应用气象学报

THE IMPACTS OF SEA-SALT AND NSS-SULFATE AEROSOLS ON CLOUD MICROPROPERTIES

Zhao Chunsheng, Peng Dayong, Duan Ying

2005, 16(4): 417-425.

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Abstract:
Impacts of nss-sulfate and sea-salt on marine clouds microphysical properties are investigated using a mutil-component size-resolving aerosol model. Numerical results show that the vertical distribution of liquid water content remains almost constant as sea salts number and updrafts increase. The effective radius decreases as cloud drops number increases. The number of cloud drops is dominated by nss-sulfate. Sea-salt plays a critical role in cloud microphysical processes. Due to its large radius sea-salt particles are activated into cloud drops in the initial cloud development. Sea-salt activation decreases supersaturation by consuming water vapor and suppresses nss-sulfate activation. Sea salts can enhance cloud drops number concentration under the case of large updrafts and decrease under the case of low updrafts. Nss-sulfate indirect forcing may be overestimated in some conditions (such as updraft is low) because of the presence of sea-salt particles.

THE ENGINEERING METHOD FOR SOFTWARE OF METEOROLOGICAL SATELLITE FY-2C/FY-2D DATA PROCESSING CENTER

Qian Jianmei, Shi Jinming, Li Xiaorong

2005, 16(4): 426-433.

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Abstract:
The data processing center of geostationary meteorological satellite FY-2C/FY-2D ground applied system is one of the kernel operational systems. The operational characteristics of the satellite are described, also analysis is done of the deficit of the operational steadiness achieved in the research phase of the processing unit. According to reengineering theory on software engineering, a method of converse engineering to reconstruct data, code, interface and files is proposed. Furthermore, an attempt is made to construct the technological process of the processing unit and design the structure of operation system.

A BI-CHANNEL DYNAMIC THRESHOLD ALGORITHM USED IN AUTOMATICALLY IDENTIFYING CLOUDS ON GMS-5 IMAGERY

Liu Xi, Xu Jianmin, Du Bingyu

2005, 16(4): 434-444.

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Abstract:
A bi-channel dynamic threshold algorithm is used to identify clouds on GMS-5 images. Threshold values of clouds and surface objects are gained in visible and infrared window channels by means of a statistic histogram analysis made of 32×32 pixel matrixes, followed by cloud recognition done from pixel to pixel each of the matrixes. The effect on cloud recognition of the chosen segment and bin size for dynamic smoothing in obtaining threshold values is concerned in terms of the histogram analysis. Results show that it is appropriate to choose 32×32 as segment size, thus ensuring a sufficiently large number of samples for each king in histograms clustering analysis; when the histogram is smoothed it is appropriate to choose the small bin at 1.2%(1.6K) for the visible (IR) channel so that a relatively short step length is applied in determining dynamic threshold value for required accuracy. Test of the results by visually examining images shows that with visible and IR data available the recognition precision from the algorithm is quite good at middle and low latitudes but the precision is not so good at higher latitudes where surface is colder, snow cover is large and the sun's elevated angle is low.

ESTIMATE OF POTENTIAL PREDICTABILITY OF SUMMER PRECIPITATION IN GUANGXI

Wu Hongbao, Wang Panxing, Lin Kaiping

2005, 16(4): 445-452.

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Abstract:
To investigate and access the short-term climate forecast techniques it is necessary to know how much of interannual variability of the monthly or seasonal mean quantities is potentially predictable. It is generally accepted that the total interannual variability can be partitioned into a potentially predictable component, which arises primarily from the persistence forcing by the lower boundary conditions of atmosphere and an unpredictable component induced by "weather noise". The ratio of the two components variance provides the measure of potential predictability. By means of daily precipitation data set the predictable climate signal and weather noise variance of seasonal precipitation in summer over the Guangxi are estimated in terms of low frequency white noise extension method and the analysis of variance under the assumptions of independence and dependence. Results show that there are potentially predictable climate signals over the region, the most strong, most weak climate signals are in the center and the east, the south of the region respectively. With the absolute error smaller than 0.68 standard deviation as the criterion of correct prediction, the upper limit of correctness would be 72%, 59%, 62% in the center and the east, the south, the north and the west respectively.

K-NEAREST NEIGHBOR NONPARAMETRIC REGRESSION FOR PROBABILITY FORECASTING WITH ITS APPLICATIONS

Zhai Yumei, Zhao Ruixing, Xiao Renchun, Wang Liwei

2005, 16(4): 453-460.

