Investigating the forcing-per-emission relationship of regional BC direct and cloud-related climate effects
Abstract
It is now well-known that black carbon (BC) has an important climate impact. BC can directly affect the climate by absorbing light and warming the atmosphere. Acting as cloud condensation nuclei, BC particles can further affect the cloud albedo and cloud lifetime (a.k.a., aerosol indirect effects). In addition, as it absorbs sunlight, BC within, below or above clouds alters the atmospheric vertical temperature structure and consequently affects cloud formation and evolution. This is known as the semi-direct effect. As a short-lived climate forcer with potentially large positive forcing, BC reduction may be considered as an effective way to slow anthropogenic global warming in the short-term period. It is therefore important to estimate BC forcing under different emission reduction scenarios. However, it is unrealistic to run model simulations for each combination of reductions due to the expensive computational resources and long simulation time required for comprehensive climate models. Our goal is to investigate the forcing change in individual receptor regions, resulting from emission change in the same region or other regions, and thus to help quantify the impact of BC reduction. A modified version of Community Earth System Model (CESM) with tagged BC emission from different regions in the world has been used to simulate BC forcing by altering BC emissions in a certain region, such as North America or East Asia. Both direct forcing and cloud-related forcing of BC over the source region (North America, East Asia) and other receptor regions in the world was obtained. Direct forcing of BC over the source region shows a good linear relationship with emission. The relationships between emission in the source region and cloud-related forcing over the source region and other regions are more complicated and non-linear as the meteorology and loading of other aerosol species respond to the change in BC.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.A11C0057C
- Keywords:
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- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE Aerosols and particles;
- 1637 GLOBAL CHANGE Regional climate change;
- 1626 GLOBAL CHANGE Global climate models;
- 3305 ATMOSPHERIC PROCESSES Climate change and variability