Several theories have been developed to explain tropical biennial oscillation （TBO）, as an air-sea interactive system to impact Asian and global weather and climate, and some models have been established to produce ...Several theories have been developed to explain tropical biennial oscillation （TBO）, as an air-sea interactive system to impact Asian and global weather and climate, and some models have been established to produce a TBO. A simple 5-box model, with almost all the key processes associated with TBO, can produce a TBO by including airsea interactions in the monsoon regions. Despite that, the South China Sea/western North Pacific summer monsoon （SCS/WNPSM）, a very important monsoon subsystem, is neglected. In this paper, based on the dynamical framework of 5-box model, the term of SCS/WNPSM has been added and a 6-box model has been developed. Comparing the difference of TBO sensibilities with several key parameters, air-sea coupling coefficient α, SST-thermocline feedback coefficient γand wind-evaporation feedback coefficient λ, between the modified model and original model, TBO is more sensible to the parameters in the new model. The results imply that the eastern Pacific and local wind-evaporation play more important roles in the TBO when including SCS /WNPSM.展开更多
Relation between the volume reflectivity and frequency in view of the polar mesosphere summer echoes （PMSE） is studied using the small-scale structure of electron density caused by charged dust particles. A theoreti...Relation between the volume reflectivity and frequency in view of the polar mesosphere summer echoes （PMSE） is studied using the small-scale structure of electron density caused by charged dust particles. A theoretical expression for the radar volume reflectivity is derived, which agrees with the statistical result. Both the theoretical and statistical results are confirmed with the data obtained from simultaneous observations at three frequencies. Hence the small-scale structure caused by charged dust particles may be a useful tool for the study on the generation mechanism of PMSE.展开更多
Polar mesosphere summer echoes （PMSE） are very strong radar echoes from alti- tudes close to the polar summer mesopause. The data from sounding rocket campaigns indicate that the radar signal to noise ratio （SNR）,...Polar mesosphere summer echoes （PMSE） are very strong radar echoes from alti- tudes close to the polar summer mesopause. The data from sounding rocket campaigns indicate that the radar signal to noise ratio （SNR）, electron density and dust charge density of polar meso- sphere in summer show obvious layered structure. In this paper the theory of wave propagation in layered media is used to study the reflectance and SNR at each layer in polar mesosphere. The calculated SNR using theory of dusty plasma is found in good agreement with the experimental result, which may imply that the intensity of the radar echoes reflected by the layered structure in polar mesosphere where polar mesosphere summer echoes used to occur can interpret partially the phenomenon of PMSE. In other words, reflection may play an important role in the occurrence of PMSE.展开更多
Considering the differences between the Northeast China Cold Vortex （CV） and the Mid-Summer （MS） rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identi...Considering the differences between the Northeast China Cold Vortex （CV） and the Mid-Summer （MS） rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identification methods of defining the annual beginning and ending dates of Northeast China CV and MS rainy periods are developed respectively. The annual beginning date of the CV （MS） rainy period is as follows. In a period from April to August, if daily regional mean precipitation ryi is larger than yearly regional mean precipitation R （or 2R） on a certain day, the station precipitation rs is larger than the station yearly mean precipitation （r/ （or 2（r）） in at least 50% of stations in Northeast China, and this condition is satisfied in the following 2 （7） days, then this date is defined as the beginning date of the CV （MS） rainy period. While the definition of the ending date of the MS rainy period shows the opposite process to its beginning date. With this objective identification method, the multi-year average （1981-2010） beginning date of the CV rainy period is May 3, the beginning date of the MS rainy period is June 27, the ending day of the CV rainy period is defined as the day before the beginning date of the MS rainy period, and the ending date of the MS rainy period is August 29. Meanwhile, corresponding anomaly analysis at a 500-hPa geopotential height, 850-hPa wind, Omega and relative humidity fields all show that the definitions of the average beginning and ending dates of the CV and MS rainy periods have a certain circulation meaning. Furthermore, the daily evolution of the CV index, meridional and zonal wind index, etc. all show that these objectively defined beginning and ending dates of the CV and MS rainy periods have climate significance.展开更多
