Regular nighttime monitoring of aerosol and other atmospheric parameters was initiated in 1985 at the Indian Institute of Tropical Meteorology, Pune. This is a tropical urban station (18°32′N, 73°51′E, 559 m AMSL), situated approximately 100 km inland from the west coast of India. The multi‐year aerosol vertical profile database, utilized in the present study, consisted of more than 1200 vertical aerosol concentration profiles. These data were collected with a computer‐controlled, bistatic, argon‐ion lidar system over a 12 year period from October 1986 to September 1998 and have been utilized to study the morphology of the nighttime atmospheric boundary layer and associated air quality. The recent climatological trend in the aerosol loading at the experimental station has also been studied. The study reveals higher pollution potential during late evenings in the winter and a total increase of about 3% in the aerosol loading over the 12 year observational period. This increase can be attributed partly due to the urban heat island effect and due to growing urbanization and industrialization, as well as to the land‐usage patterns in proximity to the experimental station. Further, it has been found that the long‐term trend in aerosol loading was not uniform, but it changed from year to year depending on meteorological parameters (precipitation, in particular) and local anthropogenic activities. The short‐term variations in aerosol loading and their relationship with concurrent meteorological parameters over the observational site are discussed also. Copyright © 2002 Royal Meteorological Society

Implications of aerosol characteristics, observed during a five-year (2004–2009) period over Pune (a tropical urban location), to short-wave radiation budget are reported. A discrete ordinate radiative transfer (DISORT) model with a code, namely, Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART), has been used to carry out the radiative transfer computations. The validity of the method is demonstrated using independent ground-based remote sensing observations. Uncertainties in the estimates are also quantified. Clear-sky forcing reveals the points that include (1) Large negative bottom-of-the-atmosphere (BOA) forcing (more than−30 Wm−2) in all the months with peaks during October, December and March when the surface forcing exceeds~−40 Wm−2, and (2) Surface forcing values are higher for pre-monsoon months, while they are comparable for winter and post-monsoon months. The top-of-the-atmosphere (TOA) forcing is found to be negative during all the seasons. Large differences between TOA and...

The international journal of Aerosol and Air Quality Research (AAQR) covers all aspects of aerosol science and technology, atmospheric science and air quality related issues.

This article reports the results of a study related to variations in columnar aerosol optical depth (AOD), total column ozone (TCO), and precipitable water content (PWC) over a high-altitude station, Sinhagad (18° 21′ N, 73° 45′ E, 1450 m above mean sea level (AMSL)), employing a microprocessor-based total ozone portable spectrometer, MICROTOPS-II, comprising both a sun photometer and ozonometer, during November 2009–April 2010. The aerosol optical depth at 500 nm (AOD_{500 nm}) portrayed seasonal variation with higher values (0.39) in summer and lower values (0.15) in winter. The TCO and PWC also exhibited lower values in winter and started increasing by the pre-monsoon season. The Ångström wavelength exponent, α, was found to be high (1.79) during February, indicating the relative dominance of accumulation-mode particles. During the summer season, the lower value (0.94) of the Ångström wavelength exponent indicates the relative dominance of coarse-mode particles. The ground-based observations from MICROTOPS-II revealed good correlation with satellite observations of the Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI). The observed short-wave solar flux at the bottom of the atmosphere decreased due to aerosol extinction and was found to be 19 and 78 W m^–2 for the winter and pre-monsoon seasons, respectively. This implies that greater concentrations of accumulation-mode particles – which are due to local anthropogenic sources – affected the down-welling radiation than those from natural sources – which are due to long-range transport processes – over the experimental location.

Black Carbon (BC) aerosols are not only substantial climate-forcing drivers but also impact human health. The spatial distribution of BC aerosols depends on the combination of anthropogenic activities and meteorological conditions. In this study, we used the India Meteorological Department (IMD) Black Carbon Observational Network datasets to assess the diurnal, seasonal, and long-term BC trends for the period, 2016–2021. The majority of the IMD’s BC monitoring stations show an overall declining trend in the BC mass concentration during the study period in India. Maximum BC concentrations are observed in the post-monsoon and winter seasons due to the stubble-burning activity and lower values of Atmospheric Boundary Layer Height (ABLH). Minimum concentrations are observed at all stations in the monsoon season due to the wet scavenging of aerosols by rain. There is a clear decrease in the BC mass concentration from winter to monsoon months and an increase in the post-monsoon months. Regional emissions from crop residue burning in the post-harvesting seasons are the main contributing factor for extremely high levels of BC mass concentration. Low wind speed and shallow mixed layer were found to be the main reasons for high levels of aerosol concentration during the winter season. There is an increasing trend in Biomass Burning (BB) at most of the stations except for Thiruvananthapuram, where a prominent decreasing trend in BC concentration is also noticed. In the present study, the impact of local meteorological parameters such as wind, temperature, rainfall and Atmospheric Boundary Layer Height on BC mass concentration is investigated. The results show a negative correlation with rainfall, relative humidity, wind speed, temperature and ABL height. Both local activity and long-range transport at each study site are also found to be responsible for the significant changes in BC mass concentration.