Regional soil salinity spatiotemporal dynamics and improved temporal stability analysis in arid agricultural areas

2021 ◽  
Author(s):  
Guanfang Sun ◽  
Yan Zhu ◽  
Ming Ye ◽  
Yang Yang ◽  
Jinzhong Yang ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Soil Salinity ◽  
Temporal Stability ◽  
Spatiotemporal Dynamics ◽  
Agricultural Areas

Characterizing the spatiotemporal dynamics of soil water stable isotopes on a karst hillslope in southwestern China

2021 ◽  
Author(s):  
Qin Liu ◽  
Tiejun Wang ◽  
Cong-qiang Liu ◽  
Xi Chen
Keyword(s):  
Soil Water ◽  
Temporal Stability ◽  
Spatiotemporal Dynamics ◽  
Spatial Variations ◽  
Spatiotemporal Variability ◽  
Strong Negative Correlation ◽  
Mean Values ◽  
Spatiotemporal Features ◽  
Field Evidence ◽  
Karst Hillslope

<p>Soil water stable isotope compositions (SWSI; i.e., δD and δ<sup>18</sup>O) and soil moisture content (SMC) are widely used to illuminate water exchange processes across the atmosphere-land interface. Thus, the knowledge of spatiotemporal dynamics of these two variables is critical to help our understanding of relevant ecohydrological processes. However, in comparison to the efforts for elucidating the spatiotemporal variability in SMC, much less attention was paid to understand the spatiotemporal variability in SWSI, which also raises the question as to whether SWSI and SMC share similar spatiotemporal features. To this end, the spatiotemporal dynamics of SWSI and SMC were jointly investigated on a karst hillslope with eight sampling campaigns among two years. The method of temporal stability analysis (TSA) was adopted to evaluate the spatiotemporal patterns of SWSI and SMC in this study. Generally, both δD and δ<sup>18</sup>O exhibited considerable temporal and spatial variations; meanwhile, the variations in δD and δ<sup>18</sup>O values were relatively smaller than that of SMC. In addition, in comparison with the spatial pattern of SMC, there were no clear relationships between the standard deviation (SD) and the spatial mean of δD or δ<sup>18</sup>O. However, the SD of line-conditioned excess (lc-excess) and its mean values displayed a strong negative correlation, indicating that the spatial variations in lc-excess increased with soil evaporation. Moreover, SWSI displayed weaker temporal stability than SMC and no clear controlling factors were identified, suggesting that the spatiotemporal dynamics of SWSI might be more complex than that of SMC. This study provided comprehensive field evidence that there existed profound spatiotemporal variability in SWSI and its spatiotemporal features were different from SMC, highlighting that the spatiotemporal variability in SWSI needs to be considered in isotope-based estimations and it should be investigated separately from the spatiotemporal characteristics of SMC in future studies.</p>

Spatial Stability Analysis of a Flap Side Edge Vortex

2005 ◽  
Vol 4 (1-2) ◽  
pp. 37-47
Author(s):  
Jean-Philippe Brazier ◽  
Frédéric Moens ◽  
Philippe Bardoux
Keyword(s):  
Stability Analysis ◽  
Temporal Stability ◽  
Low Frequency ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Mean Flow ◽  
Side Edge ◽  
Amplification Rate ◽  
Edge Vortex ◽  
Flap Deflection

The flap side edge vortex is suspected to contribute to aerodynamic noise generation. Using a temporal stability analysis, Khorrami and Singer have shown that unstable modes could exist in this vortex. Due to the convective nature of this instability, a spatial analysis is more suitable. This is the subject of the present work. The mean flow past a 2D wing with a half-span flap has been computed with a steady 3D Navier-Stokes code. Then, local linear stability calculations are performed in several planes perpendicular to the vortex axis. The vortex is assumed axisymmetric and modelled with Batchelor's analytical vortex. Using Gaster's relation, the spatial amplification rate is calculated, giving by integration the relative amplitude of the fluctuations. Some low-frequency fluctuations are seen to be preferentially amplified by the vortex, but the amplifications remain small, so that this mechanism alone should not produce important noise in this particular configuration, where the flap deflection angle is moderate.

On the applicability of temporal stability analysis to raingauge network design

2019 ◽  
Vol 64 (12) ◽  
pp. 1424-1438
Author(s):  
Renato Morbidelli ◽  
Carla Saltalippi ◽  
Alessia Flammini ◽  
Marco Cifrodelli ◽  
Jacopo Dari ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Network Design ◽  
Temporal Stability
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