Changes in the timing and duration of the near-surface soil freeze/thaw status from 1956 to 2006 across China

Abstract

Abstract. The near-surface soil freeze/thaw status is an important indicator of climate change. Using data from 636 meteorological stations across China, we investigated the changes in the first date, the last date, the duration, and the number of days of the near-surface soil freeze over the period 1956-2006. The results reveal that the first date of the near-surface soil freeze was delayed by about 5 days, or at a rate of 0.10 ± 0.03 day yr −1 , and the last date was advanced by about 7 days, or at a rate of 0.15 ± 0.02 day yr −1 . The duration of the near-surface soil freeze decreased by about 12 days or at a rate of 0.25 ± 0.04 day yr −1 , while the actual number of the near-surface soil freeze days decreased by about 10 days or at a rate of 0.20 ± 0.03 day yr −1 . The rates of changes in the near-surface soil freeze/thaw status increased dramatically from the early 1990s through the end of the study period. Regionally, the changes in western China were greater than those in eastern China. Changes in the nearsurface soil freeze/thaw status were primarily controlled by changes in air temperature, but urbanization may also play an important role.

Response of seasonal soil freeze depth to climate change across China

“…Many examples of permafrost degradation have been reported, such as deeper the active layer thickness, reduced freeze time duration, and shifts in the timing of thawing and freezing in seasonally frozen ground regions (Henry, 2008;Callaghan et al, 2011;Stocker et al, 2014;Wang et al, 2015). Negative correlations are found here between SFD and temperature (including MAAT and MAGST) because of solar radiation heating the ground and energy transfer into the soil, ultimately increasing the soil temperature.…”

“…1) available four times daily at 02:00, 08:00, 14:00, and 20:00 (http://data.cma.cn/en; Wang et al, 2015). These data come already quality controlled, and station observations date back to the 1950s and 1960s.…”

“…The increasing thickness of the active layer has been indicated by many observations in permafrost regions at high latitudes and altitudes (Brown et al, 2000;Frauenfeld et al, 2004;Zhang et al, 2005;Fyodorov-Davydov et al, 2008;Wu et al, 2010;Zhao et al, 2010;Callaghan et al, 2011;Liu et al, 2014a, b;Stocker et al, 2014). Less research has focused on SFG areas Frauenfeld et al, 2004;Frauenfeld and Zhang, 2011;Wang et al, 2015), although the near-surface soil freezethaw status has been investigated using satellite passive microwave remote sensing (Zhang and Armstrong, 2001;Zhang et al, 2003Zhang et al, , 2004Li et al, 2008;Jin et al, 2015). Peng et al (2016b) analyzed the response of soil freeze-thaw states to climate change across China, based on observational data.…”

Climatology of the Timing and Duration of the Near-Surface Soil Freeze-Thaw Status Across China

“…We use this definition for the following reasons: First, almost all previous studies used daily minimum temperature to define the near-surface soil freeze because it can seriously affect plants and growing crops (Kunkel et al, 2004;McCabe et al, 2015;Wang et al, 2015). Second, daily minimum temperature is sensitive to climate change.…”

A synthesis dataset of permafrost-affected soil thermal conditions for Alaska, USA

“…Another widely used permafrost dataset is the Russian Soil Temperature dataset of daily ground temperature measurements at different depths ranging from 0 to 3.2 m for 51 years (Sherstiukov, 2012). An additional ground temperature dataset includes daily-mean ground temperatures 15 at various depths from 0 to 3.2 m at more than 800 stations in China which in selected locations dates back to the 1950s (Wang et al, 2015).…”