American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 7544497 bytes)    Cited by

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, D14104, doi:10.1029/2005JD006837, 2006

Investigation of enhanced cross-city transport and trapping of air pollutants by coastal and urban land-sea breeze circulations

Jeff C. F. Lo

Atmospheric, Marine and Coastal Environment Program, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong


Alexis K. H. Lau

Environmental Central Facility, Institute for the Environment, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong


Jimmy C. H. Fung

Department of Mathematics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong


Fei Chen

National Center for Atmospheric Research, Boulder, Colorado, USA


Abstract

Recent satellite observations show that a layer of haze perpetually hangs over the Pearl River Delta (PRD) region and surface observations show numerous violations of the Hong Kong Air Quality Objective. This layer of haze mostly concentrates in the Pearl River Estuary and a narrow (20 km wide) band along the shoreline, in particular during weak wind situations. Although researchers suspect the land-sea breeze (LSB) circulations “concentrate” or “trap” various pollutants in this region, the physical mechanism of the phenomenon has never been fully explained or quantified. In this paper, a mesoscale atmospheric model (MM5) coupled with the Noah land surface model (LSM), which has bulk urban land use treatments along with a detailed Pearl River Delta land use map, is used to investigate the unique feature and mechanism of this land-sea breeze effect and the temporal evolution. A three-dimensional particle trajectory model is used to understand its associated pollutant transport, trapping and accumulation. A conceptual model is then developed for the perpetual air pollution phenomenon in the region. Further sensitivity experiments are used to illustrate the impact of urbanization and large-scale winds on the pollution processes. Results show that urbanization enhances the pollutant trapping and therefore contributes to the overall poor air quality in the region.

Received 30 October 2005; accepted 17 April 2006; published 22 July 2006.

Keywords: land-sea breeze circulation; urbanization effect; pollutant trapping.

Index Terms: 0345 Atmospheric Composition and Structure: Pollution: urban and regional (0305, 0478, 4251); 3307 Atmospheric Processes: Boundary layer processes; 3322 Atmospheric Processes: Land/atmosphere interactions (1218, 1631, 1843); 3329 Atmospheric Processes: Mesoscale meteorology; 3339 Atmospheric Processes: Ocean/atmosphere interactions (0312, 4504).

Read Full Article (file size: 7544497 bytes)    Cited by

Citation: Lo, J. C. F., A. K. H. Lau, J. C. H. Fung, and F. Chen (2006), Investigation of enhanced cross-city transport and trapping of air pollutants by coastal and urban land-sea breeze circulations, J. Geophys. Res., 111, D14104, doi:10.1029/2005JD006837.