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31 October 2016, Volume 32 Issue 5 Previous Issue    Next Issue

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Analysis of weather process of rain to snow in Hangzhou region in 2014 LI Jin, CHEN Lian 2016, 32 (5):  1-9.  doi: 10.3969/j.issn.1673-503X.2016.05.001 Abstract ( 269 )   PDF (13395KB) ( 459 )   Save Based on the NCEP (National Centers for Environmental Prediction)reanalysis data with resolutions of 1°×1°,conventional meteorological data,intensive snowfall observations as well as satellite cloud images,the weathering process of rain to snow in Hangzhou region on February 17-19,2014 was analyzed.The results indicate that the southern branch trough at 500 hPa,shear lines at 700 hPa and 850 hPa,as well as the southwesterly jet stream at 700 hPa,provide favorable conditions for dynamic lifting and water vapor supplement during this weathering process.Additionally,warm and humid airflow at 700 hPa and continuously strengthening northeasterly flow at 850 hPa make favorable stratification conditions with warm air at upper levels and cold air at lower levels.Water vapor flux is related to the period and intensity of precipitation during the rain-snow process,and ascending motion exists in the whole troposphere.High relative humidity and convergence of water vapor show in different stages of the weathering process.When liquid precipitation occurs,it is accompanied by water vapor convergence and ascending motion in the middle and lower troposphere as well as suction effect in the middle troposphere,which is favorable for precipitation.However,when rain turns into snowfall,the water vapor convergence and ascending motion decrease gradually in the middle and lower troposphere but still maintain in the middle troposphere.Water vapor convergence is weakening and even disappears with the declining intensity of rain and snowfall,and the ascending motion at the mid-lower and middle levels also decreases gradually,accompanied by weak descending motion and rapidly decreasing relative humidity near 600 hPa.However,weak ascending motion and large relative humidity remain in the middle and lower troposphere until the snow has stopped in the morning on February 19.Due to the weak activity of cold air and high surface temperature during the process of rain turning into snow,the snow cover rate is small in spite of large precipitation and snowfall. References | Related Articles | Metrics

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Diagnostic analysis of a northward cyclone over the Yangtze-Huaihe Rivers causing storm surge in the Bohai Sea ZHU Nan-nan, LIU Bin-xian, SUN Mi-na, LIU Yi-wei 2016, 32 (5):  10-17.  doi: 10.3969/j.issn.1673-503X.2016.05.002 Abstract ( 288 )   PDF (7292KB) ( 442 )   Save Using NCEP (National Centers for Environmental Prediction) reanalysis data,conventional meteorological data and observational data from automatic weather stations,dynamic and thermal mechanisms of the weakening process of a cyclone over the Yangtze-Huaihe Rivers were analyzed when it moved northwards into the Bohai Sea during May 26-28,2013.The results show that intense warm advection at the northwest side of the subtropical high and cold air at the northeastern part of the Tibetan high make the cyclone moving northwards.Due to the blocking of the Japan Sea high,the cyclone moves slowly over the Bohai Sea,and the backwards-tilted structures of the high-level trough and the cyclone become forward-tilted.Negative vorticity and temperature advection behind the trough are the main reason for the declining of the cyclone.As the cyclone moves slowly over the Bohai Sea,a storm surge forms due to the long-time onshore winds and astronomical high tide.The advection of the positive temperature and vorticity in the middle and lower troposphere provide the dynamic and thermodynamic conditions for the development of a cyclone.Moist potential vorticity can reflect well the effects of absolute vorticity and atmospheric stability on the cyclone development.The diabatic heating effect occurs during the entire intensification and dissipation processes of the cyclone and mainly concentrates on the east side of the cyclone,which favors the development and maintenance of the cyclone on a certain degree.The convergence of upper-level jets and the weakening of steering flow are another reason for the cyclone moving slowly and declining over the sea. References | Related Articles | Metrics

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Diagnostic analysis of a snowstorm event over the southwest region of the Tibetan Plateau BU Jian-can, JI Bai-zhen, REN Lang-jie 2016, 32 (5):  18-24.  doi: 10.3969/j.issn.1673-503X.2016.05.003 Abstract ( 251 )   PDF (2899KB) ( 275 )   Save The weather process of a snowstorm event in the southwest region of the Tibetan Plateau on January 17 to 19,2013 was comprehensively analyzed using the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data with resolution of 2.5°×2.5°,conventional meteorological data and satellite cloud images in this study.The results show that the circulation situation during the snowstorm event in the southwest region of the Tibet Plateau is characterized by two troughs and two ridges at the middle and higher latitudes.The deep southern branch trough,southwesterly jet stream,and the Western Pacific subtropical high are the main influencing systems of the snowstorm event.The cyclonic vorticity reaches 15.0×10-5 s-1 during the snowstorm event,and the convergence at lower levels and divergence at middle and higher levels favor the ascending motion of the air.The positive divergence near 250 hPa is 3.5×10-5 s-1,and the powerful suction effect at middleand higher levels and the strong ascending motion play important roles in the snowstorm occurrence.Water vapor mainly comes from the Arabian Sea,and the increasing water vapor flux and its moving northeastwards divergence center indicate that water vapor is transported continually by warm and humid southwesterly flows and converges over the snowstorm area.Meanwhile,the orographic uplifting effect is favorable for the condensation of water vapor.The temperature of black body (TBB) obviously decreases when the clouds reach over the Tibet Plateau.TBB drops below -50℃ when clouds reach over the snowstorm area,and it is even lower than-60℃ over the Burang area in the western Tibet Plateau. References | Related Articles | Metrics

