ISSN 1000-0526
CN 11-2282/P

Volume 40,Issue 6,2014 Table of Contents

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  • 1  A Note on the Melting Level of Hail
    YU Xiaoding
    2014, 40(6):649-654. DOI: 10.7519/j.issn.1000-0526.2014.06.001
    [Abstract](2173) [HTML](2625) [PDF 1.95 M](2862)
    The melting level of hail is best estimated by level of the wet bulb temperature zero (WBZ). However, some misunderstanding exist among most weather forecasters in China, they think that hail’s melting level is the level of dry bulb temperature zero (DBZ). In this note, we try to explain why the melting level of hail is best estimated by level of the WBZ, and the dry air in mid troposphere can effectively lower the level of WBZ, being favorable for the hail falls.
    2  Comparative Analysis of Environmental Conditions and Structural Features for the Left Moving Supercell and the Supercell in Squall Line in April 2012 Guangdong
    WU Zhifang PANG Guqian HE Hanqing YE Aifen LIU Yunce
    2014, 40(6):655-667. DOI: 10.7519/j.issn.1000-0526.2014.06.002
    [Abstract](987) [HTML](209) [PDF 2.53 M](1515)
    In April 2012, a series of severe thunderstorms which produced more hails than normal were seen in the Guangdong Province. This paper analyses two severe convective weather events, which are one left moving supercell in the splitting storm that was observed first time in Guangdong and one supercell in a squall line, by using conventional meteorological observations, Doppler radar data and surface automatic weather station observations. The results show that a “thermal thunderstorm” initiated by local intense heating developed into a supercell storm which produced hails and severe wind gusts on 10 April. On 12 April, one squll line and the supercell which brought hails, severe wind gusts and torrential rains in a very short time were developed by the role of low level warm advection and middle level cold trough in the process of a shear line and a strong cold front moving southeastward, while the vertical wind shears went up by the advection process. The 0℃ layer heights for the two events were lower than the local mean value in April. It was found that the changing of wind shear vector with heights determined the development trend of left moving and righ moving storm: The counterclockwise changing with heights of wind shear vector initiated a left moving storm developed to a hailstorm after storms splitting on 10 April; and the clockwise changing was conducive for a squall line to be well organized and developed, and the supercell in the squall line moved to the right of the mean wind of the bearing layer. The left moving supercell was characterized by a anti mesocyclone, WER, side lobe echoes and a strong echo center on the left side. The supercell in the squall line featured a mesocyclone, WER, side lobe echoes and a strong echo center on the right side, the long TBSS and massive mid level convergence, with 31.1 m·s-1 backside downburst.
    3  Doppler Radar Product Features and Warning of Non Supercell Tornadic Storms
    DIAO Xiuguang WAN Mingbo GAO Liuxi MENG Xiangui
    2014, 40(6):668-677. DOI: 10.7519/j.issn.1000-0526.2014.06.003
    [Abstract](1262) [HTML](385) [PDF 4.70 M](2015)
    Six non supercell tornadic storms in Shandong Province were analyzed based on Doppler radar data from Jinan and Yantai in combination with environmental parameters and weather events, of which 4 tornado processes were produced in the condition of backward tilting trough and one tornado process was produced in the condition of northwest flow, and moreover 2 tornadoes were in EF0 scale, 3 in EF1 scale, and one in EF2 scale. The results showed that the environment situations are conducive for thunderstorms on 31 July 2006, 18 July 2007 and 3 August 2009. High humidity in the lower level and the 0-1 km vertical wind shear ≥7 m·s-1 play an important role in the occurrence of non supercell tornadoes. The gate to gate azimuthal shear (i.e., the gate to gate velocity difference) ≥20 m·s-1 in the 0.5° elevation angle mean radial velocity product, or the gate to gate azimuthal shear ≥15 m·s-1 in the 0.5° elevation angle storm relative mean radial velocity product can be used as a warning criteria for non supercell tornadoes. Four tornadoes form during the rapidly developing stages of thunderstorms, especially the cell tops markedly increase within 6 min. The strong updrafts that quickly build up within storms are the main incentives for the occurring of tornadoes. The rapid developing of storm needs strong updraft. The strong updrafts stretch the small vortex existing in the low level convergence line quickly, thus, the small vortex movement gets further developed, inducing small scale intense shear, and causing tornadoes to occur.
