应用气象学报

Numerical Experiments on the Effects of Qinghai-Xizang Plateau Snow Cover in Winter and Spring on General Circulation over East Asia in Summer

Lu Xianchi, Luo Yong

1994, 5(4): 385-393.

[FullText](3131) [PDF 527KB](1126)

Abstract:
Numerical experiments are conducted to study the influences of snow cover anomaly over Qinghai-Xizang Plateau in winter and spring on general circulation, ground heating field and precipitation over East Asia in summer using IAP 2-L AGCM. Preliminary results show that the effects are of strong persistence and the responses over East Asia in summer (JJA) are notable. When the Plateau snow cover in winter and spring is thicker in depth and larger in extent, 500 hPa geopotential height becomes lower over the regions from the Plateau to the northern China in summer, while higher in the southern China. The intensity of subtropical high over West Pacific is weaker. The responses of atmosphere to snow cover anomaly are of obvious characteristics of wave train. The ground temperature becomes lower over the areas of the northern part of China, while higher over the southern China. The distributions of monthly precipitation anomaly are not completely the same among summer months, which are closely related to the distribution of 500 hPa geopotential height anomaly in the same period

A Study of Remote Sensing Ozone Vertical Profile in the Atmosphere Using Brewer Ozone Spectrophotometer

Zhang Yiping

1994, 5(4): 444-453.

[FullText](3505) [PDF 439KB](1237)

Abstract:
A spherical shell model has been carried out to analyze the information content of Umkehr measurement of Brewer work wavelengths, and a new method considering the aerosol effects on ozone profile retrieval is given by using Brewer spectrophotometer. The new method which put the aerosol correction directly into Umkehr inversion algorithm is described in detail, and the aerosol optical thickness is used to calculate the aerosol correction coefficient. The Table Mountain data has been analyzed using this method. The results are in better agreement with other measurement results. Beijing data from January to March, 1991 are also processed. There exists an approximately linear relationship between stratospheric aerosol optical thickness and aerosol errors of each Umkehr layer produced by normal method without aerosol correction. The results with aerosol correction are well compared with other work

A STUDY OF THE DIFFERENCE OF LOW-FREQUENCY OSCLLLATION BETWEEN THE TYPICALOOD/DROUGHT YEARS IN CHANGJIANG VALLEY

Chen Lizhen, Zhang Xiangong, Chen Longxun

1994, 5(4): 483-488.

[FullText](2536) [PDF 325KB](1206)

Abstract:

Analysis Increment Vertical Interpolation Scheme in T63 Data Assimilation and Its Experiments

Shen Yuanfang Ding Xiaoliang Xie Shaosheng

1994, 5(4): 489-495.

[FullText](2879) [PDF 298KB](1051)

Abstract:
The analysis increment vertical interpolation scheme with the help of p-η coordinate transformation in T63 data assimilation system in NMC, SMA is described and the comparison results of control test with the ordinary interpolation scheme are presented. It is shown that increment scheme can reduce vertical interpolation error and provide better initial values. Therefore, it plays an important role in improving data assimilation and model forecasting.

Surface and Planetary Albedo over the Tibetan Plateau

Sun Zhian

1994, 5(4): 394-401.

[FullText](3632) [PDF 396KB](1757)

Abstract:
Using the ISCCP satellite data the method of determining the surface albedo over the Tibetan Plateau is discussed. On the snow-free surface, the broadband surface albedo can be calculated using radiation model based on the visible albedo provided by ISCCP. It is assumed in the calculations that the ultraviolet albedo and the ratio of the near infrared to visible albedo are both constant. It is found by sensitivity study that the assumptions would not introduce significant error in the calculations. On the mixed snow and snow-free surface, the broadband surface albedo can be expressed directly by the ISCCP visible albedo. The test results have been compared with the surface observations and agree well with them except in the desert areas. The planetary albedo in clear day over Tibetan Plateau is also computed. It is found by comparison with the ERBE satellite observations that the aerosols in the desert area around the Plateau have a significant influence on radiation budget from May to September. In the rest months, however, the effect of aerosols can be neglected. The results of model calculations are generally in good agreement with the ERBE measurements.

An Observational Study of Methane Emission of Rice Paddies in Zhenjiang Lin’an

Wang Mulin, Li Xingsheng, Cheng Hongbing, Shao Zhiqing, Liu Qijun

1994, 5(4): 402-408.

