走航式海洋多参数剖面测量系统(moving vessel profiler,MVP)是一种集成程度和自动化程度都较高的海洋调查设备,能对海洋多要素进行同时观测,获得水平方向的高分辨率数据资料。由于温度和电导率传感器响应时间的不匹配,MVP下放速度过快...走航式海洋多参数剖面测量系统(moving vessel profiler,MVP)是一种集成程度和自动化程度都较高的海洋调查设备,能对海洋多要素进行同时观测,获得水平方向的高分辨率数据资料。由于温度和电导率传感器响应时间的不匹配,MVP下放速度过快(峰值速度4 m/s)而造成非常明显的盐度尖峰现象。本研究结合Fofonoff(F)法、时间常数指数递归数字滤波(Giles and McDougall,GM)法和Grose提出的盐度尖峰订正方案,提出了一种新的方法,即MCT(match conductivity and temperature response time)法,通过对压力、温度和电导率传感器进行响应时间的匹配来减弱盐度尖峰。将SBE-9型CTD资料作为标准,发现订正后的资料与CTD盐度曲线的互相关系数为0.917,误差比订正前减小80%。对比35°N断面修正前后的盐度资料,订正后温盐跃层处出现的低盐区域消失。MVP的应用比常规海洋调查仪器CTD对于海洋现象的观测更有优势。展开更多
Landslides are a type of natural disaster that can cause substantial harm to humanity.Monitoring and predicting the initiation of potential landslides is critical to avoiding losses due to disasters and economic activ...Landslides are a type of natural disaster that can cause substantial harm to humanity.Monitoring and predicting the initiation of potential landslides is critical to avoiding losses due to disasters and economic activities.The impact of the controlled-source audio-frequency magnetotelluric method on investigating landslide surfaces is assessed through numerical simulations with a finite element approach.A Dirichlet boundary condition is selected to match the truncated boundary,resulting in a remarkable improvement in simulation effi ciency.Rederivation of the formulas for a layered medium adept to the controlled-source audiofrequency magnetotelluric method is necessary to determine the electromagnetic fi eld at any location along the truncated boundary.After the reliability evaluation of the new codes,a landslide model with a slide surface is designed,and the characteristics of its electromagnetic fi eld and the apparent resistivity are studied.Instead of the total electromagnetic fi eld,which is strongly infl uenced by topography variation,the apparent resistivity should be used for sliding surface detection.The normalized pure anomalous electromagnetic fi eld may also be employed to quickly assess the detectability of the sliding surface.Overall,this study demonstrates that the controlled-source audio-frequency magnetotelluric method can be employed for investigating landslides,and recommends survey parameters,including confi guration,frequency range,and length of survey line in landslide exploration.展开更多
Monthly projections of maximum temperature,relative humidity,precipitation,and wind speed were made based on the model of HadCM3 and the climatic change scenarios of IPCC SRES A2a and B2a for the future scenario perio...Monthly projections of maximum temperature,relative humidity,precipitation,and wind speed were made based on the model of HadCM3 and the climatic change scenarios of IPCC SRES A2a and B2a for the future scenario periods of 2010–2039（referred to as 2020s）,2040–2069（referred to as 2050s）,and 2070–2099（referred to as 2080s）.The period 1961–1990 was chosen as the baseline period.The observed and projected weather data were downscaled using delta change methods and historical relationships between weather data,area burned,and the seasonal severity rating（SSR） code of the Canadian Fire Weather Index System were examined.The variations of area burned as influenced by climate change were assessed quantitative and qualitative for the study region,assuming that the fire regimes had the similar responses to the warming climate as during the 20th century.Our results indicated that a linear regression relationship existing between the historical area burned and the mean SSR values with regression coefficient in the significant range of 0.16 to 0.61.It was evident that the increased SSR values could result in more area burned;the area burned in the study region would have an increasing pattern during the 21st century under scenarios A2a and B2a scenarios and the area burned would be doubled.Also,the future area burned would have a strong seasonal pattern that more fires would occur in summer and autumn fire season,especially in summer.The area burned in summer fire season would increase by 1.5 times compared to that in the baseline period in 2080s under A2a scenarios.展开更多
