应用气象学报

"NON-BOGUSSING" INITIALIZATION FOR TROPICAL CYCLONENUMERICAL PREDICTION AND ITS FEATURES

Yan Jinghua, Ding Weiyu, Xu Jianping

2004, 15(5): 513-522.

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Abstract:
For the demand of fine prediction and based on the features of high resolution models, the "non-bogussing" initialization was tested to make fine prediction of tropical cyclones (TC), i. e., the initial fields from 4-dimensional assimilation was adopted, without adding the TC bogussing, to avoid illusive information induced from idealized TC structure, and to acquire finer or more accurate prediction to the track, intensity and structure of TCs. The feasibility of the scheme was evaluated by using all TC cases which affected the South China in 2001. The results show that the scheme has a better capability to predict the genesis of TCs, and higher accuracy for track prediction, with prediction errors unremarkably increasing with integral time, and especially reflects better the complicated track and local effects. While it shows a higher skill for TC intensity prediction in terms of intensity change. In addition, it reflects well the asymmetric and spiral structures of cloud, rainfall and winds for the TCs, showing well practicability. All of these revealed the advantages and developing potentials of the scheme, which implies that "non-bogussing" initialization should be one of the main approaches for the TC numerical prediction techniques in the future. However, at the current condition, the scheme possesses some insufficiencies. The main problem is that due to the lack of observational information, larger errors may often occur in the initial TC position or intensity, which may cause larger prediction errors, when the TC is too weak, newly arising or far away from the mainland.

FOUNDATION OF MEDIUM-RANGE NUMERICAL FORECAST SYSTEM T213L31 ON HIGH PERFORMANCE COMPUTER IBM/SP

Chen Qiying, Jin Zhiyan, Wu Xiangjun, Yao Mingming, Ali Mechentel

2004, 15(5): 523-533.

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Abstract:
Using combined method of distributed and shared memory parallelization, new global spectral model based on ECMWF is run on high performance computer INM/SP with great efficiency in National Meteorological Center (NMC) for the first time. The model performance is improved greatly by means of changing vector length, optimizing program design, ameliorating message passing mechanism, realizing joint application of distributed and shared memory parallelization, to decrease communication, calculation and memory consumption. Now 10-day forecasts of the model with resolution T213L31 can be finished within 3 hours so as to satisfy operational time requirement.At the same time, the parallel Optimization Interpolation (OI) analysis system matching T213L31 global spectral model is constructed, and the problem of calculation load imbalance produced by spatial heterogeneousness of global observation stations is resolved, so that T213L31 global data assimilation and forecast system is built based on the above work, and so is corresponding automatic job control and watching system.

FORECASTING AND EVALUATION OF MM5 NUMERICAL PREDICTION IN SHANGHAI WITH GRAPES-3DVAR SCHEME

Zeng Zhihua, Ma Leiming, Liang Xudong, Duan Yihong

2004, 15(5): 534-542.

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Abstract:
The applications of GRAPES-3DVAR in MM5 numerical prediction was introduced briefly. Meanwhile, the 3 months' (March, 2003—May, 2003) observed data of the East China and the numerical prediction results of MM5 with GRAPES-3DVAR were used for evaluating the models 'prediction ability for precipitation. Then effects of GRAPES-3DVAR on the results of MM5 numerical prediction were analyzed. The results show that GRAPES-3DVAR scheme is rather reasonable. It was indicated that 24-hour precipitation prediction with assimilation is better than those of without assimilation for most of regions in the East China and the EH value is higher with assimilation for most of regions in the East China as well.

MULTI-SCALE TURBULENT PLANETARY BOUNDARY LAYER PARAMETERIZATION IN MESOSCALE NUMERICAL SIMULATION

Zhu Rong, Xu Dahai

2004, 15(5): 543-555.

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Abstract:
Based on the multi-scale turbulent theory the sub-model of Multi-scale turbulent planetary boundary layer parameterization is set up by analyzing the relation of the gradient of average wind and the spectrum of turbulence in atmospheric boundary layer. Then the submodel is applied in MM5 to simulate the storm rainfall. Meanwhile the result of simulating is compared to that of the boundary layer parameterization of MRF and Blackadar originally included in MM5. After simulating the heavy rainfall between Changjiang and Haihe in Jun 22nd, 2002, it shows that the effect of the physical process in atmospheric boundary layer on mesoscale rainstorm is obvious because the change on vertical transportation of the momentum, heat and vapour near ground result in great difference in wind in lower level of MM5 and have effect on the birth and development of mesoscale synoptic system. In additional, the result also shows the ability to forecast large scale weather system is relied on the initial field and the dynamical structure of numerical model. The physical process has less effect on the forecast ability of large scale synoptic system, but influence obviously the forecast ability of mesoscale synoptic system. On the several rainstorm simulating, the effect caused by turbulent exchange between ground layer and each layer in boundary layer on wind field in lower layer is obvious especially in the area with complex topographic and surface characters. Therefore, it has long-range future to apply Multi-scale turbulent boundary layer parameterization on simulating the mesoscale synoptic system. In general, it is feasible to apply Multi-scale turbulent theory on mesoscale numerical simulating. Introducing the turbulence σ_w, σ_T and the sizes of eddy make it possible that the vertical motion in atmospheric boundary layer not only directly relate to dynamic structure of ground layer, for example Z₀, but also relate to the nonuniformity of heat structure in ground layer and every layer in atmospheric boundary layer, and it is just the advantage of Multi-scale turbulent boundary layer parameterization.

