Abstract:Based upon a uniform counterpart, a gridpoint model with variable resolution is presented. It has been proved that if the former model satisfies certain conditions, has properties of mass and energy conservation and keeps the conversion between kinetic and potential energy consistent to that in the continuous transformation, then the latter model will possess the same properties and conversion as well. Further, transforming the former into the latter needs a small amount of computational operation.

Abstract:Based on the low frequency windfields, study is made of the difference in low-frequency oscillation (LFO) between flood-and drought-hit years and the relation to rainfall. Results suggest that in such years the low-frequency component makes up greatly varying portion for the circulation systems in east China and the MLCB (mid-lower Changjiang basins) rainfall-related wind features and variation are quite distinct; in 1980 as the flood year over the MLCB the change in precipitation is closely associated with the LFO in the East Asian monsoon region, especially in subtropical monsoon, with its northward propagation in a phatic manner, marked by a quasi-8 pentad period, thus responsible for the periodic variation in rainfall whilst in 1988 as the year of drought the rainfall change bears no relation to East-Asian monsoon′s LFO but to a vigorous low frequency vortex dominating the northern portion of East Asia, which originates from the one over the waters east of Japan moving north and then turning west, and the movement and development are at a quasi-8 pentad period, too, leading to change in rainfall over the MLCB.

Abstract:In the context of 1951～1995 characteristic quantities of northern circulations the secular trends of circulation variations were investigated. It turns out that for the past 45 years or so the western Pacific subtropical highs and polar vortices were intensified, and so were zonal circulations as opposed to meridional ones. Abrupt change investigation shows that discontinuity occurred largely in 1976 and early in the 1980s. The secular trends and decadal variation in these circulations represent one immediate cause of the evolution in winter temperature trend in China on a long-term basis.

Abstract:Constructed in the context of the difference in zonal wind anomaly (150 maximum westerly minus 850 hPa maximum easterly) over Atuona Marquesas Is. (9 48°S,139 2°W) is the equatorial central/eastern Pacific Walker circulation intensity index I_d, alongside the study of the relation of I_d and the length and starting season of lower-stratospheric QBO westerly phase to an ENSO event. It turns out that I_d is positively correlated, to high degree, with Southern Oscillation Index (SOI); the Walker circulation cell decelerates (accelerates) during the El Niño (La Nina) episode; the acceleration begins 20 months prior to the El Niño occurrence with upper westerly accelerated earlier and steadily; intense El Niño events happen when 30 hPa QBO westerly phase is maintained for more than 5 seasons and after the starting season (November to January, for northern winter) ends. Accordingly, we propose the “upper-level influence” concept stating that westerly momentum propagates downward from the mid stratosphere, inducing the acceleration of the Walker circulation cell over the central/eastern Pacific equatorially, thus leading to the beginning of the SSTA-related ENSO cycle.

Abstract:Response of April-June atmospheric circulations to normal and anomalous SST forcing has been investigated in terms of the perpetual integration of the General Circulation Model developed by Institute of Atmospheric Physics, Academia Sinica (IAP GCM). Evidence suggests that the perpetual run will offer a forecast one month earlier as compared to usual integration schemes without losing accuracy, thus presenting a possible approach to monthly prediction based on the GCM.

Abstract:The dynamics for a forced dissipative nonlinear critical layer is first dealt with, attaining an analytical solution of such a layer, which suggests that under the forced dissipation, a Kelvin cat′s eye emerges in the layer and the eye tends to be in a steady state as time goes on and the dissipative factor has innegligible modifying effects on a vorticity field as the Kelvin cat′s eye excited in the cirtical layer.

Abstract:A stepwise selection is made of exogenous variables (predictors) for Stepwise Logit Discrimination Analysis (SLDA) in terms of ML estimations and likehood ratio tests for Logit coefficients β, whereby is constructed a forecasting model for stepwise Logit dynamic-statistical interpretation on a daily basis for the June～September typhoon season at Nanjing.

Abstract:In the context of experimental observations and the quadratic regression revolution design, a group of models are established for three controllable cultivation factors and dynamic indices of wheat mass development between forest belts, with the yield effect related to one and all of the factors investigated, thereby sorting out an optimal scheme to provide assistance for normalized cultivation and prediction and control in advance of the crop for purposes of high yield.

