In Situ Determination of Soil Freezing Characteristics for Estimation of Soil Moisture Characteristics using a Dielectric Tube Sensor

2014 ◽  
Vol 78 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Qiang Cheng ◽  
Yurui Sun ◽  
Xuzhang Xue ◽  
Jia Guo
Keyword(s):  
Soil Moisture ◽  
Soil Freezing ◽  
Dielectric Tube

scholarly journals Validation of SMAP L2 passive-only soil moisture products using <i>in situ</i> measurements collected in Twente, The Netherlands

2019 ◽  
Author(s):  
Rogier van der Velde ◽  
Andreas Colliander ◽  
Michiel Pezij ◽  
Harm-Jan F. Benninga ◽  
Rajat Bindlish ◽  
...  
Keyword(s):  
Soil Moisture ◽  
The Netherlands ◽  
Mean Squared Error ◽  
Single Channel ◽  
Soil Depth ◽  
Soil Freezing ◽  
Horizontal Polarization ◽  
Dual Channel ◽  
Spatially Distributed

Abstract. The Twente region in the east of the Netherlands has a network with twenty soil monitoring stations that has been utilized for validation of the Soil Moisture Active/Passive (SMAP) passive-only soil moisture products. Over the period from April 2015 until December 2018, seven stations covered by the SMAP reference pixels have fairly complete data records. Spatially distributed soil moisture simulations with the Dutch national hydrological model have been utilized for the development of upscaling functions to translate the spatial mean of point measurements to the domain of the SMAP reference pixels. The native and upscaled spatial soil moisture means have been adopted as in situ references to assess the performance of the SMAP i) Single Channel Algorithm at Horizontal Polarization (SCA-H), ii) Single Channel Algorithm at Vertical Polarization (SCA-V), and iii) Dual Channel Algorithm (DCA) soil moisture estimates. In the case of the Twente network it was found that the SCA-V soil moisture retrieved SMAP observations collected in the afternoon had the best agreement with the in situ references leading to an unbiased Root Mean Squared Error (uRMSE) of 0.059 m3 m−3. This is larger than the mission target accuracy of 0.04 m3 m−3, which can be attributed to large over- and underestimation errors (> 0.08 m3 m−3) in particular at the end of dry spells and during freezing, respectively. The strong vertical dielectric gradients associated with rapid soil freezing and wetting causes the disparity in soil depth characterized by SMAP and in situ that leads to the large mismatches. Once filtered for frozen conditions and antecedent rainfall the uRMSE improves to 0.043 m3 m−3.

scholarly journals The determination of soil moisture and soil density in situ by neutron and γ-ray scattering

1967 ◽  
Vol 8 (2) ◽  
pp. 55-70
Author(s):  
Takaaki Ando ◽  
Teruo Aihara ◽  
Takao Kanai ◽  
Keiichi Kodai ◽  
Akira Unosawa
Keyword(s):  
Soil Moisture ◽  
Soil Density ◽  
Γ Ray ◽  
Ray Scattering

scholarly journals Validation of SMAP L2 passive-only soil moisture products using upscaled in situ measurements collected in Twente, the Netherlands

2021 ◽  
Vol 25 (1) ◽  
pp. 473-495
Author(s):  
Rogier van der Velde ◽  
Andreas Colliander ◽  
Michiel Pezij ◽  
Harm-Jan F. Benninga ◽  
Rajat Bindlish ◽  
...  
Keyword(s):  
Soil Moisture ◽  
The Netherlands ◽  
Mean Squared Error ◽  
Single Channel ◽  
Soil Depth ◽  
In Situ Measurements ◽  
Soil Freezing ◽  
Horizontal Polarization ◽  
Estimation Errors

Abstract. The Twente region in the east of the Netherlands has a network with 20 soil monitoring stations that has been utilized for validation of the Soil Moisture Active/Passive (SMAP) passive-only soil moisture products. Over the period from April 2015 until December 2018, seven stations covered by the SMAP reference pixels have fairly complete data records. Spatially distributed soil moisture simulations with the Dutch National Hydrological Model have been utilized for the development of upscaling functions to translate the spatial mean of point measurements to the domain of the SMAP reference pixels. The native and upscaled spatial soil moisture means computed using the in situ measurements have been adopted as references to assess the performance of the SMAP (i) Single Channel Algorithm at Horizontal Polarization (SCA-H), (ii) Single Channel Algorithm at Vertical Polarization (SCA-V), and (iii) Dual Channel Algorithm (DCA) soil moisture estimates. In the case of the Twente network it was found that the SCA-V SMAP soil moisture observations collected in the afternoon had the best agreement with the native spatial mean, leading to an unbiased root mean squared error (uRMSE) of 0.059 m3 m−3, whereas for the upscaled in situ references primarily larger biases were found. These error levels are larger than the mission's target accuracy of 0.04 m3 m−3, which can be attributed to large over- and under-estimation errors (>0.08 m3 m−3), in particular at the end of dry spells and during freezing, respectively. The strong vertical dielectric gradients associated with rapid soil freezing and wetting cause the disparity in soil depth characterized by SMAP and in situ that leads to the large mismatches. Once filtered for frozen conditions and antecedent rainfall, the uRMSE improves to 0.043 m3 m−3.

AUTOMATIC IN SITU DETERMINATION OF FIELD CAPACITY USING SOIL MOISTURE SENSORS

2011 ◽  
Vol 61 (3) ◽  
pp. 416-424 ◽  
Author(s):  
Scott Fazackerley ◽  
Ramon Lawrence
Keyword(s):  
Soil Moisture ◽  
Field Capacity ◽  
Soil Moisture Sensors

INDIREKTE PAPIERCHROMATOGRAPHISCHE METHODE ZUR BESTIMMUNG DER HARNOESTROGENE

1961 ◽  
Vol 38 (4) ◽  
pp. 545-562 ◽  
Author(s):  
L. Kecskés ◽  
F. Mutschler ◽  
I. Glós ◽  
E. Thán ◽  
I. Farkas ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Granulosa Cell ◽  
Iron Content ◽  
List Type ◽  
Granulosa Cell Tumour ◽  
Hydrolysis Of ◽  
Phenol Fraction ◽  
Qualitative Determination

ABSTRACT 1. An indirect paperchromatographic method is described for separating urinary oestrogens; this consists of the following steps: acidic hydrolysis, extraction with ether, dissociation of phenol-fractions with partition between the solvents. Previous purification of phenol fraction with the aid of paperchromatography. The elution of oestrogen containing fractions is followed by acetylation. Oestrogen acetate is isolated by re-chromatography. The chromatogram was developed after hydrolysis of the oestrogens 'in situ' on the paper. The quantity of oestrogens was determined indirectly, by means of an iron-reaction, after the elution of the iron content of the oestrogen spot, which was developed by the Jellinek-reaction. 2. The method described above is satisfactory for determining urinary oestrogen, 17β-oestradiol and oestriol, but could include 16-epioestriol and other oestrogenic metabolites. 3. The sensitivity of the method is 1.3–1.6 μg/24 hours. 4. The quantitative and qualitative determination of urinary oestrogens with the above mentioned method was performed in 50 pregnant and 9 non pregnant women, and also in 2 patients with granulosa cell tumour.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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