气候变化领域集成服务门户(CCPortal): Principal components of thermal regimes in mountain river networks

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DOI	10.5194/hess-22-6225-2018
	Principal components of thermal regimes in mountain river networks
	Isaak D.J.; Luce C.H.; Chandler G.L.; Horan D.L.; Wollrab S.P.
发表日期	2018
ISSN	1027-5606
起始页码	6225
结束页码	6240
卷号	22 期号:12
英文摘要	Description of thermal regimes in flowing waters is key to understanding physical processes, enhancing predictive abilities, and improving bioassessments. Spatially and temporally sparse data sets, especially in logistically challenging mountain environments, have limited studies on thermal regimes, but inexpensive sensors coupled with crowd-sourced data collection efforts provide efficient means of developing large data sets for robust analyses. Here, thermal regimes are assessed using annual monitoring records compiled from several natural resource agencies in the northwestern United States that spanned a 5-year period (2011-2015) at 226 sites across several contiguous montane river networks. Regimes were summarized with 28 metrics and principal component analysis (PCA) was used to determine those metrics which best explained thermal variation on a reduced set of orthogonal axes. Four principal components (PC) accounted for 93.4% of the variation in the temperature metrics, with the first PC (49% of variance) associated with metrics that represented magnitude and variability and the second PC (29% of variance) associated with metrics representing the length and intensity of the winter season. Another variant of PCA, T-mode analysis, was applied to daily temperature values and revealed two distinct phases of spatial variability - a homogeneous phase during winter when daily temperatures at all sites were < 3 C and a heterogeneous phase throughout the year's remainder when variation among sites was more pronounced. Phase transitions occurred in March and November, and coincided with the abatement and onset of subzero air temperatures across the study area. S-mode PCA was conducted on the same matrix of daily temperature values after transposition and indicated that two PCs accounted for 98% of the temporal variation among sites. The first S-mode PC was responsible for 96.7% of that variance and correlated with air temperature variation (r D 0:92), whereas the second PC accounted for 1.3% of residual variance and was correlated with discharge (r D 0:84). Thermal regimes in these mountain river networks were relatively simple and responded coherently to external forcing factors, so sparse monitoring arrays and small sets of summary metrics may be adequate for their description. PCA provided a computationally efficient means of extracting key information elements from the temperature data set used here and could be applied broadly to facilitate comparisons among more diverse stream types and develop classification schemes for thermal regimes. © Author(s) 2018.
语种	英语
scopus关键词	Atmospheric temperature; Classification (of information); Landforms; Microcomputers; Rivers; Air temperature variations; Classification scheme; Computationally efficient; Information elements; Northwestern United States; Predictive abilities; Principal Components; Spatial variability; Principal component analysis; air temperature; mountain environment; principal component analysis; river discharge; river flow; river system; spatiotemporal analysis; temporal variation; thermal regime; United States
来源期刊	Hydrology and Earth System Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/159838
作者单位	Isaak, D.J., U.S. Forest Service, Rocky Mountain Research Station, Aquatic Sciences Lab, Boise, ID 83702, United States; Luce, C.H., U.S. Forest Service, Rocky Mountain Research Station, Aquatic Sciences Lab, Boise, ID 83702, United States; Chandler, G.L., U.S. Forest Service, Rocky Mountain Research Station, Aquatic Sciences Lab, Boise, ID 83702, United States; Horan, D.L., U.S. Forest Service, Rocky Mountain Research Station, Aquatic Sciences Lab, Boise, ID 83702, United States; Wollrab, S.P., U.S. Forest Service, Rocky Mountain Research Station, Aquatic Sciences Lab, Boise, ID 83702, United States
推荐引用方式 GB/T 7714	Isaak D.J.,Luce C.H.,Chandler G.L.,et al. Principal components of thermal regimes in mountain river networks[J],2018,22(12).
APA	Isaak D.J.,Luce C.H.,Chandler G.L.,Horan D.L.,&Wollrab S.P..(2018).Principal components of thermal regimes in mountain river networks.Hydrology and Earth System Sciences,22(12).
MLA	Isaak D.J.,et al."Principal components of thermal regimes in mountain river networks".Hydrology and Earth System Sciences 22.12(2018).