Other affiliations: National Physical Laboratory of India, University College of Engineering, Goddard Space Flight Center ...read more
Bio: Abhijit Mitra is an academic researcher from University of Calcutta. The author has contributed to research in topics: Ionosphere & Ionization. The author has an hindex of 32, co-authored 227 publications receiving 5315 citations. Previous affiliations of Abhijit Mitra include National Physical Laboratory of India & University College of Engineering.
Papers published on a yearly basis
Scripps Institution of Oceanography1, Max Planck Society2, Council of Scientific and Industrial Research3, Leibniz Association4, Indiana University5, Georgia Institute of Technology6, University of California, San Diego7, University of Hawaii at Manoa8, Oregon State University9, National Center for Atmospheric Research10, Met Office11, Goddard Space Flight Center12, Desert Research Institute13, Physical Research Laboratory14, Florida State University15, Urbana University16, Lawrence Berkeley National Laboratory17, Climate Monitoring and Diagnostics Laboratory18, University of Cambridge19, University of Miami20, Pacific Northwest National Laboratory21, Université Paris-Saclay22, University of Alaska Fairbanks23, National Oceanic and Atmospheric Administration24, Complutense University of Madrid25
TL;DR: The Indian Ocean Experiment (INDOEX) documented this Indo-Asian haze at scales ranging from individual particles to its contribution to the regional climate forcing as discussed by the authors, and integrated the multiplatform observations (satellites, aircraft, ships, surface stations, and balloons) with one-and four-dimensional models to derive the regional aerosol forcing resulting from the direct, the semidirect and the two indirect effects.
Abstract: Every year, from December to April, anthropogenic haze spreads over most of the North Indian Ocean, and South and Southeast Asia. The Indian Ocean Experiment (INDOEX) documented this Indo-Asian haze at scales ranging from individual particles to its contribution to the regional climate forcing. This study integrates the multiplatform observations (satellites, aircraft, ships, surface stations, and balloons) with one- and four-dimensional models to derive the regional aerosol forcing resulting from the direct, the semidirect and the two indirect effects. The haze particles consisted of several inorganic and carbonaceous species, including absorbing black carbon clusters, fly ash, and mineral dust. The most striking result was the large loading of aerosols over most of the South Asian region and the North Indian Ocean. The January to March 1999 visible optical depths were about 0.5 over most of the continent and reached values as large as 0.2 over the equatorial Indian ocean due to long-range transport. The aerosol layer extended as high as 3 km. Black carbon contributed about 14% to the fine particle mass and 11% to the visible optical depth. The single-scattering albedo estimated by several independent methods was consistently around 0.9 both inland and over the open ocean. Anthropogenic sources contributed as much as 80% (±10%) to the aerosol loading and the optical depth. The in situ data, which clearly support the existence of the first indirect effect (increased aerosol concentration producing more cloud drops with smaller effective radii), are used to develop a composite indirect effect scheme. The Indo-Asian aerosols impact the radiative forcing through a complex set of heating (positive forcing) and cooling (negative forcing) processes. Clouds and black carbon emerge as the major players. The dominant factor, however, is the large negative forcing (-20±4 W m^(−2)) at the surface and the comparably large atmospheric heating. Regionally, the absorbing haze decreased the surface solar radiation by an amount comparable to 50% of the total ocean heat flux and nearly doubled the lower tropospheric solar heating. We demonstrate with a general circulation model how this additional heating significantly perturbs the tropical rainfall patterns and the hydrological cycle with implications to global climate.
Max Planck Society1, Scripps Institution of Oceanography2, National Center for Atmospheric Research3, Georgia Institute of Technology4, University of Maryland, College Park5, Utrecht University6, University of Innsbruck7, National Oceanic and Atmospheric Administration8, Physical Research Laboratory9, National Physical Laboratory10, Lawrence Berkeley National Laboratory11, University of California, Riverside12, Stockholm University13
TL;DR: It is shown that agricultural burning and especially biofuel use enhance carbon monoxide concentrations and Fossil fuel combustion and biomass burning cause a high aerosol loading, which gives rise to extensive air quality degradation.
