Atmospheric and Climate Modeling

Many Harvard-China Project studies of air pollution use chemical transport models, including a nested-grid version of GEOS-Chem focused on East Asia. Other studies consider the effects of climate change on air quality, renewable power potentials, and energy demands for heating and cooling, using ensembles of climate models such as CMIP6.

Validated by agreement of modeled concentrations with measurements made by ground stations, aircraft, and satellites, nested-grid models can differentiate air transport mechanisms for regions of east and south Asia on a finer scale than previously possible. They capture the effects of sources far outside of the target domain and also of seasonally changing meteorology—such as cold fronts in winter and monsoons in summer—on regional air quality. 
 
The China Project's atmospheric research is committed to building observationally validated, fundamental research on the physical and chemical dimensions of China’s atmospheric environment, from urban to global scales. Complementing the model-based research described here, it includes atmospheric observations and both bottom-up and top-down emissions research

Related Publications

Yu Zhao, Yutong Wang, Yiming Liu, Yueqi Jiang, Bo Zheng, Jia Xing, Yang Liu, Shuai Wang, and Chris Nielsen. 2023. “Sustained emission reductions have restrained the ozone pollution over China.” Nature Geoscience. Publisher's VersionAbstract

Near-surface ozone pollution, associated with complex responses to changing precursor emissions and meteorological conditions, has become one of the biggest challenges in China’s air quality management. Here, we present the spatiotemporal evolution of ozone concentrations from 2010 to 2021 using measurements of the national air quality monitoring network. We evaluate the effectiveness of the national air pollution control programme, including Phase 1 (2013–2017) and Phase 2 (2018–2021), in reducing the ozone level over China, using an optimized machine learning approach, high-resolution emission estimates and an improved air quality model. We find that while emission changes in Phase 1 increased the ozone level over the five highly developed regions, further reductions of nitrogen oxide emissions in Phase 2 have generally constrained the ozone pollution. The changing effect of emission controls on ozone pollution is due to the shift in the prevailing regime for ozone formation and the weakened effects of aerosol declines, as emission reductions continue. We further find that current emission controls have been more effective in rural locales in four of the five regions, and more effective in summer than winter. Therefore, further control of ozone pollution should consider these regional and seasonal variations to identify the most important precursors for the pollution.

Jonathan D'Souza, Felix Prasanna, Luna-Nefeli Valayannopoulos-Akrivou, Peter John Sherman, Elise Penn, Shaojie Song, Alexander Archibald, and Michael B McElroy. 2021. “Projected changes in seasonal and extreme summertime temperature and precipitation in India in response to COVID-19 recovery emissions scenarios.” Environmental Research Letters, 16, Pp. 114025. Publisher's VersionAbstract
Fossil fuel and aerosol emissions have played important roles on climate over the Indian subcontinent over the last century. As the world transitions toward decarbonization in the next few decades, emissions pathways could have major impacts on India's climate and people. Pathways for future emissions are highly uncertain, particularly at present as countries recover from COVID-19. This paper explores a multimodel ensemble of Earth system models leveraging potential global emissions pathways following COVID-19 and the consequences for India's summertime (June-July-August-September) climate in the near- and long-term. We investigate specifically scenarios which envisage a fossil-based recovery, a strong renewable-based recovery and a moderate scenario in between the two. We find that near-term climate changes are dominated by natural climate variability, and thus likely independent of the emissions pathway. By 2050, pathway-induced spatial patterns in the seasonally-aggregated precipitation become clearer with a drying in the fossil-based scenario and wetting in the strong renewable scenario. Additionally, extreme temperature and precipitation events in India are expected to increase in magnitude and frequency regardless of the emissions scenario, though the spatial patterns of these changes as well as the extent of the change are pathway dependent. This study provides an important discussion on the impacts of emissions recover pathways following COVID-19 on India, a nation which is likely to be particularly susceptible to climate change over the coming decades.
Xinyu Chen, Yaxing Liu, Qin Wang, Jiajun Lv, Jinyu Wen, Xia Chen, Chongqing Kang, Shijie Cheng, and Michael McElroy. 2021. “Pathway toward carbon-neutral electrical systems in China by mid-century with negative CO2 abatement costs informed by high-resolution modeling.” Joule, 5, 10 (20 October), Pp. 2715-2741. Publisher's VersionAbstract
China, the largest global CO2 emitter, recently announced ambitious targets for carbon neutrality by 2060. Its technical and economic feasibility is unclear given severe renewable integration barriers. Here, we developed a cross-sector, high-resolution assessment model to quantify optimal energy structures on provincial bases for different years. Hourly power system simulations for all provinces for a full year are incorporated on the basis of comprehensive grid data to quantify the renewable balancing costs. Results indicate that the conventional strategy of employing local wind, solar, and storage to realize 80% renewable penetration by 2050 would incur a formidable decarbonization cost of $27/ton despite lower levelized costs for renewables. Coordinated deployment of renewables, ultra-high-voltage transmissions, storages, Power-to-gas and slow-charging electric vehicles can reduce this carbon abatement cost to as low as $−25/ton. Were remaining emissions removed by carbon capture and sequestration technologies, achieving carbon neutrality could be not only feasible but also cost-competitive post 2050.
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