In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angl...In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angle test and the shear test. The durability of the approach is examined by the accelerated abrasion test, and the skid resistance of the pavement with surface coating is examined by the British pendulum test and the surface texture depth test. In the contact angle test, the contact angle between hydrophobic admixture and water is 100.2°. In the shear test, the maximum shear stress is 0.06 MPa for the specimen coated with hydrophobic admixture, which is much lower than that of the specimen without hydrophobic admixture coating, 3.5 MPa. Furth- ermore, the ice and asphalt surface are completely separated for the coated specimen while not for the uncoated specimen. Based on the accelerated abrasion test, the residual hydro- phobic admixture in the veins of the pavement after abrasion still has a deicing effect. From the skid resistance tests, the British pendulum number (BPN) and the texture depth (TD) of the specimen coated with hydrophobic admixtures are larger than those of the standard requirements. The overall experi-mental observation indicates that the approach can effectively reduce close contact between asphalt pavement and ice; therefore, it can be a promising solution to road icing problems in winter.展开更多
The Regional Integrated Environmental Model System (RIEMS 2.0) with NCEP Reanalysis II is utilized to simulate the severe freezing rain and snow storm event over southern China in January 2008, which caused severe d...The Regional Integrated Environmental Model System (RIEMS 2.0) with NCEP Reanalysis II is utilized to simulate the severe freezing rain and snow storm event over southern China in January 2008, which caused severe damage in the region. The relationships between the freezing rain process and the large-scale cir- culation, in terms of the westerly and low-level jets, water vapor transportation, and northerly wind area/intensity indices, were analyzed to tmderstand the mechanisms of the freezing rain occurrence. The results indicate the fol- lowing: (1) RIEMS 2.0 reproduced the pattern of precipi- tation in January 2008 well, especially for the temporal evolution of daily precipitation averaged over the Yangtze River valley and southern China; (2) RIEMS 2.0 repro- duced the persistent trough in the South Branch of the westerlies, of which the southwesterly currents trans- ported abundant moisture into southern China; (3) RIEMS 2.0 reasonably reproduced the pattern of frequencies of light and moderate rain, although it overestimated the frequency of rain in southern China. This study shows that RIEMS 2.0 can be feasibly applied to study extreme weather and climate events in East Asia.展开更多
The study of snow and ice melt (SIM) is important in water-scarce arid regions for the assessment of water supply and quality. These studies involve unique difficulties, especially in the calibration of hydro-models...The study of snow and ice melt (SIM) is important in water-scarce arid regions for the assessment of water supply and quality. These studies involve unique difficulties, especially in the calibration of hydro-models because there is no direct way to continuously measure the SIM at hydrostations. The recursive digital filter (RDF) and the isotopic hydro-geochemical method (IHM) were coupled to separate the SIM from eight observed series of alpine streamflows in northwestern China. Validation of the calibrated methods suggested a good capture of the SIM characteristics with fair accuracy in both space and time. Applications of the coupled methods in the upper reaches of the Hei River Basin (HRB) suggested a double peak curve of the SIM fraction to streamflow for the multi-component recharged (MCR) rivers, while a single peak curve was suggested for the rainfall-dominant recharged (RDR) rivers. Given inter-annual statistics of the separation, both types of the alpine rivers have experienced an obvious decrease of SIM since 196os. In the past 10 years, the SIM in the two types of rivers has risen to the levels of the 1970s, but has remained lower than the level of the 1960s. The study provided a considerable evidence to quantify the alpine SIMbased on the separation of observed data series at gauge stations. Application of the coupled method could be helpful in the calibration and validation of SIM-related hydro-models in alpine regions.展开更多
文摘In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angle test and the shear test. The durability of the approach is examined by the accelerated abrasion test, and the skid resistance of the pavement with surface coating is examined by the British pendulum test and the surface texture depth test. In the contact angle test, the contact angle between hydrophobic admixture and water is 100.2°. In the shear test, the maximum shear stress is 0.06 MPa for the specimen coated with hydrophobic admixture, which is much lower than that of the specimen without hydrophobic admixture coating, 3.5 MPa. Furth- ermore, the ice and asphalt surface are completely separated for the coated specimen while not for the uncoated specimen. Based on the accelerated abrasion test, the residual hydro- phobic admixture in the veins of the pavement after abrasion still has a deicing effect. From the skid resistance tests, the British pendulum number (BPN) and the texture depth (TD) of the specimen coated with hydrophobic admixtures are larger than those of the standard requirements. The overall experi-mental observation indicates that the approach can effectively reduce close contact between asphalt pavement and ice; therefore, it can be a promising solution to road icing problems in winter.
基金supported by the National Basic Research Program of China (Grant Nos. 2010CB950900 and 2009CB421100)the National Natural Science Foundation of China (Grant No. 91025003)
文摘The Regional Integrated Environmental Model System (RIEMS 2.0) with NCEP Reanalysis II is utilized to simulate the severe freezing rain and snow storm event over southern China in January 2008, which caused severe damage in the region. The relationships between the freezing rain process and the large-scale cir- culation, in terms of the westerly and low-level jets, water vapor transportation, and northerly wind area/intensity indices, were analyzed to tmderstand the mechanisms of the freezing rain occurrence. The results indicate the fol- lowing: (1) RIEMS 2.0 reproduced the pattern of precipi- tation in January 2008 well, especially for the temporal evolution of daily precipitation averaged over the Yangtze River valley and southern China; (2) RIEMS 2.0 repro- duced the persistent trough in the South Branch of the westerlies, of which the southwesterly currents trans- ported abundant moisture into southern China; (3) RIEMS 2.0 reasonably reproduced the pattern of frequencies of light and moderate rain, although it overestimated the frequency of rain in southern China. This study shows that RIEMS 2.0 can be feasibly applied to study extreme weather and climate events in East Asia.
基金supported by the following grants:National Key Research and Development Program of China (Grant No. 2009CB421306)the NSFC Project (Grant Nos. 41001014, 51209119) NSFC Projects (Grant Nos. 41240002, 91225301)+1 种基金the NSFC Key Project (Grant No. 91125010)the MAIRS Project funded by the NASA LCLUC Program (Grant No. NNX08AH50G)
文摘The study of snow and ice melt (SIM) is important in water-scarce arid regions for the assessment of water supply and quality. These studies involve unique difficulties, especially in the calibration of hydro-models because there is no direct way to continuously measure the SIM at hydrostations. The recursive digital filter (RDF) and the isotopic hydro-geochemical method (IHM) were coupled to separate the SIM from eight observed series of alpine streamflows in northwestern China. Validation of the calibrated methods suggested a good capture of the SIM characteristics with fair accuracy in both space and time. Applications of the coupled methods in the upper reaches of the Hei River Basin (HRB) suggested a double peak curve of the SIM fraction to streamflow for the multi-component recharged (MCR) rivers, while a single peak curve was suggested for the rainfall-dominant recharged (RDR) rivers. Given inter-annual statistics of the separation, both types of the alpine rivers have experienced an obvious decrease of SIM since 196os. In the past 10 years, the SIM in the two types of rivers has risen to the levels of the 1970s, but has remained lower than the level of the 1960s. The study provided a considerable evidence to quantify the alpine SIMbased on the separation of observed data series at gauge stations. Application of the coupled method could be helpful in the calibration and validation of SIM-related hydro-models in alpine regions.