10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A Device Development for Measuring Atmospheric Columnar Integrated Air Pollution
Hardik Gajjar, DAYA KAUL, Pandit Deendayal Petroleum University
Abstract Number: 242 Working Group: Instrumentation
Abstract Aerosols have varied impact on climate and human health. Aerosols of highly scattering in nature increases the albedo of the earth and thereby cools the surface and thus, effectively offsets greenhouse gas warming by about 25-50%; whereas, absorbing types of aerosols (e.g. black carbon) absorbs solar radiation, hence increases the surface temperature; Absorbing types of aerosols are largely present in urban environment due to presence of relatively larger number of vehicle fleet and subsequent more fossil fuel combustions than in rural areas. This aggravates the already present Urban Heat Island (UHI) induced atmospheric heating due to almost ubiquitous presence of concrete structures in urban areas.
One of the important parameters in aerosol measurement is aerosol optical depth (AOD). Several instruments and techniques are used to measure AOD such as with satellite and ground based sun-photometry, ground and airborne radiometers and LIDARs. The ground based sun photometry is preferred more over other approaches because of its customizable spatial and temporal resolution and good accuracy. Satellite data is also most frequently used due to its large spatial coverage; however its accuracy is always under much debate due to improper treatment of reflection and aerosol models used in AOD algorithm. The uncertainty is even more significant over areas where satellite overpass does not coincide with the area or period of interest and nearest satellite pass data is approximated and is considered for studies. The airborne radiometer and LIDAR retrieval are able to derive vertical profile of AOD and have flexible measurement recording time. Still these are not in widespread use for AOD monitoring because they require complex instrumentation and high maintenance cost is always an issue for areas where technical and financial support are acutely limited.
In response to bring down the cost, affordability and portability problem, a camera based AOD retrieval was developed which measured AOD at three wavelength using CMOS sensor of camera. Certain modifications were required to do so, which included addition of narrow band pass and neutral density filters to protect the image sensor and not to allow saturation of solar images produced. The details of the method, instrument and result will be presented in the conference.