Radar echoes intensity of polar mesosphere summer echoes（PMSE） is greatly affected by the temperature of dusty plasma and the frequency of electromagnetic wave about the radar.In this paper,a new method is developed...Radar echoes intensity of polar mesosphere summer echoes（PMSE） is greatly affected by the temperature of dusty plasma and the frequency of electromagnetic wave about the radar.In this paper,a new method is developed to explain the active experiment results of PMSE.The theory of wave propagation in a layered media is used to study the propagation characteristics of an electromagnetic wave at different electron temperatures.The simulation results show that the variation tendency of the reflected power fraction almost agrees with the results observed by radar in the European Incoherent Scatter Scientific Association（EISCAT）.The radar echoes intensity of PMSE greatly decreases with the increase of the radio frequency and the enhancement of the electron temperature.展开更多
Understanding how tree species respond to drought in their natural environment is needed to predict forest adaptation and management practices under global environmental changes.This study was carried out to determine...Understanding how tree species respond to drought in their natural environment is needed to predict forest adaptation and management practices under global environmental changes.This study was carried out to determine and compare physiological and biochemical responses to variations in environmental conditions during summer drought of mixed natural stands of Pinus nigra Arn.subsp.pallasiana(Lamb.)Holmboe and Pinus brutia Ten.Midday xylem water potential(ψmd),water relations,photosynthetic pigments,total soluble sugar and proline contents were investigated during the growing season.ψmd followed a similar seasonal trend in both species but P.nigra subsp.pallasiana had higher ψmd than P.brutia.The ψmd gradually decreased from June,reached its lowest value in August,and then increased again.Gradual decreases in the osmotic potential at turgor loss point(ψnTLP)were observed during the summer.Generally,ψnTLP was lower in P.brutia.Total soluble sugars decreased from April to June for P.brutia,then increased and stayed relatively constant August to October.Similar changes were found at lower values in P.nigra subsp.pallasiana.Prolin accumulation and photosynthetic pigments were higher in P.brutia.The results indicate that physiological and biochemical responses of both species against changing environmental conditions were in different degrees but followed similar trends.P.nigra subsp.pallasiana is more sensitive to summer drought than P.brutia in their natural environment.展开更多
Suppose I remind you of that final week before school closedfor summer vacation.Of how you would be sitting at your desk,sweating and sleepy,in a room turned white from the diamond-bright June sun blasting in.And of h...Suppose I remind you of that final week before school closedfor summer vacation.Of how you would be sitting at your desk,sweating and sleepy,in a room turned white from the diamond-bright June sun blasting in.And of how every once in a while,展开更多
Welcome to high summer[盛夏],dear CE:Teens readers!When we are young, summer can be a magical[不可思议的] time, free from many of the more stressful[紧迫的] parts of our lives,namely,school! But summer can also be a c...Welcome to high summer[盛夏],dear CE:Teens readers!When we are young, summer can be a magical[不可思议的] time, free from many of the more stressful[紧迫的] parts of our lives,namely,school! But summer can also be a confusing[混乱的] time of year When faced with a long holiday,after we have caught up with friends we haven’t seen for a long time, slept late for the twentieth展开更多
[Chorus] Hey,friend Summer is here Get ready for the hottest Time of the year!（x2） [Verse 1] Will you go somewhere alone？ Or go out with some friends？ Just remember to have fun now Before the summer ends!
