Land-surface conditions, such as surface roughness and SWC （soil-water content）, control the saltation activity and dust emission in northeast Asia. Information on spatial and temporal changes in surface SWC is need...Land-surface conditions, such as surface roughness and SWC （soil-water content）, control the saltation activity and dust emission in northeast Asia. Information on spatial and temporal changes in surface SWC is needed for dust-modeling systems used to predict dust events with the aim of preventing the damage they cause. A MTVDI （modified temperature-vegetation dryness index） was tested to see if it could reproduce the surface SWC observed in Zhangye, China, and the Tottori Sand Dunes of Japan, and the threshold wind speed at the Tottori Sand Dunes. MTVDI was calculated from land-surface temperature using the MODIS （moderate resolution imaging spectroradiometer） product, and the aerodynamic minimum and maximum surface temperatures were estimated based on meteorological data. A greater correlation is seen between MTVDI and SWC than between SWC from AMSR-E （advanced microwave scanning radiometer-earth observing system） and SWC in Zhangye. The threshold wind speed for saltation activity decreased with increasing MTVDI, that is, with drying of the soil surface of the Tottori Sand Dunes. The correlation between MTVDI and threshold wind speed is statistically significant （R2 = 0.2987）.展开更多
Urbanization influences hydrologic cycle significantly on local,regional even global scale.With urbanization the water resources demand for dense population sharpened,thus it is a great challenge to ensure water suppl...Urbanization influences hydrologic cycle significantly on local,regional even global scale.With urbanization the water resources demand for dense population sharpened,thus it is a great challenge to ensure water supply for some metropolises such as Beijing.Urban area is traditionally considered as the area with lower evapotranspiration(ET) on account of the impervious surface and the lower wind speed.For most remote sensing models,the ET,defined as latent heat in energy budget,is estimated as the difference between net radiation and sensible heat.The sensible heat is generally higher in urban area due to the high surface temperature caused by heat island,therefore the latent heat(i.e.the ET) in urban area is lower than that in other region.We estimated water consumption from 2003 to 2012 in Beijing based on water balance method and found that the annual mean ET in urban area was about 654 mm.However,using Surface Energy Balance System(SEBS) model,the annual mean ET in urban area was only 348 mm.We attributed this inconsistence to the impact of anthropogenic heat and quantified this impact on the basis of the night-light maps.Therefore,a new model SEBS-Urban,coupling SEBS model and anthropogenic heat was developed to estimate the ET in urban area.The ET in urban area of Beijing estimated by SEBS-Urban showed a good agreement with the ET from water balance method.The findings from this study highlighted that anthropogenic heat should be included in the surface energy budget for a highly urbanized area.展开更多
文摘Land-surface conditions, such as surface roughness and SWC （soil-water content）, control the saltation activity and dust emission in northeast Asia. Information on spatial and temporal changes in surface SWC is needed for dust-modeling systems used to predict dust events with the aim of preventing the damage they cause. A MTVDI （modified temperature-vegetation dryness index） was tested to see if it could reproduce the surface SWC observed in Zhangye, China, and the Tottori Sand Dunes of Japan, and the threshold wind speed at the Tottori Sand Dunes. MTVDI was calculated from land-surface temperature using the MODIS （moderate resolution imaging spectroradiometer） product, and the aerodynamic minimum and maximum surface temperatures were estimated based on meteorological data. A greater correlation is seen between MTVDI and SWC than between SWC from AMSR-E （advanced microwave scanning radiometer-earth observing system） and SWC in Zhangye. The threshold wind speed for saltation activity decreased with increasing MTVDI, that is, with drying of the soil surface of the Tottori Sand Dunes. The correlation between MTVDI and threshold wind speed is statistically significant （R2 = 0.2987）.
基金supported by the National Natural Science Foundation of China(Grant Nos. 51479088,41630856 & 51279208)
文摘Urbanization influences hydrologic cycle significantly on local,regional even global scale.With urbanization the water resources demand for dense population sharpened,thus it is a great challenge to ensure water supply for some metropolises such as Beijing.Urban area is traditionally considered as the area with lower evapotranspiration(ET) on account of the impervious surface and the lower wind speed.For most remote sensing models,the ET,defined as latent heat in energy budget,is estimated as the difference between net radiation and sensible heat.The sensible heat is generally higher in urban area due to the high surface temperature caused by heat island,therefore the latent heat(i.e.the ET) in urban area is lower than that in other region.We estimated water consumption from 2003 to 2012 in Beijing based on water balance method and found that the annual mean ET in urban area was about 654 mm.However,using Surface Energy Balance System(SEBS) model,the annual mean ET in urban area was only 348 mm.We attributed this inconsistence to the impact of anthropogenic heat and quantified this impact on the basis of the night-light maps.Therefore,a new model SEBS-Urban,coupling SEBS model and anthropogenic heat was developed to estimate the ET in urban area.The ET in urban area of Beijing estimated by SEBS-Urban showed a good agreement with the ET from water balance method.The findings from this study highlighted that anthropogenic heat should be included in the surface energy budget for a highly urbanized area.
