应用气象学报

TIME-DEPENDENT SOLUTION OF COUPLED AIR-SEA CLIMATE MODEL

Feng Guolin, Cao Hongxing

1996, 7(2): 212-220.

[FullText](2740) [PDF 309KB](1080)

Abstract:
By utilizing the method of quantum mechanics,a time dependent solution of the coupled air-sea stochastic dynamic model is obtained accurately.The solution reveals that the air-sea system is in a way of Brownian motion if the system is of basic state,herefrom the standpoint of Hasselmann's stochastic climate model is proved theoretically.If the system is of the first excited state,the system is in a way of decay with time or in a way of periodic oscillation with a main period of 2.3 years in certain conditions of the system. Finally,the solution is applied to study the effect of doubling CO2 on the climate.

UPPER TROPOSPHERIC MOISTURE DISTRIBUTION OVER THE TIBETAN PLATEAU AS REVEALED FROM GMS-5 WATER VAPOUR IMAGES

Xu Jianmin, Zheng Xinjiang, Xu Huan, Fang Xiang

1996, 7(2): 246-251.

[FullText](2805) [PDF 1049KB](1238)

Abstract:
With GMS-5 Water vapour images the upper tropospheric moisture distribution over the Tibetan Plateau is analyzed.It is indicated that water vapour accumulation over the Tibetan Plateau is mainly in one of the following ways:(a)Climbing up through Yarlung Zangbo River and Brahmaputra River valley;(b)Acrossing Himalayas;(c)Drifted from upstream Pamir through Tarim Basin;(d)Local ascending motion. Mean moisture pattern reveals a moisture region in the southeast part and a dry region in the northwest part of the Plateau.The boundary between the two regions is along the mountain ranges in the middle of the Plateau.This boundary is the place where new systems is triggered,which may cause regional precipitation later in the eastern part of China in July and August of 1995.Of seven major regional precipitation events in Northern China,five events were related with system triggered in the Tibetan Plateau.It is also shown that water vapour images can reveal the genesis of systems over the Plateau which are favorable to the improvement of regional,precipitation forecast for the eastern part of China.

Features of Asian-Australian Monsoon’s Seasonal Cycle and Its Interannual Anomaly as Revealed from TBB Data

Zhu Qiangen, He Jinhai, M.Murakami

1996, 7(2): 129-137.

[FullText](2781) [PDF 581KB](1420)

Abstract:
Based on TBB data from Japanese GMS satellite observations, the seasonal cycle features of Asian-Australian Monsoon (AAM) are investigated. The results show that TBB data do reflect the variation of mid-low latitude circulation systems to a considerable degree. It not only reaffirms the former studies on the seasonal progress/retrogress of AAM, but also reveals some new phenomena, thereby deriving an entire picture for AAM’s seasonal cycle. The studies are also made of the formation for TBB bi-low-value-belt near the equator and the characteristics of AAM interannual anomaly revealed from TBB Data.

Two Kinds of Cyclonic Disturbances and Their Accompanied Heavy Rain in the Yangtze River Valley During the Mei-Yu Reriod

1996, 7(2): 138-144.

[FullText](2934) [PDF 1146KB](1329)

Abstract:
A case of heavy rain (1989) and a case of extremely heavy rain (1982) in the middle reaches of Yangtze River are analysed, respectively. They were associated with two kinds of low vortexes during the mei-yu period. The genesis and evolution of the two kinds of mei-yu vortexes and the accompanied torrential rain development processes are studied. One is the typical southwest vortex, it likes a weak baroclinic cyclone, but its baroclinoic structure is generated in the dynamic-thermal process of its own genesis and development in the subtropical warm environment. Another is the small-size positive vorticity disturbance traveling through the mei-yu shear line, its evolution process is more complicated. According to the two cases, some previous results from the authors themselves are verified, substantiated and summed up in this paper. And, some difficult points of the forecasting of complicated heavy rain development processes are discussed.

Composite Analyses of Monthly Sea Surface Temperature Anomalies Associated with the ENSO Cycle

Qian Weihong

1996, 7(2): 145-152.

