Change in plant phenology is one of the most sensitive ecological responses to climate warming. Little information is known about the effects of climate warming on phenology of urban tree species in the northern fores...Change in plant phenology is one of the most sensitive ecological responses to climate warming. Little information is known about the effects of climate warming on phenology of urban tree species in the northern forest of China. In this study, we investigated the phenological characteristics of the main tree species in the urban forest of Shengyang City in China and the correlation between phenology and atmospheric temperature from the discontinuous data during past 42 years over three time periods(from 1962 to 1965, 1977 to 1978, and 2000 to 2005). The results showed that the annual average temperature in Shenyang City showed an increasing trend and increased by 0.96℃ from 1962 to 2005 due to climate warming. The germination phenology of the urban trees was negatively correlated with the temperature in winter and early spring. The leafing phenology was mainly influenced by the temperature in spring before leafing. Influenced by climate warming, the germination, leafing, and flowering phenologies of this urban forest in 2005 were 14, 13, and 10 days earlier than those in 1962, respectively. We inferred that further warming in winter might prolong the growing season of urban trees in the northern forest of China.展开更多
Effects of extratropical solar penetration on the North Atlantic Ocean circulation and climate are investigated using a coupled ocean-atmosphere model.In this model,solar penetration generates basinwide cooling and wa...Effects of extratropical solar penetration on the North Atlantic Ocean circulation and climate are investigated using a coupled ocean-atmosphere model.In this model,solar penetration generates basinwide cooling and warming in summer and winter,respectively.Associated with SST changes,annual mean surface wind stress is intensified in both the subtropical and subpolar North Atlantic,which leads to acceleration of both subtropical and subpolar gyres.Owing to warming in the subtropics and significant saltiness in the subpolar region,potential density decreases(increases) in the subtropical(subpolar)North Atlantic.The north-south meridional density gradient is thereby enlarged,accelerating the Atlantic meridional overturning circulation(AMOC).In addition,solar penetration reduces stratification in the upper ocean and favors stronger vertical convection,which also contributes to acceleration of the AMOC.展开更多
This work is part of a large experimental study on the distribution of internal temperatures in two similar test cells, but with different systems of coverage. The main goal of this paper is to present results on an e...This work is part of a large experimental study on the distribution of internal temperatures in two similar test cells, but with different systems of coverage. The main goal of this paper is to present results on an experimental field to determine the influence of solar radiation on the internal environmental conditions of different roof systems. Dry bulb temperature and internal surface temperatures were measured in two test cells with different roof systems （green roof and conventional ceramic roof）. Their thermal performances were compared on days with differing air mass domain, based on dynamic climatic approach. This research was based on the spatial and temporal approaches of dynamic climatology, from the climatic regime of the city of Itirapina, S^o Paulo State, analysed as representative episodes. Climatic data were provided by an automatic weather station and verified by satellite imagery, and the internal temperatures of the cells were collected by thermocouples installed on the surfaces of ceilings, floors, walls, and suspended inside the buildings. The results indicate that the solar radiation is mainly responsible for the great variations in temperature and its impact on indoor environments, since there were great differences in temperature inside comparing the two days of the experiment. This refutes the notion that the outside temperature is responsible for daily variations in temperature inside buildings.展开更多
The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variat...The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variations in solar irradiance on the variability of the climate remains a hot topic of debate.Most studies focus on the effects of solar variation on the Earth's climate on long time scales.This study presents the responses of regional climates to solar variations on shorter time scales using two datasets:one for the air temperature in Nanjing and the Greenwich sunspot number,and the other for the air temperature in Shijiazhuang and the United States sunspot number.Employing empirical mode decomposition,both the 11-year quasi-period of the sunspot number and similar periods including approximately 5.5-and 10.5-year cycles of the air temperature in Nanjing and Shijiazhuang are obtained.However,correlation analysis of similar periodic components for the sunspot number and air temperature indicates that changes in the air temperature on short and medium time scales are not linked to solar variations.This is further confirmed by a test of whether a mode component is a stochastic noise signal.Many shorter periods are also found at the 95% confidence level;in particular,the 3.1-year period of the Nanjing air temperature coincides with a previously obtained empirical result.Moreover,no temperature variations on shorter time scales correlate with solar variability.展开更多
基金National Natural Science Foundation of China(No.31270518,31170573)National Science and Technology Major Project(No.2012ZX07202-008)National Science and Technology Support Program(No.2012BAC05B00)
文摘Change in plant phenology is one of the most sensitive ecological responses to climate warming. Little information is known about the effects of climate warming on phenology of urban tree species in the northern forest of China. In this study, we investigated the phenological characteristics of the main tree species in the urban forest of Shengyang City in China and the correlation between phenology and atmospheric temperature from the discontinuous data during past 42 years over three time periods(from 1962 to 1965, 1977 to 1978, and 2000 to 2005). The results showed that the annual average temperature in Shenyang City showed an increasing trend and increased by 0.96℃ from 1962 to 2005 due to climate warming. The germination phenology of the urban trees was negatively correlated with the temperature in winter and early spring. The leafing phenology was mainly influenced by the temperature in spring before leafing. Influenced by climate warming, the germination, leafing, and flowering phenologies of this urban forest in 2005 were 14, 13, and 10 days earlier than those in 1962, respectively. We inferred that further warming in winter might prolong the growing season of urban trees in the northern forest of China.
