ISSN 1000-0526
CN 11-2282/P

Volume 45,Issue 11,2019 Table of Contents

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  • 1  Convection-Allowing Ensemble Forecasts of Intense Rainfall and Hail: Case Study
    SUN Min DAI Jianhua
    2019, 45(11):1501-1516. DOI: 10.7519/j.issn.1000-0526.2019.11.001
    [Abstract](1038) [HTML](329) [PDF 7.39 M](1185)
    Abstract:
    Convective-allowing ensemble forecasts are analyzed for severe convection associated with short-duration intense rainfall and hail, which occurred in southern Jiangsu Province and Shanghai Region during the night of 28 April 2015. The data integration analysis is conducted at the initial time, using ARPS Data Analysis System (ADAS). The distribution of water substance is adjusted and more small-scale information is added to the initial field by using ADAS. Qualitative and quantitative verifications against Shanghai Nanhui dual-polarization radar observations are performed on the 12-14 h ensemble forecasts, including predicted reflectivity, differential reflectivity and hail. The results show that ADAS ensemble predicts the structure and location of the total and convective precipitation coverage more realistically compared with observations, and it also has higher forecast skill than the control (CTRL) ensemble. Differential reflectivity varies dramatically within a small distance, thus increasing the difficulty to make accurate predictions. In terms of the simulated differential reflectivity, the ADAS ensemble may produce higher values, but the overall position and intensity are closer to observations. The ADAS ensemble is more skillful for the prediction of large particles, which shows a better description of the microphysics-related features. Compared with ground hail observations and dual-polarization radar observations, the predicted high proba-bility hail location in ADAS ensemble is closer to the observations, which is of great significance to the prediction of hail falling area. Also, the ADAS ensemble improves the long-lead-time hail prediction and has higher confidence than the CTRL ensemble. The predicted dual-polarization variable has the advantage of distinguishing between intense rainfall and hail, providing an effective tool to evaluate the accuracy of the microphysical process description in the numerical model compared with the observation.
    2  Diagnostic Analysis of Ensemble Dynamic Factors During the Warm-Sector Torrential Rain in South China
    SU Ran LIAO Fei QI Yanbin
    2019, 45(11):1517-1526. DOI: 10.7519/j.issn.1000-0526.2019.11.002
    [Abstract](743) [HTML](264) [PDF 1.11 M](1144)
    Abstract:
    In this paper, 20 cases of the prefrontal torrential rain in Guangdong Province from April to June of 2015-2017 were selected, and the distribution characteristics of ensemble dynamic factors of the warm-sector torrential rain were analyzed by using the GFS 0.5°×0.5° data. The results are as follows. (1) Among the four types of warm-sector torrential rain in Guangdong Province, the correlation between the ensemble dynamic factors and the accumulated precipitation is the highest in the prefrontal trough torrential rain, followed by the southwest jet torrential rain and the lowest correlation is with the backflow torrential rain. There are common ensemble dynamic factors between the prefrontal trough and the backflow torrential rain, and also between the high-level trough and subtropical jet torrential rain and southwest jet stream torrential rain. (2) Three orders of magnitude weighting index are constructed by different ensemble dynamic factors which are the best representation of precipitation in various warm-sector torrential rains. The index (magnitude is 10-3, 10-1 and 102 respectively) is found to be increasing with the increase of precipitation level, which indicates that the index has a good indication for judging the precipitation intensity. (3) The median of each magnitude index is used as the threshold to judge the precipitation intensity, providing an objective norm for the quantity forecast of precipitation. These results further promote the practical application of ensemble dynamic factors in the prediction of warm-sector torrential rain in South China.
