Meteorological conditions and transport of air pollutants at Bachok Marine Research Station (BMRS) in Peninsular Malaysia / Noraini Mohyeddin

Noraini , Mohyeddin (2020) Meteorological conditions and transport of air pollutants at Bachok Marine Research Station (BMRS) in Peninsular Malaysia / Noraini Mohyeddin. Masters thesis, University of Malaya.

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Abstract

This study is focused at relatively new regional Global Atmospheric Watch (GAW) station at Peninsular Malaysia – Bachok Marine Research Station (BMRS) using the observational and remote sensing data. The study consists of three main objectives. Firstly, to investigate the meteorological conditions during two major Southeast Asia monsoon – NE and SW monsoon. Secondly, to determine the potential sources of air pollution at BMRS during the monsoon periods. Thirdly, to examine the relations of carbon dioxide (CO2), methane (CH4) and particulate matters (PM10, and PM2.5) with the meteorological conditions during intensive case study periods. The first case study (CS1) was conducted from 25 to 27 January 2016 while the second one (CS2) was conducted from 3 to 5 June 2016. The results of this study are divided into two parts. In the first part, the meteorological conditions, variations and transport of air pollutants during the Northeast (NE) and Southwest (SW) monsoons from 2014 – 2016 were determined. Data analysis shows BMRS is influenced by both synoptic flows and land-sea breeze events during the NE monsoon. However, BMRS dominated by land-sea breeze events during the SW monsoon. BMRS is associated with dominant flows of onshore winds, no diurnal effect and low level of air pollutants during strong synoptic influence in the NE monsoon. This period is also associated with transboundary sources originated from the continental region of China, East China Sea (ECS) and South China Sea (SCS) using Hybrid-Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and CWT analysis. In the second part, the meteorological conditions, relations and transport of air pollutants during CS1 and CS2 were shown extensively. CS1 and CS2 represent a strong synoptic and local meteorological conditions in the NE and SW monsoon respectively. During CS1, BMRS was influenced by strong easterly winds that penetrated 60 km inland and prevailed within 2500 m height with high relative humidity (>80%). This caused a weakened vertical thermal gradient hence suppressed the typical land-sea breeze event over BMRS. Conditional Probability Function Polar (CPFP) plots and HYSPLIT-CWT analysis incorporated with hotspots data shows there are influence of long-range transport of CO2 and CH4 from the continental region of China and coastal area of Vietnam which are mainly attributed to the industrial emissions and biomass burnings. Contrarily, BMRS was associated with clear vertical thermal gradient within 1000 m, strong diurnal effect and daily occurrence of land sea breeze event during CS2. The sea breeze event able to penetrate within 30 to 90 km inland in the late afternoon and prevails within 1000 m height over BMRS. The variations of air pollutants are strongly influenced by the land sea breeze event i.e. sea breeze reduces while land breeze increases the level of air pollutants significantly. BMRS is mainly influenced by local and regional sources of emissions during this period. Overall, the site at BMRS presents a valuable opportunity to study the influence of regional and local atmospheric flows to the variabilities of air pollutants, thus enabling better understanding and providing a key reference to formulate effective pollution abatement strategies.

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