文摘走航式海洋多参数剖面测量系统(moving vessel profiler,MVP)是一种集成程度和自动化程度都较高的海洋调查设备,能对海洋多要素进行同时观测,获得水平方向的高分辨率数据资料。由于温度和电导率传感器响应时间的不匹配,MVP下放速度过快(峰值速度4 m/s)而造成非常明显的盐度尖峰现象。本研究结合Fofonoff(F)法、时间常数指数递归数字滤波(Giles and McDougall,GM)法和Grose提出的盐度尖峰订正方案,提出了一种新的方法,即MCT(match conductivity and temperature response time)法,通过对压力、温度和电导率传感器进行响应时间的匹配来减弱盐度尖峰。将SBE-9型CTD资料作为标准,发现订正后的资料与CTD盐度曲线的互相关系数为0.917,误差比订正前减小80%。对比35°N断面修正前后的盐度资料,订正后温盐跃层处出现的低盐区域消失。MVP的应用比常规海洋调查仪器CTD对于海洋现象的观测更有优势。
基金supported by the Project 42374170,XDA0430101.and 2022YFF0706200.
文摘Landslides are a type of natural disaster that can cause substantial harm to humanity.Monitoring and predicting the initiation of potential landslides is critical to avoiding losses due to disasters and economic activities.The impact of the controlled-source audio-frequency magnetotelluric method on investigating landslide surfaces is assessed through numerical simulations with a finite element approach.A Dirichlet boundary condition is selected to match the truncated boundary,resulting in a remarkable improvement in simulation effi ciency.Rederivation of the formulas for a layered medium adept to the controlled-source audiofrequency magnetotelluric method is necessary to determine the electromagnetic fi eld at any location along the truncated boundary.After the reliability evaluation of the new codes,a landslide model with a slide surface is designed,and the characteristics of its electromagnetic fi eld and the apparent resistivity are studied.Instead of the total electromagnetic fi eld,which is strongly infl uenced by topography variation,the apparent resistivity should be used for sliding surface detection.The normalized pure anomalous electromagnetic fi eld may also be employed to quickly assess the detectability of the sliding surface.Overall,this study demonstrates that the controlled-source audio-frequency magnetotelluric method can be employed for investigating landslides,and recommends survey parameters,including confi guration,frequency range,and length of survey line in landslide exploration.
基金supported by the "Eleventh Five-Year" National Science and Technology Support Project (2006BAD23B04)National Forestry Public Benefit Research Founda-tion (No200804002)the Youth Foundation of Northeast Forestry University (No09051)
文摘Monthly projections of maximum temperature,relative humidity,precipitation,and wind speed were made based on the model of HadCM3 and the climatic change scenarios of IPCC SRES A2a and B2a for the future scenario periods of 2010–2039（referred to as 2020s）,2040–2069（referred to as 2050s）,and 2070–2099（referred to as 2080s）.The period 1961–1990 was chosen as the baseline period.The observed and projected weather data were downscaled using delta change methods and historical relationships between weather data,area burned,and the seasonal severity rating（SSR） code of the Canadian Fire Weather Index System were examined.The variations of area burned as influenced by climate change were assessed quantitative and qualitative for the study region,assuming that the fire regimes had the similar responses to the warming climate as during the 20th century.Our results indicated that a linear regression relationship existing between the historical area burned and the mean SSR values with regression coefficient in the significant range of 0.16 to 0.61.It was evident that the increased SSR values could result in more area burned;the area burned in the study region would have an increasing pattern during the 21st century under scenarios A2a and B2a scenarios and the area burned would be doubled.Also,the future area burned would have a strong seasonal pattern that more fires would occur in summer and autumn fire season,especially in summer.The area burned in summer fire season would increase by 1.5 times compared to that in the baseline period in 2080s under A2a scenarios.
