The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and di...The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and diurnal variations in the elevational gradients of air temperature and humidity on the southern and northern slopes in the middle Tianshan Mountain Range using data collected throughout the year via HOBO data loggers. The measurements were conducted at 12 different elevations from 1548 to 3277 m from September 2004 to August 2005. The results showed that the annual mean air temperature decreased along the elevational gradients with temperature lapse rates of(0.71±0.20)°C/100 m and(0.59±0.05)°C/100 m on the northern and southern slopes, respectively. The annual mean absolute humidity significantly decreased with increasing elevation on the northern slope but showed no significant trend on the southern slope. The annual mean relative humidity did not show a significant trend on the northern slope but increased with increasing elevation on the southern slope. The mean air temperature lapse rate exhibited significant seasonal variation, which is steeper insummer and shallower in winter, and this value varied between 0.37°C/100 m and 0.75°C/100 m on the southern slope and between 0.30°C/100 m and 1.02°C/100 m on the northern slope. The mean absolute and relative humidity also exhibited significant seasonal variations on both slopes, with the maximum occurring in summer and the minimum occurring in winter or spring. The monthly diurnal range of air temperature on both slopes was higher in spring than in winter. The annual range of air temperature on the southern slope was higher than that on the northern slope. Our results suggest that significant spatiotemporal variations in humidity and temperature lapse rate are useful when analyzing the relationships between species range sizes and climate in mountain areas.展开更多
Regulation of streamflow by a reservoir creates a flow regime much different from the preimpoundment period flow regime. Hydro-Electric Projects(HEPs) commissioned in the Western Ghat regions of the Kerala State, Indi...Regulation of streamflow by a reservoir creates a flow regime much different from the preimpoundment period flow regime. Hydro-Electric Projects(HEPs) commissioned in the Western Ghat regions of the Kerala State, India during the last four decades caused considerable changes in the flow regimes of the rivers of the Kerala State in southwest India. In this paper, the Indicators of Hydrologic Alteration(IHA) approach proposed by Richter et al.(1996) is used to analyze flow regime changes in the Periyar and Muvattupuzha Rivers, due to the construction of the Idukki(1976), Idamalayar(1987) and Lower Periyar(1997) HEPs in the high ranges of the Western Ghats. Normal rainfall years(annual rainfall values within mean ± 0.75 standard deviation limits) are only considered in the analysis to focus on hydrologic alterations due to human activities. The mean hydrologic alteration in the Periyar River(deviation from the pre-development hydrologic indicator values) after commissioning of three HEPs is 35%. Inter-basin water transfer after power generation from the Idukki HEP resulted in a higher discharge in the adjacent Muvattupuzha River, leading to considerable changes in the hydroenvironment(mean hydrologic alterations varying between 57 to 63%). IHA parameters showing hydrologic alterations above the 67 th Percentile werefurther analyzed. For each of the pre-construction hydrologic parameters ± 1 standard deviation from the mean is set as the upper and lower management target limits. The values of each IHA parameter beyond these targets are considered as nonattainment. Considerable hydrologic alterations are observed, especially for low flows in both basins. Inter-basin transfer induced larger changes in flow parameters compared to intra-basin regulations. The study shows that under a proper water release and diversion scheme, the non-attainment of IHA parameters(values fall beyond the target limits) can be reduced. The findings of the study will be greatly beneficial to regional water management and restoration of an eco-environmental system in the humid tropical region.展开更多