Abstract:A 3D fog model was applied to investigate the genesis, development and major features of wintertime local circulation over Chongqing surrounded by mountains. Evidence suggests that downslope cold air pools the center of the city at nocturnal hours, changing to a valley-wind circulation around the noon. The circulation structure plays an important role in the genesis/dispersal of fog typical of the city. A numerical experiment was excuted concerning the impact of the circulation of fog, mountains and initial stability of the atmosphere.

Abstract:In terms of May～June 1991 SSTA over the eastern Atlantic and the three level global climatic model of Oregon State University, investigation is performed of the SSTA′s effects on the flood over the Jiang Huai valleys for June 1991 alongside the mechanism relating to the deluge in that area. It turns out that the positive SSTA in the midlatitude eastern Atlantic in connection with the negative at the tropical latitudes serves as one of the major factors responsible for the excessive rainfall.

Abstract:The grey meteorological interference factor GM(1,1) coupling model comes from the grey GM(1,1) model and the model of meteorological interference factor doubly-screening and stepwise regression and is applied to examine the 1977～1994 time sequence of cattle mortality rate for the Aba region in west Sichuan, along with a successful prediction for the 1993～1994 mortality in this region and the adjacent area of Guole, Qinghai.

Abstract:A new method is proposed for computing evaporation from water surface subject to the major factors in terms of ANN (Artificial Neural Network) capable of learning and remembering. Results show that the technique is conventient in use and yields smaller errors, thereby presenting a new line for climatological research on water-surface evaporation.

Abstract:The predictability of mean temperature is investigated for ten stations located, separately, in all climatic regions of the country in terms of information transmission as the measure of climatic predictability. Evidence suggests that the transmission at a range of scales (pentad, decade, month and year) displays attenuation features of their own in relation to the climatic background. As such, the temperature information transmission represents better the predictability. The consistent attenuation in the measured and model-yielded temperature information allows to use the transmission as a useful means for testing the predictability dealt with by a model.

Abstract:Research is performed of predicting May～September precipitation in 1991 (the exceptionally great flood year) and 1994 (the drought year), using the data from six cities of east China with the aid of the model of back propagation type artificial neural network (BP-ANN). Evidence shows that the general trend predicted for the rainfall excess/deficit agress with observations and the forecasting was attempted for the summer of 1995.

Abstract:In the context of ECMWF height data, investigation is conducted of the decadal mean and anomaly characteristics of major summer monsoon systems in May, 1985 (of drought) and 1991 (severe flood). Evidence suggests that the position and vigor of the monsoons greatly differ from decade to decade between the years; summer rainfall anomaly is associated not merely with the anomalous activities of South-Asian high, polar vortex and western Pacific subtropical high but with the strength of Australian cold high and Mascarene high, and even with the meridionality of circulations at southern extropics as well.

Abstract:Diagnosis has been done of the July 1991 Meiyu front torrential rainfall event by using the diagnostic equation of frontogenesis circulation in the primitive equation model. Results suggest that the frontal lateral secondary circulation (SC) at lowerlevels was a thermally positive circulation; the SC at the exit region of low-level jet enhanced the ascenting near the frontal surface; the negative circulation in the upper troposphere formed through coupling of the northerly on the east side of the 100 hPa Qinghai-Tibetan with the mid level southerly resulting in an anti circulation superimposed on the frontal lateral circulation, thus responsible for a deep ascending motion as one of the dynamic conditions for the rainstorm; the lateral circulation at the exit of the westerly jet contributed indirectly to the enhancement of the rainfall.

Abstract:Following the thermal index for defining the northern limit of the subtropical zone during the warming in history and the simulated global mean temperature rise in the presence of CO₂ doubling, the position of the limit is predicted for the furture in terms of the empirical expression formulated from a range of climatic indices. Results show that the northern limit will be shifted, on average, 3 degrees of latitude northward, with the SW-NE orientation.

Abstract:Based on continuous observations of atmospheric aerosols from November 15 to December 10, 1993, study is performed of the concentration, daily/interdaily variations and size, with rainfall getting rid of the particles investigated.

Abstract:Based upon observational facts and numerical simulations reported abroad, review is made of the possible climatic influence of tropical deforestation with focus on the simulations of the effect for the Amazonia.