Table of Content

30 June 2019, Volume 35 Issue 3 Previous Issue    Next Issue

ARTICLES

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Comparative analysis of two typhoon rainstorm processes affecting Dalian city CHENG Hang, LI Yan, CAI Dong-mei 2019, 35 (3):  1-9.  doi: 10.3969/j.issn.1673-503X.2019.03.001 Abstract ( 861 )   PDF (8835KB) ( 201 )   Save In this paper,the data from the conventional meteorological stations,the intensively meteorological automatic observation stations,and the NCEP (National Centers for Environmental Prediction) reanalysis were used to comparatively diagnose and analyze the typhoon and rainstorm processes,Haitang (1710) and Damrey (1210),which occurred in Dalian on August 3,2017 and 2012,respectively.Through analyzing the typhoon track,circulation situation,and interaction between the two typhoon systems,it is shown that the precipitation system during the two rainstorm processes is a typical double-typhoon precipitation mode.In the north of the typhoon systems,there are cold air with different intensities invading and triggering convective instability,which facilitates the development of mesoscale rainstorm cloud clusters.There is a shear convergence at the lower 850 hPa,and a jet stream developing at the upper level.During the main rainfall periods, a strong upward movement from the low to the high levels occurs over the heavy precipitation center,and the divergence at a high level and convergence at low level are maintained over the rainstorm center.The typhoon system existing at the south of Japan sea forces the subtropical high to develop a radial distribution or to form a blocking high.The jet at low level formed between the two or three typhoons and the subtropical high provide favorable dynamic and water vapor conditions for the formation and maintenance of the rainstorms.Combined with the residual circulation of typhoon "Haitang" and the high trough,the cold air brought by the high trough is more intense and the effect of frontogenesis is more obvious,which is favorable to the occurrence and development of strong convection.The interaction between typhoons "Sula" and "Damrey" affecting Dalian leads to more vigorous warm and wet airflow,longer duration and a wider range of precipitation during the heavy precipitation stage. References | Related Articles | Metrics

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Analysis of lightning flash activity characteristics of a severe hailstorm process in Beijing GUO Run-xia, ZHANG Wen-long 2019, 35 (3):  10-17.  doi: 10.3969/j.issn.1673-503X.2019.03.002 Abstract ( 279 )   PDF (2470KB) ( 294 )   Save Due to the limitations of the lightning monitoring system,the existing studies were mostly limited to the cloud-to-ground lightning (CG) activity characteristics in the severe convective weather.In this paper,the data from the VLF/LF three-dimensional lightning monitoring and positioning system and radar observation stations were used to analyze the full lightning activity characteristics during a typical large hail weather process in Beijing.The results show that before the hail,the lightning activity is mainly distributed in the rear of the convection system,and the number of lightning is small,and the negative lightning activity is dominant.During the hail period,the frequency of lightning flashes (FLF) increases significantly,and the intracloud lightning (IC) and positive CG activities are significantly enhanced.The lightning activities in this stage are mainly concentrated at the center of the strong echo area and the regions with a large gradient of the front radar reflectivity factor of the convection system.After the hail,the strong echo center moves out of Beijing,and the FLF in Beijing decreases significantly.The proportion of positive lightning increases gradually before the occurrence of hail remains stable at a large value during the period of hail,and decreases rapidly after the end of hail.The IC lightning ratio (the frequency of IC lightning/the frequency of total lightning) shows a gradually increasing trend before and after the hail,and basically remains stable and changes little during the hail.The lightning current strength is mainly concentrated in the 5-50 kA.The IC and CG with current intensity below 20 kA mostly occur during and after the hail,and those above 20 kA are dominant before the hail.The proportion of IC with a current intensity of less than 5 kA is higher than that of CG during the hail.Before and after the hail,the IC occurs at an altitude of 2-6 km,and increases during the hail,to about 2-8 km.The peak of FLF is 5-20 min ahead of that of precipitation. References | Related Articles | Metrics

