Characterization of temporal variability in near-surface soil moisture at scales from 1 h to 2 weeks
Characterization of temporal variability in near-surface soil moisture at scales from 1 h to 2 weeks
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DOI：
10.1016/j.jhydrol.2005.09.027
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发表时间：
2006-06
影响因子：
6.4
通讯作者：
Annie-Claude Parent;F. Anctil;L. Parent
中科院分区：
文献类型：
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作者：
Annie-Claude Parent;F. Anctil;L. Parent
本研究提出了一个表征土壤水分和降水之间的时间关系在一个很短的时间尺度，即从1小时到2周。分析是基于七个土壤水分时间序列从时域传输（TDT）探头定位沿着一个90米的样带，并监测在20分钟的速率在浅层土壤（5- 25厘米），和降水观测每15分钟。小波分析被提出来表征土壤水分和降水之间的时间关系。土壤水分归一化局域小波谱在短尺度上表现出与降水事件相关的幂函数特征，在长尺度上表现出与降水事件相关的幂函数特征。降水和土壤水分的小波功率谱中所描述的方差活动被组织在小波尺度的优先波段：1- 48小时，48小时至1周，和1-2周。在1- 48小时尺度上，土壤湿度与降水发生、强度和持续时间有关;在48小时至1周尺度上，土壤湿度与降水事件的周期性有关;在1-2周尺度上，土壤湿度与干旱持续时间有关。此外，进行了距离-时间小波分析，以同时评估三个预定义波段中每个波段的空间和时间变异性。空间分析表明，系列之间的许多相似性沿着样带，归因于土壤的同质性。平均方差分析表明，降水量的93%集中在1- 48 h尺度，而土壤水分的85%集中在48 h ~ 2周尺度。降水系统持续时间短与土壤增湿过程持续时间长的差异，是由于降水能量向土壤增湿的转移。
This study proposes a characterization of the temporal relations between soil moisture and precipitation at a very short time-scale, i.e. from 1h to 2 weeks. The analysis is based on seven soil moisture time series from time domain transmission (TDT) probes positioned along a 90-m transect, and monitored at a 20-min rate in the shallow soil layer (5–25cm), and on precipitation observed every 15min. Wavelet analysis is proposed for the characterization of the temporal relationships between soil moisture and precipitation. The normalized local wavelet spectrum of soil moisture reveals power features related to the precipitation events in the short scales, and residing in the long scales. The variance activity depicted in the wavelet power spectra of precipitation and soil moisture is organized in preferential bands of wavelet scales: 1–48h, 48h to 1 week, and 1–2 weeks. For the 1–48h scale, soil moisture is linked to precipitation occurrence, intensity and duration, while for the 48h to 1 week scale soil moisture relates to the periodicity of the rainfall events, and for the 1–2 weeks scale to the duration of the dry spells. Additionally, a distance–time wavelet analysis was conducted to simultaneously assess spatial and temporal variabilities for each of the three predefined bands. The spatial analysis showed many similarities between series along the transect that were attributable to soil homogeneity. The averaging of the variance showed that 93% of the concentration of the precipitation variance was at the 1–48h scale, while most of the soil moisture variation (85%) was accounted for at the 48h to 2 weeks scale. Disparity between the short duration of precipitation system and the extension of the soil moistening process is due to the transfer of energy from precipitation to soil moistening.