Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the...Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River （MLRYR） and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River （MLRYR）. Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating （cooling） caused by the vertical thermal advection as well as the diabatic heating （cooling） caused by diabatic processes can explain the formation of the high （low） temperature events in the middle and lower reaches of the Yangtze River （MLRYR） in boreal summer.展开更多
A 70-year history of precipitation δ^18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier （33°34＇37.8″ N, 91°10＇35.3″ E, 5720 m a.s.l.） on ...A 70-year history of precipitation δ^18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier （33°34＇37.8″ N, 91°10＇35.3″ E, 5720 m a.s.l.） on Mt. Geladaindong （the source region of Yangtze River） during October and November, 2005. Based on the seasonality of δ^18O records and the significant positive relationships between monsoon/non-monsoon δ^18O values and summer/spring air temperature from the nearby meteorological stations, the history of summer and spring air temperature have been reconstructed for the last 70 years. The results show that both summer and spring air temperature variations present similar trends during the last 70 years. Regression analysis indicates that the slope of the temperature-δ^18O relationship is 1.3℃/‰ for non-monsoon δ^18O values and spring air temperature, and 0.4℃/‰ for monsoon δ^18O values and summer air temperature. Variation of air temperature recorded in the ice core is consistent with that in the Northern Hemisphere （NH）, however, the warming trend in the Geladaindong region is more intense than that in the NH, reflecting a higher sensitivity to global warming in the high elevation regions. In addition, warming trend is greater in spring than in summer.展开更多
Since 1960s, many research works on the reinforced concrete structure have been published and some concise and practical calculation methods for safety control during construction have been achieved. The reinforced co...Since 1960s, many research works on the reinforced concrete structure have been published and some concise and practical calculation methods for safety control during construction have been achieved. The reinforced concrete structure during construction is a time-dependent structure which consists of a partly completed structure and a formwork-shore system. Experience shows that the most critical condition of the time-dependent structure may happen when the formwork-shore system is partly removed or reset and accidents may occur. In the present paper, effect of ambient temperature variation between day and night is considered, new structural models for reinforced concrete frames, slab-column systems and shear wall structures are proposed, and a new software named Safety Analysis During Construction Considering Temperature(SACT) is also introduced. Compared with on-site measurements, the software SACT is validated for application on construction site.展开更多
We collected and verified documentary records of the latest spring snowing dates(LSSD)in Hangzhou during Southern Song Dynasty.Furtherly,the statistical correlation between this proxy and February–April mean temperat...We collected and verified documentary records of the latest spring snowing dates(LSSD)in Hangzhou during Southern Song Dynasty.Furtherly,the statistical correlation between this proxy and February–April mean temperature in Hangzhou was examined,and samples later than the perennial mean of the LSSD during Southern Song Dynasty were transformed into the decadal mean of LSSD by means of Boltzmann function.General characteristics of this reconstructed LSSD series with a 10-year temporal resolution was analyzed,and it was also compared with other documentary evidences and reconstructed climate series in China for the period 1131–1270.The results and discussion suggested that:(1)Records of the LSSD in Hangzhou during Southern Song Dynasty did not refer to ice pellets and graupels,which had an explicit climate significance(–0.34℃/10 d,R2=0.37,p<0.001).However,when this proxy is used to reconstruct temperature changes,all dates should be converted into proleptic Gregorian style and meet the same criterion of"true Qi"as the Chinese traditional calendar after 1929.(2)The decadal mean of LSSD can be effectively estimated by using the forefront of LSSD in the decade on the basis of Boltzmann function,whose extrapolation has a lesser uncertainty than those on the basis of linear models or polynomial models.(3)The spring climate in Hangzhou during 1131–1270 was almost as warm as the period 1951–1980.At the centennial scale,this period can be divided into two phases:the cold 1131–1170 and the warm 1171–1270.In the latter,1181–1200 and 1221–1240 were two cold intervals at the multi-decadal scale.(4)The reconstructed LSSD series was consistent well with other documentary evidences and reconstructed climate series in China for 1131–1270,which may reflect the influence on the climate over most regions of China imposed by the Pacific Decadal Oscillation(PDO).展开更多
The oxygen isotopic values of aquatic plant cellulose and carbonates in Lake Caohai sediments were measured using a continuous flow isotopic ratio mass spectrometer(CF-IRMS).Because of predictable oxygen isotopic frac...The oxygen isotopic values of aquatic plant cellulose and carbonates in Lake Caohai sediments were measured using a continuous flow isotopic ratio mass spectrometer(CF-IRMS).Because of predictable oxygen isotopic fractionation between cellulose and its source water,the oxygen isotopic composition of paleo-lake water has been established quantitatively.Combined oxygen isotopic values of cellulose and carbonates were used in the‘Craig’equation to determine paleotemperatures and their variation in the lake during the past 500 years.Results show that the paleotemperature trend correlates well with meteorological records from Weining.There are four notable cold intervals at Lake Caohai over the past 500 years,namely 1540–1570AD,1670–1715AD,1780–1870AD and 1900–1930AD,and the former three cold intervals have been observed in the conventional Little Ice Age(LIA).These cold periods at Lake Caohai correspond well with those recorded from tree ring,peat,and ice core data from adjacent regions,particularly temperature those inferred fromδ18O of peat cellulose from Hongyuan Southwestern China.The trend in paleotemperature variations at Lake Caohai are also consistent with both the change of Indian summer monsoon,derived fromδ18O values of a stalagmite in Dongge,and a recorded shift in solar activity.The findings of this study illustrate that coupled analysis ofδ18O values of cellulose and carbonates from lake sediments may be used as a paleotemperature proxy.These results also provide further evidence of the existence of LIA in southwestern China.展开更多
The ten-year mean anomalies of seasonal and annual temperatures were reconstructed on the basis of historical documents of cold events such as severe snowing and freezing of lakes and rivers.The assorted events were c...The ten-year mean anomalies of seasonal and annual temperatures were reconstructed on the basis of historical documents of cold events such as severe snowing and freezing of lakes and rivers.The assorted events were calibrated with instrumental observations of temperature and transformed into ten-year mean anomalies. The reconstructed temperature series show predominance of cold climate in the first four hundred years of the period examined.The centenary seasonal temperature anomalies for the 16th to the 19th century vary between -0.1 and -0.7K.The coldest decades concentrated in the middle of 17th and 19th centuries.It provided the irrefutable evidence of the occurrence of the Little Ice Age in China.The minima of ten-year mean temperature anomalies ranged about -1.5 to 2.0K in spring and winter.Meanwhile,the variance of ten-year mean tempera- ture was increased by more than 20％ in comparison to the 20th century.展开更多