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Research on the improvement of weather radar velocity dealiasing algorithm based on variational technique WU Bin, WEI Ming, LI Yan-fang, ZHENG Shi, ABRO Mohammad 2019, 35 (3):  18-28.  doi: 10.3969/j.issn.1673-503X.2019.03.003 Abstract ( 308 )   PDF (5923KB) ( 176 )   Save In order to effectively identify and extract Doppler weather radar wind field information,the dealiasing method of Doppler radar radial velocity data proposed by Gao and Droegemeier based on the variational technique was improved.In the original method,the information of background wind field,azimuth and radial velocity and distance gradient were simultaneously taken as constraint conditions to calibrate the Nyquist number.However,in the iterative process,a large number of numerical analysis and partial differential equation were used,resulting in the radial velocity excessively smooth and distortion.To solve this problem,based on obtaining the radial velocity analysis field,the improved algorithm combined with the original radial-velocity observation field,automatically identified the area with velocity ambiguity and calculated the Nyquist number to be corrected through the image change detection method,and then corrected the aliasing area of the observation field.The feasibility of the improved algorithm was verified by the radar volume scans data of severe convection weather and a typhoon event.Compared with the original and the operational WSR-88D algorithms,it shows that the improved algorithm can effectively solve the shortcomings of the original algorithm,reproduce the real structure and distribution characteristics of the wind field,improve the quality of velocity dealiasing,and thus obtain a more reasonable radial-velocity observation field.Moreover,the dealiasing effect of this algorithm is better than that of the WSR-88D algorithm,which is helpful for scientific research and operational application. References | Related Articles | Metrics

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Study on determining the height of the convective boundary layer in summer over Ji'nan using deviation degree method WANG Dong-cheng, QIU Can, DONG Xu-guang, CAO Jie 2019, 35 (3):  29-36.  doi: 10.3969/j.issn.1673-503X.2019.03.004 Abstract ( 239 )   PDF (876KB) ( 249 )   Save Based on the data of boundary layer wind profile radar (WPR) at Ji'nan station,the technical difficulties in determining the height of the convective boundary layer (hereinafter referred to as CBLH) using the structure constant of atmospheric refractive index (hereinafter referred to as Cn2) were studied.Through transforming the profile of Cn2 data to highlight its variable characteristics,we proposed a method to determine CBLH,namely,the deviation method based on an e-index fitting curve.Confirmed by case analysis and compared with the measurements,the results derived using this method are generally consistent with those derived using the methods of the L-sounding virtual potential temperature gradient and the moisture gradient.The correlation coefficients between the results obtained in this study and those obtained from the other two methods reach 0.988 and 0.980,respectively,and the average differences are +10.4 m and -21.8 m,the minimum differences are -70 m and-120 m,and the maximum differences are +50 m and +80 m,respectively.The comparison results of different methods show that,among thirty-one groups of samples, the results from seven groups derived by the maximum value method are significant differences from those derived by the deviation and the virtual potential temperature gradient methods.The deviation method is generally superior to the maximum value method in determining CBLH.This method can reduce the absolute error of CBLH in summer to approximately the level of the WPR vertical resolution. References | Related Articles | Metrics

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Comprehensive analysis of a heavy PM2.5 pollution event over Shenyang in November of 2015 YANG Lei, CHEN Chuan-lei, CAO Shi-teng, SUN Li, CUI Yao-peng, JIANG Chao, HUANG Hai-liang, CHEN Yu, YANG Xue 2019, 35 (3):  37-44.  doi: 10.3969/j.issn.1673-503X.2019.03.005 Abstract ( 282 )   PDF (6470KB) ( 247 )   Save The variations of meteorological conditions,vertical wind field,features of planetary boundary layer and pollutant sources during a heavy PM2.5 pollution event in Shenyang in November of 2015 were comprehensively analyzed using an observational dataset.The results show that the period of PM2.5 concentrations higher than 250 μg·m-3 lasts for 81 hours during this event,with a maximum PM2.5 concentration reaching 1287 μg·m-3 and a maximum PM2.5/PM10 ratio reaching 90%.Affected by an inverted trough at the surface and the Huanghuai cyclone,the temperature inversion layer,high humidity conditions and weak northerly winds remain in the near-surface layer,which are favorable for the hygroscopic growth and long-term accumulation of particles.The observational data from a wind profile radar showed that during the heavy pollution period,low level winds,fickle wind directions and weak subsidence of airflows near the surface remained.Based on the radar data,the ventilation index (VI) and recirculation index (R) are calculated.The values of PM2.5 concentrations have a negative correlation with the values of VI,and the mean VI on clear days is twice of that on heavy pollution days.The values of R are larger than 0.9 before the heavy pollution period and became smaller than 0.8 during this pollution period.Through analyzing the backward trajectories and fire point monitoring data,the air masses at 300 m altitude over Shenyang originate from areas with the dense biomass burning.Moreover,the variation of NO2 and CO concentrations in Shenyang are consistent with that of PM2.5.This heavy pollution event may be also associated with the biomass burning. References | Related Articles | Metrics

