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DOI	10.5194/hess-24-5559-2020
	Variability in epilimnion depth estimations in lakes
	Wilson H.L.; Ayala A.I.; Jones I.D.; Rolston A.; Pierson D.; de Eyto E.; Grossart H.-P.; Perga M.-E.; Woolway R.I.; Jennings E.
发表日期	2020
ISSN	1027-5606
起始页码	5559
结束页码	5577
卷号	24 期号:11
英文摘要	The epilimnion is the surface layer of a lake typically characterised as well mixed and is decoupled from the metalimnion due to a steep change in density. The concept of the epilimnion (and, more widely, the three-layered structure of a stratified lake) is fundamental in limnology, and calculating the depth of the epilimnion is essential to understanding many physical and ecological lake processes. Despite the ubiquity of the term, however, there is no objective or generic approach for defining the epilimnion, and a diverse number of approaches prevail in the literature. Given the increasing availability of water temperature and density profile data from lakes with a high spatio-temporal resolution, automated calculations, using such data, are particularly common, and they have vast potential for use with evolving long-term globally measured and modelled datasets. However, multi-site and multi-year studies, including those related to future climate impacts, require robust and automated algorithms for epilimnion depth estimation. In this study, we undertook a comprehensive comparison of commonly used epilimnion depth estimation methods, using a combined 17-year dataset, with over 4700 daily temperature profiles from two European lakes. Overall, we found a very large degree of variability in the estimated epilimnion depth across all methods and thresholds investigated and for both lakes. These differences, manifesting over high-frequency data, led to fundamentally different understandings of the epilimnion depth. In addition, estimations of the epilimnion depth were highly sensitive to small changes in the threshold value, complex thermal water column structures, and vertical data resolution. These results call into question the custom of arbitrary method selection and the potential problems this may cause for studies interested in estimating the ecological processes occurring within the epilimnion, multi-lake comparisons, or long-term time series analysis. We also identified important systematic differences between methods, which demonstrated how and why methods diverged. These results may provide rationale for future studies to select an appropriate epilimnion definition in light of their particular purpose and with awareness of the limitations of individual methods. While there is no prescribed rationale for selecting a particular method, the method which defined the epilimnion depth as the shallowest depth, where the density was 0.1 kgm-3 more than the surface density, may be particularly useful as a generic method. © Author(s) 2020.
语种	英语
scopus关键词	Ecology; Time series analysis; Automated algorithms; Comprehensive comparisons; Degree of variability; High frequency data; Potential problems; Spatio-temporal resolution; Three-layered structures; Water temperatures; Lakes; epilimnion; lake ecosystem; seasonality; spatiotemporal analysis; stratification; surface layer; thermal water; time series analysis; vertical distribution; water column
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/159252
作者单位	Wilson, H.L., Centre for Freshwater and Environmental Studies, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland; Ayala, A.I., Department of Ecology and Genetics Limnology, Uppsala University, Uppsala, Sweden; Jones, I.D., Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, United Kingdom; Rolston, A., An Fóram Uisce - The Water Forum, Nenagh, Co. Tipperary, Ireland; Pierson, D., Department of Ecology and Genetics Limnology, Uppsala University, Uppsala, Sweden; de Eyto, E., Marine Institute Catchment Research Facility, Furnace, Newport, Co. Mayo, Ireland; Grossart, H.-P., Institute for Biochemistry and Biology, Potsdam University, Potsdam, Germany; Perga, M.-E., University of Lausanne, Faculty of Geoscience and Environment, Lausanne, 1015, Switzerland; Woolway, R.I., Centre for Freshwater and Environmental Studies, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland; Jennings, E., Centre for Freshwater and Environmental Studies, Dundalk...
推荐引用方式 GB/T 7714	Wilson H.L.,Ayala A.I.,Jones I.D.,et al. Variability in epilimnion depth estimations in lakes[J],2020,24(11).
APA	Wilson H.L..,Ayala A.I..,Jones I.D..,Rolston A..,Pierson D..,...&Jennings E..(2020).Variability in epilimnion depth estimations in lakes.Hydrology and Earth System Sciences,24(11).
MLA	Wilson H.L.,et al."Variability in epilimnion depth estimations in lakes".Hydrology and Earth System Sciences 24.11(2020).