ISSN 1000-0526
CN 11-2282/P

Volume 40,Issue 8,2014 Table of Contents

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  • 1  Classification and Characteristics of Cloud Patterns Triggering Regional Thunderstorm High Winds
    FANG Chong ZHENG Yongguang LIN Yinjing ZHU Wenjian
    2014, 40(8):905-915. DOI: 10.7519/j.issn.1000-0526.2014.08.001
    [Abstract](1705) [HTML](93) [PDF 3.87 M](1366)
    Based on the satellite data, observational data of upper air and significant weather report from 2005 to 2011, the weather situation at 500 hPa and the cloud patterns of 18 processes of thunderstorm high winds are classified and analyzed. The development of cloud patterns can be divided into 4 stages: initial, growing, mature and dissipating. The brightness temperature difference between IR1 channel and water vapor channel is mostly negative, and the number’s decreasing indicates that the severe convective clouds are still developing. We need to pay more attention to the right part or the right single cell storm of the elongated strong convective clouds when we monitor and forecast the cloud system of thunderstorm high winds, especially the low TBB areas, the high TBB gradient part and the area coordinating with the negative area of IR1 and WV channel brightness temperature difference. Quantitative statistical analysis of the characteristic value are made on the basis of subjective analysis, and we get the distribution of the infrared brightness temperature, water vapor brightness temperature, channel brightness temperature difference and infrared brightness temperature gradient near the sites observing the thunderstorm high winds. We discover that the majority of thunderstorm high winds often take place during the period when the infrared brightness temperature develops from a sharp decline to a gentle decline and at the time point when the channel brightness temperature gently slows down or becomes stable. Moreover, most examples are near the time period when the channel brightness temperature difference changes from positive to negative, and at the point when the infrared brightness temperature gradient approaches the largest area or begins to decline.
    2  Characteristics of Mesoscale and Microscale Systems During a Severe Squall Line Process
    MA Zhongyuan SU Limin CHEN Yun RUAN Zheng CHEN Baofa PENG Wangminzi CHEN shendong
    2014, 40(8):916-929. DOI: 10.7519/j.issn.1000-0526.2014.08.002
    [Abstract](1964) [HTML](65) [PDF 11.10 M](4936)
    By using the conventional observation data, disastrous loss data, AWS data, satellite infrared images, radar echoes and wind profiler products, a strong squall line process on 10 April 2012 was analyzed with statistical analysis and feature extraction method. The results show that: (1) The squall line is tightly belt shaped and composed of several tilt and deep convective cells. (2) The characteristics of mesoscal convective system (MCS) structure can be seen in FY2E infrared images. The sharp surface temperature front begins to form with MCS moving to east and precipitation cooling, moisture and heat transported by the southwest airflow and surface temperature rising. (3) Several parallel comb shaped short ribbon echoes appear and convection cells are continuously generated in the south side of the MCS. Finally they develop into a squall line echo belt in the earlier stage of the squall line system. (4) Local supercell hail storms with the structure of “front extend”, TBSS and false echo are generated continuously ahead of the squall line, causing most of the damages during this hail process. (5) The evolution of southwest jet stream including the gale area can be seen clearly in 5 min intervals wind profiler data in the early stage. (6) When the squall line system approaches, strong ascending motion ahead of the squall line can extend to 6000 m height influenced by the squall line mesoscale circulation, but the vertical velocity, Cn2 and SNR values are low. With the squall line passing, the horizontal wind shear is strong. Due to the dragging down action of strong rainfall, vertical velocity, Cn2 and SNR are significantly increased. After the squall line passes, all signals return to the initial phase.