Abstract: The Indian Ocean Experiment (INDOEX) was an international, multiplatform field campaign to measure long-range transport of air pollution from South and Southeast Asia toward the Indian Ocean during the dry monsoon season in January to March 1999. Surprisingly high pollution levels were observed over the entire northern Indian Ocean toward the Intertropical Convergence Zone at about 6°S. We show that agricultural burning and especially biofuel use enhance carbon monoxide concentrations. Fossil fuel combustion and biomass burning cause a high aerosol loading. The growing pollution in this region gives rise to extensive air quality degradation with local, regional, and global implications, including a reduction of the oxidizing power of the atmosphere.
TL;DR: It is projected that malaria is likely to persist in Orissa, West Bengal and southern parts of Assam in 2050s, however, it may shift from the central Indian region to the south western coastal states of Maharashtra, Karnataka and Kerala.
Abstract: The focus in this paper is to understand the likely in flu ence of climate change on vector production and malaria transmission in India. A set of transmission wind ows typic al to India have been deve loped, in terms of different temperature ranges for a particular range of relative hu midity, by analysing the present climate trends and corresponding malaria incidences. Using these transmission window criteria, the most endemic malarious regions emerge as the central and eastern In dian regions of the country covering Madhya Pra desh, Jharkhand, Chhatisgarh, Orissa, West Be n gal and Assam in the current climate conditions. Appl ying the same criteria under the future climate change conditions (results of HadRM2 u sing 1S92a scenario) in 2050s, it is projected that malaria is likely to pe rsist in Orissa, West Bengal and southern parts of Assam, bordering north of West Bengal. Ho w ever, it may shift from the central Indian region to the south western coastal states of Maharashtra, Karn ataka and Kerala. Also the northern states, in cluding Himachal Pradesh and Arunachal Pradesh, Nagaland, Manipur and Mizoram in the northeast may become malaria prone. The duration of the transmission wi n dows is likely to widen in northern and western states and shorten in the southern states. The extent of vu lnerability due to malaria depends on the prevailing socio -economic cond i-tions . The increase or decrease in vulnerability due t o climate change in the 205 0s will therefore d epend on t he developmental path followed by India. Therefore it is important to understand the current adaptation mechanisms and improve the coping c apacities of the vulnerable section of the population by helping to e n-hance their accessibility to health services, im proved surveillance and forecasting technol ogies. Keywords: Climate determinants, malaria incidence, P. falciparum , P. vivax , transmi ssion window, vector. C
TL;DR: In this article, an in situ experiment for wheat straw burning was undertaken for developing India specific emission factors (EFs) and the EFs of CO 2, CH 4, CO, N 2 O, NO x, NO and NO 2 were found to be 1787 ± 36, 3.6 ± 2.7, 28.1 ± 20.
Abstract: Major crops subject to field burning of crop residue (FBCR) generated an estimated 284 Tg of residue in India, of which 40% was contributed by wheat in the year 2000. About 7.5% of this total generated wheat straw was subjected to on-site burning, that is expected to emit large amounts of trace gases and particulate matter (PM) to the atmosphere, whose country-specific estimates and emission factors (EFs) are presently not available. An in situ experiment for wheat straw burning was undertaken for developing India specific EFs. The EFs of CO 2 , CH 4 , CO, N 2 O , NO x , NO and NO 2 were found to be 1787 ± 36 , 3.6 ± 2.7 , 28.1 ± 20.1 , 0.74 ± 0.46 , 1.70 ± 1.68 , 0.78 ± 0.71 and 0.56 ± 0.47 g kg - 1 , whereas those for organic carbon (OC), black carbon (BC) and total carbon (TC) were 0.3 ± 0.1 , 0.2 ± 0.1 , and 0.5 ± 0.2 g kg - 1 , respectively. Although these EFs have been generated from a single field experiment nevertheless they address important information gap on FBCR in the region. Further, the total emissions of CH 4 , CO 2 , CO, N 2 O , NO x , NO, NO 2 , OC, BC and TC from wheat straw burning in India for the year 2000 was estimated as 68 ± 51 , 34435 ± 682 , 541 ± 387 , 14 ± 9 , 33 ± 32 , 15 ± 14 , 11 ± 9 , 6 ± 2 , 3 ± 1 and 10 ± 4 Gg, respectively.