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Abstract:
Although probability forecasts based on a parametric regression scheme have good fitting rates the results are not so stable. For this reason, a new approach is proposed to such forecasts by means of a K-nearest neighbor nonparametric regression technique, and the technique includes 4 main components such as a database of historical samples, production of nearest neighbor subsets, their optimization and estimate of predictands. Case experiments are conducted on univariate (cloudiness or precipitation) and multivariate joint (e. g., rainfall, total cloudiness, wind speed and temperature) probability forecasting, with the results tested. Results show that forecasts from the nonparametric regression scheme are high-stability, with good prospects in operational weather forecast.

PRELIMINARY ANALYSES OF THE INFORMATION ON METEOROLOGICAL STATION HISTORICAL EVOLUTION AND ITS IMPACTS ON HOMOGENEITY OF OBSERVATIONAL RECORDS

Wu Zengxiang

2005, 16(4): 461-467.

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Abstract:
Information of meteorological station's historical evolution includes various messages that maybe impact on homogeneity of sequence of climatological data. They are important reference bases for analyzing and verifying as well as correcting sequence of climatological data. Introduced herein are both the basic content of meteorological station historical evolution and the basic condition of meteorological station change of our country. By contrast analyses of meteorological observational data, the change of meteorological stations historical evolution impacts on homogeneity of sequence of climatological data is discussed. The results show that the change of meteorological station historical evolution is one of important facts which causes inhomogeneity of climatological data sequence. Especially, the movement of observational station and change of station's environment as well as change of observational instrument type or observational time has directly effect on continuity of observational records and the homogeneity of long sequence of climatological data. So, the archives of meteorological station historical evolution are of significance for studying the homogeneity of climatological data sequence.

CHARACTERISTICS OF SURFACE WINDS IN TAKLA-MAKAN DESERTS AND THEIR RELATIONSHIP TO THE ORIENTATION OF DUNES IN NEIGHBORING REGIONS

Zu Ruiping, Zhang Kecun, Qu Jianjun, Ling Yuquan

2005, 16(4): 468-475.

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Abstract:
Study is performed of the near-surface wind fields in the Takla-Makan Deserts by use of 17-station winds and the high-level circulation situation, with focus on the relation between wind-filed features and dunes arranged in the neighboring areas. Results suggest that in the background of upper-air westerlies, the near-surface wind features are produced from the dynamic bifurcation and lifting by Tibetan Plateau and Tianshan Mountain Ranges, as shown in the following: in winter easterly (westerly) winds prevail east (west) of the Niya River; in summer northwesterly and westerly (northeasterly) winds are prevalent west (east) of the Keriya River; the NE (NW) winds get decreased (increased) form east to west, with N—S wind strength changing in a complex manner; the sand transport potential is less than 200 VU in the Takla-Makan Deserts except Ruoqiang County, the Deserts falling into a low-energy wind environment dominated by a single-peak or an acute bi-peak form, with the energy higher in the eastern and middle parts and low in the western and southern portions of the Deserts; the orientation of dunes depends largely on the concluded angle between the major and minor winds for carrying sands and the ratio of their transported sands, with the orientation perpendicular to the maximum sand amount transferred.

MAIN CLIMATIC FACTORS AND LAND COVER EFFECTS ON SANDSTORMS IN THE CENTRAL PART OF INNER MONGOLIA PLATEAU

Tian Yuhong, Ji Zhongkui, Liu Hongyan

2005, 16(4): 476-483.

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Abstract:
Study is conducted of effects of such climate factors as rainfall, temperature and 0-cm ground temperature as well as surface vegetation cover in relation to diverse land cover types and land use modes upon the frequency and intensity of sandstorms in the central part of Inner Mongolia Plateau. It can be assumed that there is no universal feature regarding effects of such climate factors as temperature, precipitation and vegetation cover except greater effect given by rainfall, the higher impact of vegetation is limited to agriculture-pasture transitional zones and pasture land in sub-meadows and sub-steppes in the grazing land. The anti-desertization for reducing the danger of sandstorm should be specific to regional condition and vegetation restoring is suggested as the focus in the transitional zone.

RELATIONSHIP BETWEEN QINGHAI-XIZANG PLATEAU REGION MONSOON FEATURES AND ABNORMAL CLIMATE IN CHINA

Bai Huzhi, Ma Zhenfeng, Dong Wenjie

2005, 16(4): 484-491.