    3  Cause Analysis on the Severe Rainfall in Zhejiang During  the Weakening of Fitow
    ZHOU Fu QIAN Yanzhen ZHU Xianchun DU Kun JIN Liang
    2014, 40(8):930-939. DOI: 10.7519/j.issn.1000-0526.2014.08.003
    [Abstract](1484) [HTML](63) [PDF 4.77 M](984)
    The abnormal severe rainfall resulting from depression circulation of Typhoon Fitow (1323) is analyzed using routine observation data, AWS data, Liangmao Mountain wind tower data, radar data, satellite data and NECP reanalysis data. The results show that the heavy rainstorm occurs during the weakening of Typhoon Fitow. When the weak cold air to the north of Fitow invades into the air column from low layers, it causes the development of the vertical vorticity, the ascending current and the upper outflow and the accumulation of energy frontal zone as well as the convergence expanding, producing the meso and micro scale weather system in this process. The persistently strong easterlies in the north of Zhejiang are responsible for the movement of Typhoon Danas to its east, which provides abundant water vapor and heat energy, making the low level convergence stronger. The convergence of easterly flow and northeast flow in the surface layer is the dynamic mechanism for this extremely heavy rainfall. The strength of the easterlies increases 2 hours earlier than the increase of the rainfall. The water vapor increases and decreases 6 hours earlier than the increase and decrease of the rainfall. The bell shaped Hangzhou Bay which has higher terrain in its west and south has precipitation enhancement effect by the windward slope and topographic convergence. Therefore the predicted rainfall time should be prolonged when cold air intrudes into the typhoon in autumn, and the wind in the Hangzhou Bay is obviously stronger when the prevailing wind directs from east, for it may increase the precipitation in surrounding areas. Improving the usage of the local and PBL observation data of local and PBL has significant effects on the nowcasting of rainstorm.
    4  Exploration of the Low Frequency Synoptic Chart Used by EOF
    XIN Fei LI Delin WANG Chao SUN Guowu
    2014, 40(8):940-947. DOI: 10.7519/j.issn.1000-0526.2014.08.004
    [Abstract](1449) [HTML](62) [PDF 7.15 M](1084)
    Based on NCEP/NCAR1 reanalysis data and GFS model data, using empirical orthogonal function (EOF) decomposition and Morlet wavelet transform to produce EOF low frequency (LF) synoptic map. The method can adjust the LF cycle according to atmospheric own LF characteristics. Analysis showed that: EOF LF synoptic map seems better in terms of location and flow of the system’s main LF low latitude areas critical convergence zone while Butterworth LF synoptic map is good at high latitudes LF systems. Also, we try to use GFS model forecast fields to get the next 1-10 days EOF LF forecast map to increase the extended forecast by LF synoptic maps method.
    5  Numerical Simulation on a Rare Severe Convective  Event in Karamay City in July 2012
    LU Bing SHI Yongqiang
    2014, 40(8):948-956. DOI: 10.7519/j.issn.1000-0526.2014.08.005
    [Abstract](1159) [HTML](71) [PDF 2.54 M](1115)
    One severe convective weather event which is so rarely seen in arid areas, occurred in Karamay City of Xinjiang on 14 July 2012. The convective event lasted for more than an hour, accompanied by short time severe downpour and hail. The process of convection is studied with composite dataset including NCEP FNL analyses, automatic weather station observations, satellite cloud image, Doppler weather radar and simulations of mesoscale numerical model WRF. The results show that, in the background of large scale instable moist stratification and complex mountain terrain, horizontal temperature gradient and topographic convergence shear get enhanced on the lee side of mountain where convective weather develops easily. The numerical simulation results of WRF model indicate that the configuration of high and low level wind, vertical shear of horizontal wind and saddle type of vertical pseudo equivalent potential temperature provides power for the ascending motion, driving the W wind speed rapidly to the maximum 6.5 m·s-1 and top level of ascending up to 9 km. The thin layer of moist neutral stratification limits the growing of vertical ascending motion so that the area of ascending motion is narrow and small, causing the severe precipitation to happen only in a local area. Mountainous terrain plays an obvious and complicated role in developing strong convection. The convergence of ground wind is enhanced by orographic effect, and the nonlinear disturbance of airflow over mountain prompts the rapid development of severe convection.
