A frozen soil parameterization coupling of thermal and hydrological processes is used to investigate how frozen soil processes affect water and energy balances in seasonal frozen soil. Simulation results of soil liqui...A frozen soil parameterization coupling of thermal and hydrological processes is used to investigate how frozen soil processes affect water and energy balances in seasonal frozen soil. Simulation results of soil liquid water content and temperature using soil model with and without the inclusion of freezing and thawing processes are evaluated against observations at the Rosemount field station. By comparing the simulated water and heat fluxes of the two cases, the role of phase change processes in the water and energy balances is analyzed. Soil freezing induces upward water flow towards the freezing front and increases soil water content in the upper soil layer. In particular, soil ice obviously prevents and delays the infiltration during rain at Rosemount. In addition, soil freezingthawing processes alter the partitioning of surface energy fluxes and lead the soil to release more sensible heat into the atmosphere during freezing periods.展开更多
The land-atmosphere energy and turbulence exchange is key to understanding land surface processes on the Tibetan Plateau(TP). Using observed data for Aug. 4 to Dec. 3, 2012 from the Bujiao observation point(BJ) of the...The land-atmosphere energy and turbulence exchange is key to understanding land surface processes on the Tibetan Plateau(TP). Using observed data for Aug. 4 to Dec. 3, 2012 from the Bujiao observation point(BJ) of the Nagqu Plateau Climate and Environment Station(NPCE-BJ), different characteristics of the energy flux during the Asian summer monsoon(ASM) season and post-monsoon period were analyzed. This study outlines the impact of the ASM on energy fluxes in the central TP. It also demonstrates that the surface energy closure rate during the ASM season is higher than that of the post-monsoon period. Footprint modeling shows the distribution of data quality assessments(QA) and quality controls(QC) surrounding the observation point. The measured turbulent flux data at the NPCE-BJ site were highly representative of the target land-use type. The target surface contributed more to the fluxes under unstable conditions than under stable conditions. The main wind directions(180° and 210°) with the highest data density showed flux contributions reaching 100%, even under stable conditions. The lowest flux contributions were found in sectors with low data density, e.g., 90.4% in the 360° sector under stable conditions during the ASM season. Lastly, a surface energy water balance(SEWAB) model was used to gap-fill any absent or corrected turbulence data. The potential simulation error was also explored in this study. The Nash-Sutcliffe model efficiency coefficients(NSEs) of the observed fluxes with the SEWAB model runs were 0.78 for sensible heat flux and 0.63 for latent heat flux during the ASM season, but unrealistic values of-0.9 for latent heat flux during the post-monsoon period.展开更多
Despite all of the many discrepancies and contradictions in the estimate of the water balance in the Barada Awaj basin, all the research and reports, both local and international, indicate that the basin suffers from ...Despite all of the many discrepancies and contradictions in the estimate of the water balance in the Barada Awaj basin, all the research and reports, both local and international, indicate that the basin suffers from water depletion. The agricultural sector is the largest consumer of water, and the area of land irrigated by the basin has risen significantly. Rapid population growth as a result of natural increase and massive immigration to the basin, piratical well-digging without permits, the failure to increase the area of land irrigated by modern methods and a decrease in rainfall and the drought that has affected Syria in general and the Barada Awaj basin in particular, have led to a water shortage in the basin during the first decade of this century.展开更多
The radiation energy environment, energy balance and water environment have been studied by means of the 3 treatments of covering plastic film, straw and planting Trifolium repens on the ground of Zanthoxylum bungeanu...The radiation energy environment, energy balance and water environment have been studied by means of the 3 treatments of covering plastic film, straw and planting Trifolium repens on the ground of Zanthoxylum bungeanum plantation in Feng County, Shaanxi. The results showed that the ground reflectivity and the canopy net radiation increased in the conditions of covering plastic film, straw and planting T. repens on the ground, so that the reflections in the middle part increased 53.3%,26.3% and 0.8% than that of the contrast. In the heat balance, the hidden heat flux in the conditions of covering plastic film, straw and planting T. repens accounts for 60.2%,62.4% and 65.8% of the net radiation energy, the reaction heat flux accounts for 30.4%,29.7% and 27.1%, and the soil heat flux accounts for 9.4%,7.9% and 7.1%. The soil water content in 0～50 cm were higher 5.6%,8.7% and 13.9% in covering plastic film, straw and planting T. repens on the ground than in the contrast. The transpiration rate of the leaves of Z. bungeanum were 1.6,1.4,1.1 times in planting T. repens,covering plastic film and straw on the ground as that of the contrast in May.展开更多
