Table of Content

30 December 2017, Volume 33 Issue 6 Previous Issue    Next Issue

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Introduction of LAPS and its application in a rainstorm case in Liaoning province YANG Lei, WANG Ying, SUN Li, LIU Rui-xia, CAI Kui-zhi, LI Ming-jian 2017, 33 (6):  1-8.  doi: 10.3969/j.issn.1673-503X.2017.06.001 Abstract ( 294 )   PDF (2478KB) ( 415 )   Save After localization,the LN-LAPS (LiaoNing-Local Analysis and Prediction System) can assimilate the prediction field of T639 and the radiosonde,automatic weather station,FY satellite and Doppler radar data,and output an analyzing field with 3 km×3 km spatial resolution.The basic framework and designing theory of the LN-LAPS were introduced,and its applicability in a rainstorm event occurring over Fushun city of Liaoning province on August 16,2013,was discussed.The results show that the analyzing field produced by the LN-LAPS assimilating with multiple observations can reveal the features of meso-and small-scale convective systems,and help to correct the precipitation region and intensity predicted by the numerical weather prediction models.The strong ascending motion accompanying with abundant water vapor and instability energy in the surroundings indicate the occurrence of this rainstorm.Meanwhile,the cloud microphysical characteristics and radar echo point out the extreme property of this rainstorm process. References | Related Articles | Metrics

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Comparison analysis of formation mechanisms of two tornado cases under the background of Northeast Cold Vortex WANG Ting-ting, WANG Ning, YAO Yao, ZHANG Meng-yuan, FU Dong-xue, YANG Xue-yan 2017, 33 (6):  9-15.  doi: 10.3969/j.issn.1673-503X.2017.06.002 Abstract ( 283 )   PDF (3759KB) ( 734 )   Save Using conventional and unconventional observational data with high temporal and spatial resolutions,the formation mechanisms of two tornado cases that occurred on May 31 and June 8,2015 in Tongyu County (referred to as "513" Tornado and "608" Tornado) were analyzed in detail.The results showed that the two tornados are both affected by the sub-scale short-wave trough or shear line in front of the Northeast Cold Vortex.The area of the large temperature difference between 700 hPa and 500 hPa moves eastwards due to the strong westerly jet at middle levels of the troposphere,and the area of high moisture obviously stretches northwards due to the low-level southwest jet.Tornados occur at the edge of a moist tongue and the vicinity of overlaying area of the multi-scale systems.The "531" Tornado has larger jet velocity,the temperature difference between 700 hPa and 500 hPa,and the 925 hPa dew point value and stronger intensity than those of the "608" Tornado,because the convergence and ascending motion are stronger due to the shear line and negative variable pressure at 850 hPa.Before the formation of the two tornado events,the atmosphere is characterized by the convective available potential energy (CAPE) larger than 1500 J·kg-1,a temperature inversion layer at lower levels,the low lifting condensation level (LCL),and a shallow moist layer.The convergence shear line or cold front is the direct trigger mechanism of the two tornados,and the significant convergence of wind speed at both sides of the convenience line during the "531" Tornado event provides strong inflows to enhance a convective storm.Few clear physical characteristics occurred before the formation of the Tornado,such as the large pressure zone with the higher CAPE value,the lower height of LCL,but the thickness of the wet layer is very thin,the shear lines moving slowly to the east which are the direct facts triggering the formation of the tornados.The both sides of the shear line of "531" tonado have wind speed convergence which provides the strong inflow for the development of the convective storm.The "531" Tornado belongs to a supercell tornado under conditions of strong vertical shear of horizontal winds,while It has a clear hook structure,a weak echo area at lower levels and the draping characteristics of echos in the middle and high levels with the echo top height of higher than 11 km.The supper cell crosses the boundary of a shear line and locates at the side of cold air.The horizontal vorticity reached a maximum due to the effect of atmospheric baroclinicity.A strong meso-cyclone occurs at low levels,with its bottom extending to the height of less than 1 km,and exhibits obvious characteristics of tornado vortexes,which is favorable for the formation of tornados.the "608" Tornado is a non-supercell tornado and it is under the conditions of weak vertical wind shear. References | Related Articles | Metrics

