气温衍生品是天气衍生品交易中最活跃的合约之一,确定合理预测气温动态变化的模型,是气温衍生品开发设计的基础。考虑到气温在时间变化上具有趋势性、季节性和周期性等特点,文中使用了以O-U均值回复过程为基础的Continuous Time Autoreg...气温衍生品是天气衍生品交易中最活跃的合约之一,确定合理预测气温动态变化的模型,是气温衍生品开发设计的基础。考虑到气温在时间变化上具有趋势性、季节性和周期性等特点,文中使用了以O-U均值回复过程为基础的Continuous Time Autoregressive Model(CAR)模型、Seasonal Autoregressive Integrated Moving Average(SARIMA)模型和小波神经网络算法,并选择漠河、北京、乌鲁木齐、芜湖、昆明和海口具有地域性代表的城市气温进行拟合,使用无偏绝对百分比误差、绝对百分比误差和平均绝对比例误差检验指标检验了模型的预测精度。研究结果表明,小波神经网络算法在预测6个城市的无偏绝对百分比误差、绝对百分比误差和平均绝对比例误差的值最小;同时,相比CAR模型、SARIMA模型,其预测效果最优。因此,小波神经网络算法能够很好地拟合气温数据的变化,可以为我国气温天气衍生品的定价提供一定的指导。展开更多
To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments w...To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.展开更多
To reveal the influencing factors and changing rules for the hydrothermal interaction process of highway subgrade, the field measurements of Shiwei-Labudalin Highway in Inner Mongolia, China was conducted for 3 years,...To reveal the influencing factors and changing rules for the hydrothermal interaction process of highway subgrade, the field measurements of Shiwei-Labudalin Highway in Inner Mongolia, China was conducted for 3 years, based on which the freezing-thawing rules and water content changing characteristics were analyzed. The main results show the subgrade presents a frequent freezing-thawing alternation, and the water content of subgrade exhibits an obvious seasonal alternation. The subbase has the maximum water content, while the base has the minimum water content. The change of water flux is concentrated in the thawing period and consistent with the change of temperature gradient. The subbase layer has the most active water flux due to the heat absorption and impermeability of pavement that easily causes the water accumulation in this layer. Therefore, the prevention and treatment for the freezing-thawing disease should be started from heat insulation and water resistance.展开更多
From Aug.2013 to Oct.2015,a Rayleigh lidar has been used to study the middle atmosphere at Golmud(36.25°N,94.54°E),Qinghai,located in the northeastern part of the Tibetan Plateau.Mesospheric density profiles...From Aug.2013 to Oct.2015,a Rayleigh lidar has been used to study the middle atmosphere at Golmud(36.25°N,94.54°E),Qinghai,located in the northeastern part of the Tibetan Plateau.Mesospheric density profiles from 50 to 90 km were retrieved based on 205 nights of lidar observation,with a total of 1616hours of operation.We compared our lidar density measurements with SABER observations onboard TIMED satellite and MSIS-00 model data.The results showed that the annual mean density measured by lidar agreed well with SABER data,but both were lower than that of MSIS-00.All datasets exhibited dominant annual oscillation in the mesosphere.From 63 to 85 km,the annual amplitude of lidar density is larger than those of SABER and MSIS-00.PDD(Percentage of Density Difference)was calculated to investigate the mesospheric density climatology.The largest density variations of lidar,MSIS-00,and SABER occurred at around 72 km.Both lidar and SABER PDD reached their maximum in May,about one month earlier than the MSIS-00;while the minimum PDD appeared in late December for all datasets.展开更多
The detailed high-resolution emission inventory of black carbon (BC) from China in the year 2000 was calculated. The latest fuel consumption data including fossil and biomass fuels, and socio-economic statistics used ...The detailed high-resolution emission inventory of black carbon (BC) from China in the year 2000 was calculated. The latest fuel consumption data including fossil and biomass fuels, and socio-economic statistics used were obtained from government agencies, mostly at the county level, and some new emission factors (Efs) from local measurements were also used. National and regional summaries of emissions were presented at 0.2°×0.2°resolution. Total BC emission was 1499.4 Gg in 2000, mainly due to the burning of coal and biomass. The BC emission estimated here is higher than those in previous studies, mainly because the emissions from coal burning by rural industries and residences were previously underestimated. More BC aerosols were emitted from eastern China than western China. A strong seasonal dependence was observed for BC emissions, with peaks in January and December and low emissions in July and August; and this seasonality is mainly due to patterns in residential heating and the open burning of crop residues.展开更多
