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1. chinaXiv:202010.00019 [pdf]

Applying seepage modeling to improve sediment yield predictions in contour ridge systems

LIU,Qianjin; MA,Liang; ZHANG,Hanyu
Subjects: Geosciences >> History of Geosciences

Contour ridge systems may lead to seepage that could result in serious soil erosion. Modeling soil erosion under seepage conditions in a contour ridge system has been overlooked in most current soil erosion models. To address the importance of seepage in soil erosion modeling, a total of 23 treatments with 3 factors, row grade, field slope and ridge height, in 5 gradients were arranged in an orthogonal rotatable central composite design. The second-order polynomial regression model for predicting the sediment yield was improved by using the measured or predicted seepage discharge as an input factor, which increased the coefficient of determination (R2) from 0.743 to 0.915 or 0.893. The improved regression models combined with the measured seepage discharge had a lower P (0.007) compared to those combined with the predicted seepage discharge (P=0.016). With the measured seepage discharge incorporated, some significant (P<0.050) effects and interactions of influential factors on sediment yield were detected, including the row grade and its interactions with the field slope, ridge height and seepage discharge, the quadratic terms of the field slope and its interactions with the row grade and seepage discharge. In the regression model with the predicted seepage discharge as an influencing factor, only the interaction between row grade and seepage discharge significantly affected the sediment yield. The regression model incorporated with predicted seepage discharge may be expressed simply and can be used effectively when measured seepage discharge data are not available.

submitted time 2020-10-20 From cooperative journals:《Journal of Arid Land》 Hits1719Downloads179 Comment 0

2. chinaXiv:202010.00032 [pdf]

Application of SALTMED and HYDRUS-1D models for simulations of soil water content and soil salinity in controlled groundwater depth

Subjects: Geosciences >> History of Geosciences

Salinization is a gradual process that should be monitored. Modelling is a suitable alternative technique that saves time and cost for the field monitoring. But the performance of the models should be evaluated using the measured data. Therefore, the aim of this study was to evaluate and compare the SALTMED and HYDRUS-1D models using the measured soil water content, soil salinity and wheat yield data under different levels of saline irrigation water and groundwater depth. The field experiment was conducted in 2013 and in this research three controlled groundwater depths, i.e., 60 (CD60), 80 (CD80) and 100 (CD100) cm and two salinity levels of irrigation water, i.e., 4 (EC4) and 8 (EC8) dS/m were used in a complete randomized design with three replications. Soil water content and soil salinity were measured in soil profile and compared with the predicted values by the SALTMED and HYDRUS-1D models. Calibrations of the SALTMED and HYDRUS-1D models were carried out using the measured data under EC4-CD100 treatment and the data of the other treatments were used for validation. The statistical parameters including normalized root mean square error (NRMSE) and degree of agreement (d) showed that the values for predicting soil water content and soil salinity were more accurate in the HYDRUS-1D model than in the SALTMED model. The NRMSE and d values of the HYDRUS-1D model were 9.6% and 0.64 for the predicted soil water content and 6.2% and 0.98 for the predicted soil salinity, respectively. These indices of the SALTMED model were 10.6% and 0.81 for the predicted soil water content and 11.0% and 0.97 for the predicted soil salinity, respectively. According to the NRMSE and d values for the predicted wheat yield (9.8% and 0.91, respectively) and dry matter (2.9% and 0.99, respectively), we concluded that the SALTMED model predicted the wheat yield and dry matter accurately.

submitted time 2020-10-20 From cooperative journals:《Journal of Arid Land》 Hits75Downloads34 Comment 0

3. chinaXiv:201703.00308 [pdf]

Target brightness temperature simulation and analysis for the geostationary interferometric microwave sounder (GIMS)

Zhang, Ying; Liu, Hao; Wu, Ji; He, Jieying; Zhang, Cheng
Subjects: Geosciences >> Space Physics

Target brightness temperature maps can be used in geostationary interferometric microwave sounder (GIMS) system simulation. System simulation with accurate target brightness temperature maps can evaluate system performance in near real case and thus help adjust design parameters for the sensor before it is finally put into use. In this paper, method of simulating target brightness temperature using Weather Research and Forecasting Model and Radiative Transfer for TOVS (RTTOV) has been discussed. Target brightness temperature simulation results at oxygen absorption band and water-vapor absorption band have been presented. Some preliminary analyses of simulated brightness temperature for GIMS' observation have also been given.

