This study proposes the relationship between fungal bioaerosols and biotic stress on crops using a case study on wheat leaf rust reported from northern India. We sampled and quantified the size-resolved fungal bioaerosols using the Next-Generation Sequencing technique from a wheat crop field during winter. Puccinia recondita , the fungal pathogen t...
The Arctic is a unique part of the Earth system that is currently undergoing a warming phase called the Arctic Amplification (AA). Changes in aerosol abundance and composition are under the influence of the AA and may be, in turn, important drivers to the AA. However, their ground and space observations are particularly difficult and spatio-tempora...
Tropospheric chlorine chemistry can strongly impact the atmospheric oxidation capacity and composition, especially in urban environments. To account for these reactions, the gas-and aqueous-phase Cl chemistry of the community atmospheric chemistry box model CAABA/MECCA has been extended. In particular, an explicit mechanism for ClNO 2 formation fol...
The Arctic climate has changed significantly over the past two to three decades. Aerosols play various roles in the radiative forcing in the Arctic, both directly and indirectly, depending on the changes in loading and composition. However, their observation from the ground or with airborne instruments is challenging and thus measurements are spars...
Aerosol-cloud-precipitation interaction represents the largest uncertainty in climate change’s current and future understanding. Therefore, aerosol properties affecting the cloud and precipitation formation and their accurate estimation is a first step in developing improved parameterizations for the prognostic climate models. Over the last couple...
Dispersion and atmospheric transport of fungal bioaerosols help fungal migration and colonization worldwide. The particle size of fungal propagules mainly controls this and influences the taxonomic composition of fungal bioaerosols in a region. The study reports the size-resolved genomic characterization of the pathogenic and non-pathogenic fungal...
The COVID lockdown presented a unique opportunity to study the anthropogenic emissions from different sectors under relatively cleaner conditions in India. The complex interplays of power production, industry, and transport could be dissected due to the significantly reduced influence of the latter two emission sources. Here, based on measurements...
The acidity of atmospheric particles can promote specific chemical processes that result in the production of extra condensed phases from lesser volatile species (secondary fine particulate matter), change the optical and water absorption characteristics of particles, and enhance trace metal solubility that can function as essential nutrients in nu...
Black carbon (BC) aerosols critically impact the climate and hydrological cycle. The impact of anthropogenic emissions and coastal meteorology on BC dynamics, however, remains unclear over tropical India, a globally identified hotspot. In this regard, we have performed in situ measurements of BC over a megacity (Chennai, 12° 59′ 26.5″ N, 80° 13′ 51...
High cloud forming potential of anthropogenic sulfate aerosols arising from SO2 emissions of a coal-fired power plant during relatively cleaner conditions of Covid lockdown in India
Atmospheric trace gases play pivotal role in atmospheric chemistry, climate, and air quality. While greenhouse gases (e.g., carbon dioxide) influence the earth's radiative forcing, others (e.g., tropospheric ozone) are crucial in atmospheric chemistry and air quality. Thus, understanding the detailed underlying mechanisms and their variability is v...
Purpose of Review
Fine particulate matter (PM2.5) and ground-level ozone (O3) pose a significant risk to human health. The World Health Organization (WHO) has recently revised healthy thresholds for both pollutants. The formation and evolution of PM2.5 and O3 are however governed by complex physical and multiphase chemical processes, and therefore,...
Evaluating and quantifying the scientific output of a researcher is a complex problem that may not benefit from standardized or uniformly accepted solutions. Over the past few decades, various indices, including the most popular h-index, have been introduced for assessing the output and quality of research publications. The uniform application of a...
Aerosol Liquid Water Content (ALWC), a ubiquitous component of atmospheric aerosols, modulates atmospheric chemistry through aerosol surface reactions and reduces the atmospheric visibility. However, the complex dependency of ALWC on aerosol chemistry and relative humidity (RH) in the Indian region remains poorly characterized. Here, we combine ava...
The occurrences of pollution episodes have brought out the strong linkages of pollution with health subsequently catalysing numerous regulations worldwide. Pollution episodes have been driven by a variety of mechanisms such as accidental large emission, trapping of pollution by stagnant meteorology and intense photochemistry involving strong anthro...
Black Carbon (BC) aerosols critically impact the climate and hydrological cycle. The impact of anthropogenic emissions and coastal meteorology on BC dynamics, however, remain unclear over tropical India, a globally identified hotspot. In this regard, we have performed in situ measurements of BC over a megacity (Chennai, 12°59'26.5"N, 80°13'51.8"E)...
The interaction between water vapor and atmospheric aerosol leads to enhancement in aerosol water content, which facilitates haze development, but its concentrations, sources, and impacts remain largely unknown in polluted urban environments. Here, we show that the Indian capital, Delhi, which tops the list of polluted capital cities, also experien...
Gaseous and particulate chlorine species play an important role in modulating tropospheric oxidation capacity, aerosol water uptake, visibility degradation, and human health. The lack of recent global continental chlorine emissions has hindered modeling studies of the role of chlorine in the atmosphere. Here, we develop a comprehensive global emiss...
The Indo‐Gangetic Plain (IGP) is one of the dominant sources of air pollution worldwide. During winter, the variations in planetary boundary layer (PBL) height, driven by a strong radiative thermal inversion, affect the regional air pollution dispersion. To date, measurements of aerosol‐water vapor interactions, especially cloud condensation nuclei...
Machine learning (ML) has emerged as a powerful technique in the Earth system science, nevertheless, its potential to model complex atmospheric chemistry remains largely unexplored. Here, we applied ML to simulate the variability in urban ozone (O3) over Doon valley of the Himalaya. The ML model, trained with past variations in O3 and meteorologica...