The present study was conducted to see the short term impact of organic and inorganic fertilizers on soil microbial biomass both in spring and summer. Also aimed to observe the correlation between soil microbial bioma...The present study was conducted to see the short term impact of organic and inorganic fertilizers on soil microbial biomass both in spring and summer. Also aimed to observe the correlation between soil microbial biomass and soil DNA. The study concluded that type of fertilizer might alter the soil microbial biomass and DNA contents. In soil treated with organic fertilizers resulted in higher concentrations of microbial biomass and DNA contents in summer as compared to spring dute to increase in temperature. Correspondingly, in case of inorganic fertilizer, concentrations of soil microbial biomass and DNA detected higher in summer instead of spring. The statistical correlation between soil microbial biomass, DNA and ODR in spring and summer along with organic and inorganic fertilizers were calculated highly significant （p〉0.01）. This study demonstrated the impact of fertilizers and seasonal variations on soil microbial biomass and also revealed significant correlation between soil microbial biomass and soil DNA.展开更多
The study aims to investigate the thermal comfort requirements in residential buildings and to establish an adaptive thermal comfort model in the cold zone of China.A year-long field study was conducted in residential...The study aims to investigate the thermal comfort requirements in residential buildings and to establish an adaptive thermal comfort model in the cold zone of China.A year-long field study was conducted in residential buildings in Xi’an,China.A total of 2069 valid questionnaires,along with indoor environmental parameters were obtained.The results indicated occupants’thermal comfort requirements varied with seasons.The neutral temperatures were 17.9,26.1(highest),25.2,and 17.4℃(lowest),and preferred temperatures were 23.2,25.6(highest),24.8,and 22.4℃(lowest),respectively for spring,summer,autumn,and winter.The neutral temperature and preferred temperature in autumn are close to the neutral temperature in summer,while the neutral temperature and preferred temperature in spring are close to that in winter.Besides,the 80%and 90%acceptable temperature ranges,adaptive thermal comfort models,and thermal comfort zones for each season were established.Human’s adaptability is related to his/her thermal experience of the current season and the previous season.Therefore,compared with the traditional year-round adaptive thermal comfort model,seasonal models can better reflect seasonal variations of human adaptation.This study provides fundamental knowledge of the thermal comfort demand for people in this region.展开更多
This paper presented a preliminary research on the central solar heating system with seasonal storage(CSHSSS)used in cold climate in China.A mathematical model of the solar energy seasonal storage water tank used in t...This paper presented a preliminary research on the central solar heating system with seasonal storage(CSHSSS)used in cold climate in China.A mathematical model of the solar energy seasonal storage water tank used in the central solar heating system was firstly developed based on energy conservation.This was followed by the simulation of the CSHSSS used in a two-floor villa in Harbin,and analysis of the impacts on storage water temperature of tank volume,solar collector area,tank burial depth,insulation thickness around the tank,etc.The results show there is a relatively economical tank volume to optimize the system efficiency,which decreases with increasing tank volume at the constant collector area,and increases with increasing collector area at the constant tank volume.Furthermore,the insulation thickness has obvious effect on avoiding heat loss,while the tank burial depth doesn't.In addition,the relationship between the solar collector efficiency and storage water temperature is also obtained,it decreases quickly with increasing storing water temperature,and then increases slowly after starting space heating system.These may be helpful for relevant design and optimization in cold climates in China and all over the world.展开更多
Aiming at wind turbines,the opportunistic maintenance optimization is carried out for multi-component system,where minimal repair,imperfect repair,replacement as well as their effects on component’s effective age are...Aiming at wind turbines,the opportunistic maintenance optimization is carried out for multi-component system,where minimal repair,imperfect repair,replacement as well as their effects on component’s effective age are considered.At each inspection point,appropriate maintenance mode is selected according to the component’s effective age and its maintenance threshold.To utilize the maintenance opportunities for the components among the wind turbines,opportunistic maintenance approach is adopted.Meanwhile,the influence of seasonal factor on the component’s failure rate and improvement factor’s decrease with the increase of repair’s times are also taken into account.The maintenance threshold is set as the decision variable,and an opportunistic maintenance optimization model is proposed to minimize wind turbine’s life-cycle maintenance cost.Moreover,genetic algorithm is adopted to solve the model,and the effectiveness is verified with a case study.The results show that based on the component’s inherent reliability and maintainability,the proposed model can provide optimal maintenance plans accordingly.Furthermore,the higher the component’s reliability and maintainability are,the less the times of repair and replacement will be.展开更多
