OA20
Sub-decadal changes in fog occurrence over Asia: trends, mechanisms and predictive tools.

Main Organiser
M.K. Tiwari
National Physical Laboratory, India
mktiwari@mail.nplindia.ernet.in

Brief Description
Major portions of India and China and a few other regions in Asia experience extensive fog periods during the winter season. Fog is not only a well known cause of air and road traffic disruption but also influences agricultural yields. Significant change in fog occurrence frequency in several regions during the last decade is a cause of concern due to damage to agricltural crops this has caused. The potential driving factors of change in fog occurrence over the years are climate change, changes in irrigation pattern and linked changes in extent of water-logged areas causing changes in soil/air temperature and moisture regimes, changes in geogrphical areas of inland water bodies, sub-decadal scale changes if any in aerosol trajectories in free troposphere across geographical boundaries, increasing amounts of fertilizer applications to achieve higher agricultural yields, changes in near ground aerosols for reasons other than agricultural activities such as pollution control regime changes, etc. The concern being expressed is that if number of fog days per year on average becomes significantly higher than its already increased value, it could seriously affect the winter crops in fog affected areas; such a possibility cannot be denied because of the need of further agricultural intensification/inputs to meet food demands of increasing population. There is a necessity, therefore, to understand through extensive cross-regional muti-disciplinary research efforts, the effect of increasing outputs from past and future anthropogenic activities on fog formation processes as well as on the characteristics of fog, such as frequency, density and longevity, in various regions of Asia and thereby to attempt to evolve predictive mechanisms for future trends in fog occurrence and their impact. Inputs in such an exercise are needed from aerosol scientists, meteorologists, planetary boundary experts, past and current satellite data analysis experts, agricultur e dynamics experts, land cover change analysts, neural network and other modellers. This session will pay emphasis on trend analysis and prediction of fog occurrence and its driving forces as well as relationship among them using past and current observational data and/or using various modelling techniques. Apart from invited and contributed papers a discussion meeting to evolve cross-regional research strategies will also be held.