THE PARALLEL COMPUTATION OF GUANGZHOU AREA NUMERICAL PREDICTION MODEL

Yuan Jinnan, Wang Zaizhi, Xue Jishan

2004, 15(5): 556-563.

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Abstract:
The parallel computation of the recently developed Guangzhou area numerical prediction model was researched by using Message Passing Interface (MPI) method. According to the characters of model structure and model computing process, the model is suited to parallel computation by using horizontal section-method. The parallel computation of the model has been realized by using one dimensional and two dimensional section-method, respectively, and parallel efficiency, parallel acceleration-rate and percent of parallel communication-time of the model have been tested on DAWN-3000 parallel computer. Results show that two parallel methods can finish 72-hour forecast in one hour by using 8 CPUs, the parallel efficiency of one dimensional section-method keeps about 90%, which can meet the operational need. When more than 8 CPUs are used in the model, the communication-time of the model increases rapidly and beyond 50% of the computation time, the parallel efficiency of the model decreases dramatically. One dimensional section-parallel-method of the model is simpler and more efficient by using the same CPU than two dimensional section-parallel-method of the model.

ANALYSIS OF SCATTERED SIGNAL IN GEOSATIONARY METEOROLOGICAL SATELLITE IMAGE

Wei Caiying, Zhang Xiaohu, Qiu Kangmu

2004, 15(5): 564-571.

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Abstract:
The images of infrared, water vapor and visible channel from GMS 5 raw data and GMS 5, FY-2A, FY-2B S-VISSR data are analyzed by using method of pseudo color enhancement and histogram. Some scattered signals are found in the images of three Geostationary satellites, FY-2A, FY-2B and GMS 5. This problem completely depends on the optimize of the optical structure of the spin scan radiometer. When S-VISSR data are produced in real time, it is possible that scattered signals within cold space area of the image can be reduced or eliminated, but it is more difficult to eliminate those in the image of earth area.

EXTRACTING BASIC FLOW FROMOBSERVATIONAL WIND

Huang Sixun, Zhang Ming, An Jie

2004, 15(5): 572-578.

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Abstract:
A f-plane approximation, linear and nonviscous two-dimensional Boussinesq equations is used to extract basic flow from observational wind find by determining functional minimum. On one hand, the basic flow extracted by this method is satisfied with the governing equation. On the other hand, squared the mode of dispersion between the basic flow and the observational wind, then take the average of them along the perpendicular direction, the result obtained is minimum. Subtracting the basic flow from observational wind field, the disturbance wind field can be extracted, and the instability problem of basic field and the temporal evolvement of disturbance field are studied. Here the scheme of numerical calculation and the cases of real operational works are presented too, which indicate the feasibility of the method.

STUDY OF CINRAD/SA PRODUCTS FOR A HAIL STORM

Zhu Junjian, Diao Xiuguang, Huang Xiushao

2004, 15(5): 579-589.

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Abstract:
The products of CINRAD/SA during the course of generation, development and motion of a hail-storm which occurred near Dong'e county in Shandong Province on September 27, 2002 are analyzed. The storm has the characteristics of supercell, such as a "V-notch", a boundary weak echo range (BWER) and a mesocyclone. Mesocyclone exists in the storm for almost 90 min. The speed of relative movement (SRM) in different slice can also display the procedure of the mesocyclone occurring, developing and dying out. The storm tracking information (STI), mesocyclone (M), hail index (HI) and vertical integrated liquid water (VIL) are valuable for identifying and forecasting the hail.

THE DIFFERENCES OF SYNOPTIC PHYSICAL CONDITION BETWEEN MCC AND MESO-β-SCALE CONVECTIVE CLOUD CLUSTER

Qin Danyu, Jiang Jixi, Fang Zongyi, Ma Lan

2004, 15(5): 590-600.

