Abstract:The interdecadal variation of spring Greenland sea ice extent and its relationships with the North Atlantic and Arctic Oscillations are examined by using GISST sea ice extent and SST datasets along with NCEP/NCAR 40 year reanalysis.It is found that the spatial distribution and temporal variation of spring Greenland sea ice extent can be represented by its leading EOF mode.The variation of spring sea ice extent are evidently out of phase to the variations of NAO and AO in precedent winter as well as JFMA mean SSTA in North Atlantic warm current region.Aquasi-60 year period is detected in the variations of the four.As a cold source of the atmosphere,sea ice anomalous variation has significant impacts on the latent and sensible heat fluxe form theocean to the atmosphere as well as the surface net radiation.The larger sea ice extent decreases the surface heat transports to the atmosphere.Consequently,the anomalies of spring sea ice can impact the atmosphere in following seasons.When sea ice extent is larger(smaller),the Icelandics low and Aleutian low weaken(strengthen),and summer heat lows over North African and Asian continents intensify(weaken) accompanied by evident lower(higher) SLPs.

Abstract:The circulation character of 500hPa climatic height fields in two hemispheres is investigated by using hemispherical climatic field intensity( I_c) and the improved scheme for spherical function analysis.The main findings are as the followings:1)the intensity of 500hPa hemispherical climatic height field of winter(Northern Hemisphere) is stronger than that of summer(Southern Hemisphere);the transition velocity of hemispherical circulation from winter to summer about the same in two hemispheres but the transition from summer to winter in Northern Hemisphere is more rapid than in Southern Hemisphere.2)The spherical function spectrum structure of 500hPa hemispherical climatic fields is simple,and the fields are mainly composed of ultra-long waves(0≤m,k≤3;m,k not equal to 0 simultaneously),specially of zonal spherical function(m=0),thus showing a low order and dimension on feature.3)The 500hPa climatic height field can be accurately fitted by using 20 important spherical function components(criteria byr_m,k^*≥0.05%) in Northern Hemisphere, but by using only 10 in Southern Hemisphere,that is to say,the spectrum structure in Northern Hemisphere is more complicated.4)The seasonal variation of 500hPa climatic height fields in Northern Hemisphere is more remarkable than that in Southern Hemisphere.

Abstract:Based on summer 500hPa geo-potential high fields,mid-latitude blocking high indexes of three areas (Okhotsk Sea,Baikal Lake,Ural Mountains) in Asia are calculated in this paper and the relation between blocking high indexes and summer precipitation in North China is investigated by means of correlation and composite analysis.Results show that the blocking high indexes of the three areas all have distinct inter-decadal variations,and are close related with summer precipitation in North China on inter-decadal time scales,with correlation coefficents being -0.4622,-0.6763 and -0.6713,respectively.When the Asian mid-latitude blocking high occurs frequently,the mid-latitude westerly turns into two branches,forming polar and sub-tropical fronts,and the East Asian summer monsoon is weaker than normal,the sub-tropical high lies south of normal position,and the summer rain-belt lies south of normal,resulting in summer drought in North China.It is vice versa if the Asian mid-latitude blocking high occurs infrequently.

Abstract:The features of raindrop size distributions and evolution of microstructure parameters in mountain area are analyzed and M-P distribution and Г distribution are developed based on the precipitation data observed in Tianshan area from June to July 2001.The contribution of the raindrops in various diameter ranges to total number density and rainfall intensity as well as the formation and brokenness of small raindrops are discussed.Moreover,similarities and differences between precipitation in Tianshan area and that in other region are also studied.

Abstract:The important effect of inertial stability on heavy rain accompanied by low level south-westerly jet and upper level northerly strong flow is analyzed theoretically in this paper.The results show that the existence of the maximum of inertial stability in the left front of the low level jet is favorable to the accumulation of moist thermal energy and that the conditional symmetric instability or convective instability can be expected in this region.The maintenance of the upper level strong flow provides a beneficial circumstance for the generation of the dry symmetric instability in its right rear region.Furthermore,the inertial stability can cause a slantwise convection at low level more vertical and therefore support the convection,which in turn makes the slantwise convection more horizontal at upper level and benefits the divergence over there.

Abstract:Based on the response eqution of temperature-sensing element solved by means of convolution integral in time domain,the response of the element,especially its automatic average ability,is described,from which it is discovered that the output of the element at a certain time is a weighted average of the input of environmental temperature in the previous time.The weight increases exponentially as it approaches to the output time.This result is used to discuss the problems concerning assimilation of different temperature data,which is of significance for the improvement of the skill of data-assimilation.

Abstract:A set of single Doppler velocity models are presented for low-level jets, and a rainstorm case in Anhui province is analyzed based on the 24th to 27th July 2000 observations of Doppler weather radar of Hefei.Results show that:1)no matter how wind direction changes,the positive/negative Doppler speed areas of low-level jets are always symmetric about the radar site,and the real wind speed profile can be inferred from the zero velocity contour distribution of Doppler velocity;2)the rainstorm occurrs in sites on the left side within 200 km from the connecting line between positive and negative speed centers;3)the sustained of low-level jet supplies plentiful vapor for the formation and maintenance of the rain gush.

