George Mwaniki
George Mwaniki
Topic: Air Quality
Dr. George Mwaniki is an air quality expert within UNEP’s Division of Technology Industry and Economics. He is currently working on the UNEA’s resolution to strengthen UNEPs role in air ...
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Number of questions: [1]
Posted on 31/07/2015 04:41:26
Dear Dr. Mwaniki,
Having read your profile, I assumed that you were involved in a research that studied Atmospheric Brown Clouds (ABCs) on Mount Kenya. Indeed, I had thought that the ABCs were largely confined in Asia. What has been the impact of the ABCs on the local climate around Mount Kenya? My understanding is that the Atmospheric Brown Clouds formed from sulphate aerosols tend to cool temperatures in the troposphere by masking/reflecting the sunlight. Therefore, efforts being undertaken to encourage the use of cleaner transport and reduce the amount of sulphur in fuels have been unmasking the warming of sunlight thus increasing temperatures in the troposphere. Besides, Atmospheric Brown Clouds formed from soot aerosols tend to absorb insolation, thus warm temperatures in the troposphere.
Francis Bagambilana (from Tanzania (United Republic of))
Dear Francis,
Many thanks for your question. You are quite right that ABCs are largely associated with Asia; but this does not mean they are confined there. In previous studies, substantial loadings of ABCs over Eastern USA and Europe have also been observed; mostly during summer time months when these areas experience reduced precipitation. During the Mount Kenya ABCs study, our main aim was to assess the level of regional and subregional black carbon emissions. From the study we saw substantial black carbon emissions from the region and this is expected to increase in the future, thus ABCs concentration in the region will be a major climate driver in the future. During this study we did not concentrate on sulphates and nitrates and their role in driving ABCs’ concentration, this is mainly because black carbon emissions from the region are known to be the most important drivers of ABCs. Maybe this will change in the future as economic and population growth increase the emissions of both NOx and SOx, although it is also important to mention that the region has made substantial efforts towards low sulfur fuels. So I do hope future studies will also look at the effect of these other important drivers.