The grey forecasting model has been successfully applied to many fields. However, the precision of GM(1,1) model is not high. In order to remove the seasonal fluctuations in monitoring series before building GM(1,1) m...The grey forecasting model has been successfully applied to many fields. However, the precision of GM(1,1) model is not high. In order to remove the seasonal fluctuations in monitoring series before building GM(1,1) model, the forecasting series of GM(1,1) was built, and an inverse process was used to resume the seasonal fluctuations. Two deseasonalization methods were presented , i.e., seasonal index-based deseasonalization and standard normal distribution-based deseasonalization. They were combined with the GM(1,1) model to form hybrid grey models. A simple but practical method to further improve the forecasting results was also suggested. For comparison, a conventional periodic function model was investigated. The concept and algorithms were tested with four years monthly monitoring data. The results show that on the whole the seasonal index-GM(1,1) model outperform the conventional periodic function model and the conventional periodic function model outperform the SND-GM(1,1) model. The mean Absolute error and mean square error of seasonal index-GM(1,1) are 30.69% and 54.53% smaller than that of conventional periodic function model, respectively. The high accuracy, straightforward and easy implementation natures of the proposed hybrid seasonal index-grey model make it a powerful analysis technique for seasonal monitoring series.展开更多
The ionosphere varies over multiple time scales,which are classified into two categories: the climatology and weather variations.In this national report,we give a brief summary of recent progresses in ionospheric clim...The ionosphere varies over multiple time scales,which are classified into two categories: the climatology and weather variations.In this national report,we give a brief summary of recent progresses in ionospheric climatology with focus on(1) the seasonal variations,(2) solar cycle effects, and(3) empirical modeling of the ionosphere.The seasonal variations of the ionosphere have been explored in many works to give a more detailed picture with regional and global features at various altitudes by analyzing the observation data from various sources and models.Moreover,a series of studies reported the response of the ionosphere to solar cycle variations,which revealed some novel and detailed features of solar activity dependence of ionospheric parameters at different altitudes. These investigations have improved our understanding on the states of the ionosphere and underlying fundamental processes,provided clues to future studies on ionospheric weather,and guided ionospheric modeling,forecasting and related applications.展开更多
Affected by the natural environmental and human activity factors,significant seasonal differences appear on the regional scattering characteristic and ground deformation of saline soil.Interferometric decorrelation du...Affected by the natural environmental and human activity factors,significant seasonal differences appear on the regional scattering characteristic and ground deformation of saline soil.Interferometric decorrelation due to season replacement limits the conventional multi-temporal interferometric synthetic aperture radar(MT-InSAR)technique and its application in such areas.To extend the monitoring capability in the salt desert area,we select a vast basin of saline soil around Howz-e-Soltan Salt Lake of Iran as the study area and present an improved MTInSAR for experimental research.Based on 131 C-band Sentinel-1 A images collected between October 2014 to July 2020,1896 refined interferograms in total are selected from all interferogram candidates.Interferometric coherence analysis shows that the coherence in the saline soil area has an apparent seasonal variation,and the soil moisture affected by the precipitation may be the main factor that leads to the seasonal variation.Subsequently,the deformation characteristics of saline soil under different environmental conditions and human activity factors are compared and analyzed in detail.Related deformation mechanisms of different saline soil types are initially revealed by combining interferometric coherence,meteorological data,and engineering geological characteristics of saline soil.Related results would provide reference for the large-scale infrastructure construction engineering in similar saline soil areas.展开更多
