Abstract

Biogenic emissions of volatile organic compounds (VOCs) have been studied extensively for several years due to their role in tropospheric ozone chemistry and secondary aerosol formation. Most of the biogenic VOC emission research effort has focused on quantifying and characterising .uxes of these compounds from North American and European habitats. However, in recent years, some attention has been given to the study of biogenic VOCs from tropical habitats. For example, the EXPRESSO and SAFARI programs in South Africa, and the LBA initiative in Amazonia have resulted in a recent series of publications. In spite of these new initiatives, there is a paucity of data from tropical ecosystems, which are estimated to contribute about half of all global biogenic VOC emissions. In particular, there are no studies to date on biogenic VOC emissions from tropical forest canopies in South East Asia. This study, funded by a NERC Fellowship, aims to make inroads into the problem of quantifying biogenic emissions from a variety of tropical forest canopies in the vicinity of Danum Valley Field Centre (DVFC), Sabah, Borneo, and to investigate environmental controls for these .uxes. The hypotheses to be examined are (1) emissions of VOCs from tropical forest vegetation are controlled in the short term by diurnal variations in photosynthetically active radiation (PAR), temperature and precipitation, (2) environmental and physiological controls of biogenic VOC emissions can be related to metabolic energy requirements, and (3) using parameterizations derived from (1) and (2), .rst estimates of biogenic VOC .uxes from tropical habitats will be made and used to improve models that predict tropospheric ozone and aerosol formation in tropical regions. These 3 hypotheses will be tested using a combination of laboratory, .eld and desk studies. To explore the effect of the estimated biogenic VOC .ux in the production of ozone and secondary aerosols downwind of the extrapolation domain, biogenic VOC .ux estimates for tropical canopies in S.E. Asia will be used in the Cambridge Tropospheric and Transport and Chemistry model (CittyCat).