A compact fiber-optic diode-laser sensor system for measuring relative humidity is studied. In such a system, a distributed feedback laser lasing near 1877 nm is used as light source while a high-precision Pt resistan...A compact fiber-optic diode-laser sensor system for measuring relative humidity is studied. In such a system, a distributed feedback laser lasing near 1877 nm is used as light source while a high-precision Pt resistance as temperature sensor, an accuracy of 0.1% relative-humidity can be achieved. The laser sensor system is able to lock to the absorption peak and calculate the density of water vapor without any additional reference measurements. Using programs built in to the microcontroller unit, the laser system can switch functions between direct measurement at high density and second-harmonic detection at low density. The system can switch between the two modes automatically and work in a wide dynamic range.展开更多
深圳市在人口结构和经济社会发展方面很特殊,而对于其热带向副热带过渡的气候特征对流感发病的影响仍缺乏深入研究。本研究收集长序列(2003—2019年)的深圳市流感样病例(Influenza Like Illness,ILI)监测数据,采用分布滞后非线性模型(DL...深圳市在人口结构和经济社会发展方面很特殊,而对于其热带向副热带过渡的气候特征对流感发病的影响仍缺乏深入研究。本研究收集长序列(2003—2019年)的深圳市流感样病例(Influenza Like Illness,ILI)监测数据,采用分布滞后非线性模型(DLNM)系统分析了ILI与多种气象因子的关联,并分别使用Prophet时间序列和多元逐步回归模型对流感风险进行预报。近17年来深圳ILI发病在2003—2009年增加、2010—2014年平稳、2015—2019年下降,年周期特征凸显;多数年份发病率呈夏季单峰型,与高温、高湿的气候背景高度相符;个别年份在年末出现次高峰,常与大规模暴发疫情有关。DLNM揭示,高温对ILI风险的即时性影响较强,气温达到29.9℃,相对危险度值(RR)可达1.237(95%置信区间(95%CI):1.203—1.272);而低温效应在滞后2—3周起主导作用。70%—75%的湿度范围对应ILI高风险段,70%相对湿度的RR为1.089(95%CI:1.046—1.135)。偏高的湿度与高温共存可诱使ILI最高风险点出现,即二者有协同增强效应,在其长夏短冬气候下尤其需要注意。ILI危险度在气温日较差为4—6℃或>9℃时均有显著增加,即日内温差对流感的活跃程度亦有显著影响;由于深圳的风速整体较小,其影响整体较弱。Prophet时间序列模型和逐步回归模型的回报准确率相近(>86%),而同时考虑了气象因子和前期发病人数的回归模型预测准确率更高(>80%)。简言之,深圳市ILI风险与温、湿度的非线性协同影响关系最为密切,其发病率很大程度上是可预测的。展开更多
基金supported by the National Key R&D Program of China(2017YFA0605101)the National Natural Science Foundation of China(31770489,41273098 and 31621091)
文摘The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and diurnal variations in the elevational gradients of air temperature and humidity on the southern and northern slopes in the middle Tianshan Mountain Range using data collected throughout the year via HOBO data loggers. The measurements were conducted at 12 different elevations from 1548 to 3277 m from September 2004 to August 2005. The results showed that the annual mean air temperature decreased along the elevational gradients with temperature lapse rates of(0.71±0.20)°C/100 m and(0.59±0.05)°C/100 m on the northern and southern slopes, respectively. The annual mean absolute humidity significantly decreased with increasing elevation on the northern slope but showed no significant trend on the southern slope. The annual mean relative humidity did not show a significant trend on the northern slope but increased with increasing elevation on the southern slope. The mean air temperature lapse rate exhibited significant seasonal variation, which is steeper insummer and shallower in winter, and this value varied between 0.37°C/100 m and 0.75°C/100 m on the southern slope and between 0.30°C/100 m and 1.02°C/100 m on the northern slope. The mean absolute and relative humidity also exhibited significant seasonal variations on both slopes, with the maximum occurring in summer and the minimum occurring in winter or spring. The monthly diurnal range of air temperature on both slopes was higher in spring than in winter. The annual range of air temperature on the southern slope was higher than that on the northern slope. Our results suggest that significant spatiotemporal variations in humidity and temperature lapse rate are useful when analyzing the relationships between species range sizes and climate in mountain areas.