An efficient double-layer formwork curing method using an“inner supporting formwork+outer insulation formwork”was proposed in this study to address the early cracking of precast concrete components in high altitude ...An efficient double-layer formwork curing method using an“inner supporting formwork+outer insulation formwork”was proposed in this study to address the early cracking of precast concrete components in high altitude regions.Steel and plywood formwork were designed as inner support formwork,while polystyrene(PS)and polyurethane(PU)were used as outer insulation formwork.Indoor experiments and two finite element methods(The complete simulation method focuses on computational accuracy,and the equivalent simulation method emphasizes computational efficiency)were employed to analyze the evolution of the concrete temperature field under different double-layer formwork curing methods throughout the curing period,combined with compressive strength and pore structures testing.The results show that steel+5-mm-thick PU insulation formwork curing method can significantly mitigate the impact of large diurnal temperature variations on the internal temperature of concrete.Unlike traditional steam-curing,this method does not deteriorate the pore structure or compressive strength of the concrete.This study is of great significance in addressing the problem of early cracking of precast concrete components exposed to large diurnal temperature vriations in high altitude regions.展开更多
This paper verifies the low Mach number limit of the non-isentropic compressible magnetohydrodynamic(MHD)equations with or without the magnetic diffusion in a three-dimensional bounded domain when the temperature vari...This paper verifies the low Mach number limit of the non-isentropic compressible magnetohydrodynamic(MHD)equations with or without the magnetic diffusion in a three-dimensional bounded domain when the temperature variation is large but finite.The uniform estimates of strong solutions are established in a short time interval independent of the Mach number,provided that the slip boundary condition for the velocity and the Neumann boundary condition for the temperature are imposed and the initial data is well-prepared.展开更多
In this paper we analyze daily mean, minimum, and maximum temperature data collected at 119 meteorological stations over five regions of China during the period 1951-2010. The series of minimum, maximum, and mean temp...In this paper we analyze daily mean, minimum, and maximum temperature data collected at 119 meteorological stations over five regions of China during the period 1951-2010. The series of minimum, maximum, and mean temperatures from each climatic region have similar signatures, but there are differences among the five regions and the countrywide average. The results indicate that the periods of faster warming were not synchronous across the regions studied： warming in northeast China and Tibet began in 1986, while in central-east, southeast, and northwest China the warming emerged in 1995. Furthermore, central-east and northwest China, and Tibet, have warmed continuously since 2000, but the temperature has decreased during this period in southeast China. We evaluated the evolution of these temperature series using a novel nonlinear filtering technique based on the concept of the lifetime of temperature curves. The decadal to secular evolution of solar activity and temperature variation had similar signatures in the northeast, southeast, and northwest re- gions and the average across the whole country, indicating that solar activity is a significant control on climate change over secular time scales in these regions. In comparison with these regions, the signatures were different in central-east China and Tibet because of regional differences （e.g., landforms and elevation） and indirect effects （e.g., cloud cover influencing the radiation balance, thereby inducing climate change）. Furthermore, the results of wavelet analysis indicated that the El Nino Southem Oscillation （ENSO） has had a significant impact on climate change, but at different times among the regions, and these changes were most probably induced by differing responses of the atmospheric system to solar forcing.展开更多
The relationships between variations of sea surface temperature anomalies (SSTVA) in the key ocean areas and the precipitation / temperature anomalies in China are studied based on the monthly mean sea surface tempera...The relationships between variations of sea surface temperature anomalies (SSTVA) in the key ocean areas and the precipitation / temperature anomalies in China are studied based on the monthly mean sea surface temperature data from January 1951 to December 1998 and the same stage monthly mean precipitation/ temperature data of 160 stations in China. The purpose of the present study is to discuss whether the relationship between SSTVA and precipitation / temperature is different from that between sea surface temperature anomalies (SSTA) and precipitation/ temperature, and whether the uncertainty of prediction can be reduced by use of SSTVA. The results show that the responses of precipitation anomalies to the two kinds of tendency of SSTA are different. This implies that discussing the effects of two kinds of tendency of SSTA on precipitation anomalies is better than just discussing the effects of SSTA on precipitation anomalies. It helps to reduce the uncertainty of prediction. The temperature anomalies have more identical re-sponses to the two kinds of tendency of SSTA than the precipitation except in the western Pacific Ocean. The response of precipitation anomalies to SSTVA is different from that to SSTA, but there are some similarities. Key words Variations of sea surface temperature anomalies - Precipitation anomalies - Temperature anomalies - Statistical significance test Sponsored jointly by the “ National Key Developing Program for Basic Sciences” (G1998040900) Part I and the Key Program of National Nature Science Foundation of China “ Analyses and Mechanism Study of the Regional Climatic Change in China” under Grant No.49735170.展开更多
Field surveys covering a spring-neap tidal period were conducted to investigate the characteristics of tidal dynamics within a curved channel in the southern Hangzhou Bay, China. The channel has a maximum depth of mor...Field surveys covering a spring-neap tidal period were conducted to investigate the characteristics of tidal dynamics within a curved channel in the southern Hangzhou Bay, China. The channel has a maximum depth of more than 100 m with an average tidal range of 2.5 m, serving as the main tidal passage in the southern part of the Hangzhou Bay. Water salinity, temperature and velocity data were collected from the ship-based transects and mooring measurements. During flood tide, the tidal current intrudes into the Hangzhou Bay through the northern side of the channel with a maximum velocity of about 2 m/s, while retreats through the southern side during ebb tide with a maximum velocity of 1.8 m/s. Due to the pressure, density gradients, the Coriolis force and centrifugal effect, a lateral exchange flow is generated as the tidal current relaxes from flood to ebb. Salinity and temperature data show that the water in the channel is weakly stratified during both spring and neap tides in summer time.However, mixing in the middle region will be enhanced by the lateral circulation. Mooring data indicate that the temperature and salinity are varying at a frequency similar to tidal current but higher than sea level oscillation.Our results support the hypothesis that the high frequency salinity and temperature variations could be generated by combination of the tidal current and the lateral exchanging flow.展开更多
Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are th...Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are the key factors affecting the cutting performance when drilling through formations with thermally damaged rock. To better investigate the temperature rise, a series of rock samples treated at high temperatures (9–300℃) were broken with a PDC cutter. The performance of the PDC cutter on these samples was studied using cutting force sensors, high-speed photography, and the thermal infrared imager. Based on the experimental data, a new cutting force evaluation parameter, η, is suggested. The link between the cutting force and rock properties is discussed in detail. The present results indicate that the average cutting force of high-temperature-treated granite is 3–5 times that of the thermally damaged sandstone. Furthermore, a critical temperature for thermal damage has been identified in granite cutting at 100–200℃ and in sandstone at 100℃. This corresponds to the temperature at which interlayer water loss and thermal crack closure occur. The results also indicate that when the treatment temperature exceeds the critical threshold, both the cutting force and temperature rise exhibit more significant changes with increasing temperature. Additionally, the maximum temperature of the PDC cutter during granite cutting can reach 47.6 ℃, which is almost 34℃ higher than that of sandstone. Regarding debris size, granite is much less sensitive to the treatment temperature, showing only slight changes in debris size compared to sandstone as the treatment temperature increases. The increasing cutter-rock interface area can significantly reduce frictional heat generation while increasing the cutting force and enhancing the temperature rise. The parameter valuation of the newly defined parameter η, which is related to frictional heating, shows that the capacity of the thermal generation and the heat transfer change as the temperature rises at the cutter-rock interface. At last, the correlation analysis indicates that the cutting force of sandstone and granite is highly correlated with , E/σc and σt. This study serves as a theoretical support and technical guidance for cutting hot dry rock (HDR), which is of great significance to HDR drilling.展开更多
Studying the causes of summer(June–July–August)precipitation anomalies in the middle and lower reaches of the Yangtze River(MLYR)and accurately predicting rainy season precipitation are important to society and the ...Studying the causes of summer(June–July–August)precipitation anomalies in the middle and lower reaches of the Yangtze River(MLYR)and accurately predicting rainy season precipitation are important to society and the economy.In recent years,the sea surface temperature(SST)trend factor has been used to construct regression models for summer precipitation.In this study,through correlation analysis,winter SST anomaly predictors and the winter Central Pacific SST trend predictor(CPT)are identified as closely related to the following MLYR summer precipitation(YRSP).CPT can influence YRSP by inducing anomalous circulations over the North Pacific,guiding warm and moist air northward,and inhibiting the development of the anomalous anticyclone over the Northwest Pacific.This has improved the predictive skill of the seasonal regression model for YRSP.After incorporating the CPT,the correlation coefficient of the YRSP regression model improved by 40%,increasing from 0.45 to 0.63,and the root mean squared error decreased by 22%,from 1.15 to 0.90.展开更多
In this paper,based on the observation data of air temperature during 1951-2009 in Shenyang,the interannual and interdecadal variation of annual average temperature,maximum and minimum temperature in Shenyang were con...In this paper,based on the observation data of air temperature during 1951-2009 in Shenyang,the interannual and interdecadal variation of annual average temperature,maximum and minimum temperature in Shenyang were conducted the statistical analysis by means of linear trend estimation and mutation detection by using Mann-Kendall method.As was demonstrated in the results,the annual average temperature,maximum and minimum temperature in Shenyang showed an upward trend,whose linear tendency rate was 0.231,0.181 and 0.218 respectively.The increment trend of annual average temperature,maximum and minimum temperature was extremely clear.The increase in minimum temperature was more significant than that in mean temperature and maximum temperature.The abrupt change point of annual mean temperature in Shenyang appeared in 1981;the abrupt change point of annual mean maximum temperature appeared in 1994;the annual mean minimum temperature underwent mutation in 1978.展开更多
We consider a Ginzburg-Landau modified model of layered high-temperature superconductor under pressure. We have theoretically studied the relation between the pressure and the temperature of layered high-temperature s...We consider a Ginzburg-Landau modified model of layered high-temperature superconductor under pressure. We have theoretically studied the relation between the pressure and the temperature of layered high-temperature superconductor. If the pressure is not a constant, we have a relation of quadratic equation between the pressure and the temperature of layered high-temperature superconductor. In a special case, we find the critical temperature decreases with further increasing pressure. In another special ease, the critical temperature increases with further increasing pressure.展开更多
In this study, a monthly dataset of temperature time series （1961-2010） from 12 meteorological stations across the Three-River Headwater Region of Qinghai Province （THRHR） was used to analyze the climate change. T...In this study, a monthly dataset of temperature time series （1961-2010） from 12 meteorological stations across the Three-River Headwater Region of Qinghai Province （THRHR） was used to analyze the climate change. The temperature variation and abrupt change analysis were examined by using moving average, linear regression, Spline interpolation, Mann-Kendall test and so on. Some important conclusions were obtained from this research, which mainly contained four aspects as follows. （1） There were several cold and warm fluctuations for the annual and seasonal average temperature in the THRHR and its three sub-headwater regions, but the temperature in these regions all had an obviously rising trend at the statistical significance level, especially after 2001. The spring, summer, autumn and annual average temperature increased evidently after the 1990s, and the winter average temperature exhibited an obvious upward trend after entering the 21st