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Characteristics and causes of a heavy haze event in Changsha during winter of 2017 ZHOU Li, LAN Ming-cai, ZHANG Jian-qi, ZHOU Hui, TANG Jie, XU Lin, WEN Ping 2019, 35 (3):  45-51.  doi: 10.3969/j.issn.1673-503X.2019.03.006 Abstract ( 305 )   PDF (5852KB) ( 149 )   Save Based on air quality monitoring data and conventional meteorological observations,the characteristics of a heavy haze event in Changsha region on January 27 to 29,2017 was analyzed,including the vertical and horizontal dispersion,surface humidity and dynamical conditions.The results showed that a southern branch trough deepens and moves eastwards during the pollution period,and strong southwesterly flows ahead of the trough transport water vapor from the Bay of Bengal to Changsha,which further increases air humidity in this region.Meanwhile,warm advection ahead of a ridge that continuously moves eastwards greatly impacts on the increase of temperature in the middle and lower levels of atmosphere,which is favorable for the formation of the stable atmospheric stratification.Changsha is located at the bottom of a weak high pressure and controlled by a weak saddle pattern of pressure field,leading to the development of a warm inverted surface trough.Weak winds at the surface and in the low-level atmosphere due to the weak high pressure suppress the horizontal dispersion of air pollutants and favors the surface radiation cooling at night.Stable atmospheric circulation provides steady and stable atmospheric environment for the formation of severe haze pollution.Temperature inversion and stable stratification weaken vertical turbulence exchange and turbulent convection.The weak dilution of particle favors the persistence and enhancement of this pollution event.In addition,Changsha is located between the Luoxiao mountains and the Xuefeng mountains.Such a local surrounding terrain blocks the subsequently horizontal transport of air pollutants after accumulating in Changsha region due to the descending airflows,which is also a major reason for the occurrence of this haze pollution event. References | Related Articles | Metrics

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Comparison of air quality and atmospheric self-purification capacity between coastal and inland areas of Ningbo YANG Dong, ZHU Jia-min, YAO Ri-sheng, TU Xiao-ping 2019, 35 (3):  52-59.  doi: 10.3969/j.issn.1673-503X.2019.03.007 Abstract ( 270 )   PDF (2836KB) ( 122 )   Save Based on air pollutant monitoring data from 2013 to 2017 and the LiDAR data from December of 2015 to February of 2017 observed at Zhenhai (a coastal station) and Fenghua (an inland station) in Ningbo,the characteristics of air quality at the two stations were comparatively analyzed,and the aerosol sources and difference of atmospheric self-purification capacity at the two stations were evaluated using the reanalysis data from National Centre for Environment Prediction (NCEP) Global Data Assimilation System (GDAS) and ERA-Interim high-resolution dataset.The results showed that moderate and heavier air pollution occur mostly in winter in the coastal and inland areas of Ningbo,with PM2.5 as the primary pollutants commonly.The NO2 concentrations in Zhenhai area are significantly higher than that in Fenghua,and concentrations of PM2.5 and PM10 between the two areas are close to each other.In winter,an aerosol layer below 3 km with large extinction coefficient are observed at both stations,and the average of extinction coefficient below 3 km at Zhenhai station is about 40% larger than that observed at Fenghua station.When moderate and heavier pollution occur at both stations,aerosols are mainly originated from the northwestern inland region of Ningbo,reaching 90% for Zhenhai and 63% for Fenghua,respectively.The rest aerosols in Zhenhai are mainly related to the short-range transport by easterly flows at low levels,and that in Fenghua are primarily due to the short-range transport from the southwestern region of Zhejiang province.The northern coastal areas in Zhejiang province is usually dominated by northeasterly and northwesterly winds when air quality in Ningbo region reaches grades of excellence,moderate,and heavier pollution during winter,with mean wind speed of the former higher than the latter. The ratio of atmospheric self-cleaning capacity between air quality grades of excellence and moderate and heavier pollution decreases from the northwest to the southeast in Zhejiang province,with the value about 1.5 times Ningbo area.The difference of atmospheric self-purification capacity under different air quality grades can be used as a reference for forecasting the occurrence,development and dissipation of air pollution. References | Related Articles | Metrics

