ZHANG Yan-huan , GUO Pin-wen , ZHOU Hui
2005, 28(1):1-8.
Abstract:Using the daily and monthly NCEP/NCAR reanalysis data from 1951 to 2000 and monthly precipitation of 160 stations in China in summer from 1951 to 2000, the climatic distribution of heat source are computed.the responses of the Asian monsoon circulation to the annual anomaly of the heat source over the Bay of Bengal in summer and the annual relationship between the heat source and the precipitation of China in summer are analyzed .The results show that the strongest heat source heating center was located over the north-east of the Bay of Bengal in summer.When the heat source over the Bay of Bengal was abnormally strong(weak),the southern Asian high extended westward(eastward),and the western Pacific subtropical high extended eastward(westward),and the Indian summer monsoon was stronger(weaker),and the eastern Asian tropical summer monsoon was weaker(stronger).The influence of the heat source anomalies over the Bay of Bengal was significant on the south Asian high and the south Asian summer monsoon and the western Pacific subtropical high,but not very significant on the eastern Asian tropical summer monsoon.There existed obviously negative correlation between the heat source over the Bay of Bengal and the precipitation of the south of the Yangtze River and the east of south China in summer,and obviously positive correlation between the heat source and the precipitation of the area from southwest in China to the west of south China.
DENG Zi-wang , GAO Jian-yun , ZHOU Xiao-lan , ZHANG Rong-yan , SONG De-zhong
2005, 28(1):9-17.
Abstract:The temporal/spatial varition features of Fujian drought/flood for the past 500 years are studied by means of FFT,continuous wavelet (CWT) and orthogonal wavelet transformation (OWT).The analysis show that:1)there are significant 2~3 years and 10 years periodic signals in the drought/flood grade series of Fujian,but there are spatial/temporal variations for other periods;2)on the centurial scale,the past 500 years can be divided into 6 dry/moist phases and currently it is in a dry to moist transition period in the northern region,whereas in the eastern and southern areas the past 500 years can be divided into 5 spells and now it’s still in the dry period,on the decadal scale,the past 500 years can be divided into 4 dry/moist periods and now Fujian is in a moist period;3)in northern regions,the grades series had a weak positive (dring) trend in the period from the end of the 16th century to the beginning of the 20th century and a negative trend in the 20th centry,and in the eastern region the grade series showed a weak decreasing (wetting) trend before the 20th century and an increasing (drying) trend in the first period of the 20th century,whereas the grade series had no obvious trend in the southern region.The variance contribution percentages of interannual,interdecadal and centurial changes to the three subregions’ drought/flood grade variations are >80%,<15% and <5% respectively.
ZHOU Chang-yan , HE Jin-hai , LI Wei , CHEN Long-xun
2005, 28(1):18-27.
Abstract:Climatological characteristics are investigated for large-scale water vapor transfer over East Asia in summer based on the vertically integrated water vapor flux from 1980 to 1997.It is found that a planetary-scale water vapor transport band of high value is formed through the converging of large-scale water vapor transfer bands from different sources;and it starts from the southern Hemisphere,crosses the Asian monsoon area,and then flows to the north Pacific.The north border of moisture transferred by the East Asian southerlies is the north of northeast China near 50°N,and the west border of moisture transferred by the southeast wind from the south side of the West Pacific subtropical high the southeast of Gansu near 100°E.The strong convergence areas,which coincide with the heavy rain belts,mostly lie in the planetary-scale water vapor transport band of high value.
WANG Yong-qing , LUO Zhe-xian , GUO Jian-xia
2005, 28(1):28-35.
Abstract:The possible reason for the aridification of the representative summer month (July) in the east of NW China in the last twenty years is investigated by a method combined with the EOF,probability density function and the similarity of two fields.It is for the first time pointed out that there exists two weather regimes in July East Asian atmospheric general circulation,namely the A regime and B regime.The A regime is associated with the drought circulation pattern for the east of northwest China,and the B regime with the comparatively wet pattern.The possible reason for the aridification of summer in the east region of NW China in recent 20 years is that the frequency of positive similarity with the A regime (drought pattern) persistently increases and the frequency of positive similarity with the B regime (comparatively wet pattern) persistently decreases.
CHEN Bing , GUO Pin-wen , XIANG Yu-chuan
2005, 28(1):36-43.
Abstract:The interannual relationships and its interdecadal variabilities between the intensity of summer 850hPa cross-equatorial flows in the Eastern Hemisphere and ENSO are analyzed by using NCEP/NCAR reanalysis data and the sea surface temperatures data of Hadley Center.Results show that Mascarene High was weaker(stronger) and Australia High stronger(weaker) than normal in the El Nino(La Nina) years,which caused summer 850hPa Somali jet was weaker(stronger) and the cross-equatorial flows of about 90°E,105°E,125°E and 150°E were stronger(weaker) than normal.The interannual relationship between Somali jet and ENSO was weakened in the late 1970s while the interannual relationships between the cross-equatorial flows of about 105°E,125°E and 150°E and ENSO were enhanced in the late 1960s.