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Abstract:
The differences of synoptic physical condition between the mesoscale convective complex (MCC) on June 22—23, 2002 and the meso-β-scale convective cloud clusters (MβCCC) on July 23—24, 2002 are analyzed by using NCEP/NCAR 1°×1° reanalysis data as well as GMS infrared body temperature (TBB) data. Results demonstrate that the MCC develops in a weak baroclinic environment, a 850 hPa horizontal wind shear line with a vortex dominated in the low levels and an anticyclone in upper levels, without baroclinic wave trough accompanying in midlevels. In contrast to MCC, the MβCCCs tend to develop in the right entrance region of a mean 200 hPa jet stream. Although the low level conditions are quite similar for both MCC and MβCCC, the evolution of the MβCCC is more related to a midlevel short-wave trough (main forcing) more than MCC, which is driven by a low-level θ_se gradients. Evidence also supports that the MCC needs abundant higher energy supply than the MβCCCs with larger and deeper θ_se tongue and a broader convective instability area.

OBSERVATIONAL AND NUMERICAL STUDY OF TOPOGRAPHY INFLUENCE ON MONGOLIA CYCLOGENESIS

Jiang Xuegong, Shen Jianguo, Liu Jingtao, Chen Shoujun, Wang Yingchun

2004, 15(5): 601-611.

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Abstract:
Observational study and numerical simulation are conducted on the topography influences on the Mongolia cyclogenesis. The results show that the Mongolia cyclogenesis can be divided into two processes, namely triggering process and development process, according to the appearance of surface cyclonic cold front. In the development process, the baroclinicity is the main forcing mechanism causing the development of Mongolia cyclone. The topography influences focus on: 1) The Altai-Sayan complex mountains retarded the cold air in the lower troposphere so that the Mongolia cyclone developed slowly before the cold air completely toughed the lee side and after that it developed explosively. 2) The baroclinicity was enhanced by the complex mountains (steepened the isentropic surface), which made the enhancement of vorticity concentrated downward at the low troposphere and so reinforced the development of surface cyclone. 3) The complex mountains affected the position, range and strength of the lowel level jet. In the upper troposphere the isentropic potential vorticity (IPV) advection contributed to the cyclogenesis and its effect was limited.

INSTABILITY OF INTERANNUAL TELECONNECTIONS BETWEEN THE SUMMER RAINFALL IN JIANGHUAI REGIONS AND THE 500 hPa CIRCULATION IN NORTHERN HEMISPHERE

Yang Qiuming

2004, 15(5): 612-622.

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Abstract:
The interdecadal variations of the interannual teleconnections between the summer rainfall in the Jianghuai regions and the 500 hPa height field anomalies over the Northern Hemisphere are studied based on both sets for two periods 1957-1976 and 1977-2000. A teleconnection instabitity index is introducted, and the spatial and seasonal variations of the instability are discussed. Results show that difference of the teleconnection spatial distributions for two periods is dominant, in which the intensity of lagged teleconnection is stronger for the former period than the latter. Correlation of WP pattern in winter with summer rainfall in Jianghuai regions shows a coherent region of strong correlation before 1976 and no region with statistically significant correlation thereafter, but the correlation with EU pattern in spring was stronger for the latter period, and in the summer the correlation of EAP wave train with the rainfall is more significant for the latter than the former. It is resulted from the effects of Pacific decadal oscillation (PDO) on the interannual relationships between the East Asian monsoon rainfall and the circulation. This instability of the teleconnections is closely related to the interaction between interannual and interdecadal variations.

USING RADIANT BALANCE THEORY TO CALCULATE CONCRETE ROAD-SURFACE TEMPERATURE IN SUMMER

Liu Ximing, Yu Yingchun, Lei Guilian, Liu Zhiping

2004, 15(5): 623-628.

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Abstract:
By using energy balance method and considering the balance among solar short-wave radiation, atmospheric and ground long-wave radiations, latent heat fluxes and sensible heat fluxes, an operational forecasting model for concrete road-surface temperature is established, the parameterizations of absorption and scattering of vapor, aerosol and cloud are also adopted in this model. The daily observation data Nanchang City (from July 26, 2002 to Augest 24, 2002) have been used in the validation of model, results show that when sunshine hour per day in summer is less than 5 h, the biggest error of forecasting for the highest road-surface temperature is than 4℃, and the mean absolute value of the errors in validation period is less than 2.13℃, which proves that the model is practically useful. But in rainy or non-sunshine days, the model doesn't work well.

A REVIEW OF THE CURRENT DEVELOPMENTOF ATMOSPHERIC AEROSOL MODELS

Yan Peng, Li Weiliang, Qin Yu

2004, 15(5): 629-640.

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Abstract:
The development and utilizations of atmospheric aerosol models are briefly reviewed. The characteristics of some currently used gas-aerosol thermodynamic equilibrium models and the more complicated integrated dynamics-chemistry models are described, which are suitable for urban and regional air quality assessment. Also the complexity in developing a comprehensive dynamic-chemistry aerosol model are discussed, and some aspects for model development and improvement are indicated, which include the mechanism of organic aerosol formation and transformation, aerosol formation and transformation under cloudy or foggy conditions, and the coupling of complicated aerosol physical-chemical model with regional or global models.

Vol.15, NO.5, 2004