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Impact of sea surface temperatures in Western Pacific warm pool on precipitation in Shanxi province in mid-summer season ZHANG Dong-feng, WANG Yong-guang, ZHANG Guo-hong 2019, 35 (3):  60-67.  doi: 10.3969/j.issn.1673-503X.2019.03.008 Abstract ( 266 )   PDF (4456KB) ( 67 )   Save Correlations between precipitation in Shanxi province and the sea surface temperature in the Central and Eastern Equatorial Pacific and the Western Pacific warm pool during mid-summer season (July and August) from 1961 to 2016 were analyzes using precipitation observational data and National Oceanic and Atmospheric Administration (NOAA) extended reconstructed sea surface temperature (SST) data.The results showed that precipitation in Shanxi province has a significant negative correlation with the SST in the Central and Eastern Equatorial Pacific and a positive correlation with the SST in Western Pacific warm pool;such a positive correlation enhances since the late 1970s and the early 1980s with a significance level exceeding 0.05 and is associated with the negative SST anomaly in the Central and Eastern Equatorial Pacific.The SST anomaly in Western Pacific warm pool can influence the atmospheric circulation,positions of monsoon trough and the East Asian monsoon,resulting in the anomaly precipitation in Shanxi province.When the SST anomaly in the Central and Eastern Equatorial Pacific is negative,the positive (negative) SST anomaly in Western Pacific warm pool can cause the Europe-Asian-Pacific (EAP) teleconnection pattern and negative Pacific-Japan (PJ) waves.Subsequently,this makes the monsoon trough move westward and northward (eastward and southward),the Western Pacific Subtropical High move northward (southward),and the monsoon index become smaller (larger),leading to more (less) precipitation in Shanxi province during the mid-summer season. References | Related Articles | Metrics

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Effects of climate change on emission rate of dust of grassland soil by wind erosion in Bashang area,Hebei province WU Jian-guo, XU Tian-ying 2019, 35 (3):  68-78.  doi: 10.3969/j.issn.1673-503X.2019.03.009 Abstract ( 202 )   PDF (1657KB) ( 64 )   Save Based on the data of RCP2.6,RCP4.5,RCP6.0 and RCP8.5 climate change scenarios produced by the global climate model of NorESM1-M and calculation method of dust emission by soil wind erosion recommended by former Ministry of Environmental Protection of People's Republic of China,the effects of future climate change on the seasonal and annual emission rates of dust TSP (Total Suspended Particle),PM10 and PM2.5 by soil wind erosion from sandy loam,clay loam,loam,sandy loam,sandy soil and sandy soil grasslands in Bashang area of Hebei province were analyzed.The results show that the air temperature will increase and the annual precipitation and wind speed will obviously fluctuate with increasing and decreasing trends in Bashang area.Compared with the baseline scenario,the seasonal emission rates of TSP,PM10 and PM2.5 are 15%,47%,28% and 46% higher in spring,17%,54%,45% and 38% higher in autumn,36%,42%,39% and 44% lower in winter in RCP2.6,RCP4.5,RCP6.0 and RCP8.5 scenarios,respectively.In summer,the seasonal emission rates of TSP,PM10 and PM2.5 are 1% lower in RCP2.6 and are 14%,3% and 7% higher in RCP4.5,RCP6.0 and RCP8.5 scenarios than those in the baseline scenario,respectively.Under the background of future climate change,the annual emission rates of TSP,PM10 and PM2.5 by soil wind erosion will respectively increase 25%,54%,35% and 54% in RCP2.6,RCP4.5,RCP6.0 and RCP8.5 scenarios relative to those in the baseline scenario.Under the baseline and future climate change scenarios,the seasonal and annual emission rates of TSP,PM10 and PM2.5 by soil wind erosion and their differences are in the order from large to small by sandy loam,sandy soil,sandy loam,clay loam,clay and sand soil.The results suggest that the increase of the rate of dust by wind erosion in grassland soil in Bashang area of Hebei province will be caused by future climate change,but existing differences in different seasons and climate change scenarios. References | Related Articles | Metrics