    6  Establishment and Analysis of the Daily Monitoring Index for Huaxi Autumn Rain
    WANG Chunxue MA Zhenfeng ZHANG Shunqian WANG Jinting FANG Yihe
    2014, 40(8):957-964. DOI: 10.7519/j.issn.1000-0526.2014.08.006
    [Abstract](1209) [HTML](230) [PDF 7.22 M](821)
    Based on the daily precipitation and daily sunshine hour data from 1972 to 2011 at meteorological observation stations, a new monitoring index (Daily Autumn Rain Index, DARI) of Huaxi autumn rain is defined. The temporal spatial applicability of DARI is analyzed and the intraseasonal variability is researched too. Based on the actual meteorological disaster records the strong years when more autumn rains occurred in the related provinces are indentified. Compared with the new monitoring index (DARI) it is found the DARI and the strong years are consistent in most cases. Of course, there exist some inconsistencies as well. In some years the monitoring indicators show the strong side, but there are no disaster records. Some literatures and the actual rainfall data indicate that the monitoring index matches with the actual situation. In some years there are disaster records, but little autumn monitoring index. Further research indicates that the disasters tend to occur only in a few days, in most of the remaining time it is normal or weak, so there is no reflection in the year index. In climatic mean status, the intensity of Huaxi antumn rain weakens with fluctuation. The period from 6 to 16 September is the strongest period of the three. There is obvious interdecadal variation for the interseasonal variation of DARI. There are two significant periods in 1970s, three in 1980s, three in 1990s and three at the beginning of the 21st century. The application case shows that DARI can demonstrate the whole variation process of occurrence, development and disappearance of Huaxi autumn rain.
    7  Study on Diffusion Regularity and Operation Design of  Antiaircraft Gun, Rocket and Plane Cloud Seeding
    ZHOU Yuquan ZHU Bing
    2014, 40(8):965-980. DOI: 10.7519/j.issn.1000-0526.2014.08.007
    [Abstract](1014) [HTML](85) [PDF 3.09 M](1009)
    This article gave out the diffusion calculation model of different seeding ways such as antiaircraft gun, rocket and plane, based on the analytical solution of cloud seeding diffusion in clouds, and studied the diffusion regularity and effective range of different seeding ways. Farthermore, the paper examined the calculation scheme by using a flight seeding track caught by satellite, and discussed the problems such as adequate seeding flight designing. The main conclusions are as follows: Taking antiaircraft gun as point source, and using single antiaircraft gun for work, the operation range is found to be only 0.5 km. So, it would be better if we take multi shell for work to keep concentration and diffusion range, and the result can be improved largely when nucleation rate is raised. The works of rockets and planes are regarded as line sources. The widths beyond threshold value one hour after seeding are 7 km and 6.6 km, which can be taken as the basis of multi line seeding flight interval. Single line seeding cannot reach the requirement of sufficient catalyzing. Impacted by winds, the diffusion area would disperse or overlap when using ‘S’ seeding way. So, the ‘8’ form flight route design based on wind velocity can make the target area get adequate seeded. The cloud seeding diffusion calculation and work designing software developed based on diffusion calculation model are convenient to calculate the diffusion range, concentration and evolution by using plane, antiaircraft gun and rocket in real operations. Besides, it is effective in designing the seeding ways for different target areas, and the results are direct and clear, offering assistance for actual operational application and seeding designing of diffusion calculation.