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Typical case study on external pollution sources influencing air quality in Beijing area WU Qing-mei, LIU Zhuo, ZHANG Sheng-jun, LI Qing-chun 2016, 32 (5):  25-31.  doi: 10.3969/j.issn.1673-503X.2016.05.004 Abstract ( 278 )   PDF (1983KB) ( 328 )   Save Based on the hourly PM2.5 concentration observed at eighty environmental monitoring stations and conventional meteorological data,the spatial-temporal characteristics of PM2.5 concentration during three typical severe pollution events over the Beijing-Tianjin-Hebei region in January of 2013 were analyzed.The effect of external pollution sources on the pollutants transport in the Beijing area was investigated by analyzing the characteristics of wind field during the period of rapidly increasing PM2.5 concentration.The results indicate that there are three high-value centers of PM2.5 concentration over the Beijing-Tianjin-Hebei region in January of 2013,and they are located at the Shijiazhuang-Baoding,Langfang,and Tangshan areas in Hebei province,respectively.The external pollution sources for the Beijing area mainly come from the middle and southern regions of Hebei province such as the Shijiazhuang-Baoding and Langfang areas.Pollutants can be transported from long distance by the southerly winds in the boundary layer,and the convergence line and inversion structure in the boundary layer strengthen the accumulation of pollutants in the Beijing area.Under the persistent stable weather condition,PM2.5 pollutants are transported and accumulated in front of the Yanshan and Taihang mountains.This leads to PM2.5 concentration in the Beijing area larger than that in the middle and southern regions of Hebei province,and that in the suburban areas higher than that in the urban areas of Beijing. References | Related Articles | Metrics

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Study on forecast method of thunderstorm based on weather types and physical diagnostic analysis in eastern region of Northwest China KONG De-bing, WANG Jie-hua, SHANG Ke-zheng, YE Wei, ZHAO Wen-jing, WANG Shi-gong, YANG Liu-gui 2016, 32 (5):  32-39.  doi: 10.3969/j.issn.1673-503X.2016.05.005 Abstract ( 221 )   PDF (1366KB) ( 450 )   Save Based on the meteorological observations from 169 meteorological stations and the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data with resolution of 1°×1° in the eastern region of Northwest China from 2008 to 2013,weather types of thunderstorm days were classified using calculated convective parameters,and the operational forecast of thunderstorm in 2013 was carried out according to parameter thresholds of different weather types.The results show that thunderstorm days mostly occur from May to September and account for 85.9% of the total thunderstorm days during this study period.There are four weather types of thunderstorm days,including the lower vortex type,the lower trough type,the northwesterly flow type,and the southwesterly flow type.The automatic identification method of the four weather types is investigated by introducing a weather type intense index,and it is examined to be able to identify different weather types correctly with fewer omitted samples.The physical diagnostic analysis by weather type identification indicates that the omitted samples decrease significantly.The threat score (TS) of back-substitution forecast on thunderstorm days in the eastern region of Northwest China from 2008 to 2012 is 54.1%,with four days of omitted samples,while TS of operational forecast on thunderstorm days in 2013 is 51.8%,with ten days of omission.TS in back-substitution forecast and operational forecast is both larger than climatic probabilities,which means the forecast performs good and can provide a reference to the study on a thunderstorm in the eastern region of Northwest China. References | Related Articles | Metrics

