Aerosol Laboratory  

 Aerosols are suspended particulates in the atmosphere and have implications for climate and health through different mechanisms. Several studies have suggested that aerosols may be mitigating global warming by increasing the planetary albedo, although the sign and magnitude of aerosol effects on climate are still uncertain as outlined in the International Panel of Climate change (IPCC) reports. Compounding to the complexity of this problem is the interaction of aerosols with clouds. Aerosols change cloud properties, alter precipitation patterns and have serious consequences for altering the hydrological balance of the earth-atmosphere system. Given this background, it is imperative that aerosol measurements from space, ground and aircraft are performed carefully to answer crucial questions related to climate change.

An aerosol climate observatory (ACO) was set up at CAOS, IISc, Bangalore during 2001 with a number of sophisticated instruments for the measurements of various parameters related to aerosols as well as radiation with an objective to characterize aerosols over this region and to assess its radiative impact. The instruments set up include the following and the parameter measured is provided inside brackets.

(a)    multi-wavelength solar radiometer (spectral optical depth)

(b)   aethalometer (aerosol black carbon)

(c)    micro-pulse LIDAR (aerosol vertical distribution)

(d)   optical particle counter (aerosol size distribution)

(e)    high-volume aerosol sampler (aerosol chemical composition)

(f)     sky-scanning radiometer (sky radiance)

(g)    shadow-band radiometer (direct, diffuse and global radiation)

(h)    three-wavelength nephelometer (spectral scattering coefficient)

(i)      automatic weather station (meteorological parameters)

A similar observatory is also operational at Minicoy island (part of Lakshadeep group of islands) using a sub set of the above instruments under the leadership of CAOS scientists. In addition to these two fixed observatories, for characterizing aerosol spatial heterogeneity, aerosol measurements were made using identical or nearly identical instruments, carried in several instrumented mobile platforms. Over ocean aerosol measurements were carried out onboard R/V Sagar Kanya (of Department of Ocean Development). Vertical distribution of aerosol properties were characterised by mounting a micro pulse lidar (MPL) onboard a research aircraft (of Department of Space) and by making measurements over continental and coastal India as well as over oceanic regions adjacent to Indian sub continent.

The major objective is to make contributions for addressing the crucial aerosol related questions. These observations were integrated into satellite data and radiative forcing of aerosols in the Indian region was carefully characterised which was needed for the research community at large.