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Abstract:
Time series of pentad mean 600 hPa height indices of Qinghai-Xizang Plateau region Monsoon features and derived from 1951—2000 NCEP/NCAR reanalysis of daily gridded data (2.5 °×2.5°), with which to investigate basic features and trends of Qinghai-Xizang Plateau high field index (QXPFI) on an interdecadal basis. Results indicate that the 600 hPa level is under the control of a low (high) in summer (winter), with the low tending to appear ahead of time and intensity progressively, on the whole, the annual variation in the indices is similar to that of the number of rainy days in Qinghai-Xizang Plateau. Moreover, correlation of QXPFI to the 160-station precipitation and air temperature in China shows that, on a simultaneous basis, the indices are significantly correlated to the precipitation as "﹣+﹣ " in zonal bands from northern to southern China, and the indices display a positive correlation with winter temperature, which is most significant over eastern edge of Qinghai-Xizang Plateau and South China.

INTERANNUAL AND INTERDECADAL OSCILLATIONS OF MEIYU OVER THE MIDDLE-LOWER REACHES OF THE CHANGJIANG RIVER FOR 1885 —2000

Wei Fengying, Xie Yu

2005, 16(4): 492-499.

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Abstract:
A scheme is proposed for detecting multi-scale climate accidents by means of the combination of Morlet wavelet transform and statistical validation with which to examine multiscale spectrum structure of Meiyu intensities in the timeseries for 1885-2000 over middle-lower reaches of the Changjiang River, and make significance tests of the abrupt change points at different scales. Also the time-dependent evolution and variance contribution of Meiyu intensity series are investigated using wavelet energy density technique. Results show that on a large-scale basis, 1941 can be viewed as the division between high and low intensities and multiple abrupt change points appears at diverse time scales, for instance, during the 1885-1941 for stronger rainfall stage two phases of relatively weak rainfall occur and in 1942-2000 weak rainfall stage the 1991-2000 relatively high rainfall occur; the 2-3 and 6-7 years oscillations have higher variance in interannual variation over the study basin, the 2-3 years oscillations have pronounced variance contribution in 1978-1987 and 1996-2000, so are the 6-7 years oscillations in 1920-1932; the 23-24 and 36-37 years oscillations have higher variance contribution after the 1940s on an interdecadal basis.

ANALYSIS OF DOPPLER RADAR PRODUCTS ABOUT TYPHOON RANANIM

Zhu Longbiao, Zheng Zheng, He Caifen

2005, 16(4): 500-508.

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Abstract:
Detect products of Nongbo Doppler radar during the period of typhoon Rananim are analysed. Results show that Rananim's center located by Ningbo radar coincides with the guidance from NMC, reports from Zhoushang and Wenzhou Doppler radar. Velocity products of the Doppler radar can describe the maximum velocity pattern of typhoon Rananim well when comparing the maximum radius velocities of Doppler radars in Ningbo and Wenzhou with the extreme wind speeds occurring at Dachen and Shipu weather stations. Precipitation intensity is in good relationship with products of the echo, their relationship is further discussed, STP is about 50% of the observation.

ANALYSIS OF CONTINOUS RAINFALL IN SHAANXI IN 2003 AUTUMN WITH CIRCULATION FEATURES

Fang Jiangang, Bai Aijuan, Tao Jianling, Gao Ju

2005, 16(4): 509-517.

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Abstract:
Analysis is undertaken of spatial-temporal distributions of autumn rainfall over Shaanxi in 2003, as well as the synoptic and thermal features of atmospheric circulation, indicating that the fallout zones and time are relatively concentrated, rainfall intensity is great and duration is prolonged, which is the most severe event ever observed since 1954. In the transition from a summer to a winter pattern of circulations, with upper troposphere westerly jet moved southward to 400N, areas on the northeast side of the northeast side of the Tibetan Plateau including eastern NW China in which is located Shaanxi are under the control of upper-air divergence to the south of the jet and the areas have high temperature and rich moisture in lower levels, answerable for active rising motion, leading to a mechanism for lower-convergence and higher-level divergence. At this site a relatively stable situation is kept for 500 hPa circulations over Eurasia. A stronger and more eastern and western subtropical high has its outer-region southerly flows responsible for transporting large amounts of vapor, thus leading to a spell of continuous overcast and rainy weather in the northwest part of the country, which comes to an end when a midlatitude Xinjing high is established and subtropical high moves eastward and retreats toward the south.

STUDY ON SOUNDING BALLOON DRIFTING AND ITS IMPACT ON NUMERICAL PREDICTIONS

Liu Hongya, Xue Jishan, Shen Tongli, Zhuang Shiyu, Zhu Guofu

2005, 16(4): 518-525.