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Composite analysis of environmental and physical quantity fields of heavy rainstorm in Liaoning province SUN Xin, CHEN Chuan-lei, LIANG Han, YANG Qing, HE Hui, LU Jing-long, ZHAO Ming 2016, 32 (5):  40-46.  doi: 10.3969/j.issn.1673-503X.2016.05.006 Abstract ( 297 )   PDF (2159KB) ( 332 )   Save Based on data from 61 national observation stations from 1960 to 2013 and NCEP (National Centers for Environmental Prediction) reanalysis data,the environmental and physical quantity fields of a rainstorm at multiple time periods in Liaoning province were synthetically analyzed using synoptic meteorology and physical diagnosis methods.Sixty regional heavy rainstorm processes were selected in this study.The results show that the heavy rainstorms in Liaoning province are controlled by the interacting results among polar,westerlies,subtropic and tropic systems.The cold polar air that is entrained by cold shear lines at low layer invades Liaoning province from a more northerly path.A low-level jet is strengthened by the eastward movement of the westerly shortwave trough.It makes the ground convergence line form a front and at last triggers a heavy regional rainstorm.The falling area and strength of heavy rainstorm in Liaoning province are related to the paths and strengths of the low-level jet and cold and warm air.The moisture and thermal conditions are the bases for the generation of a heavy rainstorm.The dynamic uplifting condition is a determining factor for the intensity of precipitation.It proves that the composite analysis of environmental and physical quantity fields can reveal the common issue in the heavy rainstorm in Liaoning province.It expects that this work could provide a useful reference for forecasting heavy rainstorm in Liaoning province in the future. References | Related Articles | Metrics

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Rainfall thresholds and probability forecast of Yingxia railway for blocking alert PENG Xiao-song, WU Fan, WANG Jun-sheng, JING Yuan-shu 2016, 32 (5):  47-51.  doi: 10.3969/j.issn.1673-503X.2016.05.007 Abstract ( 213 )   PDF (779KB) ( 340 )   Save Based on the data from flood disaster and precipitation in Yingxia railway from 2004 to 2014,the temporal variation and spatial distribution of flood disaster were analyzed,and rainfall thresholds and their probability forecast model of the Yingxia railway for blocking alert were studied.The results show that there is a remarkable change in the flood disaster year by year along the Yingxia railway,normally occurring during the flood season,and meanwhile its spatial distribution is non-uniform with a strong localization feature.The rainfall thresholds for alerting to block the Yingxia railway include 1-h rainfall amount reaching 47 mm before the flood disaster occurs,24-h rainfall amount reaching 108 mm before the flood disaster occurs,the cumulative rainfall amount reaching 228 mm,1-h rainfall amount reaching 30 mm before the flood disaster occurs and meanwhile the cumulative rainfall amount reaching 160 mm,or the 24 h rainfall amount reaching 100 mm before the flood disaster occurs and at the same time the cumulative rainfall reaching 160 mm.The hindcast accuracy rate of the probability forecast model is 90.2%.The accuracy rate to judge whether block the railway or not according to the weather processes is higher when combining the probability forecast model with the alerting rainfall thresholds.This work provides useful guidance for operating the railway safely and efficiently. References | Related Articles | Metrics

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Evaluation of ability of climate model for simulating precipitation in Northeast China and precipitation prediction WANG Tao, WANG Yi-shu, CUI Yan, AO Xue, ZHAO Chun-yu, WANG Ying, ZHOU Xiao-yu, HOU Yi-ling, LIU Ming-yan, GU Zheng-qiang 2016, 32 (5):  52-60.  doi: 10.3969/j.issn.1673-503X.2016.05.008 Abstract ( 299 )   PDF (2435KB) ( 306 )   Save Based on datasets from global climate model CMIP 5 (Coupled Model Intercomparison Project Phase 5) and regional climate model RegCM 4 (Regional Climate Model 4),as well as precipitation data from 162 meteorological stations in Northeast China (NEC),the capability to simulate precipitation by CMIP 5 and RegCM 4 was evaluated.Additionally,precipitation changes in NEC in the future were predicted and assessed using these two models under two greenhouse gas emission scenarios,i.e.RCP (Representative Concentration Pathways) 4.5 and RCP 8.5.The results show that these two models can well simulate annual and seasonal precipitation in NEC.The spatial distributions of precipitation,which gradually decreasing from southeast to northwest in NEC,are well reproduced by the two models.The simulated precipitation center lies in the north of observed position,and precipitation intensity is stronger than that of observations.The simulated precipitation in summer is more accurate than that in winter and precipitation deviation in winter is much larger.Overall,simulated results of precipitation in NEC by CMIP 5 are better.The prediction results of future precipitation show that annual and seasonal precipitation in NEC simulated by CMIP 5 increases under emission scenarios of RCP 4.5 and RCP 8.5.The precipitation deviation percentage in winter is larger than that in other seasons.Under emission scenario of RCP 8.5,precipitation's increments in NEC are significant.The spatial distribution of precipitation increments decreases from south to north,and precipitation deviation percentages decrease from southwest to northeast.Under emission scenario of RCP 4.5,precipitation increments are less.The spatial distribution of predicted precipitation decreases from southeast to northwest,and precipitation deviation percentages decrease from west to east. References | Related Articles | Metrics