submitted time 2017-03-10 Hits17214Downloads1432 Comment 0

4. chinaXiv:201703.00291 [pdf]

Analysis and simulation of GIMS observation on dynamic targets

Zhang, Ying; Liu, Hao; Wu, Ji; Zhang, Cheng; He, Jieying
Subjects: Geosciences >> Space Physics

Imaging period is an important consideration to geostationary interferometric microwave sounder (GIMS) when mapping fast changing target such as typhoon. GIMS simulation system with near real case observation target can evaluate system performance in different system configurations and thus help determine the optimal imaging period. In this paper, GIMS simulation system using MATLAB and near real case observation modeled by FNL/WRF/RTTOV method has been used to analyze the effect of imaging period on image quality. System simulation results for each frequency channel will be presented and analyses of imaging period's effect on image quality will also be given. ?2016 IEEE.

submitted time 2017-03-10 Hits2078Downloads805 Comment 0

5. chinaXiv:201703.00258 [pdf]


Xiaobin Yin; Lanjie Zhang; Hao Liu; Risheng Yun; Lin Wu; Xingou Xu; Di Zhu
Subjects: Geosciences >> Space Physics

A 1-D interferometric system at 1.4GHz, 6.9GHz, 18.7 GHz and 23.8GHz combined with a scatterometer at 1.26GHz, called microwave imager combined active/passive (MICAP), has been proposed to retrieve sea surface salinity (SSS) and to reduce geophysical errors due to surface roughness and sea surface temperature (SST). The MICAP will be a candidate payload onboard the Ocean Salinity Satellite of China. The sensitivity of active/passive microwave observations to SSS, SST and wind is analyzed and the stability requirement of the instruments is estimated, with the objective of designing an optimized satellite instrument, dedicated to an "all-weather" estimate of the SSS with high accuracy from space.

submitted time 2017-03-10 Hits1122Downloads606 Comment 0

6. chinaXiv:201701.00227 [pdf]

Invariant modulation of IMF clock angle on the solar wind energy input into the magnetosphere

HAN JinPeng; LI Hui; Tang BinBin; WANG Chi
Subjects: Geosciences >> Space Physics

By use of the global PPMLR Magnetohydrodynamics(MHD) model, a serial of quasi-steady-state numerical simulations were conducted to examine the modulation property of the interplanetary magnetic field clock angle theta on the solar wind energy input into the magnetosphere. All the simulations can be divided into seven groups according to different criteria of solar wind conditions. For each group, 37 numerical examples are analyzed, with the clock angle varying from 0?to 360?with an interval of 10? keeping the other solar wind parameters(such as the solar wind number density, velocity, and the magnetic field magnitude) unchanged. As expected, the solar wind energy input into the magnetosphere is modulated by the IMF clock angle. The axisymmetrical bell-shaped curve peaks at the clock angle of 180? However, the modulation effect remains invariant with varying other solar wind conditions. The function form of such an invariant modulation is found to be sin(0/2)2.70 + 0.25.

submitted time 2017-01-22 Hits867Downloads409 Comment 0

7. chinaXiv:201605.00291 [pdf]


Yun, Risheng; Xu, Xingou; Dong, Xiaolong; Zhu, Di
Subjects: Geosciences >> Space Physics

The RFSCAT(Rotating Fan-beam SCATterometer) is one of the two payloads of CFOSAT, the China-France Oceanography Satellite. It is a radar scatterometer designed to measure the electromagnetic back-scatter from wind roughened ocean surface. The operating frequency of the scatterometer is 13.256GHz (Ku-band) and has a swath about 1,000 kilometers. In this paper, based on the characteristics of echo signal of RFSCAT, the on-board processing of RFSCAT signal is introduced. A Doppler pre-compensation LUT and A slice division LUT are developed, and the signal processing algorithms are validated and the wind retrieval performances of RFSCAT are analyzed based on the well-developed data simulation system of CFOSAT RFSCAT.

submitted time 2016-05-03 Hits1002Downloads621 Comment 0

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