• Allen, R. J., , and S. C. Sherwood, 2010: The impact of natural versus anthropogenic aerosols on atmospheric circulation in the Community Atmosphere Model. Climate Dyn., 36, 19591978, doi:10.1007/s00382-010-0898-8.

    • Search Google Scholar
    • Export Citation
  • Bollasina, M. A., , Y. Ming, , and V. Ramaswamy, 2011: Anthropogenic aerosols and the weakening of the South Asian summer monsoon. Science, 334, 502505, doi:10.1126/science.1204994.

    • Search Google Scholar
    • Export Citation
  • Chung, C. E., , V. Ramanathan, , and T. K. Jeffrey, 2002: Effects of the South Asian absorbing haze on the northeast monsoon and surface–air heat exchange. J. Climate, 15, 24622476.

    • Search Google Scholar
    • Export Citation
  • Emanuel, K. A., 1995: On thermally direct circulations in moist atmospheres. J. Atmos. Sci., 52, 15291534.

  • Ganguly, D., , P. J. Rasch, , H. Wang, , and J.-H. Yoon, 2012: Climate response of the South Asian monsoon system to anthropogenic aerosols. J. Geophys. Res., 117, D13209, doi:10.1029/2012JD017508.

    • Search Google Scholar
    • Export Citation
  • Gent, P. R., and Coauthors, 2011: The Community Climate System Model version 4. J. Climate, 24, 49734991.

  • Kajikawa, Y., , T. Yasunari, , S. Yoshida, , and H. Fujinami, 2012: Advanced Asian summer monsoon onset in recent decades. Geophys. Res. Lett., 39, L03803, doi:10.1029/2011GL050540.

    • Search Google Scholar
    • Export Citation
  • Kim, D., , C. Wang, , A. M. L. Ekman, , M. C. Barth, , and P. Rasch, 2008: Distribution and direct radiative forcing of carbonaceous and sulfate aerosols in an interactive size-resolving aerosol-climate model. J. Geophys. Res., 113, D16309, doi:10.1029/2007JD009756.

    • Search Google Scholar
    • Export Citation
  • Kuhlmann, J., , and J. Quaas, 2010: How can aerosols affect the Asian summer monsoon? Assessment during three consecutive pre-monsoon seasons from CALIPSO satellite data. Atmos. Chem. Phys., 10, 46734688, doi:10.5194/acp-10-4673-2010.

    • Search Google Scholar
    • Export Citation
  • Lau, K. M., , and K. M. Kim, 2007: Does aerosol weaken or strengthen the Asian monsoon? Mountains: Witnesses of Global Changes: Research in the Himalaya and Karakoram: SHARE-Asia Project, R. Baudo, G. Tartari, and E. Vuillermoz, Eds., Developments in Earth Surface Processes, Vol. 10, Elsevier, 370 pp.

  • Lau, K. M., , M. K. Kim, , and K. M. Kim, 2006: Asian summer monsoon anomalies induced by aerosol direct forcing: The role of the Tibetan Plateau. Climate Dyn., 26, 855864, doi:10.1007/s00382-006-0114-z.

    • Search Google Scholar
    • Export Citation
  • Meehl, G. A., , J. M. Arblaster, , and W. D. Collins, 2008: Effects of black carbon aerosols on the Indian monsoon. J. Climate, 21, 28692882.

    • Search Google Scholar
    • Export Citation
  • Menon, S., , J. Hansen, , L. Nazarenko, , and Y. Luo, 2002: Climate effects of black carbon aerosols in China and India. Science, 297, 22502253, doi:10.1126/science.1075159.

    • Search Google Scholar
    • Export Citation
  • Prive, N. C., , and R. A. Plumb, 2007: Monsoon dynamics with interactive forcing. Part I: Axisymmetric studies. J. Atmos. Sci., 64, 14171430.

    • Search Google Scholar
    • Export Citation
  • Ramanathan, V., and Coauthors, 2001: Indian Ocean experiment: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze. J. Geophys. Res., 106 (D22), 28 37128 398.

    • Search Google Scholar
    • Export Citation
  • Ramanathan, V., and Coauthors, 2005: Atmospheric brown clouds: Impacts on South Asian climate and hydrological cycle. Proc. Natl. Acad. Sci. USA, 102, 53265333.

    • Search Google Scholar
    • Export Citation
  • Randles, C. A., , and V. Ramaswamy, 2008: Absorbing aerosols over Asia: A Geophysical Fluid Dynamics Laboratory general circulation model sensitivity study of model response to aerosol optical depth and aerosol absorption. J. Geophys. Res., 113, D21203, doi:10.1029/2008JD010140.