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Diagnostic analysis of an unusual flash heavy rain in Bayingolin Mongol Autonomous prefecture LIU Guo-qiang, TONG Xin-yi, YANG Lian-mei, ZHOU Xue-ying, HUO Da 2017, 33 (6):  16-24.  doi: 10.3969/j.issn.1673-503X.2017.06.003 Abstract ( 239 )   PDF (3850KB) ( 411 )   Save Based on the hourly precipitation,real-time radiosonde data and the NCEP/NCAR(National Centers for Environmental Prediction/National Center for Atmospheric Research)reanalysis data with resolutions of 1°×1°,we analyzed the characteristics of critical circulation systems,vapor transportation,dynamics,moist potential vorticity and vertical helicity of a flash heavy rain event happening in Bayingolin Mongol Autonomous Prefecture on August 23 to 24,2016.The results indicate that the flash heavy rain occurs under the following circulation conditions:South Asia high with an eastern pattern increases dramatically and the long wave trough from Western Siberia to the Balkhash Lake moves eastward slowly.The rapid convergence of the wind direction and wind speed at the lower tropospheric level provides the power and vapor conditions for the flash heavy rain.There are three components for the water vapor sources at three rainstorm stages.One is the western water vapor transport produced by the convergence between the southward cold air guided by the northerly wind in front of the Ural ridge and the westerly flow;the second is the west-southern water vapor transport carried by the low vortex at the southwest side of Tibetan Plateau;the third is the southerly water vapor transport brought by the pacific subtropical high,in which 94.26% of water vapor transportation comes from the west and south airflow.At the early stage before the flash heavy rain occurred,a mesoscale vertical circulation cell forming over the east and west sides of the heavy rainfall area is the main dynamic mechanism for its occurrence.The vertical helicity evolution is closely related to the flash heavy rain.The appearance of heavy precipitation usually accompanies with the coupling between the negative vertical helicity value at the upper level and positive one at the lower level.Heavy rain often appears in the area with steep and dense θse lines.The downward spread of high moist potential vorticity at the upper tropospheric level triggers the release of potential instability energy,resulting in the occurrence of heavy rain. References | Related Articles | Metrics

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Diagnostic analysis on Meiyu rainstorm triggered by mesoscale vortex in Yangtze and Huaihe River in 2015 HUANG Wen-juan, CHEN Yong-lin, SHU Jiong 2017, 33 (6):  25-33.  doi: 10.3969/j.issn.1673-503X.2017.06.004 Abstract ( 206 )   PDF (2666KB) ( 326 )   Save Based on the equivalent black body temperature at the cloud top derived from FY-2G and the NCEP (National Centers for Environmental Prediction) reanalysis data with resolutions of 1°×1°,a sustained heavy rain in Yangtze-Huaihe river basin on June 16-17,2015 was analyzed.The results show that the intensity of this precipitation is essentially consistent with the evolution of mesoscale convective vortex (MCV) and the southwest jet.The MCV is triggered together by the latent heat release induced by the organized development of convection and the low-level convergence and upper-level divergence.The MCV extends from the lower troposphere to 250 hPa,and the strongest center for vorticity is at the middle-low level of the troposphere.During the mature stage,mesoscale convective system (MCS) can help to stimulate updraft and is a benefit to transport heat and water vapor because the convergence zone of wet Q vector corresponded to the center of positive vorticity,which promoted the development of MCV.The horizontal advection at the middle-lower level contributes negatively to the vorticity during the whole MCV stage.The formation and development of MCV is determined by the horizontal convergence and divergence.Ascending motion of the vortex has a direct impact on the vertical transportation of vorticity and further influences on the development of the vortex in the vertical. References | Related Articles | Metrics