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Evaluation of forecast skill of monthly rainfall over Northeast China using multi-models LI Yong-sheng, DUAN Chun-feng, WANG Ying 2016, 32 (5):  61-66.  doi: 10.3969/j.issn.1673-503X.2016.05.009 Abstract ( 216 )   PDF (1020KB) ( 368 )   Save The prediction skill of four climate models for monthly rainfall over Northeast China was evaluated using three qualitative evaluation methods,i.e.,anomaly correlation coefficient (ACC),trend anomaly inspection evaluation (Ps) and anomaly symbol consistency rate (Pc).Many data were used in this study,including 172 meteorological stations over Northeast China supplied by the National Meteorological Information Center,the hindcast experimental results of rainfall over Northeast China from 1983 to 2010 according to four climate models from China,America,Japan and Europe,and the operational application results over Northeast China from 2011 to 2014.The results indicate that the monthly rainfall prediction skills of EC (European Center for Medium-Range Weather Forecasts) and CFSv 2 (Coupled Forecast System Model Version 2) models are better than those of BCC (Beijing Climate Center) and TCC (Tokyo Climate Center) models.Looking at the spatial distribution,there is a significant difference in the distribution of each monthly Pc for CFSv 2 model,indicating that this model has a big space for its improvement.The CFSv 2 model has some prediction skills in early summer during typical drought and flood years,and the prediction effect in typical flood years is better than that in typical drought years. References | Related Articles | Metrics

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Characteristics of tropical cyclones influencing Shandong province from 1949 to 2012 CONG Chun-hua, WU Wei, SUN Sha-sha 2016, 32 (5):  67-73.  doi: 10.3969/j.issn.1673-503X.2016.05.010 Abstract ( 214 )   PDF (2073KB) ( 460 )   Save Based on data from Tropical Cyclone (TC) Yearbook of China and surface meteorological observations,the TCs influencing Shandong province from 1949 to 2012 were statistically analyzed.The results show that the averaged annual number of TCs influencing Shandong province is two from 1949 to 2012.The maximum number of seven occurred in 1985 and 2012,respectively.These TCs usually occur from May to November and concentrate between July and September,with the maximum frequency of 46.3% occurring in August.These TCs usually have parabolic shaped tracks and mostly start from the ocean around the Philippines,move northwestwards to the mid-higher latitudes,and then turn northeastwards.Only a few of them move northwestwards from high latitudes into the inland of China.When these TCs moved close to Shandong province,their intensifications have usually weakened.The landing points of TCs in Shandong province are mainly along the coasts of the southeastern region of Shandong province and the southern part of Shandong Peninsular.The distributions of precipitation and strong winds are different due to the different TC tracks.TC precipitation mostly occurs in the middle and eastern parts of Shandong province,with the extreme precipitation areas in the southeastern region of Shandong and the southern and eastern parts of Shandong Peninsular.The rate of extratropical transition among TCs influencing Shandong province is 58.2% that is much higher than that in the northwest Pacific Ocean on average.These TCs have obvious interaction with systems at middle latitudes. References | Related Articles | Metrics

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Characteristics of summer temperature and its impact factors in Northeast China from 1951 to 2012 LI Ji, JIAO Min, HU Chun-li, LI Fei, ZHANG Xiao-yue, ZHANG Qi, WANG Ying, ZHU Xin-yu 2016, 32 (5):  74-83.  doi: 10.3969/j.issn.1673-503X.2016.05.011 Abstract ( 254 )   PDF (3354KB) ( 567 )   Save The inter-decadal variation of summer temperature and its impact factors in Northeast China were studied based on monthly mean temperature observed at 26 stations in Northeast China,74 circulation characteristic indexes from the National Climate Center,and the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data from 1951 to 2012.The results demonstrate that there is a significant difference in the atmospheric circulation patterns before and after the inter-decadal transition period of summer temperature in Northeast China from 1951 to 2012.The inter-decadal breaking point in summer temperature is consistent with those in polar vortex area,zonal circulation,and the northeast cold vortex.Therefore,the variation results in these circulation factors may be one of the reasons that lead to a suddenly inter-decadal variation in summer temperature in Northeast China.There is a remarkable inter-decadal transition in the correlation between summer temperature and the main circulation factors at different temporal and spatial scales.The correlation of summer temperature with the western Pacific subtropical high,zonal circulation,and the northeast cold vortex show a strengthening trend at inter-decadal scale,while its correlation with the polar vortex area is weaken with inter-decadal time.The influence scope and intensity of these circulation factors on summer temperature change obviously as well on the inter-decadal scale. References | Related Articles | Metrics