[FullText](3750) [PDF 459KB](2244)

Abstract:
Based on 5o×5o latitude-longitude grid SST departure data, which was edited by UK and MIT in 1990 for the years of 1968~1977 and 1982~1983, the monthly global SST departure composite analyses for four El Nino events and three La Nina events during the two periods have been conducted. The results show that some warming low-frequency fluctuation centers travel obviously eastward along the equator during onset phase of El Nino event, while stable strengthening cold centers extend westward along the Pacific coast of South-North America during onset phase of La Nina event.

The Maintenance of Mei-yu Front and Development Associated Disturbance

Sun Shuqing, Du Changxuan

1996, 7(2): 153-159.

[FullText](2766) [PDF 437KB](1771)

Abstract:
A case of mei-yu front with heavy rainfall in the Changjiang and Huaihe River valley is studied in this paper. By calculating the deformation field, divergence and their corresponding terms of frontogenesis functions, their roles on the maintenace of the front and the development of frontal turbulence are analyzed. The unstable low level jet on the south side of the front is investigated. And, a special dynamic role resulting from its coupling with upper level flow, which would construct a specific secondary circulation, is also studied.

The Low- and Mid-latitude Circulation Characteristics and Moisture Transfer During the Rainstorms Period in the Middle Reaches of the Huanghe River

Dong Liqing, Ren Jinsheng, Wang Jianzhong

1996, 7(2): 160-168.

[FullText](3695) [PDF 545KB](1535)

Abstract:
Based on the meteorological data from June to September, 1981~1991, a study on low- and mid-latitude circulation characteristics and moisture moisture transfer during the rainstorms period in the middle reaches of the Huanghe River is made by composite analysis. According to the circulation systems associated with 11 cases of extremely torrential rains, two types of rainstorm processes would be summarized. One appears in the flood season (mid-summer), another is in the early or late summer. The distributions of moisture flux, divergence of moisture flux and wind vector for the two types are analysed, respectively. The results show that there are great differences in the source regions, transport tracks and convergence intensities of water vapor between the two types of rainstorms.

Researce on the Soil Reservoir Moisture Storage Capability in the Dry Farming Region Province in Eastern Gansu

Deng Zhenyong, Fang Debiao

1996, 7(2): 169-174.

[FullText](2669) [PDF 339KB](1339)

Abstract:
Based on the soil moisture data at 0~200 cm depth from 14 stations in the dry farming region of eastern Gansu Province in years 1989 to 1992, the soil reservoir moisture storage capability and its change rule of the different climate patterns in the region are studied according to the atmospheric precipitation-soil moisture circulation system. The paper gives both the soil moisture storage standards under the different degrees of agricultural drought and the deficit of the storage capability, which provide the base for the exploiting and utilizing of soil reservoir potential.

Features of the East Asian Winter Monsoon Intensity on Multiple Time Scale in Recent 40 Years and Their Relation to Climate

Shi Neng

1996, 7(2): 175-182.

[FullText](6318) [PDF 439KB](2637)

Abstract:
Utilizing the East Asian monsoon intensity indexes the features of their trend, interannual and interdecadal changes of the monsoon in January during the period of 1950~1989 and their relation to the China’s winter weather-climate are studied. It is found that the interannual and interdecadal changes of the East Asian winter monsoon were closely related to the weather in China. It was cold/dry when the winter monsoon was strong, and warm/moist weather then the monsoon was weak. However, the relationship between the monsoon and China’s climate change trend was not as good as that of the interannual and interdecadal changes. During the past 40 years, the air temperature experienced a remarkable increase, while the monsoon underwent a pronounced reduction. Since the mid-1980s, however, the winter monsoon has become rather weakened. It is also found that when the East Asian winter monsoon was strong, the atmospheric circulation showed the strong WP pattern and the EU teleconnection pattern.

Effects of Atmosphere on the Snisotropic Characteristics of Reflected Solar Radiances of AVHRR Channels

Wang Hongqi, Zhao Gaoxiang

1996, 7(2): 183-189.