Abstract:By means of the intensive observation data of the second TIPMEX(Tibetan Plateau Meteorological Science Experiment) in 1998 and the NCEP/NCAR reanalysis data,the diagnostic analyses on water vapor fluxs during the key period(June to July) of heavy rainfall processes in 1998 are performed,and the water vapor inflow on the lateral boundaries is numerically inrestigeted in this paper.The results show that the exceptional torrential rainfall processes of 1998 in the Yangtze Basin occurred under favorable conditions of sustained anomalous and steady synoptic scale environment and meso-scale wind fields;the water vapor transport feature in June was different from that in July;the water vapor transport on both the west and south boundaries of the region played an important role in the torrential rainfall processes,i.e. The noticeable change in the water vapor source and its corridor was important to the formation,and development of torrential rain at different stage of the meiyu period in the Yangtze Basin;the spatially and temporally distribution characteristics of water vapor gave some important clues for the prediction of sustained exceptional torrential rain over Yangtze River basin.

Abstract:This thesis uses the daily Meteorological data at 19 representative locations over more than 50 years to analyze Northern Vietnam’s climatic changes and its effects on agricultural production and the distribution of the climate and climatic changes, climate productive force changes are given by adopting(EOF),integrating regression and other statistic methods.

Abstract:By use of the key time method for studying catastrophic laws,this paper deals with the influence of drought and higher temperature on the outbreaks of the Oriental Migratory Locust(Locusta migratoria manilensis Meyen).Results show that the precipitation less than normal in April(drought) is one of main induction factors,which causes plagues of the pest.Moreover,the regionally averaged rainfall in April plays more important role in the outbreak of summer locusts than in that of autumn locusts.The temperature higher than normal in November also contributes to the outbreak of the next summer locusts.

Abstract:On the base of previous work,put forward in this paper is a new bogus typhoon initialization scheme,in which the bogus typhoon is more adaptable to the environmental field,and more asymmetrical information is included.In sensitive experiments,the simulated path by use of the new bogus typhoon initialization scheme is closer to the real path than that by other schemes.

Abstract:Atmospheric circutation characteristics associated with summer flood/drought,which is graded by a new scheme,over North China are addressed in this papar in terms of the 1951-2000 monthly rainfall and 500 hPa heights from National climate center by using the correlation,composite and singular value decomposition(SVD) methods.Results show that in North China drought/flood years prominent circulation anonmalies occur all over Northern Hemisphere,and the most significant anomalies appear in the low-latitude area from North Africa to West Asia,the Qinghai-Xizang Plaeau region,the northeast of Ural mountains,and the east of Canada.The trend of the circulation anomaly is consistent with that of summer rainfall in North China.The circulation anomalies in Asia display a "positive-negative-positive" pattern from high-latitudes to low-latitudes in summer flood years and a "negative-positive-negative" pattern in summer drought years.

Abstract:According to the thoughtway of the research of breeding super hybrid rice,4 varieties 20 facrors related to plant morphology are detected and their correlations are analyed for Liangyoupeijiu(PeiAi64s/9311),65396,9311,E32,SanYou63,Peiai64s and 399-seven varieties with differnt plant morphologies.We believ that plant height and leaf angle are two most important factors in breeding and culitivating varieties with supper high yield.Analyzing the relation between eco-condition and Liangyoupeijiu’s plant height shows that 12.6 percent of the height is resulted from temperature,and the ecological prediction model of plant height developed.The theoretical simulation calculation fo the sunlight per unit area recieved by top three leaves at 8 leaf angle after heading confirms that the optimal plant morpholog should be that the distances from the flag leaf to top second leaf and from the top second leaf the third top leaf are 15 cm and 25cm,respectively,the flag leaf angle is between 4° and 6°,the top second leaf angle upper is between 9° and 11°,the top third leaf angle is between 14° and 16°.The above results may provide ascientific basis for breeding in plant morphology of super hybird rice.

Abstract:Based on the observational data,the effect of enhanced UV-B radiation on the growth of wheat is investigated and the ecological feature of the plant community productivity is calculated under the condition fo UV-B enhancement.The results show that this effect is mainly displayed in delaying plant growth,reducing leaf area,tiller and number of flowering,shortening plant height,decreasing the number of green leaves,the weight of dried stuff,leaf and ear.In addition,it also affects the productivity of wheat such as its community growth rate,comparative growth rate,leaf area index,daily leaf accommulation,net assimilation rate,all of which are decreaed significantly in the middle and late stages of its growing period.As a result,the number of wheat plant per unit area,the ear number of single plant,the grain number per ear and the weight of 1000 grains are reduced substantially,which influences the yield product of biology and economy of wheat community.

Abstract:A variable-frequency control technique is applied to the flyback converter to reduce converter’s switching loss.It makes the flyback transformer working at the boundary of the continuous conduction mode (CCM) and discontinuous conduction mode(DCM) and having a wider range of the load than ever;meawhile the converter’s efficiency is improved.

Abstract:The classification,development work and recent advances of regional climate models are reviewed comprehensively in this paper.Great advances in regional climate model have been made in the recent years.The main advances are:introduing snow-cover and soil-water into regional climate models;the development of the regional climate model nested in a general circulation model from 1D to 3D and from 1 layer to multi-layers;the development of more reasonable parameterization schemes.But there are still some defalts,such as,the inadequate calculation method of vegetation cover in desert,and rough depection in sub-grid topogtaphy and turbulent flux transfer etc.Therefore,nonlinear methods(fractal etc) for the retrieval of remote sensing date and the multi-scale two-direction nesting are suggesed to be used in future regional climate simulations.

Abstract:The representative works at home and abroad on atmospheric angular momentum(AAM) balance since the 1980s are emphatically analyzed in this papar,and angular momentum exchanges between the earth and the atmosphere,angular momentum transfer,and their relationships with mountain torque anomaly,friction torque anomaly,Earth’s rotation anomaly and El Nino and Southern Oscillation(ENSO) etc are summarized.A few aspects that should further be studied are also given.