Tingjun Zhang

Lanzhou University

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Cuicui Mu

Lanzhou University

Bin Cao

Institute of Tibetan Plateau Research

Xiaoqing Peng

First Affiliated Hospital of Anhui Medical University

Qingbai Wu

Northwest Institute of Eco-Environment and Resources

Kang Wang

Hainan Tropical Ocean University

Kevin Schaefer

Cooperative Institute for Research in Environmental Sciences

Lin Liu

Chinese University of Hong Kong

Oliver W. Frauenfeld

Texas A&M University

Xinyue Zhong

Anhui Agricultural University

Shichang Kang

Chinese Academy of Sciences

Cooperative Institutions

Chinese Academy of Sciences

192

University of Chinese Academy of Sciences

104

Lanzhou University

Northwest Institute of Eco-Environment and Resources

University of Alaska Fairbanks

University of Colorado Boulder

Institute of Tibetan Plateau Research

United States Geological Survey

Cooperative Institute for Research in Environmental Sciences

Center for Excellence in Tibetan Plateau Earth Sciences

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Spatiotemporal variability of snow depth across the Eurasian continent from 1966 to 2012

The cryosphere (2018)

Xinyue Zhong Tingjun Zhang Shichang Kang Kang Wang Lei Zheng

Abstract. Snow depth is one of the key physical parameters for understanding land surface energy balance, soil thermal regime, water cycle, and assessing water resources from local community to regional industrial water supply. Previous studies by using in situ data are mostly site specific; data from satellite remote sensing may cover a large area or global scale, but uncertainties remain large. The primary objective of this study is to investigate spatial variability and temporal change in snow depth across the Eurasian continent. Data used include long-term (1966–2012) ground-based measurements from 1814 stations. Spatially, long-term (1971–2000) mean annual snow depths of >20 cm were recorded in northeastern European Russia, the Yenisei River basin, Kamchatka Peninsula, and Sakhalin. Annual mean and maximum snow depth increased by 0.2 and 0.6 cm decade−1 from 1966 through 2012. Seasonally, monthly mean snow depth decreased in autumn and increased in winter and spring over the study period. Regionally, snow depth significantly increased in areas north of 50° N. Compared with air temperature, snowfall had greater influence on snow depth during November through March across the former Soviet Union. This study provides a baseline for snow depth climatology and changes across the Eurasian continent, which would significantly help to better understanding climate system and climate changes on regional, hemispheric, or even global scales.

Peninsula

10.5194/tc-12-227-2018

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Citations (63)

Thermal state of the active layer and permafrost along the Qinghai-Xizang (Tibet) Railway from 2006 to 2010

The cryosphere (2012)

Qingbai Wu Tingjun Zhang Y. Liu

Abstract. In this study, we investigated changes in active layer thickness (ALT) and permafrost temperatures at different depths using data from the permafrost monitoring network along the Qinghai-Xizang (Tibet) Railway (QXR) since 2005. Among these sites, mean ALT is ~3.1 m, with a range of ~1.1 to 5.9 m. From 2006 through 2010, ALT has increased at a rate of ~6.3 cm a−1. The mean rate of permafrost temperature rise at the depth of 6.0 m is ~0.02 °C a−1, estimated by linear regression using 5 yr of data, and the mean rate of mean annual ground temperature (MAGT) rise at a depth of zero amplitude is ~0.012 °C a−1. Changes for colder permafrost (MAGT −1.0 °C). This is consistent with results observed in the Arctic and subarctic.

Subarctic climate

Active layer

Elevation (ballistics)

Lapse rate

10.5194/tc-6-607-2012

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Citations (162)

Supplementary material to "Brief Communication: Evaluation and comparisons of permafrost map over Qinghai-Tibet Plateau based on inventory of in-situ evidence"

Bin Cao Tingjun Zhang Qinghai Wu Yu Sheng Lin Zhao

10.5194/tc-2018-190-supplement

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The organic carbon pool of permafrost regions on the Qinghai–Xizang (Tibetan) Plateau

Cuicui Mu Tingjun Zhang Xiaoqing Peng Bin Cao X. Zhang

Abstract. Presently, Northern Circumpolar Soil Carbon Database was not involved permafrost organic carbon storage on the Qinghai–Xizang (Tibetan) Plateau (QXP). Here we reported a new estimation of soil organic carbon (SOC) pools of the permafrost regions on the QXP at different layers from the top 1 to 25 m depth using a total of 706 soil profiles. The SOC pools were estimated to be 15.29 Pg for the 0–1 m, 4.84 Pg for the 1–2 m, 3.89 Pg for the 2–3 m and 43.19 Pg for the layer of 3–25 m. The percentage (64.3%) of SOC storage in deep layer (3–25 m) on the QXP was larger than that (38.8%) in the northern circumpolar permafrost region. In total, permafrost region on the QXP contains approximately 67.2 Pg SOC, of which approximately 47.08 Pg (70.1%) stores in perennially frozen soils and deposits. The present study suggested that the permafrost organic carbon pools of Northern Hemisphere should be updated from 1672 to 1739 Pg.

