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Spatiotemporal variations of maximum seasonal freezedepth in 1950s–2007 over the Heihe River Basin,Northwest China
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Citation of this paper:QingFeng Wang,TingJun Zhang,2014.Spatiotemporal variations of maximum seasonal freezedepth in 1950s–2007 over the Heihe River Basin,Northwest China.Sciences in Cold and Arid Regions,6(3):0209~0218.
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Author NameAffiliationE-mail
QingFeng Wang State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, CAS, Lanzhou, Gansu 730000, China  
TingJun Zhang 1. College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, Gansu 730000, China 2. National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, 80309, USA tjzhang@lzu.edu.cn 
Abstract:Investigation on spatiotemporal variations of maximum seasonal freeze depth (MSFD) over the Heihe River Basin is of great importance for systematic understanding of regional climate and environmental change, ecological-hydrological processes, water resources assessment, construction and resource development. Based on soil and air temperatures at the meteorological stations of the China Meteorological Administration (CMA) over the Heihe River Basin, MSFDs time series are structured into a composite time series over the 1960–2007 period. Evaluating the averaged MSFD time series for 1960–2007 reveals a statistically significant trend of -4.0 cm/decade or a net change of -19.2 cm for the 48-year period over the basin. The MSFD had significantly negative correlation with mean annual air temperature (MAAT), winter air temperature, mean annual ground surface temperature (MAGST), degree days of thawing for the air (DDTa) as well as for the surface (DDTs), and degree days of freezing for the surface (DDFs). While there was significantly positive correlation between DDFs and MSFD time series, MSFD was deeper and changed greatly in the Heihe River source area. It was shallower in the east-central basin and gradually deepened in other sections of the basin. The MSFD distribution pattern in 2003–2005 is consistent with that of averaged degree days of freezing for air (DDFa) in 1960–2007. However, the maximum of MSFD may not be accurate, because there is no long term observation data in the deep seasonally frozen ground regions near the lower boundary of permafrost. With increasing elevation, averaged DDFa increased at a rate of 51.6 °C-day/100m, therefore, the MSFG and the date reaching MSFG became deeper and later, respectively.
keywords:spatiotemporal variations  MSFD  potential driving variables  seasonally frozen ground  Heihe River Basin
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