[FullText](2993) [PDF 388KB](1967)

Abstract:
Through radiative transfer calculations, the effects of atmosphere on the anisotropic transformation coefficients of reflected solar radiances of NOAA/AVHRR visible and near infrared channels have been investigated for some different solar zenith angles and some surfaces. Under the assumption of Lambert surfaces, the atmospheric aerosol has an effect on enhancing the anisotropy and modifying the pattern of angular distribution of reflected radiances.

Estimating Paddy Area in Shanghai Region Using NOAA/AVHRR Data

Wu Jianping

1996, 7(2): 190-194.

[FullText](4647) [PDF 281KB](1489)

Abstract:
The data of NOAA/AVHRR, because of their some advantages, have been applied in many fields including estimation of crop area. This research applies fuzzy supervised classification to decomposing the mixed pixels of NOAA/AVHRR data and estimates the paddy area of 10 counties in Shanghai during 1992 and 1993. As compared with the statistic data in the same period the results show that the overall accuracies (ratios of estimated to statistic area) are 92.0% and 95.4%, respectively

An Objective Analysis Method of Multivariate Optimum Interpolation in Mesoscale Model

Shen Tongli, Zhou Huixi

1996, 7(2): 195-202.

[FullText](3103) [PDF 425KB](1317)

Abstract:
The forecast results from numerical weather prediction models are closely related to their initial values. Thus, the improvement of the objective analysis would result in the increase of forecast accuracy. In this study, based on the features on the features of the MOMS mesoscale model, an objective analysis method with multivariate optimum interpolation is advanced. The forecast results of T42 model is used as the first guess and the features of mesoscale model have been taken into consideration in the selection of observational stations, correction of the records, and filling up a vacancy of observation data. The objective analysis schemes have provided good initial values for mesoscale numerical weather prediction model and diagnostic analysis, which is favourable for the great improvement of the forecast accuracy of mesoscale model.

A Typhoon Numerical Model With Horizontally Threefold Structure and Its Applications

1996, 7(2): 203-211.

[FullText](3060) [PDF 523KB](1266)

Abstract:
A typhoon numerical model with horizontally threefold structure has been developed based on the MM4 model introduced from PSU/NCAR. The model was constructed of the inner, middle, outer regions with three kinds of different resolutions, respectively, and the double-way boundary feedbacks are also available between the different regions of the model. Integral physical processes are considered in the model including the effects of mountains and surface frictions, diffusions of momentum, heat and water vapor, effects of latent and sensible heat at the earth’s surface, effects of cloud and radiations and cumulus convection. The studies and the operational application results have shown that the model can predict not only the landing and recurvature tracks of typhoon and their circulation changes, but also the locations and intensities of the typhoon centers, the total rainfall amount, the rain areas and its expansion in the different typhoon processes.

Time-dependent Solution of Coupled Air-sea Climate Model

1996, 7(2): 212-220.

[FullText](2504) [PDF 309KB](1030)

Abstract:
By utilizing the method of quantum mechanics, a time dependent solution of the coupled air-sea stochastic dynamic model is obtained accurately. The solution reveals that the air-sea system is in a way of Brownian motion if the system is of basic state, here-from the standpoint of Hasselmann’s stochastic climate model is proved theoretically. If the system is of the first excited state, the system is in a way of decay with time or in a way of periodic oscillation with a main period of 2.3 years in certain conditions of the system. Finally, the solution is applied to study the effect of doubling CO2 on the climate.

A Study on the Vertical Profiles of Convective Heating over China and Numerical Experiments

Zhu Rong, Xu Dahai

1996, 7(2): 221-228.