century. Except the standard value of spring temperature, the annual and seasonal temperature standard value in the THRHR and its three sub-headwater regions increased gradually, and the upward trend for the standard value of winter average temperature indicated significantly. （2） The tendency rate of annual average temperature in the THRHR was 0.36℃ 10a^-1, while the tendency rates in the Yellow River Headwater Region （YERHR）, Lancangjiang River Headwater Region （LARHR） and Yangtze River Headwater Region （YARHR） were 0.37℃ 10a^-1, 0.37℃ 10a^-1 and 0.34℃10a^-1 respectively. The temperature increased significantly in the south of Yushu County and the north of Nangqian County. The rising trends of temperature in winter and autumn were higher than the upward trends in spring and summer. （3） The abrupt changes of annual, summer, autumn and winter average temperature were found in the THRHR, LARHR and YARHR, and were detected for the summer and autumn average temperature in the YERHR. The abrupt changes of annual and summer average temperatures were mainly in the late 1990s, while the abrupt changes of autumn and winter average temperatures appeared primarily in the early 1990s and the early 21st century respectively. （4） With the global warming, the diversities of altitude and underlying surface in different parts of the Tibetan Plateau were possibly the main reasons for the high increasing rate of temperature in the THRHR.展开更多
In order to study the effect of gas temperature variation on cooling stave, temperature, stress and displacement distributions of cooling stave were analyzed respectively when gas temperature inside- blast furnace inc...In order to study the effect of gas temperature variation on cooling stave, temperature, stress and displacement distributions of cooling stave were analyzed respectively when gas temperature inside- blast furnace increases from 1000 to 1 600 ℃. The results show that the temperature field on cold side is under control of cooling pipes and hardly changes when gas temperature increases. The temperature gradient and change rate with time near hot sides are greater than those in other regions and the later can reach 100 ℃/s. The stress intensity near middle area of hot surface is up to 400 MPa and that＇s why there are lots of cracks at this place. The edge of stave is bent to cold side and middle regions between fixed bolts and pin moves to hot side. The displacement around fixed pin is smaller but larger on the edge and the maximum is located on hot side of top surface. The maximum displacement in z direction is about 4 mm and 3 mm in y direction. If the expansion coefficient of packing layer is 1/4, the thickness of packing layer between the cooling staves is 32 mm and 24 mm between sides up and down.展开更多
Micro prism film used in LCD industry can be manufactured by roll to roll method with copper-plated roll mold. As copper-plated roll mold is getting larger, pitch error is getting severer. The pitch error drops the qu...Micro prism film used in LCD industry can be manufactured by roll to roll method with copper-plated roll mold. As copper-plated roll mold is getting larger, pitch error is getting severer. The pitch error drops the quality of micro prism film. The main cause of the pitch error was investigated during machining large roll mold whose machined length was 1 200 mm. The temperature of machining system was elevated during machining roll mold, and this elevation induced thermal expansion of the system. The temperature variation around the roll mold also made thermal expansion of the roll mold. The amount of thermal expansion had strong relationship to the amount of pitch error. Therefore, the roll mold was machined after warming-up of machining system and precise temperature controller around copper-plated roll mold was installed, which minimized the temperature variation. Finally, precise micro prism patterns without pitch error were machined on the large roll mold.展开更多
Biologists have considered both winter coldness and temperature seasonality as major determinants of the northern limits of plants and animals in the Northern Hemisphere,which in turn drive the well-known latitudinal ...Biologists have considered both winter coldness and temperature seasonality as major determinants of the northern limits of plants and animals in the Northern Hemisphere,which in turn drive the well-known latitudinal diversity gradient.However,few studies have tested which of the two climate variables is the primary determinant.In this study,we assess whether winter coldness or temperature seasonality is more strongly associated with the northern latitudinal limits of tree species and with tree species richness in North America.Tree species were recorded in each of 1198 quadrats of 110 km×110 km in North America.We used correlation and regression analyses to assess the relationship of the latitude of the northern boundary of each species,and of species richness per quadrat,with winter coldness and temperature seasonality.Species richness was analyzed within 38 longitudinal,i.e.,north-south,bands(each being>1100 km long and 110 km wide).The latitudes of the northern range limits of tree species were three times better correlated with minimum temperatures at those latitudes than with temperature seasonality.On average,minimum temperature and temperature seasonality together explained 81.5%of the variation in the northern range limits of the tree species examined,and minimum temperature uniquely explained six-fold(33.7%versus 5.8%)more of this variation than did temperature seasonality.Correlations of tree species richness with minimum temperatures were stronger than correlations with temperature seasonality for most of the longitudinal bands analyzed.Compared to temperature seasonality,winter coldness is more strongly associated with species distributions at high latitudes,and is likely a more important driver of the latitudinal diversity gradient.展开更多
The temperature variation trend,cold and warm phases and asymmetric and inter-annual changes of maximum andminimum temperature were analyzed based on the average temperature data of annual,summer (from June to August)...The temperature variation trend,cold and warm phases and asymmetric and inter-annual changes of maximum andminimum temperature were analyzed based on the average temperature data of annual,summer (from June to August) and winter (from December to February) and the day by day maximum andminimum temperature data in January and July from 1954 to 2008 in Huailai County.The results showed that temperature in Huailai has risen in recent 55 years;The cold phase was from 1954 to 1986 and warm phase from 1987 to 2008;the linear warming rate ofminimum temperature in January was 0.070 8℃/a,and the maximum temperature in July increased slightly with the warming rate of 0.009 7℃/a,leading to higher temperature in winter and summer in Huailai.展开更多
基金The key technology R&D program of China, No.2007BAC29B02Project of Jiangsu Key Laboratory of Meteorological Disaster, No.KLME060101
文摘Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River （MLRYR） and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River （MLRYR）. Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating （cooling） caused by the vertical thermal advection as well as the diabatic heating （cooling） caused by diabatic processes can explain the formation of the high （low） temperature events in the middle and lower reaches of the Yangtze River （MLRYR） in boreal summer.
