scholarly journals Three-in-one: GPS-IR measurements of ground surface elevation changes, soil moisture, and snow depth at a permafrost site in the northeastern Qinghai-Tibet Plateau

2020 ◽  
Author(s):  
Jiahua Zhang ◽  
Lin Liu ◽  
Lei Su ◽  
Tao Che
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Active Layer ◽  
Snow Depth ◽  
Soil Moisture Content ◽  
Ground Surface ◽  
Surface Elevation ◽  
Tibet Plateau ◽  
Elevation Changes ◽  
Qinghai Tibet Plateau

Abstract. Ground surface elevation changes, soil moisture, and snow depth are all essential variables for studying the dynamics of the active layer and permafrost. GPS interferometric reflectometry (GPS-IR) has been used to measure surface elevation changes and snow depth in permafrost areas. However, its applicability to estimating soil moisture in permafrost regions has not been assessed. Moreover, these variables were usually measured separately at different sites. Integrating their estimates at one site facilitates the comprehensive utilization of GPS-IR in permafrost studies. In this study, we run simulations to elucidate that the commonly-used GPS-IR method for estimating soil moisture content cannot be directly used in permafrost areas, because it does not consider the bias introduced by the seasonal surface elevation changes due to thawing of the active layer. We propose a solution to improve this default method by introducing modeled surface elevation changes. We validate this modified method using the GPS data and in situ observations at a permafrost site in the northeastern Qinghai-Tibet Plateau (QTP). The root-mean-square error and correlation coefficient between the GPS-IR estimates of soil moisture content and the in situ ones improve from 1.85 % to 1.51 % and 0.71 to 0.82, respectively. We also implement a framework to integrate the GPS-IR estimates of these three variables at one site and illustrate it using the same site in the QTP as an example. This study highlights the improvement to the default method, which makes the GPS-IR valid in estimating soil moisture content in permafrost areas. The three-in-one framework is able to fully utilize the GPS-IR in permafrost areas and can be extended to other sites such as those in the Arctic. This study is also the first to use GPS-IR to estimate environmental variables in the QTP, which fills a spatial gap and provides complementary measurements to those of ground temperature and active layer thickness.

scholarly journals Three in one: GPS-IR measurements of ground surface elevation changes, soil moisture, and snow depth at a permafrost site in the northeastern Qinghai–Tibet Plateau

2021 ◽  
Vol 15 (6) ◽  
pp. 3021-3033
Author(s):  
Jiahua Zhang ◽  
Lin Liu ◽  
Lei Su ◽  
Tao Che
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Active Layer ◽  
Snow Depth ◽  
Soil Moisture Content ◽  
Ground Surface ◽  
Surface Elevation ◽  
Tibet Plateau ◽  
Elevation Changes ◽  
Qinghai Tibet Plateau

Abstract. Ground surface elevation changes, soil moisture, and snow depth are all essential variables for studying the dynamics of the active layer and permafrost. GPS interferometric reflectometry (GPS-IR) has been used to measure surface elevation changes and snow depth in permafrost areas. However, its applicability to estimating soil moisture in permafrost regions has not been assessed. Moreover, these variables were usually measured separately at different sites. Integrating their estimates at one site facilitates the comprehensive utilization of GPS-IR in permafrost studies. In this study, we run simulations to elucidate that the commonly used GPS-IR algorithm for estimating soil moisture content cannot be directly used in permafrost areas, because it does not consider the bias introduced by the seasonal surface elevation changes due to active layer thawing. We propose a solution to improve this default method by introducing modeled surface elevation changes. We validate this modified method using the GPS data and in situ observations at a permafrost site in the northeastern Qinghai–Tibet Plateau (QTP). The root-mean-square error and correlation coefficient between the GPS-IR estimates of soil moisture content and the in situ ones improve from 1.85 % to 1.51 % and 0.71 to 0.82, respectively. We also propose a framework to integrate the GPS-IR estimates of these three variables at one site and illustrate it using the same site in the QTP as an example. This study highlights the improvement to the default algorithm, which makes the GPS-IR valid in estimating soil moisture content in permafrost areas. The three-in-one framework is able to fully utilize the GPS-IR in permafrost areas and can be extended to other sites such as those in the Arctic. This study is also the first to use GPS-IR to estimate environmental variables in the QTP, which fills a spatial gap and provides complementary measurements to ground temperature and active layer thickness.

scholarly journals Multi-channel ground-penetrating radar to explore spatial variations in thaw depth and moisture content in the active layer of a permafrost site

2010 ◽  
Vol 4 (3) ◽  
pp. 269-283 ◽  
Author(s):  
U. Wollschläger ◽  
H. Gerhards ◽  
Q. Yu ◽  
K. Roth
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Active Layer ◽  
Ground Penetrating Radar ◽  
Soil Moisture Content ◽  
Late Summer ◽  
Bare Soil ◽  
Thaw Depth ◽  
Ground Penetrating ◽  
Gravel Road

