永久冻土
雪
环境科学
纬度
土壤科学
活动层
气候学
水文学(农业)
地质学
地貌学
岩土工程
图层(电子)
海洋学
化学
大地测量学
有机化学
薄膜晶体管
作者
Bin Cao,Stephan Gruber,Donghai Zheng,Xin Li
出处
期刊:The Cryosphere
[Copernicus Publications]
日期:2020-08-12
卷期号:14 (8): 2581-2595
被引量:66
标识
DOI:10.5194/tc-14-2581-2020
摘要
Abstract. ERA5-Land (ERA5L) is a reanalysis product derived by running the land component of ERA5 at increased resolution. This study evaluates ERA5L soil temperature in permafrost regions based on observations and published permafrost products. We find that ERA5L overestimates soil temperature in northern Canada and Alaska but underestimates it in mid–low latitudes, leading to an average bias of −0.08 ∘C. The warm bias of ERA5L soil is stronger in winter than in other seasons. As calculated from its soil temperature, ERA5L overestimates active-layer thickness and underestimates near-surface (<1.89 m) permafrost area. This is thought to be due in part to the shallow soil column and coarse vertical discretization of the land surface model and to warmer simulated soil. The soil temperature bias in permafrost regions correlates well with the bias in air temperature and with maximum snow height. A review of the ERA5L snow parameterization and a simulation example both point to a low bias in ERA5L snow density as a possible cause for the warm bias in soil temperature. The apparent disagreement of station-based and areal evaluation techniques highlights challenges in our ability to test permafrost simulation models. While global reanalyses are important drivers for permafrost simulation, we conclude that ERA5L soil data are not well suited for informing permafrost research and decision making directly. To address this, future soil temperature products in reanalyses will require permafrost-specific alterations to their land surface models.
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