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Characteristics and causes of an elevated thunderstorm case happening after a cold front in Zhengzhou area CUI Hui-hui 2017, 33 (6):  34-41.  doi: 10.3969/j.issn.1673-503X.2017.06.005 Abstract ( 327 )   PDF (3903KB) ( 333 )   Save Based on conventional meteorological observation and the NCEP (National Centers for Environmental Prediction) 6 hourly 1°×1° reanalysis data,the characteristics and causes of an elevated thunderstorm weather process happening in Zhengzhou area in early spring of 2015 were analyzed.The results showed that the ground cold pad,850 hPa and 700 hPa strong warm jet and trough at 500 hPa provide favorable dynamic,thermal and moisture conditions for the occurrence of an elevated thunderstorm.A large vertical wind shear between 700 hPa and 850 hPa and the large temperature difference between 700 hPa and 500 hPa show that there is a strong convective instability above the inversion layer,which is helpful for the occurrence of this elevated thunderstorm.A negative moisture vapor flux divergence and strong humidity advection at the low level provide an abundant water vapor for the elevated thunderstorm.Before the occurrence of thunderstorm,Δθse between 700 hPa and 500 hPa is above 0℃,and the atmosphere above 700 hPa is in a convective instability condition.The negative MPV1 (Moist Potential Vorticity) at the low level indicates that there is a moist symmetric instability condition in this layer,and the strong thunderstorm falls just in the convective instability zone and the negative area of MPV1.All these results indicate that this elevated thunderstorm is the result of joint interaction between convective instability and moist symmetrical instability.The warm air mass on the ground cold pad is gradually strengthened.It further exacerbates the atmospheric stratification stability above the inversion layer.By comparing with historical cases,it is found that the two elevated thunderstorm weather processes over Zhengzhou have some common features.The pumping action in front of 500 hPa troughs,low-level shear line,the convergence ascending motion at the left side of the low-level jet and the uplift of the ground cold pad should be the focus to forecast the elevated thunderstorms. References | Related Articles | Metrics

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Spatial-temporal distribution characteristics of short-time strong precipitation in the flood season under different terrains over Anhui province TONG Jin, WEI Ling-xiang, YE Jin-yin, ZHOU Kun, YUAN Song 2017, 33 (6):  42-48.  doi: 10.3969/j.issn.1673-503X.2017.06.006 Abstract ( 262 )   PDF (1180KB) ( 541 )   Save Based on the hourly precipitation data collected from automatic weather stations over Anhui province and hourly TBB (Black Body Temperature) data from FY-2E meteorological satellite,the spatial-temporal distribution characteristics of short-time strong precipitation (STSP) in the flood season under different terrains over Anhui province and their relationships with the mesoscale convective activities were analyzed and spatial-temporal characteristics of the extreme STSP were discussed preliminarily.Results showed that the STSP occurs mainly in the mountain area of southern Anhui,followed by Dabie Mountains and the hilly area in the mid-eastern part of Anhui province,while least in Huaibei plain under different terrains during 2011-2015.The monthly variation of the STSP frequencies presents a single-peak pattern,i.e.the highest frequency is in July,which is different from the circumstances in the others months.Meanwhile,the pentad variation of the STSP frequency indicates a characteristic of multi-peaks and intermittency,that is,the STSP intensively occurs during the first pentad in June to the sixth pentad in August.Specifically,the pentad variation is largest in Huaibei plain and smallest in the mountain area of southern Anhui.In addition,the diurnal variations of the STSP frequency have a characteristic of single-peak and its peak value intensively appears in 15:00-19:00.Besides,the change characteristics of STSP frequency in the mountain area of southern Anhui and the hills in mid-eastern Anhui are similar to that averaged in Anhui province,i.e.the STSP mainly occurs in the afternoon.Although the STSPs in Huaibei plain and Dabie Mountains frequently appear in the afternoon,they also occur between 06:00-07:00 and 02:00-03:00 as well as 10:00,that is,a multi-peak pattern of STSP frequency is indicated in above-mentioned areas.The extreme STSP is dispersedly distributed in Anhui province and does not intensively occur in any area,and its time-varying trait with statistical regularity is similar to that of the STSP.More specifically,the extreme STSPs most intensively occur during 16:00-19:00 in the mountain area of southern Anhui in July,especially during the fifth pentad in July.They also occur in the hills in mid-eastern Anhui in July with the relatively uniform pentad variation,as well as at 02:00 in Dabie Mountains.Furthermore,the extreme STSP in Huaibei plain mainly occurs in August especially for the sixth pentad and it shows a duration variation without evident peak value.Thus,a certain corresponding relationship is possibly indicated between the STSP and the mesoscale convective activities and shows a local dissimilarity. References | Related Articles | Metrics