    3  Analysis on Moist Symmetric Instability and Frontogenesis of One Zonal Torrential Rain
    DENG Chengzhi ZHANG Yaping FANG Dexian ZHAI Danhua WU Zheng HE Yue
    2019, 45(11):1527-1538. DOI: 10.7519/j.issn.1000-0526.2019.11.003
    [Abstract](1058) [HTML](191) [PDF 3.67 M](926)
    Abstract:
    Using conventional observation data, automatic station data, NCEP/NCAR (1°×1°) reanalysis data and WRF simulation data, this paper diagnostically analyzed the characteristics of the zonal rainband and its moist symmetric instability in the torrential rain that occurred in southern Chongqing and surrounding places from 27 to 28 June 2016. The results showed that: (1) The zonal rain belt was formed in the area with low-level moist symmetric instability. The moist symmetric instability increased before the formation of the zonal rain belt, and released gradually after the formation. The sustained release of moist symmetric instability promoted the continuous development of zonal rain belt. (2) The negative increase in horizontal component of moist potential vorticity MPV2 caused by the increase of zonal frontogenesis, was beneficial to the enhancement and maintenance of moist symmetric instability, and probably was the important mechanism of the formation and continuous development of the zonal rain belt in the torrential rain process.
    4  Characteristics and Predictive Focus of Torrential Rain Along the Outer Boundary of West Pacific Subtropical High in Hebei Province
    LI Jiangbo KONG Fanchao ZENG Jiangang WANG Yuhong SUN Zhuo
    2019, 45(11):1539-1549. DOI: 10.7519/j.issn.1000-0526.2019.11.004
    [Abstract](693) [HTML](350) [PDF 5.53 M](1008)
    Abstract:
    Composite analyses of 69 torrential rain cases along the outer boundary of West Pacific subtropical high (WPSH) are carried out, based on the upper-level and surface observations, NCEP/NCAR reanalysis and the rainfall data of Beijing, Tianjin and Hebei Province. The results show that: (1) The frequency of torrential rain events increases obviously from the northwest to the southeast of Hebei Province, accompanied by three high-frequency areas, which are located in Qinhuangdao and Tangshan at the south foot of Yanshan Mountain, Xingtai at the east foot of Taihang Mountain and Cangzhou and Hengshui in Hebei Plain, respectively. There are two low-frequency areas, located in the mountains of the northwest of Baoding and the area in the north of Zhangjiakou and the north of Chengde respectively. (2) The 69 torrential rain cases can be divided into three groups according to the flow patterns of WPSH, which are called blocking, quasi-east-west banding and northeast-southwest banding WPSH, respectively. Some typical flow patterns at 500 hPa and the frequency of rainfall over 50 mm and 100 mm in each group are plotted by composite analysis, and spatial distributions of the elements including the atmospheric precipitable water vapor, CAPE, vertical velocity at 700 hPa, pseudo-equivalent potential temperature and K index etc. are given out. (3) Based on the statistics, the mean and extreme values of some physical quantities of the 69 torrential rain cases are counted, which can be considered as the important clues to forecast the amount and location of heavy rainfall, and to estimate the extremity of torrential rain in weather forecasting operation. (4) More attentions should be paid to the location and intensity of the middle/low-level convergence in addition to the location, intensity and flow pattern of WPSH and the upper trough in the operational forecasting of the torrential rain along the outer boundary of WPSH. Severe rainfalls are prone to occurr in the areas along the 584 or 586 dagpm line at 500 hPa, the shear or the center of the vortex at 700/850 hPa, as well as the inverted trough or the center of the surface low pressure.
    5  Impact Analysis of Frozen Soil and Snow on Key Parameters of Land Atmosphere Flux at Longbao, Yushu in Winter 2014
    ZHANG Haihong JIANG Haimei ZHOU Bingrong QI Donglin
    2019, 45(11):1550-1559. DOI: 10.7519/j.issn.1000-0526.2019.11.005
    [Abstract](537) [HTML](185) [PDF 2.34 M](833)
    Abstract:
    Using the observation data from Longbao, Yushu of Qinghai Province, daily variations of momentum flux and sensible heat flux during unfrozen, frozen and frozen with snow covered periods are analyzed, momentum bulk transfer coefficient, sensible heat bulk transfer coefficient, aerodynamic roughness length, thermal roughness length are calculated, relationship between additional damping and roughness reynolds number are analyzed and three kB-1 parameterization schemes are compared. The results show that daily ranges of momentum flux and sensible heat flux are the biggest in frozen period and the smallest in frozen with snow covered period. Momentum bulk transfer coefficient CD and sensible heat bulk transfer coefficient CH are the biggest in frozen period and the smallest in frozen with snow covered period. Aerodynamic roughness length and thermal roughness length are the smallest in frozen period and the biggest in frozen with snow covered period. Power function type of three kB-1 parameterization schemes is the most suitable during unfrozen, frozen, and frozen with snow covered periods.