    4  Application Experiment of Instability Index Retrieved with Hyper Spectral Atmospheric Infrared Sounding (AIRS) Data in Severe Convective Weather Case
    LIU Hui SHOU Yixuan QI Chengli
    2014, 40(6):678-686. DOI: 10.7519/j.issn.1000-0526.2014.06.004
    [Abstract](964) [HTML](196) [PDF 5.00 M](1251)
    Using the instability index computed with radiosonde, NCEP FNL data and hyper spectral Atmospheric Infrared Sounding (AIRS) standard retrieval data, this paper analyzes the atmospheric instability before occurrence of the severe convective weather in Beijing on June 23, 2011. The findings suggest that the instability index computed with radiosonde shows the change of the unstable energy over Beijing before and after “the 23 June Storm”, and no sounding data in the upstream key region. The instability index computed with AIRS and NCEP shows that upstream key region in Beijing is extremely unstable before the occurrence of the severe convective weather (K index is greater than 40, and SI index is equal to or less than -5), being conducive to the occurrence of severe convective weather. The research results of the paper show that the radiosonde data cannot monitor the severe convective weather because of its lower spatial and temporal resolution. After quality control the instability index calculated by AIRS data can be used in monitoring the occurrence of convective weather. The NCEP data with lower spatial resolution have weak capability in monitoring small scale atmospheric unstable stratification. In summary, AIRS retrieval products have the advantage of high spatial and temporal resolution. We can monitor the atmosphere unstable energy accumulation of the upstream key areas before “the 23 June Storm” weather occurs by using the clear atmospheric instability index computed with AIRS L2 products, providing supplementary information for forecasters.
    5  Study on Characteristics of Tropical Plumes Related to Cold Season Rainstorms in Southern China
    SHOU Yixuan LU Feng WANG Jiechun Ewanlen I. Rufus
    2014, 40(6):687-696. DOI: 10.7519/j.issn.1000-0526.2014.06.005
    [Abstract](870) [HTML](105) [PDF 14.60 M](1129)
    Cold season rainstorm is not rare in China and sometimes its strength and induced disaster is greater than that of warm season. Statistics show that about 80% cold season rainstorm events in South China are related to tropical plumes (TP). Therefore, in this paper, seven year (2005-2011) FY 2 geostationary satellite data, TRMM adjusted merged infrared precipitation dataset (3B42), ECMWF Interim reanalysis data and conventional observations including surface and soundings are used to examine the characteristics and behavior of tropical plumes which are dealt with cold season rainstorms in South China. The analyses reveal that most of the tropical plumes related to the cold season rainstorms in South China are generated within 0°-10°N, 70°-140°E area. The topographical effect to TP caused by the Tibetan Plateau can not be ignored. According to the propagation characteristics, the tropical plumes before eruption exhibit westward propagating in longitude time (Hovmoller) space, with a preferred phase speed of 15-20 m·s-1, comparable to or faster than the synoptic baroclinic wave. Generally, tropical plumes which are related to heavy rainfall always move faster in the pre eruption stage and are significantly influenced by the dynamic forcing coming from the mid upper level of troposphere than those dealt with weak rainfall. The pattern of the tropical plumes after eruption in the longitude time space suggest that the convection part in the cloud moves slowly and concentrates at the south west end of plumes. The sub tropical upper level jets act only to make the cloud cover to expand eastward quickly. The above features may cause the heavy rainfall centralized only over some stations.
    6  National Satellite Meteorological Centre, 100081
    REN Suling JIANG Jianying XU Jianmin
    2014, 40(6):697-705. DOI: 10.7519/j.issn.1000-0526.2014.06.006
    [Abstract](1033) [HTML](149) [PDF 10.26 M](1371)
    In eastern China, there is one kind of rainfall that is related to the upper troposphere anticyclone, i.e., the South Asian High (SAH). The average heavy rainfall of central eastern China in annual cycle happens in the northeastern side of the SAH ridge line and shows a quasi biweekly oscillation in latitude when the SAH ridge line shifts northward or southward. The satellite water vapor (WV) images reveal the atmosphere movement of upper troposphere. The WV image and the derived wind can describe the location of the anticyclone center of upper troposphere and its ridge line and can also trace the downward dry and cold flow from middle high latitude, which is important to heavy rainfall in summer. The small scale dark area extending southward on WV images is usually the strong potential vorticity area in mid high latitude, and it can intensify the rainfall when moving to rainfall belt. There are two severe rainfall areas related to the SAH, one is in the southwest side of the SAH and another is in the northeast side of the SAH where the flow is divergent in the upper troposphere. In the north side of the SAH subtropical westerlies exist when the westerlies are strong, the divergence in the northeast side of the SAH in the upper levels is strong, which can induce strong precipitation in China. The SAH can affect most of China when it advances and withdraws from early May to early October. As a result, the concept model of the satellite image characteristics which is got from the cases over Huaihe River region in summer can also be used in other seasons or places such as Northwest China and North China regions. The location and shape of the SAH can affect the region and intensity of heavy rainfalls and meanwhile severe precipitation also has feedback on the SAH, leading the asymmetric instability development of the SAH.
