Evaluating the impacts of environmental factors on soil moisture temporal dynamics at different time scales

Qi Chai,Chongli Di,Tiejun Wang

doi:10.2166/wcc.2020.011

Abstract

AbstractSoil moisture displays complex spatiotemporal patterns across scales, making it important to disentangle the impacts of environmental factors on soil moisture temporal dynamics at different time scales. This study evaluated the factors affecting soil moisture dynamics at different time scales using long-term soil moisture data obtained from Nebraska and Utah. The empirical mode decomposition method was employed to decompose soil moisture time series into different temporal components with several intrinsic mode functions (IMFs) and one residual component. Results showed that the percent variance contribution (PVC) of IMFs to the total soil moisture temporal variance tended to increase for the IMFs with longer time periods. It indicated that the long-term soil moisture variations in study regions were mainly determined by low-temporal frequency signals related to seasonal climate and vegetation variations. Besides, the PVCs at short- and medium-temporal ranges were positively correlated with climate dryness, while negatively at longer temporal ranges. Moreover, the results suggested that the impact of climate on soil moisture dynamics at different time scales might vary across different climate zones, while soil effect was comparatively less in both regions. It provides additional insights into understanding soil moisture temporal dynamics in regions with contrasting climatic conditions.

Highlights

Soil moisture plays a pivotal role in understanding earth system dynamics and decision-making processes, e.g., from the global hydrological and energy cycles to agricultural management and drought assessment (Gerten et al ; McColl et al )
The soil moisture time series retrieved from the Nebraska Mesonet (NM) and Soil Climate Analysis Network (SCAN) stations was decomposed by the empirical mode decomposition (EMD) method into components with different temporal scales
Given the major controls of climate and soil properties on regional soil moisture spatial variability as shown in previous studies, meteorological and soil textural data for the NM and SCAN sites were compiled to evaluate their impacts on soil moisture temporal dynamics under arid and semiarid conditions

Summary

Introduction

Soil moisture plays a pivotal role in understanding earth system dynamics and decision-making processes, e.g., from the global hydrological and energy cycles to agricultural management and drought assessment (Gerten et al ; McColl et al ). Soil moisture can exert profound influences on climate systems and the partitioning of energy at the. Numerous modeling studies have shown that the forecasting skills of land surface and climate models were dependent on the accurate representation of soil moisture states in those models (Timbal et al ; Koster et al ). It is crucial to understand the spatiotemporal characteristics of soil moisture patterns across scales for various research and application purposes (Famiglietti et al ; Brocca et al )

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Conclusion