Comparison of regular(diurnal,seasonal and solar cycle)variations of high-latitude,mid-latitude and low-latitude ionospheric characteristics has been provided on basis of local empirical models of the peak electron de...Comparison of regular(diurnal,seasonal and solar cycle)variations of high-latitude,mid-latitude and low-latitude ionospheric characteristics has been provided on basis of local empirical models of the peak electron density and the peak height.The local empirical models were derived from the hand-scaled ionogram data recorded by DPS-4 digisondes located at Norilsk(69°N,88°E),Irkutsk(52°N,104°E)and Hainan(19°N,109°E)for a 6-year period from December,2002 to December,2008.The technique used to build the local empirical model is described.The primary focus is diurnal-seasonal behavior under low solar activity and its change with increasing solar activity.Both common and specific features of the high-latitude(Norilsk),mid-latitude(Irkutsk)and low-latitude(Hainan)regular variations were revealed using their local empirical models.展开更多
The Heibei highway in expansion project is located in Xiaoxing’anling permafrost areas.Its total length is 148 km,and has 17 island permafrost sections.Some sugared above area exists uneven subsidence,which affects r...The Heibei highway in expansion project is located in Xiaoxing’anling permafrost areas.Its total length is 148 km,and has 17 island permafrost sections.Some sugared above area exists uneven subsidence,which affects road life and the stability of roadbed largely. The main reason for this is seasonal freezing and thawing of soil,resulting in the changes of foundation bearing capacity,and then the roadbed instability.In addition,many weak layers in the sugared area展开更多
The 5°S-10°S band in the Indian Ocean,named recently as Seychelles-Chagos Thermocline Ridge (SCTR),is a region where several phenomena of significant climatic influence build up.It is a generation region for...The 5°S-10°S band in the Indian Ocean,named recently as Seychelles-Chagos Thermocline Ridge (SCTR),is a region where several phenomena of significant climatic influence build up.It is a generation region for tropical cyclones striking the inhabited islands in the Indian Ocean and the African coast.It was recently shown that it is one of the regions where atmospheric intraseasonal variability (e.g.Madden Julian Oscillation,MJO) is展开更多
The concept of water mass was carried within the early development ofoceanography and the analysis of water mass has so far become one of theimportant subjects of physical oceanography. The formation and charactersof ...The concept of water mass was carried within the early development ofoceanography and the analysis of water mass has so far become one of theimportant subjects of physical oceanography. The formation and charactersof ocean water mass are described and discussed at length in many famousbooks and classical textbooks on physical oceanography, such as "The Oceans"展开更多
Guilin area is situated in the northeastern part of the Guangxi Zhuang Autonomous Region, 110°9′to 110°42′E and 24°40′to 25°40′N. It has a subtropical monsoon humid climate characterized by sha...Guilin area is situated in the northeastern part of the Guangxi Zhuang Autonomous Region, 110°9′to 110°42′E and 24°40′to 25°40′N. It has a subtropical monsoon humid climate characterized by sharp contrast between dry season and rainy season, with an annual mean temperature of 18.3℃ and precipitation of 1936mm, which coincide with the thresholds of temperature and precipitation for tropical karst.展开更多
基金Project(40571032) supported by the National Natural Science Foundation of ChinaProject(2006G011-B-3) supported by Science Studies and Development Plan Foundation of Railway Ministry
文摘To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.
基金Project(2018-MSI-018) supported by the Key Science and Technology Project of the Ministry of Transport of ChinaProject(NJ-2018-28) supported by the Construction Science and Technology of the Department of Transport of Inner Mongolia Autonomous Region of China+2 种基金Project(2019MS05029) supported by the Natural Science Fund Project of Inner Mongolia Autonomous Region of ChinaProject(2020MS05077) supported by the Natural Science Fund Project of Inner Mongolia Autonomous Region of ChinaProject(NJ-2020-05) supported by the Research on Complete Survey Technology of Highway Road Area in High-latitude Permafrost Region, China。
文摘To reveal the influencing factors and changing rules for the hydrothermal interaction process of highway subgrade, the field measurements of Shiwei-Labudalin Highway in Inner Mongolia, China was conducted for 3 years, based on which the freezing-thawing rules and water content changing characteristics were analyzed. The main results show the subgrade presents a frequent freezing-thawing alternation, and the water content of subgrade exhibits an obvious seasonal alternation. The subbase has the maximum water content, while the base has the minimum water content. The change of water flux is concentrated in the thawing period and consistent with the change of temperature gradient. The subbase layer has the most active water flux due to the heat absorption and impermeability of pavement that easily causes the water accumulation in this layer. Therefore, the prevention and treatment for the freezing-thawing disease should be started from heat insulation and water resistance.