基金National Natural Science Foundation of China, No.40401054 National 973 Program of China, No. 2005CB422004+1 种基金 CAS Hundred Talents Program Knowledge Innovation Program of CAS, No. KZCX3-SW-339/334
文摘A 70-year history of precipitation δ^18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier （33°34＇37.8″ N, 91°10＇35.3″ E, 5720 m a.s.l.） on Mt. Geladaindong （the source region of Yangtze River） during October and November, 2005. Based on the seasonality of δ^18O records and the significant positive relationships between monsoon/non-monsoon δ^18O values and summer/spring air temperature from the nearby meteorological stations, the history of summer and spring air temperature have been reconstructed for the last 70 years. The results show that both summer and spring air temperature variations present similar trends during the last 70 years. Regression analysis indicates that the slope of the temperature-δ^18O relationship is 1.3℃/‰ for non-monsoon δ^18O values and spring air temperature, and 0.4℃/‰ for monsoon δ^18O values and summer air temperature. Variation of air temperature recorded in the ice core is consistent with that in the Northern Hemisphere （NH）, however, the warming trend in the Geladaindong region is more intense than that in the NH, reflecting a higher sensitivity to global warming in the high elevation regions. In addition, warming trend is greater in spring than in summer.
文摘Since 1960s, many research works on the reinforced concrete structure have been published and some concise and practical calculation methods for safety control during construction have been achieved. The reinforced concrete structure during construction is a time-dependent structure which consists of a partly completed structure and a formwork-shore system. Experience shows that the most critical condition of the time-dependent structure may happen when the formwork-shore system is partly removed or reset and accidents may occur. In the present paper, effect of ambient temperature variation between day and night is considered, new structural models for reinforced concrete frames, slab-column systems and shear wall structures are proposed, and a new software named Safety Analysis During Construction Considering Temperature(SACT) is also introduced. Compared with on-site measurements, the software SACT is validated for application on construction site.
基金National Key R&D Program of China,No.2017YFA0603300Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA19040101。
文摘We collected and verified documentary records of the latest spring snowing dates(LSSD)in Hangzhou during Southern Song Dynasty.Furtherly,the statistical correlation between this proxy and February–April mean temperature in Hangzhou was examined,and samples later than the perennial mean of the LSSD during Southern Song Dynasty were transformed into the decadal mean of LSSD by means of Boltzmann function.General characteristics of this reconstructed LSSD series with a 10-year temporal resolution was analyzed,and it was also compared with other documentary evidences and reconstructed climate series in China for the period 1131–1270.The results and discussion suggested that:(1)Records of the LSSD in Hangzhou during Southern Song Dynasty did not refer to ice pellets and graupels,which had an explicit climate significance(–0.34℃/10 d,R2=0.37,p<0.001).However,when this proxy is used to reconstruct temperature changes,all dates should be converted into proleptic Gregorian style and meet the same criterion of"true Qi"as the Chinese traditional calendar after 1929.(2)The decadal mean of LSSD can be effectively estimated by using the forefront of LSSD in the decade on the basis of Boltzmann function,whose extrapolation has a lesser uncertainty than those on the basis of linear models or polynomial models.(3)The spring climate in Hangzhou during 1131–1270 was almost as warm as the period 1951–1980.At the centennial scale,this period can be divided into two phases:the cold 1131–1170 and the warm 1171–1270.In the latter,1181–1200 and 1221–1240 were two cold intervals at the multi-decadal scale.(4)The reconstructed LSSD series was consistent well with other documentary evidences and reconstructed climate series in China for 1131–1270,which may reflect the influence on the climate over most regions of China imposed by the Pacific Decadal Oscillation(PDO).
基金supported by the National Natural Science Foundation of China(Grant No.40673068)the National Science and Technology Support Program of China(Grant No.2011BAC02B0201)the Natural Science Foundation of Guizhou Province,China
文摘The oxygen isotopic values of aquatic plant cellulose and carbonates in Lake Caohai sediments were measured using a continuous flow isotopic ratio mass spectrometer(CF-IRMS).Because of predictable oxygen isotopic fractionation between cellulose and its source water,the oxygen isotopic composition of paleo-lake water has been established quantitatively.Combined oxygen isotopic values of cellulose and carbonates were used in the‘Craig’equation to determine paleotemperatures and their variation in the lake during the past 500 years.Results show that the paleotemperature trend correlates well with meteorological records from Weining.There are four notable cold intervals at Lake Caohai over the past 500 years,namely 1540–1570AD,1670–1715AD,1780–1870AD and 1900–1930AD,and the former three cold intervals have been observed in the conventional Little Ice Age(LIA).These cold periods at Lake Caohai correspond well with those recorded from tree ring,peat,and ice core data from adjacent regions,particularly temperature those inferred fromδ18O of peat cellulose from Hongyuan Southwestern China.The trend in paleotemperature variations at Lake Caohai are also consistent with both the change of Indian summer monsoon,derived fromδ18O values of a stalagmite in Dongge,and a recorded shift in solar activity.The findings of this study illustrate that coupled analysis ofδ18O values of cellulose and carbonates from lake sediments may be used as a paleotemperature proxy.These results also provide further evidence of the existence of LIA in southwestern China.