    7  Comparative Analysis of Two Severe Rainfall Events with Different Dry Moist Characteristics on Satellite Water Vapor Imagery
    JIANG Jianying WANG Yueguo
    2014, 40(6):706-714. DOI: 10.7519/j.issn.1000-0526.2014.06.007
    [Abstract](1247) [HTML](128) [PDF 3.91 M](1440)
    Two severe rainfall processes happened in the south of the lower reaches of the Yangtze River and South China in July 2010 and June 2011, respectively, which were caused by the Meiyu front and monsoon trough separately. Conventional observation data, NCAR/NCEP reanalysis data and satellite water vapor imageries are used to analyze the two severe rainfall events. The results show that the two cases have something in common, but also some differences. The water vapor imagery shows that both of the two cases have the water vapor band. The rainstorm cloud clusters all occur in the water vapor bands no matter how the water vapor patterns change. A high θse tongue (θse ≥350 K) at 850 hPa maintains within and in parallel to the direction of the water vapor band during the two heavy rainfall periods. In the former case, the dark area on the north border of the water vapor band is corresponding to an updraft belt at 700 hPa, a divergence area and a negative vorticity area at 200 hPa. The strong convective clouds are nearly coincided with the center of the upward motion at low level and the convergence center in high level. However, in the latter case, there are no such evident characteristics. The analysis on potential vorticity (PV) indicates that the dark areas are corresponding to high band of PV in the upper troposphere while the water vapor band is corresponding to low band of PV in the later case. As to the former case, the correspondence of high band of PV and dark areas is not as evident as in the later case. The similarities and differences of dry and moist characteristics on the satellite water vapor images are closely related to the different large scale ambients.
    8  Boundary Layer Structure Features and Diagnostic Analysis of One Successive Heavy Fog Event
    MA Cuiping WU Bingui LI Jiangbo YU Lei ZHAO Na CAI Ziying QU Xiaoli
    2014, 40(6):715-722. DOI: 10.7519/j.issn.1000-0526.2014.06.008
    [Abstract](2243) [HTML](106) [PDF 5.19 M](1384)
    Heavy fog occurred in most areas of middle and south of Hebei Province and Tianjin for 3 days successively from 30 November to 2 December 2010, during which Shijiazhuang experienced a 34 h dense fog, including a 7 h strong dense fog. The diagnostic analysis on structure characteristics of successive heavy fog boundary layer and the formation, development and maintenance, and dissipation of the fog was made based on intensive automatic weather station data and Tianjin 250 m meteorological tower gradient observation data as well as conventional observation data and NCEP/NCAR reanalysis data. The result shows that prior to the foggy weather, the continuous east wind on surface is beneficial to the accumulation of water vapor. When the east wind turns to north wind, the vapor begins to condense, and eventually, becomes heavy fog. After the formation of heavy fog, the direction of wind turns to east again, helping maintain and strengthen the fog density. The long time SW warm and wet flow under 850 hPa and the inversion on the near surface layer are the main causes for the durative heavy fog. The water transfer of the low level three branches of vapor and reconstruction of southwest jet at 850 hPa are responsible for the formation of the heavy fog directly. During the strengthening period, the wind speed on boundary layer is 1-2 m·s-1, especially during the strong dense fog, the wind speed is only 1 m·s-1. When the wind with speed greater than 4 m·s-1 travels down to the ground surface, the heavy fog disperses affected by the destroyed inversion.