    • Search Google Scholar
    • Export Citation
  • Wang, B., , and LinHo, 2002: Rainy season of the Asian–Pacific summer monsoon. J. Climate, 15, 386398.

  • Wang, C., 2007: Impact of direct radiative forcing of black carbon aerosols on tropical convective precipitation. Geophys. Res. Lett., 34, L05709, doi:10.1029/2006GL028416.

    • Search Google Scholar
    • Export Citation
  • Wang, C., , G.-R. Jeong, , and N. Mahowald, 2009a: Particulate absorption of solar radiation: Anthropogenic aerosols vs. dust. Atmos. Chem. Phys., 9, 39353945, doi:10.5194/acp-9-3935-2009.

    • Search Google Scholar
    • Export Citation
  • Wang, C., , D. Kim, , A. M. L. Ekman, , M. C. Barth, , and P. J. Rasch, 2009b: Impact of anthropogenic aerosols on Indian summer monsoon. Geophys. Res. Lett., 36, L21704, doi:10.1029/2009GL040114.

    • Search Google Scholar
    • Export Citation
  • Xie, P., , and P. A. Arkin, 1997: Global precipitation: A 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Amer. Meteor. Soc., 78, 25392558.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 8 8 3
PDF Downloads 7 7 3

Nonlinear Effects of Coexisting Surface and Atmospheric Forcing of Anthropogenic Absorbing Aerosols: Impact on the South Asian Monsoon Onset

View More View Less
  • 1 Center for Environmental Sensing and Modeling, Singapore–Massachusetts Institute of Technology Alliance for Research and Technology, Singapore, Singapore
  • 2 Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
© Get Permissions
Restricted access

Abstract

The direct radiative effect of absorbing aerosols consists of absorption-induced atmospheric heating together with scattering- and absorption-induced surface cooling. It is thus important to understand whether some of the reported climate impacts of anthropogenic absorbing aerosols are mainly due to the coexistence of these two opposite effects and to what extent the nonlinearity raised from such coexistence would become a critical factor. To answer these questions specifically regarding the South Asia summer monsoon with focus on aerosol-induced changes in monsoon onset, a set of century-long simulations using the Community Earth System Model, version 1.0.3 (CESM 1.0.3), of NCAR with fully coupled atmosphere and ocean components was conducted. Prescribed direct heating to the atmosphere and cooling to the surface were applied in the simulations over the Indian subcontinent, either alone or combined, during the aerosol-laden months of May and June. Over many places in the Indian subcontinent, the nonlinear effect dominates in the changes of subcloud layer moist static energy, precipitation, and monsoon onset. The surface cooling effect of aerosols appears to shift anomalous precipitative cooling away from the aerosol-forcing region and hence turn the negative feedback to aerosol-induced atmospheric heating into a positive feedback on the monsoon circulation through latent heat release over the Himalayan foothills. Moisture processes form the critical chain mediating local aerosol direct effects and onset changes in the monsoon system.

Current affiliation: Korea Institute of Atmospheric Prediction Systems, Seoul, South Korea.

Corresponding author address: Chien Wang, E19-439K, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139-4307. E-mail: wangc@mit.edu

Abstract

The direct radiative effect of absorbing aerosols consists of absorption-induced atmospheric heating together with scattering- and absorption-induced surface cooling. It is thus important to understand whether some of the reported climate impacts of anthropogenic absorbing aerosols are mainly due to the coexistence of these two opposite effects and to what extent the nonlinearity raised from such coexistence would become a critical factor. To answer these questions specifically regarding the South Asia summer monsoon with focus on aerosol-induced changes in monsoon onset, a set of century-long simulations using the Community Earth System Model, version 1.0.3 (CESM 1.0.3), of NCAR with fully coupled atmosphere and ocean components was conducted. Prescribed direct heating to the atmosphere and cooling to the surface were applied in the simulations over the Indian subcontinent, either alone or combined, during the aerosol-laden months of May and June. Over many places in the Indian subcontinent, the nonlinear effect dominates in the changes of subcloud layer moist static energy, precipitation, and monsoon onset. The surface cooling effect of aerosols appears to shift anomalous precipitative cooling away from the aerosol-forcing region and hence turn the negative feedback to aerosol-induced atmospheric heating into a positive feedback on the monsoon circulation through latent heat release over the Himalayan foothills. Moisture processes form the critical chain mediating local aerosol direct effects and onset changes in the monsoon system.

Current affiliation: Korea Institute of Atmospheric Prediction Systems, Seoul, South Korea.

Corresponding author address: Chien Wang, E19-439K, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139-4307. E-mail: wangc@mit.edu
Save