REVIEW

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Advance on highway traffic meteorological research in foreign country TIAN Hua, ZHANG Nan, ZHANG Kai-yi, YANG Jing, ZHANG Hui-chen 2019, 35 (3):  79-86.  doi: 10.3969/j.issn.1673-503X.2019.03.010 Abstract ( 235 )   PDF (493KB) ( 192 )   Save The safety of road transportation can be assured with weather monitoring,forecasting and early warning.This paper largely reviews the development of international research on siting of the Road weather information system(RWIS),road temperature & condition prediction,and impact assessment of transport meteorology.In the meanwhile,the advantage and disadvantage for above-mentioned researches are compared.Then,their future development trends are discussed.Finally,it comes to the conclusion that the abundant data and diverse methods are used on international research for road traffic meteorology.To be specific,the research on RWIS siting develops from the empirical and qualitative approaches to quantitative approaches.The research on road temperature and condition prediction mainly focuses on the improvements of numerical models based on surface radiation balance theory and application of probabilistic forecast.The impact assessment of traffic meteorology tends to develop the risk prediction technique and its application.This paper aims at providing some useful information for the development of technologies for highway traffic meteorology in China. References | Related Articles | Metrics

SCIENTIFIC NOTES

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Research on the cloud detection model of FY3D/MERSI and EOS/MODIS based on deep learning QU Jian-hua, YAN Jun-jie, XUE Juan, GUO Xue-xing 2019, 35 (3):  87-93.  doi: 10.3969/j.issn.1673-503X.2019.03.011 Abstract ( 485 )   PDF (2058KB) ( 290 )   Save Based on deep learning technology,a fully automatic cloud detection algorithm for FY3D/MERSI and EOS/MODIS image is proposed and is firstly introduced in cloud detection study.Using Deep Convolutional Neural Networks as core structure and choosing some appropriate channels as characteristic parameters based on MODIS basic cloud detection theory,classifying and network model training are conducted according to the different scenarios.As a result,cloud detection model based on deep learning is setup and its cloud detection accuracy is over 98% by testing EOS/MODIS and FY3D/MERSI data,indicating that the algorithm can be applied in cloud detection with the characteristics of high efficiency and high accuracy as well as ideal cloud detection effect. References | Related Articles | Metrics

