Impact of environmental conditions on the mesoscale characteristics of squall-line systems: Toward the development of anvil cirrus parameterization for GCMs
Our earlier studies indicated that a strong coupling exists in the mesoscale convective systems (MCSs) between deep convection and its related anvil cloud through the interaction among dynamical, thermodynamical and radiative processes. They also showed that the tilting structure of MCSs makes an important contribution to the water budget of anvil clouds, particularly the tropical anvil due to the jetlike wind profile. However, most earlier GCMs did not include a direct and physically consistent representation of this coupling. To this end, Randall et al. suggested a more realistic anvil parameterization by adding prognostic cloud water (or ice) variables to account for the formation of anvil clouds from cumulus detrainment. In addition to this effort, our recent studies further suggest the need to parameterize the tilting structure of MCSs in GCMs. The objective of this work is to parameterize the large-scale effects of this tilting structure. Our primary interest focuses on MCSs in an environment with substantial wind shear, such as squall-line systems, since they have longer lifetimes and wider coverage to affect the earth-atmosphere radiation budget and climate. Using varied convective available potential energy (CAPE), wind shear intensity, shear depth, and the pattern of shear profile over a wide range of bulk Richardson number (Ri), a sensitivity study is performed in a cloud resolving model to link its resulting mesoscale ascent/descent with GCM-resolvable variables. The ultimate goal of this research is to develop an anvil cirrus parameterization (ACP), that will couple with cumulus parameterizations in GCMs to improve the cloud-radiation feedback on large-scale climate.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 267534
- Report Number(s):
- UCRL-JC-124301; CONF-9603149-3; ON: DE96012235
- Resource Relation:
- Conference: 6. Atmospheric Radiation Measurement (ARM) science team meeting, San Antonio, TX (United States), 4-7 Mar 1996; Other Information: PBD: May 1996
- Country of Publication:
- United States
- Language:
- English
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