基金Supported by the National Key R and D Program of China(2018YFC1407301,2016YFC1400301)the National Natural Science Foundation of China(41127901)。
文摘From Aug.2013 to Oct.2015,a Rayleigh lidar has been used to study the middle atmosphere at Golmud(36.25°N,94.54°E),Qinghai,located in the northeastern part of the Tibetan Plateau.Mesospheric density profiles from 50 to 90 km were retrieved based on 205 nights of lidar observation,with a total of 1616hours of operation.We compared our lidar density measurements with SABER observations onboard TIMED satellite and MSIS-00 model data.The results showed that the annual mean density measured by lidar agreed well with SABER data,but both were lower than that of MSIS-00.All datasets exhibited dominant annual oscillation in the mesosphere.From 63 to 85 km,the annual amplitude of lidar density is larger than those of SABER and MSIS-00.PDD(Percentage of Density Difference)was calculated to investigate the mesospheric density climatology.The largest density variations of lidar,MSIS-00,and SABER occurred at around 72 km.Both lidar and SABER PDD reached their maximum in May,about one month earlier than the MSIS-00;while the minimum PDD appeared in late December for all datasets.
文摘The detailed high-resolution emission inventory of black carbon (BC) from China in the year 2000 was calculated. The latest fuel consumption data including fossil and biomass fuels, and socio-economic statistics used were obtained from government agencies, mostly at the county level, and some new emission factors (Efs) from local measurements were also used. National and regional summaries of emissions were presented at 0.2°×0.2°resolution. Total BC emission was 1499.4 Gg in 2000, mainly due to the burning of coal and biomass. The BC emission estimated here is higher than those in previous studies, mainly because the emissions from coal burning by rural industries and residences were previously underestimated. More BC aerosols were emitted from eastern China than western China. A strong seasonal dependence was observed for BC emissions, with peaks in January and December and low emissions in July and August; and this seasonality is mainly due to patterns in residential heating and the open burning of crop residues.
基金Supported by the University Science and Technology Innovation Team Construction Projects of Heilongjiang Province(2013 TD003)
文摘The present study was conducted to see the short term impact of organic and inorganic fertilizers on soil microbial biomass both in spring and summer. Also aimed to observe the correlation between soil microbial biomass and soil DNA. The study concluded that type of fertilizer might alter the soil microbial biomass and DNA contents. In soil treated with organic fertilizers resulted in higher concentrations of microbial biomass and DNA contents in summer as compared to spring dute to increase in temperature. Correspondingly, in case of inorganic fertilizer, concentrations of soil microbial biomass and DNA detected higher in summer instead of spring. The statistical correlation between soil microbial biomass, DNA and ODR in spring and summer along with organic and inorganic fertilizers were calculated highly significant （p〉0.01）. This study demonstrated the impact of fertilizers and seasonal variations on soil microbial biomass and also revealed significant correlation between soil microbial biomass and soil DNA.
基金Project(51325803)supported by the National Science Foundation for Distinguished Young Scholars of ChinaProject(2020M673489)supported by China Postdoctoral Science FoundationProject(2020-K-196)supported by the Science and Technology Project of Ministry of Housing and Urban-Rural Development,China。
文摘The study aims to investigate the thermal comfort requirements in residential buildings and to establish an adaptive thermal comfort model in the cold zone of China.A year-long field study was conducted in residential buildings in Xi’an,China.A total of 2069 valid questionnaires,along with indoor environmental parameters were obtained.The results indicated occupants’thermal comfort requirements varied with seasons.The neutral temperatures were 17.9,26.1(highest),25.2,and 17.4℃(lowest),and preferred temperatures were 23.2,25.6(highest),24.8,and 22.4℃(lowest),respectively for spring,summer,autumn,and winter.The neutral temperature and preferred temperature in autumn are close to the neutral temperature in summer,while the neutral temperature and preferred temperature in spring are close to that in winter.Besides,the 80%and 90%acceptable temperature ranges,adaptive thermal comfort models,and thermal comfort zones for each season were established.Human’s adaptability is related to his/her thermal experience of the current season and the previous season.Therefore,compared with the traditional year-round adaptive thermal comfort model,seasonal models can better reflect seasonal variations of human adaptation.This study provides fundamental knowledge of the thermal comfort demand for people in this region.