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Comparative research of the effects of temperature change on ischemic cardio-cerebrovascular diseases in different regions TAN Yu-long, YIN Ling, WANG Shi-gong, CHEN Lei, TAN Yuan-wen, KANG Yan-zhen 2019, 35 (3):  94-99.  doi: 10.3969/j.issn.1673-503X.2019.03.012 Abstract ( 217 )   PDF (979KB) ( 120 )   Save The influences of the variations of ambient temperature,daily temperature range (DTR) and temperature change between neighboring days (ΔT24),respectively,on the inducement of ischemic cardio-cerebrovascular diseases (ICCVD) were investigated.Distributed lag nonlinear model (DLNM) and generalized additive model (GAM) were applied to analyze the exposure-response relationships between ICCVD inpatients and changes of ambient temperature,DTR and ΔT24 in Fu'nan and Jinping County in Anhui province from 2015 to 2016,respectively.The results demonstrated that when DTR fluctuates more than 15℃,the ICCVD relative risk surges instantaneously and shows an immediate effect.Finally,the risk reaches a peak value of overlapping effect with lagging days and DTR increasing.In addition,the ICCVD relative risk increases obviously and indicates a significant immediate effect when the decreasing amplitudes of ΔT24 are over 7℃ and 10℃,respectively.Statistical analysis results demonstrate that the probability of reaching the above-mentioned thresholds in the two counties is higher in spring than in other seasons.Therefore,it is simultaneously discovered that the amounts of ICCVD inpatients in Fu'nan and Jinping Counties tend to reach the peaks in spring,especially from Rain Water to Ching Ming in the lunar calendar.Notably,the amount of the inpatients in Jinping county located in the west of Anhui province in summer is also numerous.Moreover,periodically increasing of the amount of ICCVD inpatients is ascribed by two main weather and climate factors,that is,the cooling process and the alternation of the solar terms. References | Related Articles | Metrics

BULLETINS

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Monitoring and assessment of meteorological drought in spring and summer of 2017 for Liaoning province LI Jing, WANG Wan-zhao, LIU Dong-ming, HUANG Yan, WANG Ying, LI Rong-ping 2019, 35 (3):  100-105.  doi: 10.3969/j.issn.1673-503X.2019.03.013 Abstract ( 174 )   PDF (8521KB) ( 43 )   Save Based on daily temperature and precipitation data of 1114 national and regional weather stations during the period from 1961 to 2017,a town-scale meteorological dataset was generated using the inverse distance squared method of interpolation.The characteristics of drought in Liaoning province during April to August in 2017 were investigated based on meteorological drought comprehensive index (MCI).The results show that abnormal high temperature and lacking of rainfall in spring and summer led to the severe meteorological drought in Liaoning province.The meteorological drought started from the central and northern areas on April 5,and then extended to the western areas at the end of April.Finally,the meteorological drought extended to the southeast of Liaoning in May and June.Statistics analysis showed that 88 percent of the studied towns affected by drought.The drought started to relieve since July.The towns that experienced longer duration of drought were concentrated in the central and northern area of Liaoning and the longest duration of drought was 153 d.Due to high temperature and shortage of rainfall,regions that suffered drought above mid-severe extent were varied with time.Extreme meteorological drought usually accompanied with high temperature.Since there are differences existing between meteorological drought and agricultural drought,the right countermeasures should be taken for agriculture service. References | Related Articles | Metrics

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Characteristics of precipitation during the spring sowing period in Shenyang from 1960 to 2017 MU Chen-ying, ZHANG Yu, XU Quan-hui, SONG Xiao-wei, ZHANG Jing, LI Shi, GAO Tong 2019, 35 (3):  106-111.  doi: 10.3969/j.issn.1673-503X.2019.03.014 Abstract ( 220 )   PDF (721KB) ( 149 )   Save Using linear inclination estimation and accumulative anomaly analysis methods,the temporal characteristic of precipitation during the spring sowing period and its relationship with the first soaking rain and the maximum continuous days without available precipitation were analyzed.The results show that the precipitation during the spring sowing period increased slowly with a rate of 3.1 mm/10 a in Shenyang from 1960 to 2017.The precipitation during the spring sowing period increased rapidly with larger fluctuations since 2004.The increase of abnormal precipitation years induced spring drought (or flood) events occurring frequently.The first soaking rain during the spring sowing period of Shenyang delayed with a rate of-0.051 d/10 a,which usually leads to the shortage of soil water during the spring sowing period and are unfavorable for spring sowing.The maximum continuous days without available precipitation increased with a rate of 0.56 d/10 a,which had significant impacts on precipitation in April.Although the total amount of precipitation during the spring sowing period had an increasing trend,its temporal distribution was uneven.Above all,the uneven distribution of precipitation and the frequently occurrence of continuous days without available precipitation will increase drought disaster risk during the spring sowing period and the sowing date may be delayed. References | Related Articles | Metrics