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Climatic and synoptic characteristics of thunderstorm gale in Dalian region YANG Jing-tai, SUI Yu-xiu, WANG Jian, ZHOU Mei-e, YU De-hua, SUN Li-juan, PAN Yu-cheng 2017, 33 (6):  49-57.  doi: 10.3969/j.issn.1673-503X.2017.06.007 Abstract ( 354 )   PDF (817KB) ( 526 )   Save Based on the observation data of thunderstorm gale,thunderstorm,hail and other weather phenomena in the region of Dalian region from 1999 to 2013,the climatic and synoptic characteristics of thunderstorm gale in Dalian were analyzed.The results reveal that occurrence regularity of thunderstorm gale in Dalian has a strong regional characteristic.The occurrence frequency at night is significantly higher than that at daytime.The number of thunderstorm gales happened on the island stations is significantly greater than that on the land stations.Thunderstorm gales mainly occur in summer.In addition,October is also the time when thunderstorm gales happened frequently.Statistics analyses show that the thunderstorm gales often occur in the thunderstorm groups which have a large spatial scale and time scale in Dalian region,and the probability that a single thunderstorm cell causes thunderstorm gales is very low.Mostly,the occurrence of thunderstorm gales accompanies with rainfall,while the occurrence of thunderstorm gale rainstorm or hail simultaneously is rare.The thunderstorm gales in Dalian region are usually formed by the combination of many favorable configurations of upper and lower altitude systems,jet stream at upper and lower level and dry air at middle and upper altitude.The most important factors that control the generation of thunderstorm gale are jet streams at the upper level and dry air at the middle and upper altitude.The jet stream at an upper level sometimes controls the location and the distributing pattern of the thunderstorm gale.Thunderstorm gales in Dalian region usually located at the areas near and down the axis of the upper level jet stream.There are three functions for dry air at the middle and upper altitude,i.e.enhancing the atmospheric instability,forming a very strong dew-point front at the junction of dry and wet areas and sometimes triggering thunderstorms,and enhancing the ascending motion when it superposes with other weather systems. References | Related Articles | Metrics

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Variation characteristics of reference crop evapotranspiration in Liaoning province from 1961 to 2015 WEN Ri-hong, ZHAO Tong-bin, WEN Zhou, LÜ Guo-hong, JIANG Peng, JIA Qing-yu, XIE Yan-bing, WANG Xiao-ying 2017, 33 (6):  58-65.  doi: 10.3969/j.issn.1673-503X.2017.06.008 Abstract ( 194 )   PDF (1471KB) ( 335 )   Save Using the daily meteorological data from 50 meteorological stations in Liaoning province from 1961 to 2015,the amount of reference crop evapotranspiration (ET0) was calculated using the Penman-Monteith formulation,and its variation trend and mutation characteristics were analyzed statistically using MK (Mann-Kendall) test and R/S (Re-scaled Range) methods.The results show that in the recent 55 years,the average value of the amount of ET0 in the whole year and each season presents a downward trend,with a maximum declining rate appearing during the 1960s to 1970s,and from east to west,it gradually increases.The average values of wind speed and sunshine hours are the main meteorological factors to influence the amount of ET0.There is a Hurst phenomenon in ET0 and meteorological factors.It suggests that the variation trend in the future will be similar to the past one,i.e.,the decreasing in wind speed and sunshine hours will result in the continuously declining in ET0 in the future. References | Related Articles | Metrics

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Effects of different sowing dates on growth process and yield of spring maize in southern Liaoning ZHAO Xian-li, LI Li-guang, CAI Fu, WANG Hong-bo, ZHAO Zi-qi, DING Kang-kang 2017, 33 (6):  66-72.  doi: 10.3969/j.issn.1673-503X.2017.06.009 Abstract ( 230 )   PDF (551KB) ( 375 )   Save Based on experimental data collected from different sowing dates with Danyu39 as tested variety and the contemporaneous meteorological observation data in Zhuanghe area from 2012 to 2014 as well as averaged occurrence dates of different growing periods and yield data during 1980-2010,the effects of different sowing dates on growth development process and yield of spring maize in Zhuanghe area were investigated.The results show that the variation of the sowing dates significantly affects the growth process of the spring maize,that is,with one-day delay in the sowing date,durations of the total growing period and the vegetative growth period shorten about 0.22-0.57 d and 0.48-0.69 d,respectively,while the reproductive growth period prolongs about 0.11-0.36 d.In addition,the duration of each growing period indicates evident difference among the different sowing dates.Specifically,the difference in the vegetation growth period is most significant,while those in the periods during heading-tasseling,tasselling-flowering,flowering-milky and milky-maturity are all not significant.The effect of the sowing dates on the maize yield is significant,which is reflected by firstly increasing and then decreasing yields with the sowing dates postponing in 2012 and 2013 except in 2014,but the interannual variation of yield is very significant.The meteorological factors affecting the growth period of the spring maize in Zhuanghe area are obviously different among the years from 2012 to 2014 and temperature,sunshine duration,average wind speed,water vapor pressure and evaporation are the main factors impacting the whole growth period,the vegetative and the reproductive growth period of the spring maize. References | Related Articles | Metrics