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Characteristics of spatial distribution of daily maximum temperature on hot days and its improving measurements in Shanghai JIANG Rong, WEI Ning, CHEN Liang, LI Jia-xuan, XIANG Wei-ning 2016, 32 (5):  84-91.  doi: 10.3969/j.issn.1673-503X.2016.05.012 Abstract ( 293 )   PDF (1593KB) ( 479 )   Save Based on data from Landsat OLI (Operational Land Imager) and meteorological stations on July 12,August 13 and 29,2013,the spatial distributions of temperature on hot days in Shanghai were evaluated using a spatial regression method.The distribution characteristics of thermal environment for low,medium and high temperature zones were analyzed from temperature division,landscape structure,and spatial autocorrelation.On the above basis,the composite characteristics of distribution and land use type of the high-temperature zone in which the daily maximum temperature is larger than 38℃ were studied combining the land use data in Shanghai.The results show that the prediction model established by a least square regression method using surface temperature,normalized water vapor index and solar radiation plays very well in predicting the temperature on hot days with RMSE (Root Mean Square Error) of 1.75℃ and R2 of 0.92.Using this model we can get a whole and continuous spatial distribution of urban thermal environment.It demonstrates non-equilibrium,variety and crushability characteristics in the urban thermal environment.Meanwhile,there is a spatial aggregation feature in the similar temperature zones.The low-temperature zones,in which the daily maximum temperature is less than 35℃,are mainly located in the water area and the southern part,and the high-temperature zones are at the urban or suburb residential areas in Shanghai.It indicates that the urban land use increases the urban thermal environment,while water and vegetation are beneficial to reduce it.Therefore,it suggests that the adverse effect resulted by the extremely high-temperature weather could be mitigated through a series of measurements,such as planning the urban reasonably,controlling the development level and increasing the greening areas in the future. References | Related Articles | Metrics

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Establishment and characteristic analysis of spatial variation pattern of thermal spectrum fingerprint LI Jia-qi, ZHANG Yu-kun, LI Yan, LUAN Jian, ZHOU Xiao-dong 2016, 32 (5):  92-98.  doi: 10.3969/j.issn.1673-503X.2016.05.013 Abstract ( 225 )   PDF (1196KB) ( 323 )   Save Thermal spectrum mapping is a kind of methods that utilizes thermal spectrum fingerprint of the road to reflect the spatial variation of road surface temperature at winter night under different weather conditions.In this paper,a spatial variation model of thermal spectrum fingerprint under three weather conditions from Taohuayuan to Heishui road section was established based on the data of road surface conditions and road surface temperature at winter night at the road section from Taohuayuan to Heishui in Baomao highway in 2015.The characteristics of thermal spectrum fingerprint under three weather conditions and their correlation,similarity and reliability,were analyzed.The results show that there is a clear difference in the change range of thermal spectrum fingerprint under different weather types at the road section from Taohuayuan to Heishui in Baomao highway in 2015.The standard difference of road surface temperature is an important indicator to distinguish the types of thermal spectrum fingerprint.The similarity degree of thermal spectrum fingerprint under different weather types is high,with similarity coefficient in a range from 0.78 to 0.92.There are strong correlation in the thermal spectrum fingerprints under different weather types,with the significant level of 0.01.The similarity and correlation degrees of thermal spectrum fingerprint under the same kind of weather are higher than those under different weather types.The pattern of spatial variation in thermal spectrum fingerprint can be used to effectively describe the change in surface temperature of regional road networks in winter night.It provides a reference for meteorological station planning in highway and winter road management and control decision. References | Related Articles | Metrics

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Analysis of the effect of street greenbelt on microclimate in a hot-humid area of China using a numerical simulation method WU Chang-guang, FANG Ya-ping, LIN Yao-yu, MA Xiao-yang, WANG Yao-wu, WANG Ke-huan 2016, 32 (5):  99-106.  doi: 10.3969/j.issn.1673-503X.2016.05.014 Abstract ( 206 )   PDF (2330KB) ( 708 )   Save The microclimatic conditions surrounding street greenbelt in a business zone of Shenzhen were simulated using an urban microclimate soft-ENVI (ENvironment for Visualizing Image)-met.The accuracy of simulating results was validated using the field measured data.It shows that the ENVI-met model can accurately describe the characteristics of microclimate spatial distribution and diurnal variation in the study area.The microclimate effects of three landscape types,i.e.tree,lawn,and waterscape,are compared using the ENVI-met model.By comparing air temperature and humidity,it indicates that the cooling and humidification effects are different among these street types.The tree greenbelt is the best,followed by lawn,and waterscape.However,the characteristics of daily variation and spatial distribution of cooling and humidification effects for them are consistent.Compared with land surface temperature,it demonstrates that there is a heating effect in the tree and lawn street greenbelts on the adjacent pavement.In contrast,the waterscape street greenbelt plays a cooling effect on the surface of surrounding pavements.These results provide valuable information for designing climatic adaptability plans on the urban street greenbelt. References | Related Articles | Metrics

