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1. Modeling Investigation on Amines and Sea-salt Aerosol Interactions to Assess Their Potential Climate Impacts

   Sundararajan, P. ; Qiu, C. ( March 2022 , Connecticut Scienece and Engineering Fair)
2. Dynamics of Asian Summer Monsoon Response to Anthropogenic Aerosol Forcing

   https://doi.org/10.1175/JCLI-D-18-0386.1  

   Wang, Hai ; Xie, Shang-Ping ; Kosaka, Yu ; Liu, Qinyu ; Du, Yan ( February 2019 , Journal of Climate)
3. An emerging Asian aerosol dipole pattern reshapes the Asian summer monsoon and exacerbates northern hemisphere warming

   https://doi.org/10.1038/s41612-023-00400-8  

   Xiang, Baoqiang ; Xie, Shang-Ping ; Kang, Sarah M. ; Kramer, Ryan J. ( December 2023 , npj Climate and Atmospheric Science)

   Since the early 2010s, anthropogenic aerosols have started decreasing in East Asia (EA) while have continued to increase in South Asia (SA). Yet the climate impacts of this Asian aerosol dipole (AAD) pattern remain largely unknown. Using a state-of-the-art climate model, we demonstrate that the climate response is distinctly different between the SA aerosol increases and EA aerosol decreases. The SA aerosol increases lead to ~2.7 times stronger land summer precipitation change within the forced regions than the EA aerosol decreases. Contrastingly, the SA aerosol increases, within the tropical monsoon regime, produce weak and tropically confined responses, while the EA aerosol decreases yield a pronounced northern hemisphere warming aided by extratropical mean westerly and positive air-sea feedbacks over the western North Pacific. By scaling the observed instantaneous shortwave radiative forcing, we reveal that the recent AAD induces a pronounced northern hemisphere extratropical (beyond 30°N) warming (0.024 ± 0.010 °C decade⁻¹), particularly over Europe (0.049 ± 0.009 °C decade⁻¹). These findings highlight the importance of the pattern effect of forcings in driving global climate and have important implications for decadal prediction.

    

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4. Relative Importance of Greenhouse Gases, Sulfate, Organic Carbon, and Black Carbon Aerosol for South Asian Monsoon Rainfall Changes

   https://doi.org/10.1029/2020GL088363  

   Westervelt, Daniel M. ; You, Yujia ; Li, Xiaoqiong ; Ting, Mingfang ; Lee, Dong Eun ; Ming, Yi ( July 2020 , Geophysical Research Letters)

   The contribution of individual aerosol species and greenhouse gases to precipitation changes during the South Asian summer monsoon is uncertain. Mechanisms driving responses to anthropogenic forcings need further characterization. We use an atmosphere‐only climate model to simulate the fast response of the summer monsoon to different anthropogenic aerosol types and to anthropogenic greenhouse gases. Without normalization, sulfate is the largest driver of precipitation change between 1850 and 2000, followed by black carbon and greenhouse gases. Normalized by radiative forcing, the most effective driver is black carbon. The precipitation and moisture budget responses to combinations of aerosol species perturbed together scale as a linear superposition of their individual responses. We use both a circulation‐based and moisture budget‐based argument to identify mechanisms of aerosol and greenhouse gas induced changes to precipitation and find that in all cases the dynamic contribution is the dominant driver to precipitation change in the monsoon region.

    

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5. The Influence of Volcanic Aerosol Meridional Structure on Monsoon Responses over the Last Millennium

   https://doi.org/10.1029/2019GL084377  

   Fasullo, John T. ; Otto‐Bliesner, Bette L. ; Stevenson, Samantha ( November 2019 , Geophysical Research Letters)

   Monsoon responses to eruptions over the last millennium (LM) are examined in an ensemble of climate simulations as a function of eruption hemisphere. A composite analysis reveals a particularly strong sensitivity of monsoon rainfall in the year following Northern Hemisphere (NH) extratropical eruptions. Additional analysis focusing on the 18th century eruption of Mt. Laki and idealized simulations representing an analogue Southern Hemisphere eruption (SH‐Laki) reveal monsoon responses that are approximately symmetric across hemispheres, despite exhibiting asymmetries in other aspects of the climate response. We conclude that 1) latitudinally mirrored eruptions result in approximately symmetric monsoon responses, 2) disproportionate weakening (strengthening) of NH (SH) monsoons by NH eruptions over the LM resulted in part from their relatively high latitudes, and 3) uncertainty in eruption latitude fundamentally limits our ability to accurately simulate associated monsoon and tropical precipitation responses in nature.

    

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