Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577781
Title: The effect of changes in anthropogenic aerosols on the regional rainfall anomalies in China
Author: Guo, Liang
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2012
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Abstract:
The response of East Asian Summer Monsoon (EASM) precipitation to long term changes of anthropogenic aerosols (sulphate and black carbon) was explored in the atmospheric general circulation model (AGCM), the atmospheric component of the U.K. High-Resolution Global Environment Model v1.2 (HiGAM). Emissions in 1950 and 2000 over East Asia were used to drive the model. The differences between the 1950 experiment and 2000 experiment are treated as the response of EASM to aerosol changes. The aerosol radia- tive effects were first estimated using an off-line radiative transfer model (Edwards-Slingo radiation code) fed with monthly output of HiGAM. The impact of sulphate and black carbon were explored separately. Results reveal the duration of the EASM is extended as either sulphur dioxide or black carbon emissions were scaled down from 2000 emissions levels to 1950 emissions levels. The warmer land surface temperature over China in September maintains the meridional surface tempera- ture gradient necessary for supporting the EASM circulation. The mechanisms causing surface temperature increase in September were different between sulphate and black car- bon experiments. In the sulphate experiment, the direct and 1st indirect effect influenced the surface temperature increase in September. In the black carbon, the direct effect was the main drive of the warming. However, low cloud cover was also increased in black carbon 1950 experiment. This cloud change counteracted the increasing solar radiation over south-western China due to the black carbon direct effect, resulting in a weak land surface temperature increase in the black carbon experiment when compared to the sul- phate experiment; the EASM precipitation response was also weaker. In our experiments, . the impact of aerosol is not obvious during the rest of the summer monsoon season (JJA) for both sulphate and black carbon. Projection scenarios in the Coupled Model Intercomparison Project Phase 5 (CMIP5) show rapid decreases in aerosol emissions over Asia, decreased since 2020 in RCP 2.6, 4.5 and 8.5 scenarios, and decreased around 2050 in RCP 6.0 scenario. The results shown in this thesis can be used to examine the changes of EASM in these future projection.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.577781  DOI: Not available
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