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Effect of summer rainfall and wind on size distribution of number concentration of inhalable particle matter in southern suburban area of Xi'an MA Qi-xiang, LIU Zhao-mei, DU Li-lao 2016, 32 (5):  107-113.  doi: 10.3969/j.issn.1673-503X.2016.05.015 Abstract ( 222 )   PDF (1289KB) ( 424 )   Save The removing effect of summer rainfall and wind on inhalable particle matters was investigated in this study.The number concentration of inhalable particle matter were measured continuously by an electrical low pressure impactor (ELPI) with a temporal resolution of 30 s in the southern suburban area of Xi'an from May to July of 2014.The simultaneous meteorological observations of precipitation,wind direction,and wind speed from a mobile automatic meteorological station were collected.These data were used to conduct this investigation.The results show that persistent moderate rainfall can remove all inhalable particle matters.The short-time persistent moderate rainfall causes an increasing number concentration of coarse particles.Persistent light rainfall has limited effects on the removing of particles in the nucleation mode and those of smaller sizes in the Aitken mode.The discontinuous light rainfall does not remove inhalable particle matters.The easterly winds prevail in summer over the southern suburban area of Xi'an.However,inhalation particle matters are mainly transported by the westerly flows.The occurrence frequency of wind speed smaller than 3.0 m·s-1 is relatively high,which isn't favorable for the pollutant diffusion.When wind speed is smaller than 5.4 m·s-1,the number concentration of particles in the nucleation mode increases with the increasing wind speed.However,that of particles in other modes decreases with the increasing wind speed.It has better removal effect on particle matters in different modes when wind speed is between 5.5 m·s-1and 7.9 m·s-1. References | Related Articles | Metrics

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Characteristics of meteorological parameters and main atmospheric pollutants of haze events in Nanchang from 1960 to 2014 CHEN Xiang-xiang, HU Lei, PENG Wang-minzi, LIU Bo 2016, 32 (5):  114-121.  doi: 10.3969/j.issn.1673-503X.2016.05.016 Abstract ( 328 )   PDF (1936KB) ( 392 )   Save Based on the conventional meteorological data from national meteorological stations in Nanchang from 1960 to 2014 and atmospheric pollutant observations from environment protection department from 2001 to 2014,an Eta correlation coefficient method and a regression analysis method were used to study the characteristics of meteorological parameters and main atmospheric pollutants of haze as well as the relationship between haze and atmospheric pollutants in Nanchang.The results show that annual haze days in Nanchang gradually increase from 1960 to 2014,and they occur mostly in autumn and winter but less in spring and summer.The averaged surface wind speed is 1.6 m·s-1 at 08:00 of haze days in recent 55 years in Nanchang,and the northeasterly winds prevail.Such small wind speed favors the formation and development of haze weather.The averaged surface air pressure at 08:00 of haze days mostly ranges in 1010-1025 hPa,with a mean value of 1015.3 hPa.The values of temperature-dew point depression at 925 hPa are larger in the northern region and smaller in the southern region.Winds blow from the dry area to the Nanchang region that is located at the bottom of a dry tongue at lower altitudes.The northeasterly flow prevails at 925 hPa,with wind speed concentrating in 3.0-8.0 m·s-1.The distribution of wind speed at 850 hPa is consistent with that at 925 hPa.Air flows divergence at lower altitudes (at 925 hPa) and a weak through at the middle altitudes (at 500 hPa) located before the Nanchang region form a favorable weather situation for haze occurrence.There are 59.1% and 45.3% of haze days with thermal inversion layer between surface and 850 hPa at 08:00 and 20:00,respectively.Inversion layer makes astable atmospheric condition that favors haze development.Concerned for main air pollutants in Nanchang,the monthly mean concentrations of PM10,NO2,SO2,and PM2.5 show the maximum value in December and January and the minimum value in July and August,which is consistent with the seasonal variation of haze.Pollutant concentrations of haze days are obviously larger than those of non-haze days.According to the Eta correlation analysis,the correlations between daily mean concentrations of four pollutants and haze decrease in order of PM10,PM2.5,NO2,and SO2.The correlation coefficient between PM10 concentration and haze is 0.694,which means a strong correlation. References | Related Articles | Metrics

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Analysis of drought characteristics based on SPI for Eastern area of the Yellow River in Gansu province SHA Li, LI Shi, SHA Sha, GUAN Yu-shan 2016, 32 (5):  122-130.  doi: 10.3969/j.issn.1673-503X.2016.05.017 Abstract ( 210 )   PDF (3513KB) ( 394 )   Save Using monthly precipitation data of 32 meteorological stations in the Eastern area of the Yellow River in Gansu province from 1971 to 2014,drought characteristics were analyzed based on a standardized precipitation index (SPI).The results show that,for annual drought from 1971 to 2014,there is a drought tendency belt extending from the north to the south of study area.The extent of drought shows a slight downward trend.Most parts of the Eastern area of the Yellow River show a drying trend in spring and summer.The extent of drought shows an upward trend in spring and a downward trend in summer.Most parts of the Eastern area of the Yellow River show a wetting trend in autumn and winter with the extent of drought decreasing.From 1971 to 2014,occurrence frequency of drought is 30% for the Eastern area of the Yellow River.The areas with high drought occurrence frequency are in north-central of Dingxi,Lanzhou,as well as the north of Longnan city.Drought occurrence frequency in winter shows a downward trend.Compared to winter,drought occurrence frequency in a single year or spring,summer and autumn experiences a decline first,but rises latter.The SPIs of annual,spring,autumn,and winter are lower during the periods of 1991 to 2010,1991 to 2000,1991 to 2000,and 1971 to 1980,respectively.Summer SPI is lower during two periods of 1971 to 1980 and 2000 to 2010. References | Related Articles | Metrics