Abstract. Multi-channel ground-penetrating radar (GPR) was applied at a permafrost site on the Tibetan Plateau to investigate the influence of surface properties and soil texture on the late-summer thaw depth and average soil moisture content of the active layer. Measurements were conducted on an approximately 85 × 60 m2 sized area with surface and soil textural properties that ranged from medium to coarse textured bare soil to finer textured, sparsely vegetated areas covered with fine, wind blown sand, and it included the bed of a gravel road. The survey allowed a clear differentiation of the various units. It showed (i) a shallow thaw depth and low average soil moisture content below the sand-covered, vegetated area, (ii) an intermediate thaw depth and high average soil moisture content along the gravel road, and (iii) an intermediate to deep thaw depth and low to intermediate average soil moisture content in the bare soil terrain. From our measurements, we found hypotheses for the permafrost processes at this site leading to the observed late-summer thaw depth and soil moisture conditions. The study clearly indicates the complicated interactions between surface and subsurface state variables and processes in this environment. Multi-channel GPR is an operational technology to efficiently study such a system at scales varying from a few meters to a few kilometers.

An Experimental Study of the Zhao He Grassland Soil Wind Erosion Characteristics on the Northern Foothills of Yin Shan Mountain

2012 ◽  
Vol 518-523 ◽  
pp. 4496-4503
Author(s):  
Jian Qiang Chen ◽  
Man Quan Zhao ◽  
Zhi Chen
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Prevention And Control ◽  
Wind Erosion ◽  
Soil Moisture Content ◽  
Ground Surface ◽  
Vegetation Coverage ◽  
Soil Wind Erosion ◽  
Erosion Test ◽  
And Control

The soil erosion test was carried out for the Zhao He grassland on the northern foothills of Yin Shan Mountain by the use of a portable wind erosion tunnel developed by Inner Mongolia Agricultural University, the variation low of soil wind erosion rate with the different wind speed and different arrangement in pairs of different soil moisture content and different vegetation coverage was obtained and the data analysis indicates that the anti-wind erosion characteristics of ground surface is most satisfactory when the vegetation coverage is 40%, soil moisture content 9.3% and the height of vegetation 50cm. The result of this study may provide a certain reference date for the application of prevention and control technology of soil wind erosion and be of vital significance to the implementation of sustainable development of livestock husbandry.

scholarly journals Multi-channel ground-penetrating radar to explore spatial variations in thaw depth and moisture content in the active layer of a permafrost site

2009 ◽  
Vol 3 (3) ◽  
pp. 919-946 ◽  
Author(s):  
U. Wollschläger ◽  
H. Gerhards ◽  
Q. Yu ◽  
K. Roth
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Active Layer ◽  
Ground Penetrating Radar ◽  
Soil Moisture Content ◽  
Late Summer ◽  
Bare Soil ◽  
Thaw Depth ◽  
Ground Penetrating ◽  
Gravel Road

Abstract. Multi-channel ground-penetrating radar was applied at a permafrost site on the Tibetan Plateau to investigate the influence of surface properties and soil texture on the late-summer thaw depth and average soil moisture content of the active layer. Measurements were conducted on an approximately 85×60 m2 sized area with surface and soil textural properties that ranged from medium to coarse textured bare soil to finer textured, vegetated areas covered with fine, wind blown sand, and it included the bed of a gravel road. The survey allowed a clear differentiation of the various units. It showed (i) a shallow thaw depth and low average soil moisture content below the sand-covered, vegetated area, (ii) an intermediate thaw depth and high average soil moisture content along the gravel road, and (iii) an intermediate to deep thaw depth and low to intermediate average soil moisture content in the bare soil terrain. From our measurements, we found plausible hypotheses for the permafrost processes at this site leading to the observed late-summer thaw depth and soil moisture conditions. The study clearly indicates the complicated interactions between surface and subsurface state variables and processes in this environment. In addition, the survey demonstrates the potential of multi-channel ground-penetrating radar to efficiently map thaw depth and soil moisture content of the active layer with high spatial resolution at scales from a few meters to a few kilometers.

scholarly journals Response of freeze-thaw processes to experimental warming in the permafrost regions of the central Qinghai-Tibet Plateau

2016 ◽  
Author(s):  
Shengyun Chen ◽  
Wenjie Liu ◽  
Qian Zhao ◽  
Lin Zhao ◽  
Qingbai Wu ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Moisture Content ◽  
Tibet Plateau ◽  
Active Layer Thickness ◽  
Experimental Warming ◽  
Freeze Thaw ◽  
Alpine Steppe ◽  
Steppe Ecosystems ◽  
Qinghai Tibet Plateau ◽  
Permafrost Regions