[FullText](3232) [PDF 312KB](1330)

Abstract:
Methane (CH4) flux from rice paddies was observed in Lin’an (34°14′N, 119°42′E) of Zhejiang province by using the static chamber during July through September 1990. Methane flux in the range of 3.67—16.14mg/m2·h was obtained during the irrigating period. The averaged methane emission flux is 10.58mg/m2·h. The CH4 release rates are shown that there is a strong diurnal variation with a maximum value at night or in the early morning and a minimum value in daytime. A seasonal variation of CH4 flux from rice paddies exhibites a rapid rising from rice plant tilling to heading periods. Then, CH4 emission decreases with water level in the rice paddies. In addition, methane emission is also related to the natural conditions, such as temperature, wind speed and rain

Numerical Experiment of the Effects of Cloud/Radiation on the Medium-range Numerical Weather Prediction

Zheng Qinglin, Hu Yihong, Gu Yu

1994, 5(4): 409-417.

[FullText](2626) [PDF 427KB](1279)

Abstract:
The T42L5 spectral model has been developed on the basis of T42L9 model, with the use of model diagnosed cloud instead of climate cloud. Using EC observed analysis of 12UTC July 1, 1982 as initial field, 5-day medium-range numerical experiments have been carried out in different cloud schemes so as to dynamically investigate the effects of cloud/radiation on the medium-range NMP. The numerical results show that: (1) The model diagnosed cloud can well simulate the real distribution of the cloud in the atmosphere and modify the calculation of radiation, and consequently improve the prediction. (2) The amount of middle and high cloud in the climate cloud is much lower than the real cloud, which results in the weakening of the synoptic system, while the model diagnosed cloud can improve the prediction due to the proper consideration of the effects of cloud and radiation. (3) The model diagnosed cloud scheme is able to successfully simulate the maximum and minimum regions of the middle and high cloud which are responded to the upward and downward areas of the Hadley circulation, respectively. In the meantime, the simulated Hadley circulation of the model diagnosed cloud is much stronger than that of the climate cloud

Several Problems of Severe Convective Storm Numerical Simulation and Its Future Prediction

Liu Yubao, Zhou Xiuji, Hu Zhijin

1994, 5(4): 418-427.

[FullText](2468) [PDF 628KB](1435)

Abstract:
By numerical simulating three cases of hailstorms with a three-dimensional elastic meso-(β‐γ) model with nested-grid, a series of basic problems of future modeling prediction of severe convective storms are investigated. It is shown that some storms may be qualitatively predicted with a simplified two-dimensional model initialized with ordinary sounding, while other storms symbolized with organized three-dimensional circulation, e. g. supercells, can only be properly done with full three-dimensional model and full environment wind components. In order to predict the life-cycle, evolution and precipitation development of various convective storms, a three-dimensional modeling computation with a comprehensive microphysical parameterization should be done and a model initial field which really represents the storm environment condition is required as well. In addition, some feedback effect of a hailstorm is also described.

A Diagnostic Study of Numerical Weather Prediction Systematic Forecast Errors in Heat

Liu Huanzhu, Zhang Shaoqing

1994, 5(4): 428-435.

[FullText](3112) [PDF 496KB](1505)

Abstract:
It is proved, that NWP systematic forecast errors in that are due to the differential equivalent potential temperature variation processes between the model atmosphere and real atmosphere during the period of validity. And it is also proved that these forcing factors which evoke the thermal variation can be split into various linear terms according to the non-acceleration theorem in a primitive equation. By applying this scheme to diagnose the forecast products of the T42L9 model (the operational model of NMC in China) in January and in July 1992, it was indicated that the model has the ability of forecasting thermal reasonable zonal mean, but there are still great errors in zonal belts, especially in the upper troposphere and low stratosphere levels in mid-latitude as well as near surface. The results of analysis by employing this scheme give reasons for the systematic forecast errors and the potential way of improving the model. And it is also shown that this scheme by applying non-acceleration theorem is an efficient tool to diagnose the NWP models physical processes.

A Study of the Correlativity Between Weather Stations and the Improvement of the Objective Analysis Scheme of MM4 Model

Zhu Rong, Xu Dahai, Zhu Tong

1994, 5(4): 436-443.

[FullText](2595) [PDF 377KB](1241)

Abstract:
Using the principal component analysis in multivariate statistical analysis, the correlations between 169 weather stations are discussed in the computation domain of the MM4 forecast model. The result shows that there are 89 key stations which play an important role in the forecasting, and the information of the other stations could be obtained from them by multivariate linear regression. It also shows that the loss of the statistical information in the whole domain is less than 2%. A storm rainfall event on 24—25, July 1992 is selected to test the regression method which is used to supplement the missing data. It is found that the objective analysis field and forecast field are improved

Application of Conjugate Equation to the Prediction of Anomalies of Monthly Mean Temperature

Ai Likun, Wu Hongbao

1994, 5(4): 454-461.