    9  Analysis on Atmospheric Low Frequency Features of Persistent Heavy Rains During Pre Flood Season in Fujian
    HUANG Lina GAO Jianyun CHEN Caizhu CHI Yanzhen
    2014, 40(6):723-732. DOI: 10.7519/j.issn.1000-0526.2014.06.009
    [Abstract](782) [HTML](102) [PDF 4.05 M](4935)
    By using the daily precipitation data of 66 stations in Fujian and NCEP reanalysis data and OLR data during 1979-2010, this paper reveals the low frequency features of precipitation during pre flood season in Fujian and analyzes the atmospheric low frequency oscillation (LFO) features during persistent heavy rain processes and the evolution characters of the previous LFO signs. The results indicate that the daily precipitation during pre flood season of Fujian has significant features of LFO. The main low frequent periods are 10-20 d, 30-60 d and 20-30 d respectively. More than two kinds of significant cycle periods are found with proportion of about 63%. The proportion of variance contribution of 10-90 d reaches 20%-30%. The correlations between the total rainfall in pre flood season and the intensity of LFO are significantly positive, and the intensity and the duration of persistent heavy rains are closely related to the features of rainfall LFO. In the years when precipitation is mainly controlled by BWO (ISO), the duration of persistent heavy rains is shorter (longer). In addition, during the persistent heavy rain weathers, there are anticyclones over the sea area to the east of Japan, the east of Somali and the South China Sea, which cause cold flows from Japan down to Bohai Bay to encounter the two cross equatorial flows from Somali and South China Sea over Fujian, and then low frequency cyclones are formed there resulting in the low frequency convergence in the lower level and divergence in the upper level and the convection enhanced. Moreover, the persistent heavy rain in Fujian is closely related to the variations of tropical and subtropical atmospheric LFO. The eastward propagation of tropical Madden Julian Oscillation (MJO) and northward propagation of East Asia Pacific ISO have denotative significance for extended range forecast.
    10  Causation Analysis of Severe Torrential Rain Process in Mountain Areas of Western Zhejiang Triggered by Typhoon Haikui
    SHEN Hangfeng GAO Tianchi ZHOU Chunyu ZHA Ben GUO Wenzheng ZHAI Guoqing
    2014, 40(6):733-743. DOI: 10.7519/j.issn.1000-0526.2014.06.010
    [Abstract](1041) [HTML](136) [PDF 5.31 M](1342)
    The WRF (Advanced Weather Research and Forecasting modeling system) was employed to simulate the local severe rainstorm process caused by typhoon Haikui over the northwestern of Zhejiang Province from 6 to 9 August 2012. The analysis of the simulation result combined with Doppler radar data, TBB (Temperature of Black Body) data, and automatic weather station data shows that there are several mesoscale systems embedded in spiral cloud band of the landed typhoon. Mesoscale systems develop, reinforce and weaken after division from spiral cloud band. It brings the local severe rainstorms over the northwestern of Zhejiang Province due to the direct effect of mesoscale systems. There generates the mesoscale divergence line which is responsible for the rainstorm by northeasterly flow and northwesterly current under advantageous topography. The topography of the northwestern of Zhejiang Province can increase the intensity of rainfall but is not so related to typhoon track and range of rainfall.
    11  Statistics on Physical Indicators of Rainstorms in Shandong Province
    ZHOU Xuesong WU Wei SUN Xingchi
    2014, 40(6):744-753. DOI: 10.7519/j.issn.1000-0526.2014.06.011
    [Abstract](1356) [HTML](175) [PDF 2.72 M](1703)
    By using daily, hourly precipitation data of Shandong Province and NCEP FNL (Final) operational global analysis data from 2000 to 2011, and based on the spatial and temporal statistics of physical indicators of rainstorms in Shandong Province, the physical indicators characteristics of rainstorms in different seasons and regions were analyzed. The results show that rainstorms have obvious nighttime enhanced trend. The physical indicators of rainstorms in daily operations have different levels of seasonal change. On one hand, the thresholds of these indicators have significant seasonal differences, for example, the specific humidity indicator is 10 g·kg-1 in April and May but it is only 14 g·kg-1 in July, and on the other hand, the effects of water vapor, dynamic and thermal instability factor on rainstorms are not the same in different seasons. The water vapor factor is usually high, and the dynamic and thermodynamic instability factors are low in summer. Furthermore, atmospheric convective instability can be stronger but baroclinicity gets weakened in summer. However it is contrary to the other seasons. Regional difference of the physical indicators of Shandong rainstorms is not the same as seasonal variations, but it is different among various factors. The rainstorms in the south of Shandong need stronger water vapor, and the thermal instability is also higher, the K index is about 0.5℃ higher than other areas while the rainstorms of east part of Shandong Peninsula have higher dynamic factors. Meanwhile, a wide range rainstorms and regional rainstorm need better moisture conditions, stronger dynamic conditions, but lower convective instability conditions.