基金financial support by Kerala State Council for Science Technology and Environment, Government of Kerala
文摘Regulation of streamflow by a reservoir creates a flow regime much different from the preimpoundment period flow regime. Hydro-Electric Projects(HEPs) commissioned in the Western Ghat regions of the Kerala State, India during the last four decades caused considerable changes in the flow regimes of the rivers of the Kerala State in southwest India. In this paper, the Indicators of Hydrologic Alteration(IHA) approach proposed by Richter et al.(1996) is used to analyze flow regime changes in the Periyar and Muvattupuzha Rivers, due to the construction of the Idukki(1976), Idamalayar(1987) and Lower Periyar(1997) HEPs in the high ranges of the Western Ghats. Normal rainfall years(annual rainfall values within mean ± 0.75 standard deviation limits) are only considered in the analysis to focus on hydrologic alterations due to human activities. The mean hydrologic alteration in the Periyar River(deviation from the pre-development hydrologic indicator values) after commissioning of three HEPs is 35%. Inter-basin water transfer after power generation from the Idukki HEP resulted in a higher discharge in the adjacent Muvattupuzha River, leading to considerable changes in the hydroenvironment(mean hydrologic alterations varying between 57 to 63%). IHA parameters showing hydrologic alterations above the 67 th Percentile werefurther analyzed. For each of the pre-construction hydrologic parameters ± 1 standard deviation from the mean is set as the upper and lower management target limits. The values of each IHA parameter beyond these targets are considered as nonattainment. Considerable hydrologic alterations are observed, especially for low flows in both basins. Inter-basin transfer induced larger changes in flow parameters compared to intra-basin regulations. The study shows that under a proper water release and diversion scheme, the non-attainment of IHA parameters(values fall beyond the target limits) can be reduced. The findings of the study will be greatly beneficial to regional water management and restoration of an eco-environmental system in the humid tropical region.
基金supported by the Meteorology Industry Research Project of China (GYHY200806033, GYHY201006045)the National Natural Science Foundation of China (61021003, 61090391, 60837001, 60820106004)+1 种基金the National High-Technology Research and Development Program of China (2009AA03Z409)the Open Fund of Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education
文摘A compact fiber-optic diode-laser sensor system for measuring relative humidity is studied. In such a system, a distributed feedback laser lasing near 1877 nm is used as light source while a high-precision Pt resistance as temperature sensor, an accuracy of 0.1% relative-humidity can be achieved. The laser sensor system is able to lock to the absorption peak and calculate the density of water vapor without any additional reference measurements. Using programs built in to the microcontroller unit, the laser system can switch functions between direct measurement at high density and second-harmonic detection at low density. The system can switch between the two modes automatically and work in a wide dynamic range.
文摘深圳市在人口结构和经济社会发展方面很特殊,而对于其热带向副热带过渡的气候特征对流感发病的影响仍缺乏深入研究。本研究收集长序列(2003—2019年)的深圳市流感样病例(Influenza Like Illness,ILI)监测数据,采用分布滞后非线性模型(DLNM)系统分析了ILI与多种气象因子的关联,并分别使用Prophet时间序列和多元逐步回归模型对流感风险进行预报。近17年来深圳ILI发病在2003—2009年增加、2010—2014年平稳、2015—2019年下降,年周期特征凸显;多数年份发病率呈夏季单峰型,与高温、高湿的气候背景高度相符;个别年份在年末出现次高峰,常与大规模暴发疫情有关。DLNM揭示,高温对ILI风险的即时性影响较强,气温达到29.9℃,相对危险度值(RR)可达1.237(95%置信区间(95%CI):1.203—1.272);而低温效应在滞后2—3周起主导作用。70%—75%的湿度范围对应ILI高风险段,70%相对湿度的RR为1.089(95%CI:1.046—1.135)。偏高的湿度与高温共存可诱使ILI最高风险点出现,即二者有协同增强效应,在其长夏短冬气候下尤其需要注意。ILI危险度在气温日较差为4—6℃或>9℃时均有显著增加,即日内温差对流感的活跃程度亦有显著影响;由于深圳的风速整体较小,其影响整体较弱。Prophet时间序列模型和逐步回归模型的回报准确率相近(>86%),而同时考虑了气象因子和前期发病人数的回归模型预测准确率更高(>80%)。简言之,深圳市ILI风险与温、湿度的非线性协同影响关系最为密切,其发病率很大程度上是可预测的。
