DOI: 10.1002/jgrd.50421
论文题名: Physical processes controlling ice concentrations in synoptically forced, midlatitude cirrus
作者: Jensen E.J. ; Lawson R.P. ; Bergman J.W. ; Pfister L. ; Bui T.P. ; Schmitt C.G.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 11 起始页码: 5348
结束页码: 5360
语种: 英语
英文关键词: cirrus
Scopus关键词: Clouds
; Computer simulation
; Models
; Nucleation
; cirrus
; Cloud microphysical process
; Computationally efficient
; Frequency distributions
; Heterogeneous nucleation
; Meteorological analysis
; Moderate concentration
; One-dimensional simulations
; Ice
; cirrus
; concentration (composition)
; heterogeneity
; ice crystal
; nucleation
; physical property
; sensitivity analysis
; simulation
; statistical analysis
英文摘要: Numerical simulations and airborne measurements are used to evaluate the impact of physical processes on synoptically forced, midlatitude cirrus ice concentrations. The agreement within a factor of 2 between ice concentrations measured with independent techniques (replicators and optical imaging probes) provides confidence in the accuracy of the in situ measurements. We use a computationally efficient modeling approach that incorporates the key cirrus physical processes, such that thousands of cloud cases can be simulated and the model results can be statistically compared with observations. One-dimensional simulations with detailed treatments of cloud microphysical processes are driven by temperatures and vertical winds extracted from meteorological analyses. Small-scale temperature and vertical wind perturbations associated with mesoscale waves are superimposed on the analysis fields. We find that in simulations with only homogeneous freezing nucleation, ice concentration statistics are very sensitive to the specified mesoscale wave vertical wind perturbations. With the frequency distribution of vertical winds adjusted to agree with aircraft observations, we obtain good agreement between the simulated and observed ice concentration frequency distributions. Both the observations and simulations indicate that relatively high ice concentrations (≥1000 L-1) occur rarely in these clouds (less than 1% of the time). Simulations including both homogeneous and heterogeneous nucleation indicate that even with moderate concentrations of ice nuclei (20 L-1), heterogeneous nucleation is an important ice production process, particularly for relatively low ice concentrations and warm temperatures. With enhanced ice nuclei concentrations (100 L-1), heterogeneous nucleation dominates ice production in the model. We find that it is critically important to include the impact of sedimentation on the evolution of ice concentrations when comparing model results with observations. Ice crystal collection efficiencies are poorly constrained at low temperatures, and we find that aggregation can significantly reduce ice concentrations. Sensitivity tests indicate that neither the agreement between observed and simulated ice crystal statistics nor the sensitivities indicated by the simulations are significantly affected by model assumptions such as the time periods simulated, geographic domain covered, trajectory paths calculated, or ice crystal habit assumed. © 2013. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63690
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: NASA Ames Research Center, Moffett Field, CA 94035, United States; Bay Area Environmental Research Institute, Sonoma, CA, United States; Spec, Inc., Boulder, CO, United States; National Center for Atmospheric Research, Boulder, CO, United States
Recommended Citation:
Jensen E.J.,Lawson R.P.,Bergman J.W.,et al. Physical processes controlling ice concentrations in synoptically forced, midlatitude cirrus[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(11)