文摘The ten-year mean anomalies of seasonal and annual temperatures were reconstructed on the basis of historical documents of cold events such as severe snowing and freezing of lakes and rivers.The assorted events were calibrated with instrumental observations of temperature and transformed into ten-year mean anomalies. The reconstructed temperature series show predominance of cold climate in the first four hundred years of the period examined.The centenary seasonal temperature anomalies for the 16th to the 19th century vary between -0.1 and -0.7K.The coldest decades concentrated in the middle of 17th and 19th centuries.It provided the irrefutable evidence of the occurrence of the Little Ice Age in China.The minima of ten-year mean temperature anomalies ranged about -1.5 to 2.0K in spring and winter.Meanwhile,the variance of ten-year mean tempera- ture was increased by more than 20％ in comparison to the 20th century.
基金support from the project of the Science and Technology Innovation Project of the Department of Transport of Yunnan Province(YJKJB[2023]150).
文摘An efficient double-layer formwork curing method using an“inner supporting formwork+outer insulation formwork”was proposed in this study to address the early cracking of precast concrete components in high altitude regions.Steel and plywood formwork were designed as inner support formwork,while polystyrene(PS)and polyurethane(PU)were used as outer insulation formwork.Indoor experiments and two finite element methods(The complete simulation method focuses on computational accuracy,and the equivalent simulation method emphasizes computational efficiency)were employed to analyze the evolution of the concrete temperature field under different double-layer formwork curing methods throughout the curing period,combined with compressive strength and pore structures testing.The results show that steel+5-mm-thick PU insulation formwork curing method can significantly mitigate the impact of large diurnal temperature variations on the internal temperature of concrete.Unlike traditional steam-curing,this method does not deteriorate the pore structure or compressive strength of the concrete.This study is of great significance in addressing the problem of early cracking of precast concrete components exposed to large diurnal temperature vriations in high altitude regions.
基金supported by National Natural Science Foundation of China(Grant Nos.11971477,12131007 and 11761141008)the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.18XNLG30)。
文摘This paper verifies the low Mach number limit of the non-isentropic compressible magnetohydrodynamic(MHD)equations with or without the magnetic diffusion in a three-dimensional bounded domain when the temperature variation is large but finite.The uniform estimates of strong solutions are established in a short time interval independent of the Mach number,provided that the slip boundary condition for the velocity and the Neumann boundary condition for the temperature are imposed and the initial data is well-prepared.
基金support of the National Natural Science Foundation of China (Grant No. 41201200)the CAS Strategic Priority Research Program (Grant No. XDA05080101)
文摘In this paper we analyze daily mean, minimum, and maximum temperature data collected at 119 meteorological stations over five regions of China during the period 1951-2010. The series of minimum, maximum, and mean temperatures from each climatic region have similar signatures, but there are differences among the five regions and the countrywide average. The results indicate that the periods of faster warming were not synchronous across the regions studied： warming in northeast China and Tibet began in 1986, while in central-east, southeast, and northwest China the warming emerged in 1995. Furthermore, central-east and northwest China, and Tibet, have warmed continuously since 2000, but the temperature has decreased during this period in southeast China. We evaluated the evolution of these temperature series using a novel nonlinear filtering technique based on the concept of the lifetime of temperature curves. The decadal to secular evolution of solar activity and temperature variation had similar signatures in the northeast, southeast, and northwest re- gions and the average across the whole country, indicating that solar activity is a significant control on climate change over secular time scales in these regions. In comparison with these regions, the signatures were different in central-east China and Tibet because of regional differences （e.g., landforms and elevation） and indirect effects （e.g., cloud cover influencing the radiation balance, thereby inducing climate change）. Furthermore, the results of wavelet analysis indicated that the El Nino Southem Oscillation （ENSO） has had a significant impact on climate change, but at different times among the regions, and these changes were most probably induced by differing responses of the atmospheric system to solar forcing.
基金Sponsored jointly by the " National Key Developing Program for Basic Sciences" !(G 1998040900) Part I and the Key Program of N
文摘The relationships between variations of sea surface temperature anomalies (SSTVA) in the key ocean areas and the precipitation / temperature anomalies in China are studied based on the monthly mean sea surface temperature data from January 1951 to December 1998 and the same stage monthly mean precipitation/ temperature data of 160 stations in China. The purpose of the present study is to discuss whether the relationship between SSTVA and precipitation / temperature is different from that between sea surface temperature anomalies (SSTA) and precipitation/ temperature, and whether the uncertainty of prediction can be reduced by use of SSTVA. The results show that the responses of precipitation anomalies to the two kinds of tendency of SSTA are different. This implies that discussing the effects of two kinds of tendency of SSTA on precipitation anomalies is better than just discussing the effects of SSTA on precipitation anomalies. It helps to reduce the uncertainty of prediction. The temperature anomalies have more identical re-sponses to the two kinds of tendency of SSTA than the precipitation except in the western Pacific Ocean. The response of precipitation anomalies to SSTVA is different from that to SSTA, but there are some similarities. Key words Variations of sea surface temperature anomalies - Precipitation anomalies - Temperature anomalies - Statistical significance test Sponsored jointly by the “ National Key Developing Program for Basic Sciences” (G1998040900) Part I and the Key Program of National Nature Science Foundation of China “ Analyses and Mechanism Study of the Regional Climatic Change in China” under Grant No.49735170.
