Abstract
The use of Geographic Information Systems (GIS) and Remote Sensing (RS) by climatologists, environmentalists and urban planners for three dimensional modeling and visualization of the landscape is well established. However no previous study has implemented these techniques for 3D modeling of atmospheric aerosols because air quality data is traditionally measured at ground points, or from satellite images, with no vertical dimension. This study presents a prototype for modeling and visualizing aerosol vertical profiles over a 3D urban landscape in Hong Kong. The method uses a newly developed technique for the derivation of aerosol vertical profiles from AERONET sunphotometer measurements and surface visibility data, and links these to a 3D urban model. This permits automated modeling and visualization of aerosol concentrations at different atmospheric levels over the urban landscape in near-real time. Since the GIS platform permits presentation of the aerosol vertical distribution in 3D, it can be related to the built environment of the city. Examples are given of the applications of the model, including diagnosis of the relative contribution of vehicle emissions to pollution levels in the city, based on increased near-surface concentrations around weekday rush-hour times. The ability to model changes in air quality and visibility from ground level to the top of tall buildings is also demonstrated, and this has implications for energy use and environmental policies for the tall mega-cities of the future.
Highlights
Estimating the atmospheric aerosol content is important in both remote sensing and climatology [1,2]
This study demonstrates a near-real time methodology for visualizing aerosol vertical profiles over an urban area, by integrating them with spatially referenced terrain elevation and building height data on a Geographic Information Systems (GIS)
The AOT values for different atmospheric heights were linked to a GIS-based 3D urban model to provide near-real time visualization over the 3D urban landscape
Summary
Estimating the atmospheric aerosol content is important in both remote sensing and climatology [1,2]. Aerosol profiles cannot be obtained directly from ground-based chemical and physical measurements, recent work [8,9,10,11] demonstrates that they can be derived by ground-based sensing of the properties of the atmospheric column using a multi-channel sunphotometer. These estimations are based on the computation of aerosol scaling height from surface visibility data as well as the columnar aerosol properties from the sunphotometer. The technical basis and theory relating to such a model are discussed below
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