Abstract:Analysis and numerical experiments are conducted in the context of ECMWF daily observations and T

Abstract:A radar meteorological equation, that is applicable to groups rotating spheroidal raindrops, has been presented for horizontally polarized radar waves. As a results, radar reflectivity factors for three different cases associated with specified orientations of rotary axes have been re-defined and correction coefficients have been calculated for radar observation of precipitation with non-spherical raindrops. The results provide a new theoretical method for improvement of accuracy of quantitative measurement of heavy rainfall.

Abstract:The relation between the interannual variation of the east Asian summer monsoon (EASM) and the summer precipitation in China is investigated in terms of the east Asian summer monsoon intensity index. The results suggests that the summer precipitation of China is indigent in the year of stronger EASM, and abundant in the weak year. The relation shows four patterns including strong monsoon with abundant precipitation, weak monsoon with abundant precipitation, strong monsoon with indigent precipitation, weak monsoon with indigent precipitation. The summer monsoon circulation supported only the background for China's rainfall variation, and rainfall and its regional differences are related to the local weather systems at that time.

Abstract:A dual-channel algorithm is developed to retrieve aerosol optical thickness of cloudless atmosphere over homogeneous underlying surface from the reflectivity data in VIS and NIR bands observed by AVHRR on board NOAA-14. The adoption of the relationship between the aerosol's scattering and wavelength in this algorithm offsets the error in the parameterization of atmospheric factors and underlying surface reflectance when a single channel is used. The significant advantage of the dual channel algorithm is that a retrieving accuracy greater than 90% has been achieved under the condition of homogeneous surface.

Abstract:This paper presents a new image compression and decompression method which combines the Block Truncation Coding technique with the Jacquin's basic automatic fractal image coding technique. A coding scheme has been designed for compression of meteorological satellite cloud pictures in the light of the characteristics of satellite imagery data. Experimental results show that the new scheme, as compared with the basic automatic fractal image coding scheme, leads to less computation time and higher compression ratio without apparent depression in quality of the reconstructed image.

Abstract:By both the diagnostic and numerical experiment method, the frequency modulation effect of diabatic heating on atmospheric low-frequency oscillation (LFO) in the mid-high latitudes is researched . First the power spectral analysis is performed for the 1979-1989 ECMWF data.The results show:(1) The main periods of waves have the shortened tendency in summer comparing to those in winter.(2) The main periods of waves in the both seasons tend to shorten and lengthen during El Nino and La Nina events, respectively. By a forcing and dissipative global spectral model of quasi-geostrophic barotropic vorticity equation the numerical experiments are run for 90 days on the condition of 3-wave quasi-resonance. The results are given as follows:(1)there exist strong interactions among the three planetary waves, and there also exist quasi-two-week and intraseasonal oscillations in every wave; (2)The stronger (weaker) the external source ,the periods of LFO the shorter (longer); (3)The frequency modulation effects of diabatic heating on LFO in the mid-high latitudes are different due to the difference in the strength and location of external sources. The above results are consistent with the former theoretical results obtained by Lu.

Abstract:Based on the POP analysis of SSTA in the global tropical oceans , we introduced a phase-categorizing scheme by considering the features of large-scale ocean's movements as well as long-range prediction, determined the phases of those typical eigenmodes, and got some phase evolution rules for predicting the development trend of SSTA. The independent sample hindcast shows that the scheme is reasonable fairly good.

Abstract:The interannual and interdecadal variation of sea surface temperature (SST) in the east equatorial Pacific(EEP) from 1854 to 1990 is investigated in terms of the method of running t-test. The results indicate that the SST of east equatorial Pacific shows three sudden increasings respectively in the end of the last century, 1920s and 1950s. Based on the caeculation of running coherence coefficients, one can find that the relationship between the SST in EEP and the counterpart in the other areas over the global ocean shows strongly indecadal variations and the change of SST in EEP is synchronous with the global warming.

Abstract:Asymptotic estimation of Taylor theorem remainder θ is given through m-1 breaks in n+m order by formula based on which Taylor theorem can be popularized intowhere R_n is the remainder, . Its superiority of extension in approximate computation is shown with examples.

Abstract:Agroclimatic indices were defined for cold and warm lawn grass according to its ecoclimatic adaptability. The whole country was regionalized using cluster analysis method based on seven agroclimatic indices and climate data collected from eighty five stations. Techniques such as grass selection, breeding and weed prevention and killing were discussed for the classified regions.

Abstract:According to numerical modelling research on wheat growing period the entire wheat growing period was classified into four stages and for each stage mathematical models were established, sub-procedures programmed and parameters determined respectively. The systematical models are valuable both in understanding quantitative effect of thermal and light condition on growing stage and in managing wheat production. The system has Chinese menus, shows friendly user interfaces and is easy to revise and expand because of its structuralization and modularization.