Air pollution in urban environments has been shown to have a negative impact on air quality and human health, particularly in megacities. Over recent decades, Delhi, India, has suffered high atmospheric pollution, with significant particulate matter (PM) concentrations as a result of anthropogenic activities. Organic aerosols (OAs) are composed of...
The rapidly increasing industrialization and urbanization, in combination with under representation of in-situ measurements, especially Volatile Organic Compounds (VOCs), has posed serious challenges in understanding air quality and atmospheric chemistry over India. Here we present yearlong measurements of VOCs, carried out during March 2014–Februa...
The human microbiome plays a crucial role in health and disease conditions. These microbiomes constitute a structured, coordinated microbial network throughout the human body. The oral cavity harbors one of the extensively diverse bacteria in the human system. Although many studies emphasize bacteriome and its interaction with the host system, very...
Ambient PM10 (particulate matter with aerodynamic diameter ≤ 10 µm) samples were collected and characterized from July 2012 to August 2013 with the objective to evaluate the variation in elemental concentration and use the same as markers for source apportionment and health risk assessment for the first time over Bhubaneswar, India. The yearly aver...
The sensitive ecosystem of the central Himalayan (CH) region, which is experiencing enhanced stress from anthropogenic forcing, requires adequate atmospheric observations and an improved representation of the Himalaya in the models. However, the accuracy of atmospheric models remains limited in this region due to highly complex mountainous topograp...
Many cities in India experience severe deterioration of air quality in winter. Particulate matter is a key atmospheric pollutant that impacts millions of people. In particular, the high mass concentration of particulate matter reduces visibility, which has severely damaged the economy and endangered human lives. But the underlying chemical mechanis...
Tropical cyclones (TCs) that make landfall over India’s east coast are responsible for significant loss of life along affected coastlines. TCs forming over the Bay of Bengal (BoB) region in October, November, and December have, in the past, intensified significantly at the time of landfall. The effects of climate change on TCs of different strength...
Dental caries is the most prevalent oral disease affecting nearly 70% of children in India and elsewhere. Micro-ecological niche based acidification due to dysbiosis in oral microbiome are crucial for caries onset and progression. Here we report the tooth bacteriome diversity compared in Indian children with caries free (CF), severe early childhood...
The recent pandemic caused by the 2019 outbreak of novel coronavirus (2019-nCoV or COVID-19) has affected
more than 3.0 million people resulting ~ 212,000 deaths across 215 countries/territories as on 28th April 2020. The
importation of the cases owing to enormous international travels from the affected countries is the foremost
reason for local cy...
Coronaviruses are single stranded RNA viruses usually present in bats (reservoir hosts), and are generally lethal, highly transmissible, and pathogenic viruses causing sever morbidity and mortality rates in human. Several animals including civets, camels, etc. have been identified as intermediate hosts enabling effective recombination of these viru...
Air pollution in urban environments has been shown to have a negative impact on air quality and human health, particularly in megacities. Over recent decades, Delhi, India has suffered high atmospheric pollution, with significant particulate matter (PM) concentrations as result of anthropogenic activities. Organic aerosols (OA) are composed of thou...
Ambient air consists of bioaerosols that constitute many microbes from biosphere due to natural and anthropogenic activities. Size-dependent ambient measurements of bioaerosols at two seminatural and three anthropogenic coastal sites in southern tropical India were taken during the summer 2017. All the five sites considered in this study considerab...
Particle number size distributions in the diameter range of 5 nm–34 µm were measured in tropical southern India during the transition season from May (pre-monsoon) to June–July (monsoon). Averaged over the entire measurement period, the particle number size distributions were bimodal with a total particle number concentration of NTot = (4.5 ± 2.7)...
Airborne fungi cause more crop diseases and damage to major crops – such as rice, potato, tomato and ginger – than bacteria and viruses, says a study by Indian Institute of Technology Madras researchers1.
Rising temperatures, they add, might increase the prevalence of fungal diseases, which are likely to extend to the Himalayan regions and the Wes...
Fine particulate matter (PM2.5 , aerodynamic diameter ≤2.5 µm) impacts the climate, reduces visibility and severely influences human health. The Indo-Gangetic Plain (IGP), home to about one-seventh of the world’s total population and a hotspot of aerosol loading, observes strong enhancements in the pM concentrations towards winter. We performed hig...
Atmospheric bioaerosols, which contain a diverse group of various biological materials, also include pathogenic microorganisms such as viruses, bacteria, and fungal spores. The dispersal of various pathogens negatively impacts the human and ecosystem health. While the impact of pathogenic bacteria and viruses on human and ecosystem health is well d...
The novel coronavirus, since its first outbreak in December, has, up till now, affected approximately 114,542 people across 115 countries. Many international agencies are devoting efforts to enhance the understanding of the evolving COVID-19 outbreak on an international level, its influences, and preparedness. At present, COVID-19 appears to affect...
The sensitive and fragile ecosystem of the central Himalayan (CH) region, experiencing enhanced anthropogenic pressure, requires adequate atmospheric observations and an improved representation of Himalaya in the models. However, the accuracies of atmospheric models remain limited here due to highly complex mountainous topography. This article deli...
Dry deposition is a major sink for tropospheric ozone, nevertheless, studies on its effects on ozone distribution are very limited over the rapidly developing South Asian region. We performed numerical simulations using the regional model WRF-Chem (Weather Research and Forecasting Model coupled with chemistry) to investigate the effect of dry depos...
Supplementary material to "Revisiting the crop yield loss in India attributable to ozone"
Crop Yield Loss (CYL) due to surface ozone substantially affects the Indian economy and the food availability for
a billion residents. Nevertheless, the incurring losses over India remain uncertain due to limited measurements
and significant uncertainties in the surface O3 simulated by chemistry-transport models, amongst other causes.
Here, we revi...