    6  Applicability Study of SPI in Multiple Time Scales in Meteorological Drought Monitoring in Anhui Province
    XIE Wusan TANG Wei’an SONG Awei
    2019, 45(11):1560-1568. DOI: 10.7519/j.issn.1000-0526.2019.11.006
    [Abstract](689) [HTML](474) [PDF 5.99 M](1014)
    Abstract:
    Based on daily precipitation data, soil moisture data and historical drought disaster data of 81 meteorological stations in Anhui Province from 1961 to 2017, this paper studies the applicability of SPI in six time scales in meteorological drought monitoring in Anhui Province, by analyzing the interannual variation, seasonal evolution, spatial distribution, and frequency distribution of the drought days, evolution of typical drought processes as well as correlations of drought days to soil moisture and to drought disaster. The results show that in drought monitoring there is significant difference in the SPI in different time scales. In interannual variation of drought days and frequency distribution of the drought at different grades, the diagnosis results got with SPI of each time scale are in accordance with the fact, but the results are not in accordance with the fact of seasonal variation and spatial difference of drought days. SPI of each time scale has a good diagnostic effect on the interannual variation of drought days and frequency distribution of the drought at different grades, but it has a poor effect on the seasonal variation and spatial difference of drought days. From the perspective of diagnosis of typical drought processes, the shorter the time scale, the higher the weight of the precipitation, thus the SPI monitoring curve is too sensitive to precipitation, such as SPI30 and SPI60. However, the response of SPI150 and SPI180 of long-time scale to precipitation is too insensitive. From the perspective of correlation with soil moisture, the short-time scale SPI30 has close correlation with surface soil moisture of 10 cm depth and the correlation coefficient is 0.91, while the long-time scale SPI180 has close correlation with deep soil moisture of 50 cm depth. In the aspects of negative correlation between SPI in different time scales and annual precipitation and the positive correlation between them and drought disaster, correlation coefficients first increase and then decrease with the time scale prolonging, and the moderate-time scale SPI120 has the closest correlation to them. Overall, SPI in different time scales represent different meanings, and the drought in different time scales should be monitored and evaluated by SPI in different time scales.
    7  Characteristics of Precipitation Parameters Reflected by Ground Laser Raindrop Disdrometer
    SHA Xiuzhu DING Jianfang CHENG Bo
    2019, 45(11):1569-1578. DOI: 10.7519/j.issn.1000-0526.2019.11.007
    [Abstract](703) [HTML](237) [PDF 2.28 M](956)
    Abstract:
    Adopting the precipitation data of 100 days in Henan Province from 2016 to 2017, this paper comparatively analyzed the difference between raindrop size distribution inversion echo and radar echo, and the difference between raindrop size distribution inversion precipitation intensity and rain gauge observation precipitation intensity. Gamma fitting of raindrop size distribution was conducted to explore raindrop size distribution and precipitation cloud types in Henan Province. Z-I fitting was done to explore relationship between precipitation echo and precipitation intensity in Henan Province. The results are as follows. (1) The variation trends of raindrop size distribution inversion echo and radar echo have good consistency. The former is generally smaller than the latter, and the possible causes are that there was a certain height difference between the radar echo above ground raindrop disdrometer that observed through the lowest elevation angle and the ground raindrop disdrometer, and that the evaporation process, when raindrops fell, could reduce the diameter of raindrops that reached the surface. (2) There is a certain difference between raindrop size distribution inversion precipitation intensity and rain gauge observation precipitation intensity, but there is no obviously large or small regularity. (3) The widths of raindrop size distribution of convective cloud and stratocumulus mixed cloud are wider than that of stratiform cloud, the density of medium-scale raindrops is larger. The density of small droplets in stratiform cloud is larger. Most precipitation processes in Henan Province are stratiform precipitations with narrower raindrop size distribution. (4) The fitting formula of precipitation echo and precipitation intensity in Henan Province is Z=262I1.34, the fitting formula of laminar cloud is Z=219I1.30 and the fitting formula of convective cloud is Z=307I1.38. (5) The raindrop concentrations in June and July are higher (about 1500 m-3), the precipitation intensity between August and October are higher (>60 mm·h-1), the maximum diameters of raindrops between April and August are higher (4.3-4.8 mm), the mean diameters of raindrops between March and April are higher (approximately 3 mm). There is no consistency in the monthly feature changes of four precipitation microphysical quantities.