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Analysis of satisfactory rainfall for agriculture and occurrence rules of drought in western Liaoning province MA Yong-zhong, HUANG Ying-hua, DIAO Jun, TANG Yuan-ming 2016, 32 (5):  131-138.  doi: 10.3969/j.issn.1673-503X.2016.05.018 Abstract ( 266 )   PDF (695KB) ( 369 )   Save Based on climatic data from 1960 to 2014 obtained from nine meteorological stations in Huludao and Chaoyang,rainfall changes,agricultural rainfall satisfactory and occurrence rules of drought during the growing season (from April to September) in the western region of Liaoning province were studied using methods of an accumulated moisture index and a moisture index.The results show that rainfall during growing season shows a downward trend from 1960 to 2014 for Huludao and Chaoyang.For recent 20 years,rainfall in the growing season decreases 8.7% and 11.1% for the southern and northern areas of Songling Mountain,respectively.The time ranges with decreased rainfall are during the period from July to September.For recent 55 years,moisture index of growing season decreases with climate tendency rates of-0.023/10 a and-0.015/10 a for the southern and northern areas of Songling Mountain,respectively.Drought occurrence frequency shows an upward trend in recent 20 years with occurrence frequencies increasing 30.0% and 25.0% for the southern and northern areas of Songling Mountain,respectively.Growing season's agricultural rainfall satisfactory decreased in recent 55 years with decreasing percentages of 11.8% and 11.2% for the southern and northern areas of Songling Mountain,respectively.Decreasing of growing season's agricultural rainfall satisfactory in Huludao and Chaoyang is attributed to the decline in precipitation.As a result,occurrence frequency of drought increases,which makes agriculture production face a threat.Therefore,to relieve the loss caused by drought damage,we should improve the management of water resources,increase efficiency of water use and adjust planting structure of agriculture. References | Related Articles | Metrics

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Evaluation index of cold wave intensity at a single station and its application in Urumqi MAO Wei-yi, CHEN Ying, CAO Xing 2016, 32 (5):  139-146.  doi: 10.3969/j.issn.1673-503X.2016.05.019 Abstract ( 223 )   PDF (640KB) ( 353 )   Save Based on the minimum temperature data from January 1,1951 to December 31,2015 in Urumqi and six intensity indexes extracted from "Grades of cold wave" (GB/T 21987-2008),the intensity of cold wave processes in Urumqi was evaluated.The variation of intensity of cold wave processes was analyzed.The results show that the intensity of cold wave processes depends on the selection of index.If a cooling range or the minimum temperature during this process is taken as an evaluation indicator,then the intensity is the strongest in winter.If the maximum cooling range within 24 h is taken as an indicator,the intensity of cold wave processes in spring becomes the strongest.The intensity of cold wave processes in autumn is the strongest if the maximum cooling range within 48 h or a lower amplitude of temperature anomaly is taken as an evaluation indicator.During the past 65 years (from 1951 to 2015),the strongest cold wave in Urumqi happened on days from November 25 to December 1,1952,based on integrative intensity index (IZ).The strongest cold wave in spring occured on April 15-16,2003.According to IZ,the strongest cold wave appears in winter followed in autumn.The intensity of cold wave appeared in spring is relatively weak.There are six cold wave processes appearing in the 1950s among the top 10 strongest cold wave processes happened in autumn and winter and five cold wave processes appearing after 2000 among the top 10 strongest cold wave processes happened in spring of Urumqi.Both the occurrence frequency and intensity of cold wave process decreased significantly from 1951 to 2015 in Urumqi.During the past 65 years,the occurrence frequency of cold wave process in autumn decreased significantly.The intensity of cold wave process in spring has increased since the 1980s,and intensity of cold wave process in recent five years (from 2011 to 2015) is the strongest among the seven decades. References | Related Articles | Metrics

