Abstract:Conventional soundings were used to investigate the helicity in three rainstorm events related to different systems. It turns out that helicity is positive below 700 hPa and negative above 300 hPa over the rainband; rainfall is generated where the positive and negative helicity centers are available, high temperature and humidity areas existent at mid and low levels, and a highenergy tongue of convective unstable energy storage present.

Abstract:In the context of the IAP 2-level AGCM, numerical study was performed of effects on summer Northern atmospheric low-frequency circulations of two kinds of heat source forcing (constant and quasi-biweekly) in the mid-upper troposphere. Evidence suggests that either of the sources is responsible for a particular teleconnection pattern associated with a characteristic system; the constant source excites a low-frequency wavetrain analogous to PNA pattern associated with 1972 ENSO at a development phase and the related low-frequency cyclone and anticyclone are produced in the tropical NW Pacific, travelling along the wavetrain and disappearing in SE North America; the quasi-biweekly one generates a very strong teleconnection, showing meridional wavenumber 1 over the tropical NW Pacificmidlatitude Asia; the low-frequency system forms in the Northern Hemisphere, moving northward at 1 degree per day and reaching its maximum strength at subtropics.

Abstract:Based on synchronous observations of micro-meteorologial field elements and grain-bearing rates by self mating in cold-water fields during a fertility-sensitive period of short low-temperature-sensitive variety 64s of the sterile strain, study was made of optimal time intervals, depth and amount of irrigated water for the crop, called the “cold fertility” technique.

Abstract:1950～1979 fluxes of latent heat, net longwave radiation, sensible heat and net solar radiation of the midlatitude North Pacific were investigated by means of power spectral, filtering, principal component and correlation techniques to reveal their timedependent variation features. Results suggest that all of the heating fields show 2～4 year oscillation in some relation to ENSO.

Abstract:Based on ECMWF daily objective wind analysis study is conducted of the onset and structure of summer monsoon in the South-China Sea. Results show that the monsoon at low levels passes through a seasonal cycle of four phases: 1) the northeasterly prevailing in winter; 2) the southeasterly blowing as the transition from late January to mid April; 3) the vigorous SW wind in summer; and 4) again, the transitional southeasterly spanning early October to early November. In particular, the southeasterly establishment over the sea in late Januaryearly February and spreading northeast-and northwestward serve as a triggering factor of summer SW monsoon dominating all over Asia. The monsoon has structure of thermally strong NE-SE-SW winds in order from top to bottom in the troposphere. In addition, the lowlevel monsoon flowfield clearly shows that the study monsoon consists largely of SW flow on the west side of Western Pacific subtropical high, 105～120 °E cross-equatorial veering flow from the Southern Hemisphere and SW flow of Indian Ocean origin, indicating the unique role of the research monsoon in bridging the counterparts in South Asia and subtropical East Asia.

Abstract:Based on the cotton biology in connection with conventional observations of a number of varieties and more than one site, a model including temperature and varieties is established for the growth periods. Evidence shows that the model can better indicate the effect of temperature on the development of different varieties of the crop, providing useful scientific basis for farmers in their field management.

Abstract:A numerical experiment was conducted in terms of a nested mode composed of Qian's prototype(1985)and Yan's model(1987)with an improved snowcover-albedo parameterization scheme introduced to investigated effect on east Asian atmospheric circulations of east/south in summer. Tibetan snow cover available in summer in an idealized condition. Evidence suggests that the model atmosphere is highly sensitive to the cover-caused thermal anomaly: the lowlevel altitude (the upper level altitude) is heightened (lowered) as opposed to the change in the corresponding surfaces in east China; cool summer and weakend summer monsoon circulation occur in much of east Asia; rainfall is greatly reduced from east China to south Janpan in contrast to the coastwise Huanghe-Huaihe plains and northern Xinjiang.

Abstract:To investigate in numerical study the effect of largescale atmospheric environment on a tropic cyclone's track, a primitiveequation 10 level model was used, with an experimental scheme proposed for large-scale circulation experiencing remarkable adjustment. Results show that such adjustment goes through quantitative to qualitative change, suggesting that it experiences gradual (～24 h) to abrupt change, and a tropical cyclone, when right in the process of such adjustment, shows its precursor of abrupt change in its path that is given more clearly in the upper than in the mid-lower troposphere.

Abstract:Attempt is made to undertake comparative study of feedforward neural network and Logit regression model, whereby some theoretical results and properties are clarified with their application to practical problems. Also, some aspects of approximation, overfitting and model selection are examined analytically and numerically.

