Aerosol remains one of the most uncertain factors in projecting climate, much owing to the sophisticated feedbacks involved in the interplays between aerosol and clouds and the difficulty in representing these processes in climate models. This project is to study these critical but still poorly understood science issues. Our achievements in research are primarily on: (a) advancing our knowledge; and (b) developing and producing the state-of-art computational tools and laboratory as well as field results to improve the representations of aerosol-cloud processes in climate models.

In advancing knowledge of aerosol-cloud interaction and it’s impacts on climate, our researches have produced many unique results and first-time findings, which are mostly published with a few still under review or to be submitted soon. These research findings could advance the frontier of our science and also have broader impacts on other science fields and the processes of making effective climate and environment mitigation policies. Here are several examples:

1. Using a large quantity of climate model results alongside observational data, we have revealed the dominant role of aerosol in determining the changing pattern of large-scale precipitation in the past, and indicated the importance for models to have physically-based representation of aerosol-cloud processes in order to reproduce observed precipitation trend.
2. We have extensively studied the influence of aerosols on the monsoons. Detailed modeling analyses have been conducted to examine various hypotheses about this effect and revealed a mechanism that soil moisture could preserve the memory of aerosol forcing in monsoon onset stage through deep monsoon stage.
3. Our recent work has identified a reversal of Indian summer monsoon rainfall since 2002 from a half-century-long drying to persistent wetting, that is opposite to many previous projections of the continuation of the long lasting drying trend. This important finding, however, raises a serious issue about the abrupt warming over Indian land area in recent decade that is found to behind this reversal, and suggests to propose new ideas regarding anthropogenic forcings including those of aerosols in causing such a change.
4. Another direction our research has made significant progress is about the climate impacts of biomass burning emitted aerosols. Our work suggests a substantial year-to-year variation of biomass burning emissions and using a simple average across multiple years, as adopted in many modeling efforts, would substantially overestimated the cooling effect of this type of aerosols. Specifically regarding frequent biomass burning activities in Southeast Asia, we have, for the first time, calculated contribution of biomass burning in comparison to that of other non-fire combustions to the worsening of air quality in that region based on observations and modeling results.
5. Our study on the potential climate outcome of energy usages in Asia suggests a significant impact on both regional and global precipitation distribution by an extensive coal usage in Asia.
6. We have also examined the geoengineering proposal of ocean fertilization to decrease atmospheric CO2 concentration, and found such practice could lead to adverse climate outcome particularly of precipitation distribution.

To assist above research efforts, we have also developed several novel modeling and data science methods. These including new methods to simulate the formation of cloud droplets or ice crystals from aerosols We have also developed the first-ever inverse modeling platform to use observational data for optimizing our estimate of black carbon emissions. Many of these have been used to improve the Multi-modal, 2-Moment, Mixing-resolving Aerosol model for Climate Research or MARC that has been coupled with NCAR-DOE Community Earth System Model CESM. MARC-CESM with improved schemes has been evaluated extensively against observations and other aerosol modules, and also used to examine the importance of many of these advancements in process-representation. 

Our team members have presented the research findings in various scientific conferences, published many peer reviewed papers, and joined communication with governments, policy-making bodies, and general public. We have published three review articles for broader communities. The aerosol model MARC developed in this project has been released in public domain. The project has also produced datasets of long-term simulations designed for examining climate responses to various aerosol configurations. These will be made available to interesting parties following the data management plan.

Last Modified: 01/12/2018
Modified by: Chien Wang