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Forecasting study of catastrophic lightning based on Logistic Regression in Bengbu region ZHOU Li-ya, WANG Kai, LIU Ni 2016, 32 (5):  147-153.  doi: 10.3969/j.issn.1673-503X.2016.05.020 Abstract ( 233 )   PDF (1330KB) ( 478 )   Save Based on data from the lightning positioning system in Anhui province and lightning disaster in Bengbu region from 2007 to 2013,four kinds of catastrophic lightning forecasting models were established using the Logistic regression method.36 catastrophic lightning cases were selected as modeling samples,and the strong convective parameters from the GFS (Global Forecast System) model were used as forecasting factors.The results show that three parameters,i.e.,CAPE (Convective Available Potential Energy),LFTX (surface LiFTed indeX) and PW (Precipitable Water),can be used as the indexes for catastrophic lightning forecasting in the Bengbu region.These catastrophic lightning forecasting models perform well in forecasting,in which the overall forecasting accuracy of the 08:00-14:00 model is the best,reaching 83%.When the output probability of the forecasting models is higher than 0.7,these models receive the highest skill score and accuracy,as well as lower error and false alarm probability.In general,the summer forecasting model has the best forecasting effect with an average forecasting accuracy of 82.2%.At the dense zones where the lightning occurs,this model can forecast the high probability distribution of lightning. References | Related Articles | Metrics

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A review of the effect of meteorological factors on plant phenology and its driving mechanisms YANG Yang, LUO Xian, LI Rong-ping, WANG Ying, WEN Ri-hong, YANG Gui-juan, JIAO Min, ZHANG Qi, ZHANG Xiao-yue 2016, 32 (5):  154-159.  doi: 10.3969/j.issn.1673-503X.2016.05.021 Abstract ( 237 )   PDF (509KB) ( 547 )   Save Studying plant phenology is of great importance not only for precise assessment of regional carbon budget but also for improvement of regional climate models.Because it is unclear how plant phenology responds to environmental factors (especially the meteorological factors),it may be wrong for the recent conclusion that the vegetation growth season is linearly extrapolated with the advance of plant leafing and postpone of leaf yellowing in the context of increasing temperature.According to the cue of plant life history,control mechanisms of light,temperature and water on the key development stages of plants were summarized in this study.The primary factor affecting different development processes of plants was revealed.Control principles of light,temperature and water on plant phenology were compared between the studies in control experiment and model research.The importance of control experiment results of light,temperature and water to plant phenology in the construction of plant phenology models was explained.We also put forward that plant phenology should be explored according to the classification of main impact factors,the relationships between intrinsic parameters of plant phenology and cooperative co-evolution of the environment should be focused,and extent and function of mutual offset for the regulation of environmental factors in plant phenology should be explicated. References | Related Articles | Metrics

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Progress of application of CFD simulation for wind energy resource CHEN Gang, LI Ke-fei, YANG Hong-bin, ZOU Xu-dong, TIAN Guang-yuan, ZHAI Qing-fei, HU Wei 2016, 32 (5):  160-164.  doi: 10.3969/j.issn.1673-503X.2016.05.022 Abstract ( 248 )   PDF (445KB) ( 605 )   Save Wind energy resources are very rich in China,and the new additions in wind capacity and the entire installed capacity in China ranks the top of the world.However,the study on prediction of wind energy resource lags behind relatively.This article reviews and discusses the application of computational fluid dynamics (CFD) for wind resource prediction.CFD is an important application field of the simulation of wind energy resources.We start with an introduction of the CFD simulation on wind energy resources in aspects of research content,method and model.We then summarize the current status and development trend of CFD simulation on the distribution of wind energy resources in China,including the 3D modeling of complex terrain,mesh generation,selection of calculation models,boundary condition setting,and flow field simulation. References | Related Articles | Metrics

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Analysis of evaluation indices of Journal of Meteorology and Environment from 2010 to 2014 LI Li-guang, WANG Hong-bo, ZHAO Zi-qi, ZHAO Xian-li, CHEN Li-qing 2016, 32 (5):  165-168.  doi: 10.3969/j.issn.1673-503X.2016.05.023 Abstract ( 180 )   PDF (456KB) ( 324 )   Save Journal of Meteorology and Environment was identified as one of the Chinese scientific and technical core journals by the Institute of Scientific and Technical Information of China in 2010.Based on the data from the Chinese Scientific and Technical Journal Citation Reports (core versions) from 2011 to 2015,the relative evaluation indices of Journal of Meteorology and Environment were analyzed.The possible ways to improve its evaluation indices were discussed as well.The results indicate that the number of the paper published by this journal constantly increases since it is identified as one of the core journals.Meanwhile,the number of its page increases year by year.The core total citation frequency increases from 330 in 2010 to 856 in 2014.Both of the core impact factor and the core non-self citing impact factor are in a fluctuating change mode while generaly show an increasing trend.The core impact factor reaches the maximum value in 2013 with 1.297.The annual core non-self citing impact factor keeps above 0.50.In addition,the reference source amount among the source citation indices is also in an increasing trend due to the increase in the number of the Journal's page.The other indices such as average citation number,region distribution number and organization distribution number all exhibit a fluctuating variation and are in an increasing trend.The ratio of papers supported by the funds exceeds 0.70. References | Related Articles | Metrics