2005, 28(1):44-50.
Abstract:The adaptive mesh technique was applied to the MM5 model,and numerical experiments were performed for the heavy rain event in the Yangtze River basin during 22th—23th July 1998.Simulated results using the adaptive mesh and uniform mesh were compared and diagnosed.The diagnostic results show that the effect of the heavy rain process simulation depends on parameters selected.
LIU Xin-gang , LvDa-ren , XIAO Wen-an , LIU Chun-tian , QU Yu
2005, 28(1):51-57.
Abstract:Based on the direct and scattering irradiance spectra measurements of ultraviolet waveband arrived at Beijing ground surface by the Sun-Atmosphere Ultraviolet Spectrum Radiometer (SAUVS),a method for retrieving the atmospheric aerosols optical depth (AOD) is given in this paper.Results show that the AOD of ultraviolet waveband decreases monotonously with increasing wavelength,and the retrieved results can be well fitted with an exponential function,and coefficients and expressions of fitting functions in three visiblities are determined statistically.At last,comparing the retrieved results with the survey data from the AERONET Beijing station suggests that the retrieval is reasonable.
HUANG Hai-hong , SUN Chong-zhi , JIN Long
2005, 28(1):58-63.
Abstract:The analysis of the meteorological and hydrological data shows that there is close correlation between the water level of the Xijiang river and the upper reach water level and areal mean rainfall.The new neural network prediction model of water level is established based on the principal component analysis(PCA).The comparison between the new model based on PCA and the traditional neural network model indicates that the new model is significantly superior to the traditiona model in prediction accuracy and prediction stability,thus having a good prospect in operational application.
LU Zhong-yan , ZHOU Jun , QIU Xin-fa , MIAO Qi-long
2005, 28(1):64-71.
Abstract:A sunshine hours distribution model in mountainous areas is designed in this paper,and the effects of slope,aspect,shade on sunshine hours at different latitudes are also discussed.Results are as follows.The latitudinal character of sunshine hours is obvious;at the same latitude and in the same aspect,sunshine hours are reduced with the increase of slope;the effect of aspect on sunshine hours is complicated,and in different aspects,sunshine hours vary with seasons and slopes;the effect of shade on sunshine hours is obvious,and it affects the sunshine hours distribution,leading to the non-zonal distribution of sunshine hours,especially in winter when the sun altitude angle is low.The sunshine hours spatial distribution map of 1:1000000 in China under the condition of actual terrain is plotted.
XU Jing-jing , ZHOU Wei-can , GUAN Yuan-hong
2005, 28(1):72-77.
Abstract:With Galerkin approximation procedure and minimax principle,the existence and uniqueness for the weak solution of a nonlinear elliptic system without resonance is proved.
ZHANG Xing-qiang , SUN Xing-chi , DING Zhi-ying
2005, 28(1):78-85.
Abstract:Application of the analysis and calculation of the barotropic/baroclinic joint instability in the storm rainfall far from a typhoon are introduced.Based on simulations and observations,analyses and calculations of barotropic and baroclinic items were carried out at different time levels and positions in the storm rainfall induced by 9711 typhoon.Results show that precipitation at the initial stage was basically caused by barotropic disturbances,and two rainfall areas,caused by the barotropic/baroclinic joint instability,occurred to the south and north of the typhoon circulation along with the coupling of the typhoon and the westerly trough.Especially,the baroclinic instability was more obvious in the north rain area,and had a strengthening trend with the non-zonal enhancement of the high-level jet.So we can conclude that the storm rainfall far from the typhoon is the offspring of the barotropic/baroclinic joint instability, and the strengthening of the baroclinic instability is closely associated with the non-zonal high-level jet.
TENG Dai-gao , LIU Xuan-fei , ZHANG Zeng-xin , WU Sheng-an
2005, 28(1):86-92.
Abstract:The interannual variation of Australian high and its effect on the Asia-Australia monsoon circulation system for 1948—2002 are analyzed,in the context of NCEP/NCAR reanalysis data.Results show that when the Australian high becomes strong,members of the Asia-Australia monsoon circulation system,such as the cross-equatorial flow between 100°E and 160°E,the ITCZ,the West Pacific subtropical high,the Meiyu front,the South Asian high,the near-equatorial easterly jet,the monsoon meridonal circulation,and the Hadley circulation etc also become strong,thus leading to the strengthen of the whole system.