基金Supported by Multi-Discipline Scientific Rearch Foundation of Harbin Institute of Technology(HIT MD2003.1)Postdoctoral Scientific Rearch Foundation of Heilongjiang Provine(LBH-Q06066)
文摘This paper presented a preliminary research on the central solar heating system with seasonal storage(CSHSSS)used in cold climate in China.A mathematical model of the solar energy seasonal storage water tank used in the central solar heating system was firstly developed based on energy conservation.This was followed by the simulation of the CSHSSS used in a two-floor villa in Harbin,and analysis of the impacts on storage water temperature of tank volume,solar collector area,tank burial depth,insulation thickness around the tank,etc.The results show there is a relatively economical tank volume to optimize the system efficiency,which decreases with increasing tank volume at the constant collector area,and increases with increasing collector area at the constant tank volume.Furthermore,the insulation thickness has obvious effect on avoiding heat loss,while the tank burial depth doesn't.In addition,the relationship between the solar collector efficiency and storage water temperature is also obtained,it decreases quickly with increasing storing water temperature,and then increases slowly after starting space heating system.These may be helpful for relevant design and optimization in cold climates in China and all over the world.
基金Project(71671035)supported by the National Natural Science Foundation of ChinaProjects(ZK15-03-01,ZK16-03-07)supported by Open Fund of Jiangsu Wind Power Engineering Technology Center of China
文摘Aiming at wind turbines,the opportunistic maintenance optimization is carried out for multi-component system,where minimal repair,imperfect repair,replacement as well as their effects on component’s effective age are considered.At each inspection point,appropriate maintenance mode is selected according to the component’s effective age and its maintenance threshold.To utilize the maintenance opportunities for the components among the wind turbines,opportunistic maintenance approach is adopted.Meanwhile,the influence of seasonal factor on the component’s failure rate and improvement factor’s decrease with the increase of repair’s times are also taken into account.The maintenance threshold is set as the decision variable,and an opportunistic maintenance optimization model is proposed to minimize wind turbine’s life-cycle maintenance cost.Moreover,genetic algorithm is adopted to solve the model,and the effectiveness is verified with a case study.The results show that based on the component’s inherent reliability and maintainability,the proposed model can provide optimal maintenance plans accordingly.Furthermore,the higher the component’s reliability and maintainability are,the less the times of repair and replacement will be.
文摘The grey forecasting model has been successfully applied to many fields. However, the precision of GM(1,1) model is not high. In order to remove the seasonal fluctuations in monitoring series before building GM(1,1) model, the forecasting series of GM(1,1) was built, and an inverse process was used to resume the seasonal fluctuations. Two deseasonalization methods were presented , i.e., seasonal index-based deseasonalization and standard normal distribution-based deseasonalization. They were combined with the GM(1,1) model to form hybrid grey models. A simple but practical method to further improve the forecasting results was also suggested. For comparison, a conventional periodic function model was investigated. The concept and algorithms were tested with four years monthly monitoring data. The results show that on the whole the seasonal index-GM(1,1) model outperform the conventional periodic function model and the conventional periodic function model outperform the SND-GM(1,1) model. The mean Absolute error and mean square error of seasonal index-GM(1,1) are 30.69% and 54.53% smaller than that of conventional periodic function model, respectively. The high accuracy, straightforward and easy implementation natures of the proposed hybrid seasonal index-grey model make it a powerful analysis technique for seasonal monitoring series.
基金supported by the Chinese Academy of Sciences(KZZD-EW-01-3)National Key Basic Research Program of China(2012- CB825604)National Natural Science Foundation of China(41074112,41174137)
文摘The ionosphere varies over multiple time scales,which are classified into two categories: the climatology and weather variations.In this national report,we give a brief summary of recent progresses in ionospheric climatology with focus on(1) the seasonal variations,(2) solar cycle effects, and(3) empirical modeling of the ionosphere.The seasonal variations of the ionosphere have been explored in many works to give a more detailed picture with regional and global features at various altitudes by analyzing the observation data from various sources and models.Moreover,a series of studies reported the response of the ionosphere to solar cycle variations,which revealed some novel and detailed features of solar activity dependence of ionospheric parameters at different altitudes. These investigations have improved our understanding on the states of the ionosphere and underlying fundamental processes,provided clues to future studies on ionospheric weather,and guided ionospheric modeling,forecasting and related applications.