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Evaluation of agricultural climate resources in the potential northward region of winter wheat ZHANG Meng-ting, ZHANG Yu-jing, TONG Jin-he, LI Kuo, PAN Jie, XU Yin-long 2017, 33 (6):  73-81.  doi: 10.3969/j.issn.1673-503X.2017.06.010 Abstract ( 218 )   PDF (3502KB) ( 341 )   Save Based on the high-resolution (50 km×50 km) future climate data from 2071 to 2097 simulated under a scenario of RCP4.5 using a model of Providing Regional Climates for Impacts Studies (PRECIS),the northward shifting boundary of winter wheat was estimated in comparison with the data from 1981 to 2010.Nine climatic factors including the sunlight,temperature and water sources were chosen to study the spatial and temporal variations of the agricultural climate resources in the potential northward shifting region of winter wheat including Liaoning province,Inner Mongolia Autonomous Region,Hebei province,Shanxi province,Shaanxi province,Ningxia Hui Autonomous Region,and Jilin province.The allocation of agricultural climate resources was evaluated based on the method of Dynamic Technique for Order Preference by Similarity to Ideal Solution (DTOPSIS).The results indicated that the radiation is high in the west and low in the east in the potential northward region of winter wheat in China from 1981 to 2010,and the variation of inter-annual radiation has a decreasing trend.Heat resources are rich in Shanxi province in the central China and are poor in Shaanxi province in the western China,in the southern part of Liaoning province.All the five indexes of heat resource such as annual mean air temperature,annual negative cumulative temperature,cumulative temperature ≥ 0℃ during the growing season,extremely lowest temperature,and frostless season exhibit increasing trends from 1981 to 2010.Water resources are rich in the east and low in the west.Annual precipitation and wet days decrease,while precipitation in the growing season increases from 1981 to 2010.Agricultural climate resources in the potential northward region of winter wheat show a better allocation in Dandong,Xiuyan and other regions in the eastern part of Liaoning province,and such allocations in Wengniute Banner in Inner Mongolia Autonomous Region,Weichang in Hebei province,Youyu and Wuzhai in Shanxi province are poor.In comparison with the period from 1981 to 2010,the area of adaptability region for winter wheat decreases in Liaoning province,while the area of sub-adaptability region increases mainly due to the transformation of inadaptability region to sub-adaptability region in Shaanxi province and NingxiaHui Autonomous Region in southwestern China region in the future northward region of winter wheat from 2071 to 2097. References | Related Articles | Metrics

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Variation characteristics of human comfort index in Wuhan urban circle from 1961 to 2010 JIN Qi, MENG Ying-jie 2017, 33 (6):  82-88.  doi: 10.3969/j.issn.1673-503X.2017.06.011 Abstract ( 206 )   PDF (1198KB) ( 505 )   Save According to the daily average temperature,relative humidity,and wind speed observation data from 9 meteorological stations in Wuhan urban circle,the human comfort indexes were calculated and the temporal and spatial distribution characteristics of human comfort index in Wuhan urban circle were analyzed.The results show that people feel comfortable all months except January.The temporal characteristics of human comfort index in 9 cities are analyzed and the results suggest that human comfort indexes of 9 cities show increasing tendencies.As to the spatial distribution,the average number of comfortable days during 1960 to 2016 in the north is less than that in the south,which shows that it is hot in south areas while it is cold in north areas.The number of comfortable days increased during the past 57 a.Especially,the number of comfortable days is more than the average days during the past 57 a when entering into the 21st century.Meanwhile,the number of hot days increases slowly and the number of cold days is decreasing year by year.From the statistical number of comfortable days for tourism,it is suitable for traveling in April,May,September,and October in Wuhan urban circle.In spring and summer,the number of comfortable days for tourism increased from south to north.While in autumn and winter,it is the vice versa. References | Related Articles | Metrics