On Tuesday,July 12th,2016,the Summer 2016 edition of Texworld USA opened its doors and show floor for business to exhibitors and visitors alike.Continuing through Thursday,July 14th and once again taking place at the ...On Tuesday,July 12th,2016,the Summer 2016 edition of Texworld USA opened its doors and show floor for business to exhibitors and visitors alike.Continuing through Thursday,July 14th and once again taking place at the Javits Convention Center in New York City,the historic 21st edition of Texworld USA presented an assortment of international suppliers from around the globe who showcased textiles,trims and accessories in 16 product categories.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 40505019） and the 0pen Research Fund of Laboratory of China Meteorological Administration （Grant No CMATG2006L03）.
文摘Several theories have been developed to explain tropical biennial oscillation （TBO）, as an air-sea interactive system to impact Asian and global weather and climate, and some models have been established to produce a TBO. A simple 5-box model, with almost all the key processes associated with TBO, can produce a TBO by including airsea interactions in the monsoon regions. Despite that, the South China Sea/western North Pacific summer monsoon （SCS/WNPSM）, a very important monsoon subsystem, is neglected. In this paper, based on the dynamical framework of 5-box model, the term of SCS/WNPSM has been added and a 6-box model has been developed. Comparing the difference of TBO sensibilities with several key parameters, air-sea coupling coefficient α, SST-thermocline feedback coefficient γand wind-evaporation feedback coefficient λ, between the modified model and original model, TBO is more sensible to the parameters in the new model. The results imply that the eastern Pacific and local wind-evaporation play more important roles in the TBO when including SCS /WNPSM.
基金supported by National Natural Science Foundation of China (No.40831062)the Foundation of the National Key Laboratory of Electromagnetic Environment of China (No.9140C08060367ZCZJ16)
文摘Relation between the volume reflectivity and frequency in view of the polar mesosphere summer echoes （PMSE） is studied using the small-scale structure of electron density caused by charged dust particles. A theoretical expression for the radar volume reflectivity is derived, which agrees with the statistical result. Both the theoretical and statistical results are confirmed with the data obtained from simultaneous observations at three frequencies. Hence the small-scale structure caused by charged dust particles may be a useful tool for the study on the generation mechanism of PMSE.
基金supported by National Natural Science Foundation of China (Nos.40831062, 60971034)the Scientific Research Starting Foundation of University of Electronic Science and Technology of China (No.Y02002010401066)
文摘Polar mesosphere summer echoes （PMSE） are very strong radar echoes from alti- tudes close to the polar summer mesopause. The data from sounding rocket campaigns indicate that the radar signal to noise ratio （SNR）, electron density and dust charge density of polar meso- sphere in summer show obvious layered structure. In this paper the theory of wave propagation in layered media is used to study the reflectance and SNR at each layer in polar mesosphere. The calculated SNR using theory of dusty plasma is found in good agreement with the experimental result, which may imply that the intensity of the radar echoes reflected by the layered structure in polar mesosphere where polar mesosphere summer echoes used to occur can interpret partially the phenomenon of PMSE. In other words, reflection may play an important role in the occurrence of PMSE.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.41205040 and 41375078)the State Key Development Program for Basic Research,China(Grant No.2012CB955203)the Special Scientific Research Project for Public Interest(Grant No.GYHY201306021)
文摘Considering the differences between the Northeast China Cold Vortex （CV） and the Mid-Summer （MS） rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identification methods of defining the annual beginning and ending dates of Northeast China CV and MS rainy periods are developed respectively. The annual beginning date of the CV （MS） rainy period is as follows. In a period from April to August, if daily regional mean precipitation ryi is larger than yearly regional mean precipitation R （or 2R） on a certain day, the station precipitation rs is larger than the station yearly mean precipitation （r/ （or 2（r）） in at least 50% of stations in Northeast China, and this condition is satisfied in the following 2 （7） days, then this date is defined as the beginning date of the CV （MS） rainy period. While the definition of the ending date of the MS rainy period shows the opposite process to its beginning date. With this objective identification method, the multi-year average （1981-2010） beginning date of the CV rainy period is May 3, the beginning date of the MS rainy period is June 27, the ending day of the CV rainy period is defined as the day before the beginning date of the MS rainy period, and the ending date of the MS rainy period is August 29. Meanwhile, corresponding anomaly analysis at a 500-hPa geopotential height, 850-hPa wind, Omega and relative humidity fields all show that the definitions of the average beginning and ending dates of the CV and MS rainy periods have a certain circulation meaning. Furthermore, the daily evolution of the CV index, meridional and zonal wind index, etc. all show that these objectively defined beginning and ending dates of the CV and MS rainy periods have climate significance.