Abstract. Assessing quantitatively effect of climate warming on freeze/thaw index (FI/TI), soil freeze-thaw processes and active layer thickness (ALT) is still lacking in the permafrost regions of the Qinghai-Tibet Plateau (QTP) until now. Experimental warming was manipulated using open top chambers (OTCs) in alpine swamp meadow and alpine steppe ecosystems in the permafrost regions of the central QTP during 2009–2011. Under OTCs treatment, air temperature (Ta) significantly increased in the daytime and decreased in the nighttime, diurnal and annual Ta range significantly enhanced, and mean annual Ta increased by 1.4 °C. Owing to the experimental warming, mean annual soil temperature at the depths from 5 cm to 40 cm was increased by 0.2 ~ 0.7 °C in alpine swamp meadow and 0.3 ~ 1.5 °C in alpine steppe. Mean annual soil moisture content at 10 cm depth decreased by 1.1 % and 0.8 %, and mean annual soil salinity at 10 cm depth significantly increased by 0.3 g L-1 and 0.1 g L-1 in alpine swamp meadow and alpine steppe, respectively. Further, FI was significantly decreased by 410.7 °C d while TI was significantly increased by 460.7 °C d. Likewise, the onset dates of shallow soil thawing at 5–40 cm depths were advanced by 9 days and 8 days while the onset dates of freezing were delayed by 10 days and 4 days in alpine swamp meadow and alpine steppe, respectively. Moreover, soil frozen days were significantly decreased by 28 days and 16 days, but thawed days were increased by 18 days and 6 days, and frozen-thawed days were significantly increased by 10 days and 10 days in alpine swamp meadow and alpine steppe, respectively. Furthermore, ALT would be significantly increased by ~ 6.9 cm and ~ 19.6 cm in alpine swamp meadow and alpine steppe ecosystems, respectively.

scholarly journals Active-Layer Soil Moisture Content Regional Variations in Alaska and Russia by Ground-Based and Satellite-Based Methods, 2002 through 2014

2015 ◽  
Vol 06 (01) ◽  
pp. 12-41 ◽  
Author(s):  
Reginald R. Muskett ◽  
Vladimir E. Romanovsky ◽  
William L. Cable ◽  
Alexander L. Kholodov
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Active Layer ◽  
Soil Moisture Content ◽  
Regional Variations

scholarly journals Soil Moisture Calibration Equations for Active Layer GPR Detection—a Case Study Specially for the Qinghai–Tibet Plateau Permafrost Regions

2020 ◽  
Vol 12 (4) ◽  
pp. 605
Author(s):  
Erji Du ◽  
Lin Zhao ◽  
Defu Zou ◽  
Ren Li ◽  
Zhiwei Wang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Soil Moisture ◽  
Active Layer ◽  
Complex Refractive Index ◽  
Tibet Plateau ◽  
Data Set ◽  
Calibration Equation ◽  
Qinghai Tibet Plateau ◽  
Moisture Estimation ◽  
Permafrost Regions

Ground-penetrating radar (GPR) is a convenient geophysical technique for active-layer soil moisture detection in permafrost regions, which is theoretically based on the petrophysical relationship between soil moisture (θ) and the soil dielectric constant (ε). The θ–ε relationship varies with soil type and thus must be calibrated for a specific region or soil type. At present, there is lack of such a relationship for active-layer soil moisture estimation for the Qinghai–Tibet plateau permafrost regions. In this paper, we utilize the Complex Refractive Index Model to establish such a calibration equation that is suitable for active-layer soil moisture estimation with GPR velocity. Based on the relationship between liquid water, temperature, and salinity, the soil water dielectric constant was determined, which varied from 84 to 88, with an average value of 86 within the active layer for our research regions. Based on the calculated soil-water dielectric constant variation range, and the exponent value range within the Complex Refractive Index Model, the exponent value was determined as 0.26 with our field-investigated active-layer soil moisture and dielectric data set. By neglecting the influence of the soil matrix dielectric constant and soil porosity variations on soil moisture estimation at the regional scale, a simple active-layer soil moisture calibration curve, named CRIM, which is suitable for the Qinghai–Tibet plateau permafrost regions, was established. The main shortage of the CRIM calibration equation is that its calculated soil-moisture error will gradually increase with a decreasing GPR velocity and an increasing GPR velocity interpretation error. To avoid this shortage, a direct linear fitting calibration equation, named as υ-fitting, was acquired based on the statistical relationship between the active-layer soil moisture and GPR velocity with our field-investigated data set. When the GPR velocity interpretation error is within ±0.004 m/ns, the maximum moisture error calculated by CRIM is within 0.08 m3/m3. While when the GPR velocity interpretation error is larger than ±0.004 m/ns, a piecewise formula calculation method, combined with the υ-fitting equation when the GPR velocity is lower than 0.07 m/ns and the CRIM equation when the GPR velocity is larger than 0.07 m/ns, was recommended for the active-layer moisture estimation with GPR detection in the Qinghai–Tibet plateau permafrost regions.

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