Soil erosion processes during a storm are strongly affected by intra-storm variations in rainfall characteristics.Four storm patterns,each with a different rainfall intensity variation were separated.The storm pattern...Soil erosion processes during a storm are strongly affected by intra-storm variations in rainfall characteristics.Four storm patterns,each with a different rainfall intensity variation were separated.The storm patterns were:(1)increasing rainfall intensity(2)increasing then decreasing intensity(3)decreasing intensity(4)decreasing then increasing intensity.After each erosive rainfall(12 events),Runoff and suspended sediment samples were collected in each plot's tank which is located on hillslopes of the basin of Khamsan.Main storm characteristics and soil losses were plotted and equation of the line of best fit were selected.Analysis of variance(ANOVA)was used to determine response of runoff and soil erosion to storm patterns.Results showed that in lower rainfall intensities a linear function fits the relationship between soil loss and rainfall intensity whereas this function tends to be non-linear at higher intensities.Also a strong non-linear relationship was found between different quartiles of storm and soil loss.Statistical analysis revealed significant differences in total runoff,soil loss and sediment concentration across four storm patterns(P<0.001)but no differences in the runoff coefficient.In particular,storms with increasing rainfall intensity yielded highest quantities of eroded sediments,total runoff and highest sediment concentrations followed by increasing then decreasing,decreasing then increasing and decreasing intensity,respectively.展开更多
An explicit simulation of the tropical cyclone Winnie （1997） was conducted by use of a triply-nested 3-D nonhydrostatic mesoscale model MM5, before and after its landfall. The simulated results show that the model c...An explicit simulation of the tropical cyclone Winnie （1997） was conducted by use of a triply-nested 3-D nonhydrostatic mesoscale model MM5, before and after its landfall. The simulated results show that the model can well reproduce the track of Winnie （1997） with a BOGUS storm-like vortex inserted in the large-scale first-guess field at the initial model time. The mean track error in a 6 h interval is 54.5 km, which is much less than that obtained with the operational prediction. Comparisons between simulation and observation near the landfall place show that the main temporal variation features of sea level pressure and surface wind speed can also be successfully captured. The characteristics of the eyewall, the spiral cloud band and the corresponding precipitation were disclosed, and the applications of the model outputs were also discussed.展开更多
In this study the changes of tropical cyclone(TC)size from 2001 to 2021 are analyzed based on linear and quadratic curve fittings of the National Hurricane Center(NHC)/Joint Typhoon Warning Center(JTWC)best track data...In this study the changes of tropical cyclone(TC)size from 2001 to 2021 are analyzed based on linear and quadratic curve fittings of the National Hurricane Center(NHC)/Joint Typhoon Warning Center(JTWC)best track data,based on the radius of maximum wind(RMW)and the average radius of 34-kt wind(AR34),in three oceanic basins of the North Atlantic(NATL),the Western North Pacific(WPAC)and the Eastern North Pacific(EPAC).The computations are done separately for two categories of tropical cyclones:tropical storms(TS)and hurricanes(HT).Size changes of landfalling and non-landfalling TCs are also discussed.Results show that there is a great inter-basin variability among the changes in TC sizes.Major conclusions include:1)overall,the inner cores of TSs have become larger in all three basins,with the increasing tendencies being significant in the NATL and WAPC,while those of HTs mostly get smaller or remain similar;2)meanwhile,comparatively large inter-basin differences are observed for the TC outer core sizes,and the sizes of landfalling TCs;3)particularly,a significant decrease in landfalling HT outer core size is observed over the EPAC;4)in contrast,significant increases in landfalling TS inner core size are found over the NATL and WPAC.The presented analysis results could benefit future research about TC forecasts,storm surge studies,and the cyclone climate and its changes.展开更多
The paper deals with the analysis of severe storms in the central Mediterranean Sea and in the US coasts of the Atlantic and Pacific Ocean. Firstly, we introduce a model for the representation of the sea storms by mea...The paper deals with the analysis of severe storms in the central Mediterranean Sea and in the US coasts of the Atlantic and Pacific Ocean. Firstly, we introduce a model for the representation of the sea storms by means of two parameters: the former is given by the maximum value of significant wave height in the actual storm and defines the storm intensity, the latter gives the storm duration. The analysis considers buoy data with different sampling Δt between two consecu- tive records, which varies in the range 0.5 - 6 hours. The sensitivity analysis of the modelled sea storm with the varia- tion of Δt shows as the structure of storms is strongly modified with large values of Δt of order of 3 - 6 hours: both the intensity and the duration may change significantly. The results are of interest to investigate the extreme events in the storms obtained with WAve Model, starting from meteorological data, where the value of Δt of 6 hours is widely applied. The conclusion is that structure of severe storms should be represented with continuous data, with Δt = 0.5 hours;a good representation is also obtained with Δt = 1 hour. The errors with increasing values of Δt are investigated.展开更多
文摘Soil erosion processes during a storm are strongly affected by intra-storm variations in rainfall characteristics.Four storm patterns,each with a different rainfall intensity variation were separated.The storm patterns were:(1)increasing rainfall intensity(2)increasing then decreasing intensity(3)decreasing intensity(4)decreasing then increasing intensity.After each erosive rainfall(12 events),Runoff and suspended sediment samples were collected in each plot's tank which is located on hillslopes of the basin of Khamsan.Main storm characteristics and soil losses were plotted and equation of the line of best fit were selected.Analysis of variance(ANOVA)was used to determine response of runoff and soil erosion to storm patterns.Results showed that in lower rainfall intensities a linear function fits the relationship between soil loss and rainfall intensity whereas this function tends to be non-linear at higher intensities.Also a strong non-linear relationship was found between different quartiles of storm and soil loss.Statistical analysis revealed significant differences in total runoff,soil loss and sediment concentration across four storm patterns(P<0.001)but no differences in the runoff coefficient.In particular,storms with increasing rainfall intensity yielded highest quantities of eroded sediments,total runoff and highest sediment concentrations followed by increasing then decreasing,decreasing then increasing and decreasing intensity,respectively.