基金The National Natural Science Foundation of China under contract Nos 41376095 and 41206006the Zhejiang Provincial Natural Science Foundation under contract Nos LQ14D060005,Y5090084 and LR/6E090001the Zhejiang University Ocean Sciences Seed Grant under contract No.2012HY012B
文摘Field surveys covering a spring-neap tidal period were conducted to investigate the characteristics of tidal dynamics within a curved channel in the southern Hangzhou Bay, China. The channel has a maximum depth of more than 100 m with an average tidal range of 2.5 m, serving as the main tidal passage in the southern part of the Hangzhou Bay. Water salinity, temperature and velocity data were collected from the ship-based transects and mooring measurements. During flood tide, the tidal current intrudes into the Hangzhou Bay through the northern side of the channel with a maximum velocity of about 2 m/s, while retreats through the southern side during ebb tide with a maximum velocity of 1.8 m/s. Due to the pressure, density gradients, the Coriolis force and centrifugal effect, a lateral exchange flow is generated as the tidal current relaxes from flood to ebb. Salinity and temperature data show that the water in the channel is weakly stratified during both spring and neap tides in summer time.However, mixing in the middle region will be enhanced by the lateral circulation. Mooring data indicate that the temperature and salinity are varying at a frequency similar to tidal current but higher than sea level oscillation.Our results support the hypothesis that the high frequency salinity and temperature variations could be generated by combination of the tidal current and the lateral exchanging flow.
基金supported by the National Natural Science Foundation of China(Grant No.52004236)the Key Program of National Natural Science Foundation of China(Grant No.52234003)+2 种基金Sichuan Provincial Returned Scholars'Scientific and Technological Activities Merit-based Funding Programs(Grant No.2023016)Open project of the International Joint Research Center for Deep Earth Drilling and Deep Earth Resources Development of the Ministry of Science and Technology(Grant No.DEDRD-2023-06)the National Natural Science Foundation of China Outstanding Youth Science Fund Program(Grant No.52222402).
文摘Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are the key factors affecting the cutting performance when drilling through formations with thermally damaged rock. To better investigate the temperature rise, a series of rock samples treated at high temperatures (9–300℃) were broken with a PDC cutter. The performance of the PDC cutter on these samples was studied using cutting force sensors, high-speed photography, and the thermal infrared imager. Based on the experimental data, a new cutting force evaluation parameter, η, is suggested. The link between the cutting force and rock properties is discussed in detail. The present results indicate that the average cutting force of high-temperature-treated granite is 3–5 times that of the thermally damaged sandstone. Furthermore, a critical temperature for thermal damage has been identified in granite cutting at 100–200℃ and in sandstone at 100℃. This corresponds to the temperature at which interlayer water loss and thermal crack closure occur. The results also indicate that when the treatment temperature exceeds the critical threshold, both the cutting force and temperature rise exhibit more significant changes with increasing temperature. Additionally, the maximum temperature of the PDC cutter during granite cutting can reach 47.6 ℃, which is almost 34℃ higher than that of sandstone. Regarding debris size, granite is much less sensitive to the treatment temperature, showing only slight changes in debris size compared to sandstone as the treatment temperature increases. The increasing cutter-rock interface area can significantly reduce frictional heat generation while increasing the cutting force and enhancing the temperature rise. The parameter valuation of the newly defined parameter η, which is related to frictional heating, shows that the capacity of the thermal generation and the heat transfer change as the temperature rises at the cutter-rock interface. At last, the correlation analysis indicates that the cutting force of sandstone and granite is highly correlated with , E/σc and σt. This study serves as a theoretical support and technical guidance for cutting hot dry rock (HDR), which is of great significance to HDR drilling.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Natural Science Foundation of China(42175061)。
文摘Studying the causes of summer(June–July–August)precipitation anomalies in the middle and lower reaches of the Yangtze River(MLYR)and accurately predicting rainy season precipitation are important to society and the economy.In recent years,the sea surface temperature(SST)trend factor has been used to construct regression models for summer precipitation.In this study,through correlation analysis,winter SST anomaly predictors and the winter Central Pacific SST trend predictor(CPT)are identified as closely related to the following MLYR summer precipitation(YRSP).CPT can influence YRSP by inducing anomalous circulations over the North Pacific,guiding warm and moist air northward,and inhibiting the development of the anomalous anticyclone over the Northwest Pacific.This has improved the predictive skill of the seasonal regression model for YRSP.After incorporating the CPT,the correlation coefficient of the YRSP regression model improved by 40%,increasing from 0.45 to 0.63,and the root mean squared error decreased by 22%,from 1.15 to 0.90.
基金Supported by the Infrastructure Project of China Meteorological Administration(CMA) in 2010~~
文摘In this paper,based on the observation data of air temperature during 1951-2009 in Shenyang,the interannual and interdecadal variation of annual average temperature,maximum and minimum temperature in Shenyang were conducted the statistical analysis by means of linear trend estimation and mutation detection by using Mann-Kendall method.As was demonstrated in the results,the annual average temperature,maximum and minimum temperature in Shenyang showed an upward trend,whose linear tendency rate was 0.231,0.181 and 0.218 respectively.The increment trend of annual average temperature,maximum and minimum temperature was extremely clear.The increase in minimum temperature was more significant than that in mean temperature and maximum temperature.The abrupt change point of annual mean temperature in Shenyang appeared in 1981;the abrupt change point of annual mean maximum temperature appeared in 1994;the annual mean minimum temperature underwent mutation in 1978.
文摘We consider a Ginzburg-Landau modified model of layered high-temperature superconductor under pressure. We have theoretically studied the relation between the pressure and the temperature of layered high-temperature superconductor. If the pressure is not a constant, we have a relation of quadratic equation between the pressure and the temperature of layered high-temperature superconductor. In a special case, we find the critical temperature decreases with further increasing pressure. In another special ease, the critical temperature increases with further increasing pressure.