    8  Study on the Relationship Between Himawari-8-Based Cloud Parameters and Precipitation
    GUI Hailin ZHUGE Xiaoyong WEI Xiaocheng LIU Bojun TANG Zhijun JIANG Qi
    2019, 45(11):1579-1588. DOI: 10.7519/j.issn.1000-0526.2019.11.008
    [Abstract](728) [HTML](382) [PDF 2.97 M](1019)
    Abstract:
    Based on the cloud products from Japanese Himawari-8 satellite, this paper analyses the precipitation data form 08:00 BT to 17:00 BT in summer (June-August) of 2017 over central and eastern China. The relationships between cloud optical depth (COD), cloud-top particle size (CPS), cloud-top temperature (CTT) and precipitation were discussed in detail. Experiments showed that the rainfall probability is highly correlated to cloud parameters. The rainfall probability increases as the COD and CPS increase, and/or CTT decreases. However, the correlation between single cloud parameters and precipita-tion intensity is not high. The correlation coefficient between COD and hourly rain rate is 0.2315, that between CPS and hourly rain rate is 0.1823, and that between CTT and hourly rain rate is -0.2235, which are all weak correlations. If two or three cloud parameters are combined to form an hourly rain rate distribution matrix, the precipitation process can be more clearly reflected. The case on 28 August 2017 indicates that, compared to the pure infrared-based algorithm, the tri-parameter method can significantly improve the estimation accuracy of hourly rain rate.
    9  Warning Model of Road Surface Icing of Expressway in Hubei Province
    SHU Si XIONG Shouquan CHEN Yingying HE Mingqiong YUAN Zhengteng LU Jing CUI Yang TANG Jun
    2019, 45(11):1589-1599. DOI: 10.7519/j.issn.1000-0526.2019.11.009
    [Abstract](964) [HTML](288) [PDF 7.36 M](947)
    Abstract:
    This paper analyzes the variation law of the icing frequency of each highway section with the temperature, using the observed 10 min air temperature and road surface tmeperature from 87 traffic and weather stations, established since 2013, along the highway in Hubei Province. It is found that the Logistic regression models are satisfied, but the ambient temperatures corresponding to icing in different highway sections are different. By studying the temperature condition probability of the road icing in each highway section, we obtain the temperature turningpoint of each section of Hubei highway. Combined with the precipitation (snow) of each highway section, it can be used for the early warning of highway icing in Hubei Province. Thus, suggestions can be made for whether to carry out ice removal measures of highways and when to carry out ice removal measures.