基金supported by the National Basic Research Program of China under Grant No 2006CB400504National Natural Science Foundation of China under Grant Nos 40605027 and 40775050
文摘A frozen soil parameterization coupling of thermal and hydrological processes is used to investigate how frozen soil processes affect water and energy balances in seasonal frozen soil. Simulation results of soil liquid water content and temperature using soil model with and without the inclusion of freezing and thawing processes are evaluated against observations at the Rosemount field station. By comparing the simulated water and heat fluxes of the two cases, the role of phase change processes in the water and energy balances is analyzed. Soil freezing induces upward water flow towards the freezing front and increases soil water content in the upper soil layer. In particular, soil ice obviously prevents and delays the infiltration during rain at Rosemount. In addition, soil freezingthawing processes alter the partitioning of surface energy fluxes and lead the soil to release more sensible heat into the atmosphere during freezing periods.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91337212, 41175008)Cold and Arid Regions Environmental and Engineering Research Institute Youth Science Technology Service Network initiative (STS)+1 种基金the China Exchange Project (Grant No. 13CDP007)the National Natural Science Foundation of China (Grant Nos. 40825015 and 40675012)
文摘The land-atmosphere energy and turbulence exchange is key to understanding land surface processes on the Tibetan Plateau(TP). Using observed data for Aug. 4 to Dec. 3, 2012 from the Bujiao observation point(BJ) of the Nagqu Plateau Climate and Environment Station(NPCE-BJ), different characteristics of the energy flux during the Asian summer monsoon(ASM) season and post-monsoon period were analyzed. This study outlines the impact of the ASM on energy fluxes in the central TP. It also demonstrates that the surface energy closure rate during the ASM season is higher than that of the post-monsoon period. Footprint modeling shows the distribution of data quality assessments(QA) and quality controls(QC) surrounding the observation point. The measured turbulent flux data at the NPCE-BJ site were highly representative of the target land-use type. The target surface contributed more to the fluxes under unstable conditions than under stable conditions. The main wind directions(180° and 210°) with the highest data density showed flux contributions reaching 100%, even under stable conditions. The lowest flux contributions were found in sectors with low data density, e.g., 90.4% in the 360° sector under stable conditions during the ASM season. Lastly, a surface energy water balance(SEWAB) model was used to gap-fill any absent or corrected turbulence data. The potential simulation error was also explored in this study. The Nash-Sutcliffe model efficiency coefficients(NSEs) of the observed fluxes with the SEWAB model runs were 0.78 for sensible heat flux and 0.63 for latent heat flux during the ASM season, but unrealistic values of-0.9 for latent heat flux during the post-monsoon period.
文摘Despite all of the many discrepancies and contradictions in the estimate of the water balance in the Barada Awaj basin, all the research and reports, both local and international, indicate that the basin suffers from water depletion. The agricultural sector is the largest consumer of water, and the area of land irrigated by the basin has risen significantly. Rapid population growth as a result of natural increase and massive immigration to the basin, piratical well-digging without permits, the failure to increase the area of land irrigated by modern methods and a decrease in rainfall and the drought that has affected Syria in general and the Barada Awaj basin in particular, have led to a water shortage in the basin during the first decade of this century.
文摘The radiation energy environment, energy balance and water environment have been studied by means of the 3 treatments of covering plastic film, straw and planting Trifolium repens on the ground of Zanthoxylum bungeanum plantation in Feng County, Shaanxi. The results showed that the ground reflectivity and the canopy net radiation increased in the conditions of covering plastic film, straw and planting T. repens on the ground, so that the reflections in the middle part increased 53.3%,26.3% and 0.8% than that of the contrast. In the heat balance, the hidden heat flux in the conditions of covering plastic film, straw and planting T. repens accounts for 60.2%,62.4% and 65.8% of the net radiation energy, the reaction heat flux accounts for 30.4%,29.7% and 27.1%, and the soil heat flux accounts for 9.4%,7.9% and 7.1%. The soil water content in 0～50 cm were higher 5.6%,8.7% and 13.9% in covering plastic film, straw and planting T. repens on the ground than in the contrast. The transpiration rate of the leaves of Z. bungeanum were 1.6,1.4,1.1 times in planting T. repens,covering plastic film and straw on the ground as that of the contrast in May.
