We describe and show results from a series of field campaigns that used balloonborne instruments launched from India and Saudi Arabia during the summers 2014–17 to study the nature, formation, and impacts of the Asian Tropopause Aerosol Layer (ATAL). The campaign goals were to i) characterize the optical, physical, and chemical properties of the ATAL; ii) assess its impacts on water vapor and ozone; and iii) understand the role of convection in its formation. To address these objectives, we launched 68 balloons from four locations, one in Saudi Arabia and three in India, with payload weights ranging from 1.5 to 50 kg. We measured meteorological parameters; ozone; water vapor; and aerosol backscatter, concentration, volatility, and composition in the upper troposphere and lower stratosphere (UTLS) region. We found peaks in aerosol concentrations of up to 25 cm–3 for radii > 94 nm, associated with a scattering ratio at 940 nm of ∼1.9 near the cold-point tropopause. During medium-duration balloon flights near the tropopause, we collected aerosols and found, after offline ion chromatography analysis, the dominant presence of nitrate ions with a concentration of about 100 ng m–3. Deep convection was found to influence aerosol loadings 1 km above the cold-point tropopause. The Balloon Measurements of the Asian Tropopause Aerosol Layer (BATAL) project will continue for the next 3–4 years, and the results gathered will be used to formulate a future National Aeronautics and Space Administration–Indian Space Research Organisation (NASA–ISRO) airborne campaign with NASA high-altitude aircraft.

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We evaluated three emission inventories of black carbon (BC) using Lagrangian particle dispersion model simulations and BC observations from a rural site in southern India (Gadanki; 13.48 • N, 79.18 • E) from 2008 to 2012. We found that 93 to 95 % of the BC load at the observation site originated from emissions in India and the rest from the neighbouring countries and shipping. A substantial fraction (33 to 43 %) of the BC was transported from northern India. Wet deposition is found to play a minor role in reducing BC mass at the site because of its proximity to BC sources during rainy season and relatively short rainy season over western and northern parts of India. Seasonally, the highest BC concentration (approx. 3.3 µg m −3 ) is observed during winter, followed by spring (approx. 2.8 µg m −3 ). While the model reproduced well the seasonal cycle, the modelled BC concentrations are significantly lower than observed values, especially in spring. The model bias is correlated to fire radiative power -a proxy of open biomass burning activity. Using potential emission sensitivity maps derived using the model, we suggest that underestimation of BC mass in the model during spring is due to the underestimation of BC fluxes over southern India (possibly from open-biomass-burning/forest-fires). The overall performance of the model simulations using three different emission inventories (SAFAR-India, ECLIPSE and RETRO) is similar, with ECLIPSE and SAFAR-India performing marginally better as both have about 30 % higher emissions for India than RETRO. The ratio of observed to modelled annual mean BC concentration was estimated as 1.5 for SAFAR, 1.7 for ECLIPSE and 2.4 for RETRO.Published by Copernicus Publications on behalf of the European Geosciences Union. Figure 3. (a) ECLIPSE (ECLIPSE v5 + GFED v3) BC emission inventory over South Asia. (b) Difference between the ECLIPSE and RETRO emissions (ECLIPSE -RETRO). (c) Difference between ECLIPSE and SAFAR India emissions (ECLIPSE -SAFAR). Here and in rest of the paper political borders are shown for cursory region identification and may not be accurate.and Bangladesh (a map of India with state names is provided in the Supplement).The RETRO emission inventory is the outcome of the project REanalysis of the TROpospheric (RETRO) chemical composition over the past 40 years. The emission inventory for BC has two parts -one for anthropogenic emissions which includes biofuel burning, industrial combustion and www.atmos-chem-phys.net/15/1447/2015/ Atmos.

[1] Indian summer monsoon exhibits significant intraseasonal variations with active and break monsoon spells. Using MODIS data of 8 years (2000 -2007), variations of cloud and aerosol properties over the Indian region associated with the active and break spells were examined. The study shows statistically significant variations of cloud properties (cloud optical depth, cloud fraction and cloud top pressure) between active and break monsoon days over central and northeast India and the equatorial Indian Ocean. During the monsoon break spells, associated with the anomalous circulation, aerosol loading from the north Arabian Sea is transported to central India. This increase in aerosol content decreases the cloud effective radii, suggesting the indirect effect of aerosols on cloud properties. There is also an inverse relationship of cloud properties over the monsoon zone over central India and the southeast equatorial Indian Ocean, suggesting possible role of southeast equatorial Indian Ocean on the development of activebreak cycles. Citation: Ravi Kiran, V., M. Rajeevan, S. Vijaya Bhaskara Rao, and N. Prabhakara Rao (2009), Analysis of variations of cloud and aerosol properties associated with active and break spells of Indian summer monsoon using MODIS data, Geophys. Res. Lett., 36, L09706,