    12  Experimental Research of the Impact of Simulated Cold Wave on Hypertension Disease
    ZHANG Xiakun ZHOU Ji ZHANG Shuyu MA Shoucun WANG Baojian
    2014, 40(6):754-758. DOI: 10.7519/j.issn.1000-0526.2014.06.012
    [Abstract](856) [HTML](107) [PDF 524.98 K](1072)
    Based on Zhang Shuyu’s research (2013), the impact of cold wave on hypertension disease is preliminarily discussed through the animal experiments. The cold wave process is simulated in the environmental test chamber (TEM1880). At the same time, 27 healthy rats are randomly divided into the control group, 3 hours before Tmin (minimum temperature) group, 1 hour before Tmin group, Tmin group, 1 hour after Tmin group, 3 hours after Tmin group, cold wave process group, 5 hours after the cold wave process group, 7 hours after the cold wave process group, respectively. Each group has 3 rats. All the groups except the control group are exposed to the cold environment and taken out in accordance with the developing progress of cold wave respectively. The following indexes are measured: systolic blood pressure (SBP), heart rate (HR), weight, blood lipid, noradrenaline (NA), angiotensin Ⅱ (Ang Ⅱ), whole blood viscosity (WBV), etc. The experimental results show that the air temperature decreases rapidly under the control of the high pressure after cold front leaves in the cold wave process. WBV, NA and Ang Ⅱ can rise to the maximum value at the Tmin, making blood pressure increase in experimental rats in the whole time, and are hard to return to the original level even after the cold wave.
    13  Global Significant Weather and Climate Events in 2013 and the Possible Causes
    WANG Yanjiao GAO Bei ZHOU Bin JIANG Tong GONG Zhiqiang SI Dong
    2014, 40(6):759-768. DOI: 10.7519/j.issn.1000-0526.2014.06.013
    [Abstract](1065) [HTML](164) [PDF 8.76 M](1422)
    In 2013, above average temperatures affected most of the global land surface areas. This is the sixth warmest year since records began in 1850, which is the same as 2007, and abnormal high temperatures were observed in Australia, northern North America, northeastern South America, northern Africa and most Eurasia. During the year, the weak cold water continually dominated the most of the eastern and central equatorial Pacific, and sea ice extent in the Arctic was still at one of the lowest levels in records, while the Antarctic sea ice extent has reached a new record. Affected by the anomalous atmospheric circulation combined with the external forcing factors of ocean and sea ice, notable climate anomalies and extreme events occurred worldwide in 2013. In early 2013, extreme cold waves and snowstorm attacked parts of Asia, Europe and North America while Australia experienced extreme high temperatures; from June to September, the Central Europe, parts of the Asia and North America suffered rainstorms and floods, while the hot weather hits the most of the Northern Hemisphere in same period. Since June, tropical storms and hurricanes attacked the East Asia, Southeast Asia and the east coast of America. The analysis results show that atmospheric circulation anomalies are the main causes for the above global extreme weather and climate events, and the Pacific sea surface temperature anomalies contribute to the atmospheric circulation anomalies by air sea interaction. In addition, during the process of global warming, the average temperature and its amplitudes of variation are all increasing, resulting in the increase of the frequencies of extreme weather and climate events, which has provided the favorable conditions for the occurrence of abnormal weathers in many countries and regions of the world.
    14  Analysis of the March 2014 Atmospheric Circulation and Weather
    DONG Quan ZHANG Tao
    2014, 40(6):769-776. DOI: 10.7519/j.issn.1000-0526.2014.06.014
    [Abstract](904) [HTML](124) [PDF 5.12 M](1748)
    The characteristics of general circulation of atmosphere in March 2014 are following. The polar vortex in the Northern Hemisphere is eccentric type with the main body located in the northern part of North America and there are two other vortex centers positioned near Novaya Zemlya and Okhotsk Sea respectively. Compared to the normal mean condition, the former one is stronger about -10 dagpm in the geopotential height anomaly and the later one is nearly neutral lying further south. The Asia ridge is stronger about 6 dagpm in geopotential height anomaly and its area is larger, because of which the mean temperature of March is 1.2℃ higher than the normal temperature 4.1℃, recorded as the 6th highest since 1961. The position and strength of East Asia trough, south branch, and subtropical high of the Northwest Pacific all are neutral compared to the normal conditions. The mean precipitation in March is 29.1 mm, approaching to the normal average 29.5 mm. In March, there are more cloudy and rainy days in the south of China, but dust weather in the north, fog and haze processes in the central and eastern part, and severe convective weathers in many provinces.

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