Sensitivity of CAM5-Simulated Arctic Clouds and Radiation to Ice Nucleation Parameterization Academic Article uri icon

abstract

  • AbstractSensitivity of Arctic clouds and radiation in the Community Atmospheric Model, version 5, to the ice nucleation process is examined by testing a new physically based ice nucleation scheme that links the variation of ice nuclei (IN) number concentration to aerosol properties. The default scheme parameterizes the IN concentration simply as a function of ice supersaturation. The new scheme leads to a significant reduction in simulated IN concentration at all latitudes while changes in cloud amounts and properties are mainly seen at high- and midlatitude storm tracks. In the Arctic, there is a considerable increase in midlevel clouds and a decrease in low-level clouds, which result from the complex interaction among the cloud macrophysics, microphysics, and large-scale environment. The smaller IN concentrations result in an increase in liquid water path and a decrease in ice water path caused by the slowdown of the BergeronFindeisen process in mixed-phase clouds. Overall, there is an increase in the optical depth of Arctic clouds, which leads to a stronger cloud radiative forcing (net cooling) at the top of the atmosphere. The comparison with satellite data shows that the new scheme slightly improves low-level cloud simulations over most of the Arctic but produces too many midlevel clouds. Considerable improvements are seen in the simulated low-level clouds and their properties when compared with Arctic ground-based measurements. Issues with the observations and the modelobservation comparison in the Arctic region are discussed.

published proceedings

  • JOURNAL OF CLIMATE

altmetric score

  • 0.75

author list (cited authors)

  • Xie, S., Liu, X., Zhao, C., & Zhang, Y.

citation count

  • 79

complete list of authors

  • Xie, Shaocheng||Liu, Xiaohong||Zhao, Chuanfeng||Zhang, Yuying

publication date

  • August 2013