Clarifying the mechanisms governing volumetric soil water content(VSWC)dynamics in soil profiles is essential,as it can help to elucidate soil water transport processes and improve the prediction accuracy of soil hydr...Clarifying the mechanisms governing volumetric soil water content(VSWC)dynamics in soil profiles is essential,as it can help to elucidate soil water transport processes and improve the prediction accuracy of soil hydrological processes.Using Spearman's rank correlation and wavelet coherence analysis methods,similarity in soil profile VSWC dynamics and factors governing VSWC soil profile dynamics in upslopes and downslopes under three vegetation types(evergreen forest[EG],secondary deciduous forest mixed with shrubs[SDFS],and deforested pasture[DP])at different time scales(hourly,daily,weekly,and monthly)and in different seasons were analyzed.The results revealed significant similarity in the VSWC of different soil depths(P<0.01),with the similarity decreasing in accordance with the increment in soil depth.Greater VSWC similarity was found in EG than SDFS and DP sites and in upslope than downslope areas at both forest sites.The average significant coherence area(SCA)of VSWC similarity among surface and deep soil layers varied with the time scale,which was in the order of monthly(58.6%)>weekly(42.8%)>daily(21.8%).The effects of soil properties(e.g.,texture,saturated hydraulic conductivity),rainfall,and potential evapotranspiration(ET_(p))on VSWC similarity were related to the time scale and season in which VSWC monitoring took place.Soil properties had apparent effects on VSWC similarity at longer time scales(i.e.,monthly),with a high SCA.In contrast,the effects of rainfall and ET_(p) on VSWC similarity were concentrated at weekly and daily scales,with a relatively low SCA.Rainfall and ET_(p) dominated VSWC dynamics in the summer and fall,respectively.These results imply the use of measured VSWC at one soil depth to predict the VSWC at other soil depths was a reliable method.While the in-fluence of time scale effects and seasonal variations on prediction accuracy of VSWC should be considered.展开更多
Based on the improved statistics model of breaking waves, we have calculated the following statistical quantities: S_t, breaking area ratio generated per unit time; V_t, the volume of water mass thrown out from the wa...Based on the improved statistics model of breaking waves, we have calculated the following statistical quantities: S_t, breaking area ratio generated per unit time; V_t, the volume of water mass thrown out from the wave surface due to breaking on a unit area per unit time; (?)_t, the breaking energy loss rate on a unit area per unit time. Under the high sea state, the phase change governed by wave breaking is mechanistic. Based on the physical and dimensional consideration we have also derived the statistical quantities of upper ocean dynamics such as whitecap coverage, exchange fluxes in the high sea state and turbulence degree in the subsurface layer. The theoretical results are consistent with the existing experimental data.展开更多
基金supported by the Natural Science Foundation of China(No.41771261 and 41601215)Hubei Province Natural Science Foundation of China(No.2015CFA141)Fundamental Research Funds for the Central Universities(No.CCNU20TD008,CCNU20QN030).
文摘Clarifying the mechanisms governing volumetric soil water content(VSWC)dynamics in soil profiles is essential,as it can help to elucidate soil water transport processes and improve the prediction accuracy of soil hydrological processes.Using Spearman's rank correlation and wavelet coherence analysis methods,similarity in soil profile VSWC dynamics and factors governing VSWC soil profile dynamics in upslopes and downslopes under three vegetation types(evergreen forest[EG],secondary deciduous forest mixed with shrubs[SDFS],and deforested pasture[DP])at different time scales(hourly,daily,weekly,and monthly)and in different seasons were analyzed.The results revealed significant similarity in the VSWC of different soil depths(P<0.01),with the similarity decreasing in accordance with the increment in soil depth.Greater VSWC similarity was found in EG than SDFS and DP sites and in upslope than downslope areas at both forest sites.The average significant coherence area(SCA)of VSWC similarity among surface and deep soil layers varied with the time scale,which was in the order of monthly(58.6%)>weekly(42.8%)>daily(21.8%).The effects of soil properties(e.g.,texture,saturated hydraulic conductivity),rainfall,and potential evapotranspiration(ET_(p))on VSWC similarity were related to the time scale and season in which VSWC monitoring took place.Soil properties had apparent effects on VSWC similarity at longer time scales(i.e.,monthly),with a high SCA.In contrast,the effects of rainfall and ET_(p) on VSWC similarity were concentrated at weekly and daily scales,with a relatively low SCA.Rainfall and ET_(p) dominated VSWC dynamics in the summer and fall,respectively.These results imply the use of measured VSWC at one soil depth to predict the VSWC at other soil depths was a reliable method.While the in-fluence of time scale effects and seasonal variations on prediction accuracy of VSWC should be considered.
基金Project supported by the National Natural Science Foundation of China.
文摘Based on the improved statistics model of breaking waves, we have calculated the following statistical quantities: S_t, breaking area ratio generated per unit time; V_t, the volume of water mass thrown out from the wave surface due to breaking on a unit area per unit time; (?)_t, the breaking energy loss rate on a unit area per unit time. Under the high sea state, the phase change governed by wave breaking is mechanistic. Based on the physical and dimensional consideration we have also derived the statistical quantities of upper ocean dynamics such as whitecap coverage, exchange fluxes in the high sea state and turbulence degree in the subsurface layer. The theoretical results are consistent with the existing experimental data.