Abstract:As a new concept for numerical study with the IAP 2-level AGCM, full control experiment (FC) is proposed that is different from commonly used concept of control experiment (C) in that it puts under control all surface thermal forcings over the globe including land. In the FC, effect of atmospheric internal dynamic processes on shortterm climate anomaly in the model atmosphere can be better separated. The FC was performed with the aid of the AGCM. Results show that the interannual anomaly of FC-produced northern summer-half-year monthly mean sea-level pressure (SLP) is weaker than that from C (with no pronounced difference of this kind found for global and southern runs) whilst the FC-given East Asia-Western Pacific counterpart is stronger, suggesting that the role of processes internal to the atmosphere for short-range climate anomaly in the model atmosphere is innegligible in this region.

Abstract:Presented in this paper is a standardized representation of the elements in HⅢ(2n)={Z∈C^2n×2n|1/2(<Z+Z'')>0,ZJ=JZ'},where J=0 I_n-I_n 0, A>0 for a Hermitian matrix A means that A is positive definite.

Abstract:Goodtime transplantation of tobacco crop was investigated by use of drought resistance and fertilizer preservation of water uptake resin, whose effects were examined on the crop's growth, fertilizer utilization, yield, the contents of N, P, and K gradients and photosynthesis, evapotranspiration and water availability.

Abstract:Mexican Hat-form wavelet transformation is used to investigate the structures of bihemispheric and global climate change at multi-time scales and the points of abrupt change. The results suggest that climate change exhibits different cold-warm structures and abrupt points at these scales, displaying remarkable difference between the hemispheres, indicating that wavelet transformation is a powerful tool in the study of climate change.

Abstract:In the context of the meso-scale dynamic model MM4 and dust-aerosol transportation model in combination, simulation was undertaken of a sandstorm weather event and sand transfer on April 22, 1992. Evidence suggests that gale begind the cold front of Mogolian cyclone was the main factor for raising sand, which went into upper levels due to strong updraft in the frontal zone and diffused downstream mainly with the front moving; genesis and development of Mogolian cyclone was dependent on the strength of southward going cold air, midlatitude frontal zone characteristics and baroclinic instability produced by temperature and pressure distributions.

Abstract:A transpiration waterconsuming model is proposed in accordance with water satisfaction in differing growth phases of crops and timedependent curve was prepared for showing growth-phase water requirement by means of the difference between rainfall plus previous soil water and field water consumption through evapotranspiration based on the water balance equation, whereby the water requirements were investigated. And dry and wet regions were separated by use of cluster analysis based on the water variation for Heilongjiang province.

Abstract:In the context of US CERES-maize model simulation was conducted of 1992～1993 data of maize sown at a range of times in Yichuan county, Henan province, resulting in good simulations of growth conditions and yield per hectare and from the relation of stand density and sowing time to the yield were proposed an appropriate density of 8.25 and even 9.25 stands·m^-2 in fields of sufficient fertile and water supply, optimal sowing period from May 31～July 5 and 6 cm depth. Comparison with simulations of openfield maize raised over Nanyang, Henan showed mean relative error of 5.6 %. Also, it was demonstrated that theoretical solar radiation could be used in place of measurements on a daily basis so that the model is applicable for operational purpose.

Abstract:Calculated with a constructed contingency table was entropy function, which was used for assessing five rainstorm forecasts (June 22-August 7, 1996) as T63 and HLAFS model products issued by China National Meteorological Center (NMC), leading to as many numerical products that offered information of 0.182 4～0.291 4 bits for different regions of Jiangsu province in preparing rainfall prediction.

Abstract:15～25 day bandpass filtering was undertaken of 1983～1985 September-November 850 hPa zonal wind. Results suggest that 110 °E meridional wind LFO (low-frequency oscillation) wave exhibits north-(southward) propagation from the Southern (Northern) Hemisphere across the equator in a phasic manner and low-frequency cross-equatorial flow displays salient propagation east-and westward, showing periodic oscillation as cyclonic and anticyclonic circulation in the pentad mean wind. They are associated with the time-varying distribution of long spells of fine and overcast/rainy weather in autumn over the Changjiang basins in east and central China.

Abstract:Emperor Kangxi (1662～1721) of Qing dynasty paid much attention to agrometeorology and bred a new variety of high-yield early-ripening rice which was named a royal rice and cultivated not only in Beijing but in Jiangsu and Zhejiang as double harvest rice where growth season was longer, thereby greatly increasing the yield.