    8  Cold Cloud Seeding Potentials Recognition Platform of  Weather Modification Based on the BJ RUC System
    JI Lei ZHOU Jun LI Hongyu ZHANG Lei
    2014, 40(8):981-991. DOI: 10.7519/j.issn.1000-0526.2014.08.008
    [Abstract](958) [HTML](80) [PDF 8.59 M](1014)
    Recognizing cold cloud seeding potentials accurately in advance can improve the scientific skill of artificial weather modification and guarantee the realization of meteorological modernization. Based on BJ RUC system, the cold cloud seeding potentials recognition platform of weather modification in Beijing (BJ CCSPR platform) was designed by Beijing Weather Modification Office. With the combination of background supporting system and foreground analyzing system, the platform has the functions of data monitoring, model calculation, generation and display of the operation products and human computer interactive operations. Based on the 3 dimension macro and micro physical quantites, thermodynamic and kinetics factors, the comprehensive indices of cold cloud seeding potentials are designed, having high levels of scientificity and creditability and being able to provide the distribution of 3D and 2D seeding potential areas directly. The operational application indicates that: This platform has stable performance and high automation; it’s easy to expand and practical highly; operational products which is combined with BJ RUC system can primarily forecast the variation of physical quantity associated with weather modification in the next 24 hours; the classic examples of a ground based flare seeding case and an aircraft seeding case indicate that the comprehensive indices of cold cloud seeding potentials can serve weather modification decision making and command progress directly and play an important role in practical operation of weather modification.
    9  Study on Wind Profile Radar Observation Features of  a Multi Phase Weather Process in Beijing
    LI Feng SHI Hongrong
    2014, 40(8):992-999. DOI: 10.7519/j.issn.1000-0526.2014.08.009
    [Abstract](1252) [HTML](74) [PDF 2.53 M](924)
    A multi phase weather process with fog, haze, rain and snow seen in Beijing on 17 March 2012 is analyzed by using wind profile radar data. The results show that the profiler products are good at diagnosing and distinguishing weather change and evolution, and can reveal the detailed variation of precipitation. The profiler is usually used to detect weak horizontal wind and weak vertical movement of atmosphere in case of fog. Its air refractive index is small while signal noise ratio (SNR) below 850 hPa is strong. Simultaneously, the profiler frequency spectrum shows the features of clear weather. Before it rains, the SNR in troposphere remarkably strengthens, the profiler vertical beam radial velocity (Vr) firstly presents positive values, in the mid and high levels, which indicates the air sinking motion is enhanced. At the same time the other two double beams (Vr) are not symmetrical anymore. When it rains, all the five beams (Vr) of profiler turn positive from surface to upper air, and the largest Vr is near surface, not concentrated in the vertical beam. Correspondingly, spectrum width maintains in 1-2 m·s-1. When precipitation phase changes, spectrum width diminishes obviously while SNR strengthens, and the Vr gets weakened. These changes usually occur in the whole boundary layer to troposphere. When rain stops, the above changes show reverse features, including spectrum width increases, SNR weakens, and all the five beams return to symmetrical state.
    10  Introduction to Advanced Technique of Atmospheric Environment Assessment
    CHEN Hui QUAN Lihong XU Dahai
    2014, 40(8):1000-1005. DOI: 10.7519/j.issn.1000-0526.2014.08.010
    [Abstract](1122) [HTML](77) [PDF 811.05 K](948)
    In recent years, air pollution in China has become a serious problem, so atmospheric environment is attached more and more attention to and atmospheric environment impact assessment is requested to be in good quality. Therefore, it is significant to introduce new, more comprehensive, finer technique into atmospheric environment impact assessment according to recent scientific progresses in sciences. We introduce a few methods including footprint function method, 4 dimensional flux method, source apportionment method and animation demo that have been used in our work in this paper according to the guideline on environment impact assessment technique, and describe the theory and application. With the models recommended in the guideline of atmospheric environment impact assessment, these methods can be used to study deeply the movement and distribution of the air pollutants from different aspects. We can choose reasonable methods to carry out the study and evaluation on atmospheric environment considering the real problem during atmospheric environment impact assessment.