DUAN Ming-keng , WANG Pan-xing , LIN Kai-ping
2005, 28(1):93-100.
Abstract:The index of regional rainfall anomaly(I index) is defined as the regional average of representative station′s JJA standardized rainfall anomaly in South China,Changjiang-Huaihe valley,and North China.And it is proved that I index is consistent with commonly used Z and R index.The correlation of I between different regions is insignificant,indicating that the interannual changes of summer rainfall are independent in the above three regions.The I index is decomposed into the interdecadal variation index (Is) and interannual variation index (If) by means of periodical analysis.And the variance analysis indicates that Is is significant among the components of I only in South China,suggesting that the regional rainfall anomaly in summer is complicated.The analysis of the curves of Is and If indicates that Is in the three regions is related to the 1970s′ transition of Pacific Decadal Oscillation (PDO),and the significant negative anomaly of If in North China is contemporaneously close related to strong El Nino events.
WU Hai-ying , ZENG Ming-jian , SHEN Shu-qing , PU Mei-juan , WANG Xiao-hua
2005, 28(1):101-107.
Abstract:The paper diagnoses the wet bulb potential vorticity field,and analyzes the structural characters of the frontogenesis secondary circulation of a highly intensive precipitation event in 21th—25th July 2002 using the Sawyer-Eliassen secondary equation.Then based on above results,this paper discusses the formation and development mechanism of the event.The analysis shows that conditional symmetric instability might be the unstable mechanism responsible for the heavy rain event.A great deal of moisture carried by the strong southwest low jet was converged in the low layer of rain region,under the geostrophic momentum approximation,the frontogenetical secondary circulation driven by frontogenesis forcing made the warm and wet air ascend and the accumulated unstable energy released,thus leading to the occurrence of the intense precipitation.
2005, 28(1):108-116.
Abstract:The ecological characters of photoperiod and temperature for 10 genic male-sterile (GMS) rice lines have been studied in this paper using the observation data from the joint ecological assessment experiment for new GMS rice lines in the Hi-tech Research and Development Program of China,and the decision variable for the growth period of each GMS line has been determined by the path analysis method.The analyses show that the photoperiodic sensitivity is strong for the late indica and japonica hybrid GMS rice lines,weak to medium for the semilate indica GMS rice line,and generally weak for the early indica GMS rice line.The temperature sensitivity is weak for only a few of 10 GMS rice line,and weak to medium strong for the majority.The decision variable for the growth period of the majoritity of 10 GMS rice line is temperature,except that for HS-3 and SE21S is photoperiod.
YAN Feng-xia , SHOU Shao-wen , ZHANG Yan-ling , SHEN Xin-yong
2005, 28(1):117-124.
Abstract:The mesoscale numerical model MM5(V3) was used to simulate a heavy rain process on a Meiyu front in the Jianghuai area during the period from 2000BST July 4 to 2000BST July 5, 2003.The high spatial and temporal resolution model outputs were used to diagnose the dry intrusion and its effect on the heavy rain process.The results show that the dry intrusion play an important role in the development of the heavy rain process,and the dry air with high potential vorticity in the upper troposphere intruded into the lower layer,which promoted the development of cyclone and convection,and subsequently the enhancement of precipitation.
PEI Yu-jie , GU Song-shan , CHEN Zhong-rong
2005, 28(1):125-132.
Abstract:The Doppler weather radar information server system based on web has perfect functions in remote radar data transmission,data process and real-time image display.The radar site and Web site are banded together to realize the net-exploration,sharing in all kinds observational data and online-service,which are convenient for different layer users.This article introduces how to use Java class and Remote invocation method(RIM) to create new link words,and use them to realize the data compress/transmits.Because Java Language implements a single interface for I/O data streams and network data streams,so not only the data can be more quickly transferred on network but also the disk space on server can be saved.
SUN Jiong-ning , FU De-sheng , XU Yong-hua
2005, 28(1):133-137.
Abstract:Because the signals and noises after the wavelet transform have the singularity,this paper proposes an unbiased risk estimate algorithm on the basis of soft thresholding given by Dohono,and applies it to the speech de-noising.The experimental results show that the algorithm has a least minimum mean-squared error than the other algorithms.
ZHAO Zhen , LEI Heng-chi , CHEN Wei-min
2005, 28(1):138-143.
Abstract:To fit the observed raindrop size distribution,the gamma size distribution function was assumed and the parameters of the function were determined by moment method.The difference in physical parameters between the Marshall-Palmer exponential distribution function and gamma distribution function determined becomes greater when the order of moment increases.The truncation effect (considering Dmin and Dmax instead of 0 and ∞) in calculating moments can be neglected under the certain condition,when Dmin and Dmax are sufficiently smaller and larger than the mean diameter.
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