Soil carbon

Circumpolar star

Carbon fibers

10.5194/tcd-8-5015-2014

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Citations (3)

Snow density climatology across the former USSR

The cryosphere (2014)

Xinyue Zhong Tingjun Zhang Kang Wang

Abstract. Snow density is one of the basic properties used to describe snow cover characteristics, and it is a key factor for linking snow depth and snow water equivalent, which are critical for water resources assessment and modeling inputs. In this study, we used long-term data from ground-based measurements to investigate snow density (bulk density) climatology and its spatiotemporal variations across the former Soviet Union (USSR) from 1966 to 2008. The results showed that the long-term monthly mean snow density was approximately 0.22 ± 0.05 g cm−3 over the study area. The maximum and minimum monthly mean snow density was about 0.33 g cm−3 in June, and 0.14 g cm−3 in October, respectively. Maritime and ephemeral snow had the highest monthly mean snow density, while taiga snow had the lowest. The higher values of monthly snow density were mainly located in the European regions of the former USSR, on the coast of Arctic Russia, and the Kamchatka Peninsula, while the lower snow density occurred in central Siberia. Significant increasing trends of snow density from September through June of the next year were observed, however, the rate of the increase varied with different snow classes. The long-term (1966–2008) monthly and annual mean snow densities had significant decreasing trends, especially during the autumn months. Spatially, significant positive trends in monthly mean snow density lay in the southwestern areas of the former USSR in November and December and gradually expanded in Russia from February through April. Significant negative trends mainly lay in the European Russia and the southern Russia. There was a high correlation of snow density with elevation for tundra snow and snow density was highly correlated with latitude for prairie snow.

Snow field

Water equivalent

Snow line

Peninsula

10.5194/tc-8-785-2014

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Citations (44)

Observed permafrost thawing and disappearance near the altitudinal limit of permafrost in the Qilian Mountains

Advances in Climate Change Research (2022)

Wen Sun Tingjun Zhang Gary D. Clow Yan-Hua Sun Wenyu Zhao

Active layer

10.1016/j.accre.2022.08.004

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Citations (10)

Spatial and temporal variations of surface albedo and snowmelt in Northern Alaska using AVHRR Polar Pathfinder datasets

Tingjun Zhang T. Haran T. A. Scambos

Snowmelt in the Arctic is a rapid process. Within a period of one to two weeks the land surface may go from completely snow-covered to completely snow-free, causing a substantial decrease in its albedo. The timing of snow disappearance in the Arctic is an indication of the onset of active layer thawing over permafrost and subsequently the start of the growth season. The timing of snow melt strongly influences summer biologic processes and the ecosystem as a whole. The pace and timing of snowmelt is also important for hydrological studies, such as water supply, river runoff, and flood forecasting. In some catchments, snow meltwater accounts for as much as 80% of the annual runoff. The objective of this paper is to investigate the spatial and temporal variations in surface albedo and snowmelt in northern Alaska. To do this, the authors use ground-based measurements and 1.25 km Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder data products. The ground-based data were acquired at nine tower sites over several years in northern Alaska by the Water Research Center, University of Alaska Fairbanks, archived at the National Snow and Ice Data Center (NSIDC), University of Colorado at Boulder. The algorithm the authors develop is based on matching the temporal pattern of surface albedo change measured at the tower sites with the albedo variations observed at each grid cell in the AVHRR product data. The pattern from the tower sites, which they call the 'kernel', is a merged pattern from all sites, with all nine data records shifted to co-align the last day of snow-cover: i.e., a template of how albedo should change during snowmelt in all areas in the Alaskan North Slope.