01 Oct 2007
University of Illinois at Urbana–Champaign1, Joint Institute for the Study of the Atmosphere and Ocean2, Cooperative Institute for Research in Environmental Sciences3, University of Leeds4, University of Oslo5, United States Environmental Protection Agency6, University of Michigan7, Pacific Northwest National Laboratory8, German Aerospace Center9, United States Department of Energy10, Max Planck Society11, University of Tokyo12, National Oceanic and Atmospheric Administration13, Forschungszentrum Jülich14, Norwegian Meteorological Institute15, Indian Institute of Technology Bombay16, China Meteorological Administration17, Peking University18, Met Office19, Desert Research Institute20, Clarkson University21, Stanford University22, European Centre for Medium-Range Weather Forecasts23, International Institute of Minnesota24, Goddard Institute for Space Studies25, Yale University26, University of Washington27, University of California, Irvine28
TL;DR: In this paper, the authors provided an assessment of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice.
Abstract: Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr−1 in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m−2 with 90% uncertainty bounds of (+0.08, +1.27) W m−2. Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m−2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m−2 with 90% uncertainty bounds of +0.17 to +2.1 W m−2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m−2, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (−0.50 to +1.08) W m−2 during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (−0.06 W m−2 with 90% uncertainty bounds of −1.45 to +1.29 W m−2). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.
TL;DR: Human activities are releasing tiny particles (aerosols) into the atmosphere that enhance scattering and absorption of solar radiation, which can lead to a weaker hydrological cycle, which connects directly to availability and quality of fresh water, a major environmental issue of the 21st century.
Abstract: Human activities are releasing tiny particles (aerosols) into the atmosphere. These human-made aerosols enhance scattering and absorption of solar radiation. They also produce brighter clouds that are less efficient at releasing precipitation. These in turn lead to large reductions in the amount of solar irradiance reaching Earth's surface, a corresponding increase in solar heating of the atmosphere, changes in the atmospheric temperature structure, suppression of rainfall, and less efficient removal of pollutants. These aerosol effects can lead to a weaker hydrological cycle, which connects directly to availability and quality of fresh water, a major environmental issue of the 21st century.
TL;DR: The second most important contribution to anthropogenic climate warming, after carbon dioxide emissions, was made by black carbon emissions as mentioned in this paper, which is an efficient absorbing agent of solar irradiation that is preferentially emitted in the tropics and can form atmospheric brown clouds in mixture with other aerosols.
Abstract: Black carbon in soot is an efficient absorbing agent of solar irradiation that is preferentially emitted in the tropics and can form atmospheric brown clouds in mixture with other aerosols. These factors combine to make black carbon emissions the second most important contribution to anthropogenic climate warming, after carbon dioxide emissions.
TL;DR: In this paper, the AERONET network of ground-based radiometers were used to remotely sense the aerosol absorption and other optical properties in several key locations, and the results showed robust differentiation in both the magnitude and spectral dependence of the absorption, a property driving aerosol climate forcing.
Abstract: Aerosol radiative forcing is a critical, though variable and uncertain, component of the global climate. Yet climate models rely on sparse information of the aerosol optical properties. In situ measurements, though important in many respects, seldom provide measurements of the undisturbed aerosol in the entire atmospheric column. Here, 8 yr of worldwide distributed data from the AERONET network of ground-based radiometers were used to remotely sense the aerosol absorption and other optical properties in several key locations. Established procedures for maintaining and calibrating the global network of radiometers, cloud screening, and inversion techniques allow for a consistent retrieval of the optical properties of aerosol in locations with varying emission sources and conditions. The multiyear, multi-instrument observations show robust differentiation in both the magnitude and spectral dependence of the absorption—a property driving aerosol climate forcing, for desert dust, biomass burning, urban‐industrial, and marine aerosols. Moreover, significant variability of the absorption for the same aerosol type appearing due to different meteorological and source characteristics as well as different emission characteristics are observed. It is expected that this aerosol characterization will help refine aerosol optical models and reduce uncertainties in satellite observations of the global aerosol and in modeling aerosol impacts on climate.