[FullText](2751) [PDF 335KB](1394)

Abstract:
To predict the anomalies of monthly mean temperature in December or June in Northeast China, the conjugate equation is employed. To testify the feasibility of the method, the historical data are put into the conjugate function formula to calculate the anomalies of monthly mean temperature, and to compare with the observations. Furthermore, a long-range prediction scheme is established by using the SST data before half a year of the initial prediction time to parameterize the equation of diabatic heat anomalies

Experiments of Real Time Numerical Weather Prediction of Typhoon Tracks

Wang Shiwen, Li Jianjun

1994, 5(4): 462-469.

[FullText](3871) [PDF 327KB](1662)

Abstract:
An experimental numerical weather prediction system of typhoon tracks has been developed by National Meteorological Center. And a modified version of the typhoon bogus developed at Japan Meteorological Agency has been installed in this experimental system. The bogus vortex, whose construction is based on the observed parameter values and empirical formula, is superposed on the original analysis as initial conditions for prediction of typhoon tracks. The initial fields can be improved by merging with the bogus vortex which resembles to the corresponding real storm in both location and structure. By using this experimental system and the bogus method, realtime forecasts are made for typhoon T9205 (ELI) and T9210 (JANIS), and results indicate considerable skill in forecasting typhoon motion.

A Review of the Symmetric Instability Theory and Its Application—PartⅡ: Non-linear Theory

Ding Yihui

1994, 5(4): 470-476.

[FullText](2798) [PDF 422KB](1929)

Abstract:
The present paper has comprehensively reviewed the state of symmetric instability theory and its application to mesoscale meteorology. Here is its part 2 which mainly deals with the nonlinear theory. It includes the general approach to study of nonlinear symmetric instability and the stability of the steady, two-dimensional non-linear symmetric circulation. Finally, the differences in application between the non-linear and linear theories are discussed

Introduction of the Operational Objective Analysis Technique in National Meteorological Center (NMC) in the Last Ten Years

Tu Weiming

1994, 5(4): 477-482.

[FullText](2709) [PDF 295KB](1643)

Abstract:
The three objective analysis schemes in NMC since 1980 are introduced and compared with each other. During this decade the objective analysis in NMC has acquired the satisfactory progress, and NWP system in NMC has been established and used in operation. The analysis results are provided for the weather stations to forecast and study weather.

A Study of the Difference of Low-frequency Oscillation Between the Typical Flood/Drought Years in Changjiang Valley

1994, 5(4): 483-488.

[FullText](2618) [PDF 325KB](1097)

Abstract:
By analysis of streamline field with 30—60 day low-frequency for the anomalous flood year (1980) and drought year (1985) over Changjiang valley during the Meiyu season, it is found that there exists a distinct difference for the pattern of low-frequency streamline field and its propagation direction. The low-frequency wave is obvious and its propagation feature in the flood year is consistent with that in the normal year, but opposite in drought year.

An Equilibrium Model for Precipitation Resources Assessment in Water Deficit Area

Zhang Jiacheng

1994, 5(4): 496-500.

[FullText](2854) [PDF 221KB](1335)

Abstract:
Based on the concept of water balance in Nature-Man System, an equilibrium model for precipitation resources assessment is proposed. The model is possible to be used as an effective tool for tapping the potentiality of all the main conponents of water resources formed from precipitation. The article succeeded to give example for its validation and suggested the mitigating approaches for solving the problem of water shortage in the deficient precipitation regions.

Dynamic Frontogenetical Equations of Meiyu Front and Its Application

Zhou Wenji

1994, 5(4): 501-505.

[FullText](3022) [PDF 220KB](2294)

Abstract:
Using Tσ as frontogenetical parameter, the frontogenetical equations which can be used in meiyu front are derived. Because horizontal temperature gradient is very weak, and the moist gradient is very strong in meiyu front, classical dynamical frontogenetical equations can not be used for diagnosis. Some cases of strong precipitation from Meiyu front over Jiang-Huai valley in 1991 are calculated. The results indicate that Meiyu front dynamical frontogenetic equations can be applied in these cases. There exist cross front secondary circulations in Meiyu front, and the circulations is nearly vertical. The cross front circulation from dry and cold regime can establish moist static stability. The frontogenetical (frontolytical) is caused mostly from ageostrophic metamorphonesis term, and it has a positive feedback relation with ascending motion of frontogenesis. The horizontal frontogenesis of Tσ in Meiyu front has well indicating action for future six hours precipitation.

A Satellite Sounding Analysis for Pinatubo Volcanic Eruption of the Philippines on 15 June 1991

Jiang Jixi

1994, 5(4): 506-512.

[FullText](3175) [PDF 392KB](1411)

Abstract:
Some significant features of evolution and propagation of volcanic ash and volcanic dust cloud of Pinatubo volcanic eruption on 15 June 1991 are studied and revealed using meteorological satellite sounding data. It provides helpful information to study the effect of this volcanic eruption on weather and climate.

Vol.5, NO.4, 1994