Snowmelt

Advanced very-high-resolution radiometer

Meltwater

Albedo (alchemy)

10.1109/igarss.2000.857339

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Citations (3)

The Last Permafrost Maximum (LPM) map of the Northern Hemisphere: permafrost extent and mean annual air temperatures, 25–17 ka BP

Boreas (2014)

Jef Vandenberghe Hugh M. French Aldar P. Gorbunov S. S. Marchenko Andrei Velichko

This paper accompanies a map that shows the extent of permafrost in the Northern Hemisphere between 25 and 17 thousand years ago. The map is based upon existing archival data, common throughout the Northern Hemisphere, that include ice‐wedge pseudomorphs, sand wedges and large cryoturbations. Where possible, a distinction is made between areas with continuous permafrost and areas where permafrost is either spatially discontinuous or sporadic. The associated mean annual palaeo‐temperatures that are inferred on the basis of present‐day analogues increase understanding of the possible changes in permafrost extent that might accompany current global warming trends. Areas with relict permafrost and areas that were formerly exposed due to lower sea level (submarine permafrost) are also mapped. Mapping is mostly limited to lowland regions (areas approximately <1000 m a.s.l.). Striking features that appear from the map are (i) the narrow permafrost zone in N orth A merica, which contrasts with the broader LPM permafrost zone in E urasia (that may be related to different snow thickness or vegetation cover), (ii) the zonal extent of former LPM permafrost (that may reflect sea‐ice distribution), which contrasts with the present‐day pattern of permafrost extent (especially in E urasia) and (iii) the relatively narrow zones of LPM discontinuous permafrost (that may indicate strong temperature gradients).

Ice wedge

Thermokarst

10.1111/bor.12070

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Citations (214)

Uncertainties in gridded air temperature fields and effects on predictive active layer modeling

Journal of Geophysical Research Atmospheres (2007)

O. A. Anisimov V. A. Lobanov S. Reneva N. I. Shiklomanov Tingjun Zhang

Several model‐based assessments predict a discernible increase in the depth of seasonal thawing and circumpolar‐scale warming of permafrost by the mid‐21st century. Quantitative estimates of the environmental and socioeconomic impacts of changing climate in northern regions require robust projection of changes in permafrost, which in turn depend on the availability of appropriate models and forcing data. We examined four high‐resolution, hemispheric‐scale gridded sets of monthly temperature and precipitation constructed using different interpolation routines and reanalysis of data from a large number of weather stations. At many of 455 Russian weather stations, the four data sets depart from empirical mean annual air temperatures averaged over the 15‐year period by 1–2°C and in cumulative daily positive temperature sums (degree days of thawing) by more than 200°C days. A permafrost model, forced with the gridded climatic data sets, was used to calculate the large‐scale characteristics of permafrost in northern Eurasia. We analyzed zonal‐mean air and ground temperatures, depth of seasonal thawing, and area occupied by near‐surface permafrost in Eurasia north of 45°N. The 0.5–1.0 °C difference in zonal‐mean air temperature between the data sets translates into a range of uncertainty of 10–20% in estimates of near‐surface permafrost area, which is comparable to the extent of changes projected for the following several decades. We conclude that more observations and theoretical studies are needed to improve characterization of baseline climatic conditions and to narrow the range of uncertainties in model‐based permafrost projections.

Forcing (mathematics)

10.1029/2006jf000593

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Citations (50)

Soil freeze/thaw cycles over snow‐free land detected by passive microwave remote sensing

Geophysical Research Letters (2001)

Tingjun Zhang R. L. Armstrong

The timing, duration, and areal extent of the near‐surface soil freeze/thaw status were investigated using passive microwave satellite remote sensing data for the 1997/98 winter over the contiguous United States. A frozen soil algorithm was validated using soil temperature data at 0 cm and 5 cm depths from more than 20 sites over the study area. Results indicated that a negative spectral gradient and a cut‐off 37‐GHz vertical polarized brightness temperature of 258.2K can be used to determine near‐surface soil freeze/thaw status with confidence. The microwave freeze/thaw boundary generally agreed with −5.0°C isotherm of air temperature although frozen soils occurred sporadically between 0°C and −5.0°C isotherms. The maximum frozen soil area over snow‐free land surface was about 3.75 × 10 6 km² or about 37% of the total study area during the 1997/98 winter. The near‐surface soils often froze before snow covered the land surface, but soil freeze/thaw status under snow cover cannot be detected using this microwave technique. The onset of soil freeze mainly occurred in October and November, while the last days of soil freeze occurred in March and April, resulting in the duration of soil freezing varying from five to seven months over the majority of the study areas. The number of days of surface soil freezing varied from several days to longer than five months.

10.1029/2000gl011952

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Citations (119)