Black carbon (BC) is an important atmospheric aerosol constituent that affects the climate by absorbing (directly) the sunlight and modifying cloud characteristics (indirectly). Here, we present first time yearlong measurements of BC and carbon monoxide (CO) from an urban location of Guwahati located in the Brahmaputra River valley (BRV) in the northeast region of India from 1st July 2013 to 30th June 2014. Daily BC concentrations varied within the range of 2.86 to 11.56 mu g m(-3) with an annual average of 7.17 +/- 1.89 mu g m(-3), while, CO varied from 0.19 to 1.20 ppm with a mean value of 0.51 +/- 0.19 ppm during the study period. The concentrations of BC (8.37 mu g m(-3)) and CO (0.67 ppm) were similar to 39% and similar to 55% higher during the dry months (October to March) than the wet months (April to September) suggesting that seasonal changes in meteorology and emission sources play an important role in controlling these species. The seasonal Delta BC/Delta CO ratios were highest (lowest) in the pre-monsoon (winter) 18.1 +/- 1.4 mu g m(-3) ppmv(-1) (12.6 +/- 2.2 mu g m(-3) ppmv(-1)) which indicate the combustion of biofuel/biomass as well as direct emissions from fossil fuel during the pre-monsoon season. The annual BC emission was estimated to be 2.72 Gg in and around Guwahati which is about 44% lower than the mega city 'Delhi' (4.86 Gg). During the study period, the annual mean radiative forcing (RF) at the top of the atmosphere (TOA) for clear skies of BC was +9.5Wm(-2), however, the RF value at the surface (SFC) was -21.1 Wm(-2) which indicates the net warming and cooling effects, respectively. The highest RF at SFC was in the month of April (-30 Wm(-2)) which is coincident with the highest BC mass level. The BC atmospheric radiative forcing (ARF) was +30.16 (annualmean) Wm(-2) varying from +23.1 to +43.8 Wm(-2). The annualmean atmospheric heating rate (AHR) due to the BC aerosols was 0.86 K day(-1) indicates the enhancement in radiation effect over the study region. The Weather Research and Forecasting model coupled with Chemistry(WRF-Chem) captured the seasonal cycle of observed BC fairly well but underestimated the observed BC during the month of May-August. Model results show that BC at Guwahati is controlled mainly by anthropogenic emissions except during the pre-monsoon season when open biomass burning also makes a similar contribution. (C) 2016 Elsevier B.V. All rights reserved.

Existing carbon offset protocols for improved cookstoves do not require emissions testing. They are based only on estimated reductions in the use of non-renewable biomass generated by a given stove, and use simplistic calculations to convert those fuel savings to imputed emissions of carbon dioxide (CO2). Yet recent research has shown that different cookstoves vary tremendously in their combustion quality, and thus in their emissions profiles of both CO2 and other products of incomplete combustion. Given the high global warming potential of some of these non-CO2 emissions, offset protocols that do not account for combustion quality may thus not be assigning either appropriate absolute or relative climate values to different technologies. We use statistical resampling of recent emissions studies to estimate the actual radiative forcing impacts of traditional and improved cookstoves. We compare the carbon offsets generated by protocols in the four carbon markets that currently accept cookstove offsets (Clean Development Mechanism, American Carbon Registry, Verified Carbon Standard, and Gold Standard) to a theoretical protocol that also accounts for emissions of carbonaceous aerosols and carbon monoxide, using appropriate statistical techniques to estimate emissions factor distributions from the literature. We show that current protocols underestimate the climate value of many improved cookstoves and fail to distinguish between (i.e., assign equal offset values to) technologies with very different climate impacts. We find that a comprehensive carbon accounting standard would generate significantly higher offsets for some improved cookstove classes than those generated by current protocols, and would create much larger separation between different cookstove classes. Finally, we provide compelling evidence for the inclusion of renewable biomass into current protocols, and propose guidelines for the statistics needed in future emissions tests in order to accurately estimate the climate impact (and thus offsets generated by) cookstoves and other household energy technologies.

Fires impact atmospheric composition through their emissions, which range from long-lived gases to short-lived gases and aerosols. Effects are typically larger in the tropics and boreal regions but can also be substantial in highly populated areas in the northern mid-latitudes. In all regions, fire can impact air quality and health. Similarly, its effect on large-scale atmospheric processes, including regional and global atmospheric chemistry and climate forcing, can be substantial, but this remains largely unexplored. The impacts are primarily realised in the boundary layer and lower free troposphere but can also be noticeable in upper troposphere/lower stratosphere (UT/LS) region, for the most intense fires. In this review, we summarise the recent literature on findings related to fire impact on atmospheric composition, air quality and climate. We explore both observational and modelling approaches and present information on key regions and on the globe as a whole. We also discuss the current and future directions in this area of research, focusing on the major advances in emission estimates, the emerging efforts to include fire as a component in Earth system modelling and the use of modelling to assess health impacts of fire emissions.

This article presents the status of aerosols in India based on the research activities undertaken during last few decades in this region. Programs, like International Geophysical Year (IGY), Monsoon Experiment (MONEX), Indian Middle Atmospheric Program (IMAP) and recently conducted Indian Ocean Experiment (INDOEX), have thrown new lights on the role of aerosols in global change. INDOEX has proved that the effects of aerosols are no longer confined to the local levels but extend at regional as well as global scales due to occurrence of long range transportation of aerosols from source regions along with wind trajectories. The loading of aerosols in the atmosphere is on rising due to energy intensive activities for developmental processes and other anthropogenic activities. One of the significant observation of INDOEX is the presence of high concentrations of carbonaceous aerosols in the near persistent winter time haze layer over tropical Indian Ocean which have probably been emitted from the burning of fossil-fuels and biofuels in the source region. These have significant bearing on the radiative forcing in the region and, therefore, have potential to alter monsoon and hydrological cycles. In general, the SPM concentrations have been found to be on higher sides in ambient atmosphere in many Indian cities but the NOx concentrations have been found to be on lower side. Even in the haze layer over Indian Ocean and surrounding areas, the NOx concentrations have been reported to be low which is not conducive of O-3 formation in the haze/smog layer. The acid rain problem does not seem to exist at the moment in India because of the presence of neutralizing soil dust in the atmosphere. But the high particulate concentrations in most of the cities' atmosphere in India are of concern as it can cause deteriorated health conditions. (C) 2002 Elsevier Science Ltd. All rights reserved.