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Applicability analysis of air temperature and humidity data retrieved from a RPG-HATPRO microwave radiometer LI Jian-qiang, LI Xin-sheng, DONG Wen-xiao, LÜ Jing-jing 2017, 33 (6):  89-95.  doi: 10.3969/j.issn.1673-503X.2017.06.012 Abstract ( 232 )   PDF (1155KB) ( 416 )   Save The data of air temperature and humidity retrieved from a German RPG-HATPRO microwave radiometer were statistically analyzed in comparison with the routine sounding data at the same observational site in Taiyuan for air temperature and dew point temperature at surface,925 hPa,850 hPa,700 hPa,500 hPa,400 hPa, and 300 hPa at 00:00 and 12:00 from February 13,2015 to June 21,2016.The results show that certain deviation exists between the temperature retrieved using the microwave radiometer and that observed by sounding at different isobaric levels.The temperature data from microwave radiometer are systematically smaller than the sounding temperature.The correlation coefficient value between the two kinds of temperature data is larger than 0.89,which means a high synchronism in the temperature data,and the correlation coefficient in dew point temperature is larger than 0.60.Precipitation has a great influence on the temperature and humidity data retrieved from the microwave radiometer.A correction model for the temperature data measured from the microwave radiometer is established to verify the accuracy of the temperature data at different isobaric levels.The temperature data are corrected using a moving average method and a T-test method for paired samples,and the bias correction is smaller than 0.5℃. References | Related Articles | Metrics

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Effective test of an artificial precipitation enhancement operation process in Liaoning province based on a regional historical regressive statistical method ZHAI Qing-fei, AO Xue, YUAN Jian, SHAN Nan, LIU Ji, CAO Jian-qiu 2017, 33 (6):  96-104.  doi: 10.3969/j.issn.1673-503X.2017.06.013 Abstract ( 232 )   PDF (5563KB) ( 320 )   Save Using a regional historical regressive statistical method and based on daily precipitation data from national surface meteorological stations in Liaoning province from 1961 to 1990,the effect of an artificial precipitation enhancement process in Fuxin on August 31,2016,was validated using Tieling as a control area.The results showed that throughout the comprehensive analysis of the data from sounding,radar,and numerical model as well as operating parameters,this artificial precipitation enhancement process meets the requirement of rationality.The increase in absolute rainfall is 20.06 mm,and the increase in relative rainfall rate is 119.43% through the significance testing with the 0.01 significant test level.In comparison with previous studies using the same method in other provinces in China,we find that the choice of statistical variables has great effects on the validation results. References | Related Articles | Metrics

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Comprehensive analysis of aircraft artificial precipitation enhancement in high-latitude areas ZHENG Kai, AN Ying-yu, HAN Shu-xin, LI Peng, GAO Qian-nan, LI Dong-nan 2017, 33 (6):  105-111.  doi: 10.3969/j.issn.1673-503X.2017.06.014 Abstract ( 230 )   PDF (1962KB) ( 309 )   Save An artificial aircraft precipitation enhancement operation in Heilongjiang province on May 24,2016 was analyzed using the conventional data from the Meteorological Information Comprehensive Analysis and Processing System (MICPS),the cloud model products from the Global/Regional Assimilation and Prediction System developed by Chinese Academy of Meteorological Sciences (GRAPES_CAMS) and satellite retrieval products,and based on the Cloud Precipitation Accurate Analysis System over the Northeast China (CPAS_NE) platform.The results show that due to the effects of a cold vortex at high levels and a low pressure at the surface,the operation target area is characterized by thick clouds and a super-cooled layer that has a certain amount of super-cooled water.Meanwhile,the radar echoes show that there is a large area of flaky stratiform cloud,which means a good catalytic capacity for aircraft precipitation.It is the best time to increase precipitation when clouds develop very deep and the vertically cumulative liquid water content is large.The physical testing of the catalytic effects on the target area and the contrast area indicates that the operation has an obvious influence on precipitation at the surface and makes the radar echoes vary small.Due to the satellite products,it can be found that the temperature of blackbody brightness in the target area decreases quickly,and cloud top temperature and height decrease.This means the catalytic effect of the artificial precipitation operation is good.After the aircraft precipitation operation,the thickness of supercool liquid layer reduces,the effective radius decreases.These changes imply that the catalyst consumes supercool liquid water and the large cloud particles become raindrops.In other words,the cloud water has been effectively converted into the rain water which indirectly validated the aircraft precipitation enhancement operation. References | Related Articles | Metrics