    10  Annual and Monthly Risk Assessment of Typhoon Disasters in China Based on the Information Diffusion Method
    GAO Ge HUANG Dapeng ZHAO Shanshan
    2019, 45(11):1600-1610. DOI: 10.7519/j.issn.1000-0526.2019.11.010
    [Abstract](875) [HTML](284) [PDF 10.36 M](1538)
    Abstract:
    By employing the typhoon disaster information, social and economic data of China during 1985-2014, spatio-temporal characteristics of annual and monthly typhoon direct economic losses in China were analyzed. Risk assessments were carried out by using the information diffusion method to provide reference for improving the capability of typhoon disaster risk management. The results are as following. Annual and monthly typhoon-caused direct economic losses from July to September in China show slightly increasing trends during 1985-2014. The monthly variations of direct economic losses are obvious, particularly in August, in which the disaster-caused typhoons are most and the economic losses are most serious in a year. Compared to the period 1985-1994, the range of monthly variations become greater and total economic losses in September and October are greater than in June and July in the recent two decades, i.e., 1995-2004 and 2005-2014. Along with the increasing of direct economic losses levels, the regions with middle and high risk levels are decreasing gradually. Under the condition with annual direct economic losses greater than or equal to 5 or 10 billion RMB yuan, risk probability in Zhejiang Province is the highest in China. Under the three risk levels (returning period=10, 20, 30 years), annual direct economic losses in Zhejiang, Guangdong, Fujian and Guangxi are kept at the specially serious degrees. Under the risk levels with 20 and 30 years returning periods, annual and monthly (August) direct economic losses in Shandong and Liaoning and annual losses in Hebei have also reached the specially serious degree. Thus, the defense response to typhoon should not be neglected in these regions.
    11  Study of Urban Barrier Effect on Local Typhoon Precipitation
    YUE Caijun TANG Yuqi GU Wen HAN Zhihui WANG Xiaofeng
    2019, 45(11):1611-1620. DOI: 10.7519/j.issn.1000-0526.2019.11.011
    [Abstract](1045) [HTML](563) [PDF 595.92 K](1315)
    Abstract:
    Urbanization has changed the surface properties and characteristics, and more attentions have been paid to its influence on weather and climate. The urban barrier effect is one of the possible physical mechanisms for the urbanization to influence the formation process of precipitation. The urban barrier effect changes the wind field, wind convergence and even the weather system itself, and further changes the humidity advection, eventually affecting the urban precipitation location and intensity. The greater the wind speed, the more obvious the barrier effect of the city. However, current studies on the effect of underlying surface on typhoon precipitation mainly focus on the impact of topography and surface conditions on typhoon precipitation location and intensity, but the influence of cities as one of underlying surface factors on typhoon precipitation has not been considered enough. In this paper, the research progress on the impact of urban barrier effect on precipitation and the influence of underlying surface on typhoon precipitation are reviewed. Shanghai is the most urbanized city in China, and it is affected by 2-3 typhoons every year on average. Previous studies have focused on the influence of urban barrier effect on local typhoon precipitation in Shanghai, but there are still obvious deficiencies in characterizing the urban barrier effect of typhoon precipitation. Finally, the paper points out the application of urban barrier effect in the study of local typhoon precipitation in Shanghai in the future.
    12  Analysis of the August 2019 Atmospheric Circulation and Weather
    ZHOU Guanbo GAO Shuanzhu
    2019, 45(11):1621-1628. DOI: 10.7519/j.issn.1000-0526.2019.11.012
    [Abstract](761) [HTML](280) [PDF 3.67 M](1284)
    Abstract:
    The main characteristics of the general atmospheric circulation in August 2019 are as follows. The polar vortex of Northern Hemisphere presented a single pattern. In the mid-high latitudes of Asia, the circulation presented a two-trough and one-ridge pattern. The Northwest Pacific subtropical high lay northward, and the subtropical high on land was stronger than the average. Meanwhile, the monthly mean precipitation amount was 110.5 mm, which is more than its normal value (105.3 mm) with 5.0% increase. The monthly mean temperature was 21.6℃, 0.8℃ higher than its climatological mean (20.8℃). Five regional torrential rainfall events happened in August, and three of them were caused by tropical cyclone. In August, six tropical cyclones were active over the Northwest Pacific and the South China Sea, and Typhoon Wipha (1907) and Lekima (1909) and Bailu (1911) made landfall over China. Northeast China and Sichuan suffered from heavy rains and floods. Drought appeared over middle and lower reaches of the Yangtze River. Persistent high-temperature occurred in the south of China. Many provinces suffered from hail attacks, and some areas had serious disasters.

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