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Abstract:
To investigate the impact of height-depending sounding balloon's drifting on numerical prediction and extract to the full utility of soundings, a positioning scheme is designed to locate the balloon's position at every pressure level, based on sounding principles. Data used before and after the position correcting are assimilated using the 3D-VAR system separately, with the assimilations applied as the initial field of the WRF model for predictions, which then undergo analysis for comparison. The main results are as follows: (1) the distance a sounding balloon drifts during operation is a lot longer than that is accepted as a horizontal resolution by present numerical models; (2) the positioning scheme presented for sounding balloons is basically applicable to a resolution of 10km×10km; (3) on the whole, the position correction leads to the fact that the resulting analytic increment field is one order of magnitude smaller than the original; (4) analysis of the model predictions shows that soundings, when positioned, would improve predictions. Moreover, the accurate position correction of leveled soundings will better the output of high-resolution numerical models to some extent but further case studies are needed.

2005, 16(4): 526-526.

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Abstract:

INFLUENCES OF SSTA IN INDIAN OCEAN, SOUTH CHINA SEA AND SOUTHEASTERN COASTAL REGION OF CHINA ON YANGTZE-HUAIHE RIVER VALLEY PRECIPITATION OF JUNE AND JULY

Wang Zhongrui, Qian Yongfu

2005, 16(4): 527-538.

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Abstract:
By using the statistics method and numerical simulations, influences of SSTA in Indian Ocean, South China Sea and southeastern coastal region of China on Yangtze-Huaihe River valley precipitation is undertaken. The results of statistic analysis show that the precipitation is plentiful (deficient) when the SSTA is positive (negative) anomaly. On the basis of analyzing OLR data, OLR of Yangtze-Huaihe River valley is positive (negative) anomaly when the OLR in Indian Ocean is positive (negative) anomaly, but the OLR of South China Sea and southeastern coastal region of China is negative (positive) anomaly. The results of numerical simulation show that the blocking high of middle-high latitude is stronger and the precipitation of Yangtze-Huaihe River valley is excessive when the SSTA of Indian Ocean is positive. In coastal region of East Asia, the general circulation is same with that of less rainfall of Yangtze-Huaihe River valley, in good agreement with statistical facts.

THE SOFTWARE FRAMEWORK AND APPLICATION OF GRAPES MODEL

Wu Xiangjun, Jin Zhiyan, Huang Liping, Chen Dehui

2005, 16(4): 539-546.

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Abstract:
GRSPES (Global and Regional Assimilation and PrEdiction System) is a new-generation general hydrostatic/non-hydrostatic, multi-scale numerical model of China developed by Research Center for Numerical Meteorological Prediction of CAMS (Chinese Academy of Meteorological Sciences) of CMA. The Model adopts a structure of standardized and module-based software and is developed in accordance with the strict requirement of software engineering, including the program-operated parallel calculation. Preliminary calculations show that the design and application of the model agree on the pre-requirements, thereby laying a good foundation for the sustainable development of the numerical prediction system of the country. Several approaches in GRAPES model: standardization, module and multi-scale community. According to the principles of software engineering, the system and its parallel computing are developed. Results of experiments show that both the design of model framework and the implementation of GRAPES model can meet the requirements of model processing. It's asserted that this framework plays an important role in GRSPES development.

DESIGN AND IMPLEMENTATION OF A GEOGRAPHIC INFORMATION SYSTEM FOR METEOROLOGICAL APPLICATIONS

Liu Pingao, Jiang Nan, Tan Ping, She Wanming, Ge Yihua, Ding Yueqiang, Tang Lin, Xu Lin

2005, 16(4): 547-553.

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Abstract:
As a thematic Geographic Information System (GIS) for meteorological applications, MeteoGIS is set up originally based upon programming in C# on the Microsoft.NET platform for general purposes. A self-copyrighted and independent GIS kernel is developed to meet the urgent needs of GIS functionalities in meteorological disaster prevention and mitigation, not relying upon any commercial GIS system and its secondary development interface. The design situation, targets, significance and many key techniques are introduced. Also, its architecture, functions and applicable perspectives are illustrated briefly.

ADVANCES IN ATMOSPHERIC THERMODYNAMICS ISSUES

Cao Hongxing

2005, 16(4): 554-416.

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Abstract:
A comprehensive overview on the advances in atmospheric thermodynamics since 1980s is presented and some non-traditional issues, such as the global warming, the urban heat island and so on, are expounded. On the basis of nonlinear theory of atmospheric non-equilibrium thermodynamics, a numerical model is developed which is devoted to emphasizing thermodynamic effect, with its necessity and possibility discussed.

Vol.16, NO.4, 2005