Abstract:In this paper, with aid of graph recognition and variance analysis, an appraisal was made on fertility category of new lines of sterile rice with which united ecological experiments had been carried out on three sites located in Sanya, Wuchang and Guiyang respectively. Fertility stability of these lines was further analyzed, which may provide important foundation for judging the practical value of newly bred lines and their suitable planting regions.

Abstract:The relationship between temperature changes of China and the whole world is revealed by using the temperature data on the global grids and over Chinese 160 stations from 1951 to 1989. After combining the data on the global grids with that over China, the EOF is applied to this united data set. It's found that North China where the annual temperature warming trend is clear, if looked from the global background, is a part of the warming region centered over center north Eurasia, whereas the decreasing trend of temperature in south-west China is a local phenomenon. The space-time structure of annual temperature variation is mostly due to winter temperature anomalies. The warming trend of winter over most part of China is accompanied with the warming(cooling) trend over Eurasia and North America(North Pacific and North Atlantic), which is attributed to the strengthening of zonal(meridional) circulation over Eurasia (North America).The trend of summer temperature over the Changjiang River Basin is opposite to that over South Asia: the summer temperature is decreasing over the Changjiang River Basin and increasing over South Asia.

Abstract:A new method of prediction/correction quasi steady state approximation (PCQSSA) for solving nonlinear kinetic equations in atmospheric chemistry presented. The method has not only the advantages in the traditional QSSA and Hybrid schemes but also leads to comparatively high computational efficiency and accuracy. Therefore the method is very suitable for complex atmospheric chemistry model as well as regional pollution model.

Abstract:An approach to compute the parameters of a seemingly unrelated regression equation (SURE) models is proposed. Orthogonal transformations are employed to avoid the difficulties in directly computing the inverse of the variance covariance matrix (or its estimate) which often lead to unnecessary loss of accuracy. The procedure for solution of the special SURE models, in which the problem is constrained so that the regressors in each equation contain the regressors in previous equations as a proper subset, is considered in detail.

Abstract:The effect of tropical cyclone horizontal scale on its motion is investigated in a nondivergent, barotropic model with no basic flow. The tropical cyclone whose horizontal scale is smaller (larger) moves toward the northwest by north (the northwest by west). The asymmetric flow of the smaller (larger) tropical cyclone causes the large scale beta gyres to countercloockwise rotate a smaller (larger) angle αl. The moving direction of tropical cyclone θc is related to the angle αl,i.e., θc≈360°-αl. Therefore, the moving direction of tropical cyclone counterclockwise deflects to the west with the increasing of horizontal scale.

Abstract:Associated correlation patterns (ACP) analysis of precipitation and temperature of July in China with principal oscillation patterns (POP) of the global tropical sea surface temperature anomalies (SSTA)revealed that weather is dry in south and north China and wet in central China with negative precipitation anomalies in south and north China and positive ones in Changjiang Huaihe valley, central China, the east of northeast China and most of northwest China, when the tyical propagation POP is in phase with the development of El Nino events; the situation is opposite when the typical propagation POP is in phase with the development of La Nina events. Besides, temperature anomalies are negative (positive) where the precipitation anomalies are positive (negative).

Abstract:In the context of 10 years data (1980～1989),we get some statistical aspects of explosive cyclone in the northern hemisphere .And by comparing the occurrence frequency of explosive cyclone in different regions, times and intensities,some significant results are obtained.

Abstract:Using the kinetic energy equations and the routine sonde data, each term in the synoptic scale, subsynoptic scale and nonlinear interaction kinetic energy equation is respectively calculated in this paper in order to analyze the main dynamical processes in the "96.8" torrential rain event. The results show that there exist nonlinear interactions between synoptic and subsynoptic systems in the event. By which the kinetic energy of the synoptic system is reduced and that of the subsynoptic system is increased. In other words, the synoptic system acts as a source of kinetic energy for the subsynoptic system to grow the torrential rain system.

Abstract:An exceptional summer drought and megatherm weather struck northern China in 1997. This paper introduces the disasters of drought and megatherm happened in northern China and its contributing factors are also analyzed.

Abstract:Emperor Kangxi (1662-1721) of Qing dynesty showed solicitude for the climate and weather condition all over his country. This paper introduces the methods of his collection of the meteorological informations. He investigated these informations and estimeted the tendency of the coming meteorological desasters. He made some suggestions to avoid or reduce the possible coming dameges of the bad meteorological conditions and put the suggestions into practice effectively.