基金Project supported by the R and D Infrastructure and Facility Development Program (Grant No: 2000DIB20096) of Ministry of Science and Technology of China and the National Natural Science Foundation of China (Grant Nos: 40333026 and 40333025)
文摘An explicit simulation of the tropical cyclone Winnie （1997） was conducted by use of a triply-nested 3-D nonhydrostatic mesoscale model MM5, before and after its landfall. The simulated results show that the model can well reproduce the track of Winnie （1997） with a BOGUS storm-like vortex inserted in the large-scale first-guess field at the initial model time. The mean track error in a 6 h interval is 54.5 km, which is much less than that obtained with the operational prediction. Comparisons between simulation and observation near the landfall place show that the main temporal variation features of sea level pressure and surface wind speed can also be successfully captured. The characteristics of the eyewall, the spiral cloud band and the corresponding precipitation were disclosed, and the applications of the model outputs were also discussed.
基金supported by the Guangdong Province Introduction of Innovative R&D Team Project China(No.2019ZT08G669)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110275)the Guangdong Science and Technology Key Project(No.21080208).
文摘In this study the changes of tropical cyclone(TC)size from 2001 to 2021 are analyzed based on linear and quadratic curve fittings of the National Hurricane Center(NHC)/Joint Typhoon Warning Center(JTWC)best track data,based on the radius of maximum wind(RMW)and the average radius of 34-kt wind(AR34),in three oceanic basins of the North Atlantic(NATL),the Western North Pacific(WPAC)and the Eastern North Pacific(EPAC).The computations are done separately for two categories of tropical cyclones:tropical storms(TS)and hurricanes(HT).Size changes of landfalling and non-landfalling TCs are also discussed.Results show that there is a great inter-basin variability among the changes in TC sizes.Major conclusions include:1)overall,the inner cores of TSs have become larger in all three basins,with the increasing tendencies being significant in the NATL and WAPC,while those of HTs mostly get smaller or remain similar;2)meanwhile,comparatively large inter-basin differences are observed for the TC outer core sizes,and the sizes of landfalling TCs;3)particularly,a significant decrease in landfalling HT outer core size is observed over the EPAC;4)in contrast,significant increases in landfalling TS inner core size are found over the NATL and WPAC.The presented analysis results could benefit future research about TC forecasts,storm surge studies,and the cyclone climate and its changes.
文摘The paper deals with the analysis of severe storms in the central Mediterranean Sea and in the US coasts of the Atlantic and Pacific Ocean. Firstly, we introduce a model for the representation of the sea storms by means of two parameters: the former is given by the maximum value of significant wave height in the actual storm and defines the storm intensity, the latter gives the storm duration. The analysis considers buoy data with different sampling Δt between two consecu- tive records, which varies in the range 0.5 - 6 hours. The sensitivity analysis of the modelled sea storm with the varia- tion of Δt shows as the structure of storms is strongly modified with large values of Δt of order of 3 - 6 hours: both the intensity and the duration may change significantly. The results are of interest to investigate the extreme events in the storms obtained with WAve Model, starting from meteorological data, where the value of Δt of 6 hours is widely applied. The conclusion is that structure of severe storms should be represented with continuous data, with Δt = 0.5 hours;a good representation is also obtained with Δt = 1 hour. The errors with increasing values of Δt are investigated.