基金The National Science and Technology Support Plan, No.2009BAC61B01
文摘In this study, a monthly dataset of temperature time series （1961-2010） from 12 meteorological stations across the Three-River Headwater Region of Qinghai Province （THRHR） was used to analyze the climate change. The temperature variation and abrupt change analysis were examined by using moving average, linear regression, Spline interpolation, Mann-Kendall test and so on. Some important conclusions were obtained from this research, which mainly contained four aspects as follows. （1） There were several cold and warm fluctuations for the annual and seasonal average temperature in the THRHR and its three sub-headwater regions, but the temperature in these regions all had an obviously rising trend at the statistical significance level, especially after 2001. The spring, summer, autumn and annual average temperature increased evidently after the 1990s, and the winter average temperature exhibited an obvious upward trend after entering the 21st century. Except the standard value of spring temperature, the annual and seasonal temperature standard value in the THRHR and its three sub-headwater regions increased gradually, and the upward trend for the standard value of winter average temperature indicated significantly. （2） The tendency rate of annual average temperature in the THRHR was 0.36℃ 10a^-1, while the tendency rates in the Yellow River Headwater Region （YERHR）, Lancangjiang River Headwater Region （LARHR） and Yangtze River Headwater Region （YARHR） were 0.37℃ 10a^-1, 0.37℃ 10a^-1 and 0.34℃10a^-1 respectively. The temperature increased significantly in the south of Yushu County and the north of Nangqian County. The rising trends of temperature in winter and autumn were higher than the upward trends in spring and summer. （3） The abrupt changes of annual, summer, autumn and winter average temperature were found in the THRHR, LARHR and YARHR, and were detected for the summer and autumn average temperature in the YERHR. The abrupt changes of annual and summer average temperatures were mainly in the late 1990s, while the abrupt changes of autumn and winter average temperatures appeared primarily in the early 1990s and the early 21st century respectively. （4） With the global warming, the diversities of altitude and underlying surface in different parts of the Tibetan Plateau were possibly the main reasons for the high increasing rate of temperature in the THRHR.
基金Item Sponsored by National Natural Science Foundation of China (60872147)
文摘In order to study the effect of gas temperature variation on cooling stave, temperature, stress and displacement distributions of cooling stave were analyzed respectively when gas temperature inside- blast furnace increases from 1000 to 1 600 ℃. The results show that the temperature field on cold side is under control of cooling pipes and hardly changes when gas temperature increases. The temperature gradient and change rate with time near hot sides are greater than those in other regions and the later can reach 100 ℃/s. The stress intensity near middle area of hot surface is up to 400 MPa and that＇s why there are lots of cracks at this place. The edge of stave is bent to cold side and middle regions between fixed bolts and pin moves to hot side. The displacement around fixed pin is smaller but larger on the edge and the maximum is located on hot side of top surface. The maximum displacement in z direction is about 4 mm and 3 mm in y direction. If the expansion coefficient of packing layer is 1/4, the thickness of packing layer between the cooling staves is 32 mm and 24 mm between sides up and down.
基金Project (2010-0008-277) supported by NCRC (National Core Research Center) Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology, Korea
文摘Micro prism film used in LCD industry can be manufactured by roll to roll method with copper-plated roll mold. As copper-plated roll mold is getting larger, pitch error is getting severer. The pitch error drops the quality of micro prism film. The main cause of the pitch error was investigated during machining large roll mold whose machined length was 1 200 mm. The temperature of machining system was elevated during machining roll mold, and this elevation induced thermal expansion of the system. The temperature variation around the roll mold also made thermal expansion of the roll mold. The amount of thermal expansion had strong relationship to the amount of pitch error. Therefore, the roll mold was machined after warming-up of machining system and precise temperature controller around copper-plated roll mold was installed, which minimized the temperature variation. Finally, precise micro prism patterns without pitch error were machined on the large roll mold.
基金supported by a grant form the National Key Research and Development Program,No.2019YFA0607302。
文摘Biologists have considered both winter coldness and temperature seasonality as major determinants of the northern limits of plants and animals in the Northern Hemisphere,which in turn drive the well-known latitudinal diversity gradient.However,few studies have tested which of the two climate variables is the primary determinant.In this study,we assess whether winter coldness or temperature seasonality is more strongly associated with the northern latitudinal limits of tree species and with tree species richness in North America.Tree species were recorded in each of 1198 quadrats of 110 km×110 km in North America.We used correlation and regression analyses to assess the relationship of the latitude of the northern boundary of each species,and of species richness per quadrat,with winter coldness and temperature seasonality.Species richness was analyzed within 38 longitudinal,i.e.,north-south,bands(each being>1100 km long and 110 km wide).The latitudes of the northern range limits of tree species were three times better correlated with minimum temperatures at those latitudes than with temperature seasonality.On average,minimum temperature and temperature seasonality together explained 81.5%of the variation in the northern range limits of the tree species examined,and minimum temperature uniquely explained six-fold(33.7%versus 5.8%)more of this variation than did temperature seasonality.Correlations of tree species richness with minimum temperatures were stronger than correlations with temperature seasonality for most of the longitudinal bands analyzed.Compared to temperature seasonality,winter coldness is more strongly associated with species distributions at high latitudes,and is likely a more important driver of the latitudinal diversity gradient.
文摘The temperature variation trend,cold and warm phases and asymmetric and inter-annual changes of maximum andminimum temperature were analyzed based on the average temperature data of annual,summer (from June to August) and winter (from December to February) and the day by day maximum andminimum temperature data in January and July from 1954 to 2008 in Huailai County.The results showed that temperature in Huailai has risen in recent 55 years;The cold phase was from 1954 to 1986 and warm phase from 1987 to 2008;the linear warming rate ofminimum temperature in January was 0.070 8℃/a,and the maximum temperature in July increased slightly with the warming rate of 0.009 7℃/a,leading to higher temperature in winter and summer in Huailai.
