Vol.9, NO.1, 1998

Display Method:
Flow Structure of Hailstorm in Beijing Area
1998, 9(1): 1-7.
By using the single-Doppler weather radar observations, synoptic situations and satellite cloud pictures, the hailstorm occurring on June 22, 1995 in Beijing area is analyzed. From the retrieved horizontal and vertical wind fields, it is shown that this process occurring along a convergence band and the air flow in the vertical sections are well-organized with upward and strong rotations. The wind structure, different from traditional supercell storm conception, has its local topographic characteristics
Study of Total Precipitable Water By GMS-5
1998, 9(1): 8-14.
The feasibility for the retrieval of precipitatble water (PW) by using GMS-5 infrared “Split Window” and vapor channel brightness temperatures (BT) is demonstrated. The relationship between GMS-5 IR channel BT and PW is discussed and an empirical formula of retrieval PW is presented by using the three channels of BT. The results show that RMS errors simulated from 60 groups of atmospheric mean profiles and retrieved by GMS-5 realtime BT data and 124 radiosonde data are 0.18 g/cm2 and 0.40 g/cm2, respectively. The wide range PW distribution of clear air can be retrieved by using this empirical formula
Growth Simulation Model of Winter Wheal and Its Application in Drought Assessment
1998, 9(1): 15-23.
Based on the previous research and field experimental data, a growth simulation model of winter wheat under actual water conditions was developed in consideration of lag effects of water stress and the different sensitivity of wheat to water stress in various developmental stages. The simulated results are fairly satisfied in comparison with the measured data of different water treatments, the average error is about 10%. The calculated weight reduction of total dry matter caused by water stress was successfully used to assess the influence of drought on growth of winter wheat. The possible effects of drought on final biomass were prospected in the end of return green and jointing stage and prior to maturity stage
Analysis of the Solar Radiation Variation of China in Recent 30 Years
1998, 9(1): 24-31.
The variation trends of global radiation, direct solar radiation and scattering solar radiation data in China from 1960 to 1990 are analyzed. The results show that the global radiation and direct radiation in most part of China had very obvious decreasing trends in recent years. The same conclusion is got after partly removing the effect cloud. The variable patterns of the cloud amount and surface visual range in recent 30 years were calculated, and the results show that the visual ranges in most part of China decreased, but the variations of cloud amount were not obvious. Based on the above analysis, the preliminary conclusion is drawn that the increase of the atmospheric turbidity is one of the possible reasons for the obvious decrease of the surface solar radiation.
Comparison Between Total Cloudiness from Satellite Cloud Pictures and Ground Observations over China
1998, 9(1): 32-37.
Based on the total cloudiness of ISCCP and ground observations, their correlativity and difference in space distribution and annual variation at single station over China are discussed, and the distribution of two kinds of total cloudiness are compared. The results show that although their general trends are about the same, the satellite cloud pictures can better reveal the cloud climatic features in the Qinghai-Xizang Plateau, Taklimakan desert and coastal areas. Morever, the distribution features of total cloudiness over Qinghai-Xizang Plateau are analysed
A Numerical Study on Factors Affecting Unusual Motion of TC 9414 (DOUG)
1998, 9(1): 38-47.
Based on the numerical simulation of TC 9414, which moved in an anomalous track, by using a 10-level primitive equation model, the main causes for the TC unusual motion are studied. The role of each factor played in TC motion is studied based upon the numerical model as well. The results show that the evolution of environmental flow is the most important cause that leads to the abrupt change of TC moving track, and the structure of TC itself has small effect on its motion
The Response of Sea Temperature Interannual Variations to Sea Surface Wind Stress and Its Sensitivity Experiment
1998, 9(1): 48-58.
A Pacific general circulation model with higher resolution has been developed based on GFDL ocean model. Using this model the main characteristics on climate state, seasonal and interannual variations of Pacific upper sea temperature have been reproduced. Forcing the model with observed wind stresses from 1985 to 1995, the associated warm and cold events are simulated clearly. The sensitivity experiment reveals that the larger the successive westerly anomaly near the date line is, the more the warming in the central and eastern equatorial Pacific is. Its influences propagate and extend eastward and can reach the east coast of the Pacific in 5 months. The propagation speed doesn’t depend on the intensity of westerly stress anomaly.
Diagnostic Analysis of Maintenance Mechanism for Two Kinds of East Asian Blocking Highs in Summer
1998, 9(1): 59-64.
The maintenance mechanism of two kinds of blocking highs is studied. The results show that the distribution regimes of mean flow transfer of quasi-geostrophic potential vorticity and transient disturbance flow transfer for two kinds of blocking highs are different, and their maintenance mechanism would be different too. The transient disturbance fields of two kinds of blocking highs in diffluent regions appear to be elongate in the north-south direction. This kind of deformation plays an important role in the maintenance of blocking high.It is also shown that the synoptic scale disturbance would reduce its scale in the process of eastward movement, when energy transformation obeys the bidirectional transformation principle, a lot of disturbed kinetic energy would transfer to mean fields, and so, blocking high could be maintained.
The Statistical Diagnosis and Numerical Experiment of Atmospheric Teleconnection Patterns in Northern Hemisphere
1998, 9(1): 65-71.
The study is aiming at researching the existence, spatial-temporal features and the formation causes of circulation teleconnection patterns on the time scale of dekad in the Northern Hemisphere by using the techniques of diagnostic analysis and numerical modeling. The results show that the five types of teleconnection patterns are very clear on the scale of dekad, being strong in winter and weak in summer; the characteristic index series of each pattern has its inherent periodicity; the anomalous SST in some ocean regions can stimulate some relevant teleconnection patterns and there are no-linter interactions among the five types of teleconnection patterns. The five types of teleconnection patterns have good relationships with the general circulation and weather anomaly, so that they can be the basis of studying long-range weather process and prediction methods.