    11  Verification and Evaluation of Forecast Method of PV Power Generation
    WANG Lin CHEN Zhenghong TANG Jun
    2014, 40(8):1006-1012. DOI: 10.7519/j.issn.1000-0526.2014.08.011
    [Abstract](1118) [HTML](211) [PDF 699.91 K](1866)
    Based on the power generation data provided by the PV power station of Hubei Meteorological Energy Development Centre and the meteorological data of the corresponding period, we carried out verification and evaluation on the radiation and generating power short term forecast method and found that: (1) Good correlation exists between the solar irradiance forecasts and the actual situation, with correlation coefficient going above 0.77, passing the 0.001 significance test. (2) The optimal method of short term forecasting methods is putting mode irradiance into photoelectric conversion model, and the relative root mean square error for the first day is 0.16. (3) Solar radiation forecasts and PV power generation forecast with solar elevation angle change present certain regularity. The maximum error is found at winter noons and the minimum is over summer nights. The error is significantly higher in rainy days than in sunny days. How to reduce the error in the rainy weather forecast is the study focus in the next step work.
    12  Simulation of Flood Disasters Based on Embedded River Raster
    JIANG Zhihuai ZHANG Yizhi CAI Zhe LI Chang
    2014, 40(8):1013-1018. DOI: 10.7519/j.issn.1000-0526.2014.08.012
    [Abstract](1506) [HTML](149) [PDF 3.74 M](1179)
    Flood disaster was simulated in Cao Shui Basin in Jiangxi Province. By revising the Digital Elevation Model (DEM) with river raster layer in, flooding simulation results carried out by FloodArea hydrological model was compared by deterministic coefficient and Nash Sutcliffe efficiency coefficient with the actual flooded traces and hydrological data from hydrological observatories during 2000-2010. The results showed that based on the embedded river raster DEM, flood disasters simulation process is significantly associated with the moving route, submerged area and depths of floods are caused by severe precipitation. The method can be used as a basic way to simulate the flood disaster caused by critical areal precipitation.
    13  Performance Verification of the Medium Range Forecasts for T639, ECMWF and Japan Models from March to May 2014
    LIU Weiyi
    2014, 40(8):1019-1025. DOI: 10.7519/j.issn.1000-0526.2014.08.013
    [Abstract](1137) [HTML](150) [PDF 1.33 M](918)
    In order to improve the ability to use the products of T639, a synoptic verification on its medium range forecasts in spring 2014 is made in comparison with the NWP of ECMWF and Japan models. The results show that all the three models have good performances on the aspect of predicting the larger scale circulation evolution and adjustment in Asian middle and high latitude areas and the evolution of southern branch trough. For the prediction of temperature at 850 hPa, ECMWF shows a better performance than the other two models. Taking the sandstorm process during the period of April 22-24, 2014 as a case, it is found that ECMWF is more effective than the other two models in medium range forecasts of strong surface wind causing the sandstorm weather process.
    14  Analysis of Atmosphere Circulation and Weather in May 2014
    CAI Xuewei ZHANG Fanghua
    2014, 40(8):1026-1032. DOI: 10.7519/j.issn.1000-0526.2014.08.014
    [Abstract](1284) [HTML](68) [PDF 0.00 Byte](0)
    The main characteristics of the general atmospheric circulation in May 2014 are as follows: There is one polar vortex center in the Northern Hemisphere, and the intensity is 524 dagpm, 4-6 dagpm stronger than normal years. The 500 hPa geopotential height presents distribution of a four wave pattern in high latitudes of Northern Hemisphere, and the most areas in the eastern region of China are controlled by west air flow, causing more short wave trough activities. Subtropical high is more westward and northward than normal, which is the main cause for the extreme precipitation seen many times in South China. Monsoon starts later than normal years over South China Sea. The monthly mean temperature is 16.5℃, 0.3℃ higher than normal. The monthly mean precipitation amount is 73.8 mm, which is 6.2% more than normal. The main weather characteristics in this month is as follows: Torrential rainfalls occur in Southern China frequently, and extreme high temperatures appear in Northern China.

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