基金supported by National Natural Science Foundation of China(Nos.41104097 and 41304119)by the National Key Laboratoryof Electromagnetic Environment,China Research Institute of Radiowave Propagation(CRIRP)
文摘Radar echoes intensity of polar mesosphere summer echoes（PMSE） is greatly affected by the temperature of dusty plasma and the frequency of electromagnetic wave about the radar.In this paper,a new method is developed to explain the active experiment results of PMSE.The theory of wave propagation in a layered media is used to study the propagation characteristics of an electromagnetic wave at different electron temperatures.The simulation results show that the variation tendency of the reflected power fraction almost agrees with the results observed by radar in the European Incoherent Scatter Scientific Association（EISCAT）.The radar echoes intensity of PMSE greatly decreases with the increase of the radio frequency and the enhancement of the electron temperature.
基金The work was supported by the Suleyman Demirel University,Scientific Research Projects Coordination Unit(Project Number:4513-YL1-15).
文摘Understanding how tree species respond to drought in their natural environment is needed to predict forest adaptation and management practices under global environmental changes.This study was carried out to determine and compare physiological and biochemical responses to variations in environmental conditions during summer drought of mixed natural stands of Pinus nigra Arn.subsp.pallasiana(Lamb.)Holmboe and Pinus brutia Ten.Midday xylem water potential(ψmd),water relations,photosynthetic pigments,total soluble sugar and proline contents were investigated during the growing season.ψmd followed a similar seasonal trend in both species but P.nigra subsp.pallasiana had higher ψmd than P.brutia.The ψmd gradually decreased from June,reached its lowest value in August,and then increased again.Gradual decreases in the osmotic potential at turgor loss point(ψnTLP)were observed during the summer.Generally,ψnTLP was lower in P.brutia.Total soluble sugars decreased from April to June for P.brutia,then increased and stayed relatively constant August to October.Similar changes were found at lower values in P.nigra subsp.pallasiana.Prolin accumulation and photosynthetic pigments were higher in P.brutia.The results indicate that physiological and biochemical responses of both species against changing environmental conditions were in different degrees but followed similar trends.P.nigra subsp.pallasiana is more sensitive to summer drought than P.brutia in their natural environment.
文摘Suppose I remind you of that final week before school closedfor summer vacation.Of how you would be sitting at your desk,sweating and sleepy,in a room turned white from the diamond-bright June sun blasting in.And of how every once in a while,
文摘Welcome to high summer[盛夏],dear CE:Teens readers!When we are young, summer can be a magical[不可思议的] time, free from many of the more stressful[紧迫的] parts of our lives,namely,school! But summer can also be a confusing[混乱的] time of year When faced with a long holiday,after we have caught up with friends we haven’t seen for a long time, slept late for the twentieth
文摘[Chorus] Hey,friend Summer is here Get ready for the hottest Time of the year!（x2） [Verse 1] Will you go somewhere alone？ Or go out with some friends？ Just remember to have fun now Before the summer ends!
文摘On Tuesday,July 12th,2016,the Summer 2016 edition of Texworld USA opened its doors and show floor for business to exhibitors and visitors alike.Continuing through Thursday,July 14th and once again taking place at the Javits Convention Center in New York City,the historic 21st edition of Texworld USA presented an assortment of international suppliers from around the globe who showcased textiles,trims and accessories in 16 product categories.