Estimating Field Evapotranspiration Using Soil Water Determined with Time Domain Reflectometry
1998, 9(1): 72-78.
The principles and methodology for measuring soil water content by time domain reflectometry (TDR) are described. Based on the determined soil moisture of different irrigation plots, the evapotranspiration (ET) of winter wheat is calculated with a field soil water budget model. The impact of the different insertion ways of TDR probes on measuring soil water storage and estimating ET is also discussed. According to the maximum passible ET values obtained in the fully-wetted root zone, actual ET under water stress root zone and ET of reference crop from meteorological data, the crop coefficient Kc and soil moisture stress factor Ks for various growth stages of winter wheat are calculated, respectively.
Estimation of Evapotranspiration of Trees and Adaptive Faculty of Water in Arid and Subarid Regions of Gansu Province
1998, 9(1): 79-87.
Using Zhang Baokun and H. L. Penman’s climatological method, the evapotranspiration of tree growing seasons is estimated in every county and city of arid and subarid regions of Gansu Province, and compared with the observed and investigated data. The results show that the two kinds of estimations could present the water requirements of fuel forest and timber forest, and the actual water resource regime are given when mean annual and daily temperature are higher than or 10 ℃ in various locations.Based on the water consumption indices of tree growing seasons and the actual water resource regime, the water adaptive faculty of trees in different climate and vegetation regions is determined using the actual wettability method
Calculation of Actual Evapotranspiration for Cotton Field by Means of the Priestley–Taylor Model
1998, 9(1): 88-93.
Based on the experimental data of evapotranspiration in the field, considering the meteorological conditions, cotton biological properties and soil moisture state, a calculation model for actual evapotranspiration of cotton field is developed by means of the Priestley-Taylor model, cotton leaf area index and relative effective soil moisture. The routine meteorological and agrometeorological data would be only needed to calculate the evapotranspiation by using the model, and there is a good precision. It can be used in arid area in China easily.
Combining Radar Network with Satellite for Quantitatively Observing and Forecasting Large Area Rainfall over the Yangtze River Valley
1998, 9(1): 94-103.
Based on the experiences of the European International Radar Network and the British NIMROD system and according to actual condition in China, a large area rainfall observation in real-time automatic system (called LARORAS) has been developed by using digitized radar network in middle reaches of Yangtze River and GMS satellite as the main technical methods and incorporating numerical wind field prediction, in which the processing technique in real time for quantitatively measuring and estimating large area rainfall accumulation over the Yangtze River valley has been successfully developed, its products have great values for preventing flood and construction of large reservoir engineering.
The Relationship Between Quasi-biennial Oscillation (QBO) of Equatorial Stratosphere and the Rainfall Belt of July in China
1998, 9(1): 104-108.
Based on the QBO data during 1953~1991, the relationship between QBO of mean zonal wind at 30~50 hPa and the rainfall belt of July in China is analysed. The results show that the position of rainfall belt in July would be to the north when it is west phase, and to the south when it is east phase. Their relations are mainly connected by the influence of QBO at equatorial stratosphere on tropospheric circulation. By using the variable rule of equatorial stratratospheric zonal wind and the characteristics of North Pacific tropospheric circulation in winter, there is practical value for the forecast of rainfall belt of July in China
The Clues for Prediction of Torrential Rain over Yangtze River and Yellow River Valleys
1998, 9(1): 109-113.
The effects of synoptic scale circumstances on the occurrence and growth of the mesoscale systems in the process of torrential rain are studied by using the synoptic and dynamic analyses methods and using a global spectral model T42L12 and a mesoscale model MM4 experiments, and from which several forecast clues of torrential rain over the middle and lower reaches of Yangtze River and Yellow River are presented. It is helpful to the operational forecast for correlative meteorological services
A Case Analysis of Bow Radar Echo Observation
1998, 9(1): 114-118.
A bow echo found in a radar observation of a severe storm is described. The characteristics, formation and structure of this echo are discussed, and the relation with the mesoscale system is analysed. It is shown that Fujita model is also suitable to mesoscale system. It is pointed out that cyclonic and anticyclonic motions would appear in the rotating head part and tail part of the bow echo, respectively. The forward movement of the tail is in a way of propagation and closely linked with divergence and convergence of near surface flow.
Synthetical Indexes of the Disaster of Snow Cover
1998, 9(1): 119-123.
By analyzing the main factors of snow damage, it is known that the snow cover burying the fodder grass is the most important disaster-causing factor, and other factors such as the depth of snow cover, a good or bad yield of grass, the physical condition and head of livestocks feeding on grass farm, the duration of snow cover are also associated with the extent of snow disaster. Therefore, a synthetical index of snow disaster is proposed.
Calculation of Earth Atmospheric Transmissivity and Radiance
1998, 9(1): 124-128.
A simplified calculation method of the earth atmospheric spectrum transmissivity and the IR radiance arrived at the top of atmosphere is introduced. Spectral range is from 4μm to ∞μm. The Elsasser band model and empirical parameters are used to calculate the absorption of H2O, and O3. The continuous absorption of H2O is calculated by LOWTRAN-6 empirical equation. The calculated results of transmissivity are coincided with those of LOWTRAN. Based on the simplified transmissivity model, a radiative transfer regression model is set up, and relevant software is developed. It is applied in data processing of satellite outgoing longwave radiation, and good results are obtained.