基金supported by the National Natural Science Foundation of China(41771402,41804009)the National Key R&D Program of China(2017YFB0502700)Sichuan Science and Technology Program(2018JY0564,2019ZDZX0042,2020JDTD0003)。
文摘Affected by the natural environmental and human activity factors,significant seasonal differences appear on the regional scattering characteristic and ground deformation of saline soil.Interferometric decorrelation due to season replacement limits the conventional multi-temporal interferometric synthetic aperture radar(MT-InSAR)technique and its application in such areas.To extend the monitoring capability in the salt desert area,we select a vast basin of saline soil around Howz-e-Soltan Salt Lake of Iran as the study area and present an improved MTInSAR for experimental research.Based on 131 C-band Sentinel-1 A images collected between October 2014 to July 2020,1896 refined interferograms in total are selected from all interferogram candidates.Interferometric coherence analysis shows that the coherence in the saline soil area has an apparent seasonal variation,and the soil moisture affected by the precipitation may be the main factor that leads to the seasonal variation.Subsequently,the deformation characteristics of saline soil under different environmental conditions and human activity factors are compared and analyzed in detail.Related deformation mechanisms of different saline soil types are initially revealed by combining interferometric coherence,meteorological data,and engineering geological characteristics of saline soil.Related results would provide reference for the large-scale infrastructure construction engineering in similar saline soil areas.
基金Supported by Russian Foundation for Basic Research(13-05-91159-GFEN_a)Project 14.518.11.7065 and agreement N8388 of the Ministry of Education and Science of the Russian Federation+1 种基金the National Natural Science Foundation(41274146)the Specialized Research Fund for State Key Laboratory in China
文摘Comparison of regular(diurnal,seasonal and solar cycle)variations of high-latitude,mid-latitude and low-latitude ionospheric characteristics has been provided on basis of local empirical models of the peak electron density and the peak height.The local empirical models were derived from the hand-scaled ionogram data recorded by DPS-4 digisondes located at Norilsk(69°N,88°E),Irkutsk(52°N,104°E)and Hainan(19°N,109°E)for a 6-year period from December,2002 to December,2008.The technique used to build the local empirical model is described.The primary focus is diurnal-seasonal behavior under low solar activity and its change with increasing solar activity.Both common and specific features of the high-latitude(Norilsk),mid-latitude(Irkutsk)and low-latitude(Hainan)regular variations were revealed using their local empirical models.
文摘The Heibei highway in expansion project is located in Xiaoxing’anling permafrost areas.Its total length is 148 km,and has 17 island permafrost sections.Some sugared above area exists uneven subsidence,which affects road life and the stability of roadbed largely. The main reason for this is seasonal freezing and thawing of soil,resulting in the changes of foundation bearing capacity,and then the roadbed instability.In addition,many weak layers in the sugared area
文摘The 5°S-10°S band in the Indian Ocean,named recently as Seychelles-Chagos Thermocline Ridge (SCTR),is a region where several phenomena of significant climatic influence build up.It is a generation region for tropical cyclones striking the inhabited islands in the Indian Ocean and the African coast.It was recently shown that it is one of the regions where atmospheric intraseasonal variability (e.g.Madden Julian Oscillation,MJO) is
文摘The concept of water mass was carried within the early development ofoceanography and the analysis of water mass has so far become one of theimportant subjects of physical oceanography. The formation and charactersof ocean water mass are described and discussed at length in many famousbooks and classical textbooks on physical oceanography, such as "The Oceans"
文摘Guilin area is situated in the northeastern part of the Guangxi Zhuang Autonomous Region, 110°9′to 110°42′E and 24°40′to 25°40′N. It has a subtropical monsoon humid climate characterized by sharp contrast between dry season and rainy season, with an annual mean temperature of 18.3℃ and precipitation of 1936mm, which coincide with the thresholds of temperature and precipitation for tropical karst.
