DOI: 10.1002/jgrd.50644
论文题名: Sensitivity of downward longwave surface radiation to moisture and cloud changes in a high-elevation region
作者: Naud C.M. ; Chen Y. ; Rangwala I. ; Miller J.R.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 17 起始页码: 10072
结束页码: 10081
语种: 英语
英文关键词: cloud effect
; longwave downward radiation
; mountains
Scopus关键词: Cloud effects
; Cloud optical thickness
; Ground-based observations
; Long waves
; Long-wave radiation
; mountains
; Neural network method
; Non-linear relationships
; artificial neural network
; fractionation
; humidity
; longwave radiation
; moisture
; optical method
; sensitivity analysis
; twentieth century
; Colorado
; United States
英文摘要: Several studies have suggested enhanced rates of warming in high-elevation regions since the latter half of the twentieth century. One of the potential reasons why enhanced rates of warming might occur at high elevations is the nonlinear relationship between downward longwave radiation (DLR) and specific humidity (q). Using ground-based observations at a high-elevation site in southwestern Colorado and coincident satellite-borne cloud retrievals, the sensitivity of DLR to changes in q and cloud properties is examined and quantified using a neural network method. It is also used to explore how the sensitivity of DLR to q (dDLR/dq) is affected by cloud properties. When binned by season, dDLR/dq is maximum in winter and minimum in summer for both clear and cloudy skies. However, the cloudy-sky sensitivities are smaller, primarily because (1) for both clear and cloudy skies dDLR/dq is proportional to 1/q, for q > 0.5 g kg-1, and (2) the seasonal values of q are on average larger in the cloudy-sky cases than in clear-sky cases. For a given value of q, dDLR/dq is slightly reduced in the presence of clouds and this reduction increases as q increases. In addition, DLR is found to be more sensitive to changes in cloud fraction when cloud fraction is large. In the limit of overcast skies, DLR sensitivity to optical thickness decreases as clouds become more opaque. These results are based on only one high-elevation site, so the conclusions here need to be tested at other high-elevation locations. Key Points DLR sensitivity to humidity is slightly reduced by clouds at high elevationsDLR sensitivity to cloud fraction increases with cloud fractionDLR sensitivity to cloud optical thickness decreases with optical thickness ©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/63363
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: Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, United States; Institute of Marine and Coastal Science, Rutgers, State University of New Jersey, New Brunswick, NJ, United States; Western Water Assessment, PSD NOAA ESRL, Boulder, CO, United States
Recommended Citation:
Naud C.M.,Chen Y.,Rangwala I.,et al. Sensitivity of downward longwave surface radiation to moisture and cloud changes in a high-elevation region[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(17)