[FullText](2908) [PDF 378KB](1540)

Abstract:
In order to use MM4 model successfully in the whole region of China, it is necessary to improve the cumulus convective heating parameters in MM4 model based on the statistical analysis of real climatic data in China. The routine radiosonde data in June~Aug, 1990~1993 are collected to calculate the vertical profile of convective heating directly at each station for each time level using Kuo’s scheme without unnecessary simplifications. The calculated results are taken statistically in terms of the district of meteorological stations. The results show that the peak values of the profiles at upper and lower parts in convective clouds are all lower (the peak values δ＝0.65~0.80) than the originals in MM4 model, and that the vertical distribution of heating rate on the region south of the Yellow River is rather uniform, but on the region north of the Yellow River the heating is mostly concentrated on some layer (the peak values δ＝0.50~0.65). All these are related to the climate condition and local circulation in each area of China. Substituting these vertical profiles of convective heating for the original heating parameters in MM4 model, it is found that the forecast accuracy on each precipitation level is improved greatly and the false alarm ratio is decreased during the last years of operational application

A Study on the Calculation Method of Turbulent Transfer from Different Underlying Surfaces

Liu Shuhua, Liu Heping

1996, 7(2): 229-237 .

[FullText](2567) [PDF 349KB](1465)

Abstract:
Based on the wind velocity and temperature gradient data of surface layers from three kinds of underlying surfaces, the sensible heat flux and the coefficient of heat exchange are obtained through iteration using the profile formula of wind velocity and temperature. Therefore the relationship formula between K h/K w and stabilityξis established. And then the latent heat flux is calculated using the aerodynamics method and Bowen ratio-energy balance method, respectively. The calculated results of these two methods are compared with each other.

The Discussion of Some Problems Existing in Current Atmospheric Dynamic Models

Liao Dongxian

1996, 7(2): 238-245.

[FullText](2588) [PDF 375KB](1450)

Abstract:
Some problems existing in current atmospheric dynamic models are proposed, such as vertical discretization, increasing resolution, prediction of the polar regions, discontinuous problems, nonlinear aliasing, computation of the longitudinal finite-difference quotient in high latitudes and so on. In analyzing those problems, possible ways for solving them are suggested and discussed. For example, in discretizing the hydrostatic equation in the vertical, taking lnσas vertical coordinate, instead of σin the case of equal interval, is able to reduce computational errors substantially, and nonlinear aliasing can be neglected only in the case that the factors of the product computation are smooth sufficiently when spherical harmonics are taken as basis functions.

Upper Tropospheric Moisture Distribution over the Tibetan Plateau as Revealed From GMS-5 Vapour Images

1996, 7(2): 246-251.

[FullText](2860) [PDF 1049KB](1518)

Abstract:
With GMS-5 water vapour images the upper tropospheric moisture distribution over the Tibetan Plateau is analyzed. It is indicated that water vapour accumulation over the Tibetan Plateau is mainly in one of the following ways: (a) Climbing up through Yarlung Zangbo River and Brahmaputra River valley; (b) Acrossing Himalayas; (c) Drifted from upstream Pamir through Tarim Basin; (d) Local ascending motion. Mean moisture pattern reveals a moisture region in the southeast part and a dry region in the northwest part of the Plateau. The boundary between the two regions is along the mountain ranges in the middle of the Plateau. This boundary is the place where new systems is triggered, which may cause regional precipitation later in the eastern part of China in July and August of 1995. Of seven major regional precipitation events in Northern China, five events were related with system triggered in the Tibetan Plateau. It is also shown that water vapour images can reveal the genesis of systems over the Plateau which are favorable to the improvement of regional, precipitation forecast for the eastern part of China.

The NOAA/AVHRR Remote Sensing Database Effective Management System

Zhao Lizheng, Zhang Shuyu, Zeng Ying, Liu Aiqin

1996, 7(2): 252-256.

[FullText](3648) [PDF 299KB](1168)

Abstract:
Based on the data in large amounts collected by the meteorological satellite data microcomputer handling system, the NOAA/AVHRR remote sensing database effective management system is developed. The general design, the principle and function, the technical captions and application are given. Through the effort for a year, the database fitted for the local areas of Shaanxi Province is built. This is a new way to manage the satellite remote sensing data effectively.

Vol.7, NO.2, 1996