基金Supported by the Key Project of National Natural Science Foundation of China(No.41130859)the Innovation Team Project(No.40921004)
文摘Effects of extratropical solar penetration on the North Atlantic Ocean circulation and climate are investigated using a coupled ocean-atmosphere model.In this model,solar penetration generates basinwide cooling and warming in summer and winter,respectively.Associated with SST changes,annual mean surface wind stress is intensified in both the subtropical and subpolar North Atlantic,which leads to acceleration of both subtropical and subpolar gyres.Owing to warming in the subtropics and significant saltiness in the subpolar region,potential density decreases(increases) in the subtropical(subpolar)North Atlantic.The north-south meridional density gradient is thereby enlarged,accelerating the Atlantic meridional overturning circulation(AMOC).In addition,solar penetration reduces stratification in the upper ocean and favors stronger vertical convection,which also contributes to acceleration of the AMOC.
文摘This work is part of a large experimental study on the distribution of internal temperatures in two similar test cells, but with different systems of coverage. The main goal of this paper is to present results on an experimental field to determine the influence of solar radiation on the internal environmental conditions of different roof systems. Dry bulb temperature and internal surface temperatures were measured in two test cells with different roof systems （green roof and conventional ceramic roof）. Their thermal performances were compared on days with differing air mass domain, based on dynamic climatic approach. This research was based on the spatial and temporal approaches of dynamic climatology, from the climatic regime of the city of Itirapina, S^o Paulo State, analysed as representative episodes. Climatic data were provided by an automatic weather station and verified by satellite imagery, and the internal temperatures of the cells were collected by thermocouples installed on the surfaces of ceilings, floors, walls, and suspended inside the buildings. The results indicate that the solar radiation is mainly responsible for the great variations in temperature and its impact on indoor environments, since there were great differences in temperature inside comparing the two days of the experiment. This refutes the notion that the outside temperature is responsible for daily variations in temperature inside buildings.
基金supported by National Natural Science Foundation of China (Grant No. 60874111)Qing Lan Project of Jiangsu Province and College Science Foundation of Jiangsu Province (Grant No. 07KJD120128)
文摘The contemporary science of climate change is increasingly focusing on the temporal and spatial characteristics of temperature oscillations and determining possible underlying causes.In particular,the effect of variations in solar irradiance on the variability of the climate remains a hot topic of debate.Most studies focus on the effects of solar variation on the Earth's climate on long time scales.This study presents the responses of regional climates to solar variations on shorter time scales using two datasets:one for the air temperature in Nanjing and the Greenwich sunspot number,and the other for the air temperature in Shijiazhuang and the United States sunspot number.Employing empirical mode decomposition,both the 11-year quasi-period of the sunspot number and similar periods including approximately 5.5-and 10.5-year cycles of the air temperature in Nanjing and Shijiazhuang are obtained.However,correlation analysis of similar periodic components for the sunspot number and air temperature indicates that changes in the air temperature on short and medium time scales are not linked to solar variations.This is further confirmed by a test of whether a mode component is a stochastic noise signal.Many shorter periods are also found at the 95% confidence level;in particular,the 3.1-year period of the Nanjing air temperature coincides with a previously obtained empirical result.Moreover,no temperature variations on shorter time scales correlate with solar variability.
