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30 April 2019, Volume 35 Issue 2 Previous Issue    Next Issue

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Characteristics of water vapor during a cold-vortex rainstorm event under blocking situation in southeastern Inner Mongolia MA Su-yan, YI Na-na, ZHAO Fei, ZHANG Xu 2019, 35 (2):  1-8.  doi: 10.3969/j.issn.1673-503X.2019.02.001 Abstract ( 316 )   PDF (2117KB) ( 234 )   Save Using the conventional meteorological data,the FY-2G satellite data,and the National Centers for Environment Prediction (NCEP) reanalysis data with a horizontal resolution of 1°×1°,a rainstorm event caused by a cold vortex on June 6-7,2017 in Southeastern Inner Mongolia was investigated.The results showed that a westerly trough moves eastwards slowly and develops into a vortex under the stable synoptic conditions characterized by "one trough and one ridge" and in presence of a stable blocking high.Rainstorm occurs during the development period of the cold vortex.The Low-Level Jets (LLJs) transport abundant water vapor from the south and the water vapor budget primarily concentrates below 700 hPa.The net income of water vapor increases obviously before the rainstorm occurs,especially from the southern and northern boundaries.In addition,warm and moist southerly flows favor the formation of unstable atmospheric stratification and the energy accumulation in the rainstorm area.The coupled high-level jets and LLJs provide dynamic conditions for the occurrence of a rainstorm.The humidity field varies significantly before and after the rainstorm,with the maximum precipitable water vapor reaches 55-60 kg·m-2.The precipitable water vapor increases significantly before the rainstorm,by nearly 2 times.The specific humidity over the rainstorm area at 700 hPa (850 hPa) is not less than 7 g·kg-1 (12 g·kg-1).Strong precipitation mainly occurs in areas where the maximum specific humidity and a temperature of the black body (TBB) <230 K occur,after the white bright zone breaks and disappears in the satellite water vapor images. References | Related Articles | Metrics

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Improvement of a self-adaption decaying average bias correction method based on ensemble forecast XIAO Yao, SHI Yi-cong, WANG Song, WANG Xin-wei 2019, 35 (2):  9-14.  doi: 10.3969/j.issn.1673-503X.2019.02.002 Abstract ( 221 )   PDF (2204KB) ( 76 )   Save Bias correction for the 2 m air temperature from the T213 ensemble forecast product performed not good on dramatically cooling days using the original self-adaption Kalman Filter-typed decaying average bias correction method.In this study,the bias correction scheme w(i,p) is improved by redefining the decaying average weight w,with i representing station information and p representing synoptic process information,and the similarity w(i,p) method and the statistical w(i,p) method are further developed through optimizing effective extraction of historical information.The new improved bias correction methods have been evaluated.The result showed that the improved w(i,p) decaying average bias correction method has a better performance than the original method.The averaged root-mean-square (RMS) error of the 24-h forecast decreases by 0.15 ℃ for each member on dramatically cooling days.The statistical w(i,p) method has the best performance,with the averaged ensemble mean bias decreases by 2.54 ℃ compared with the w(i,p) decaying average bias correction method. References | Related Articles | Metrics

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A forecast model for flash heavy rainfall in southwestern Yunnan province based on a multiple linear regression method WANG Xiu-ying, LIAO Liu-feng, WANG Jun-jie 2019, 35 (2):  15-22.  doi: 10.3969/j.issn.1673-503X.2019.02.003 Abstract ( 215 )   PDF (1469KB) ( 96 )   Save Using the data from a Doppler weather radar,the sounding data,and 5-min precipitation from meteorological stations in Puer,the evolution characteristics of environmental fields and radar echoes during 41 flash heavy rainfall events from 2015 to 2017 were analyzed.The results showed that mesoscale convergence lines,mesocyclones and adverse wind zones are important causes for the triggering and maintenance of flash heavy rainfall events.Before flash heavy rainfall occurs,the entire atmosphere has abundant water vapor and statically unstable stratification,with precipitable water (PW) ≥ 35 mm,a Showalter index (SI) ≤-0.23,and a K index >35,which can be used as determining factors of the convection potential in the environmental fields.When flashing heavy rainfall occurs,the strongest reflectance factor of radar echoes reaches 40 dBz at least,the echo tops of 35 dBz (RHI35) is larger than 5 km,and the radial velocity of convergence shear variable is larger than 5 m·s-1.A forecast model for flash heavy rainfall in Puer is established using four influencing factors with significant correlation selected through the multiple linear regression analysis,including RHI35,vertical section center height of 30 dBz,radar echo area more than 30 dBz,and the SI.The validation of this model shows that the relative root mean square (RMS) error of average rainfall intensity is 17.0%,and those of precipitation duration and the amount in local processes are 33.9% and 25.6%,respectively.The forecast error of average rainfall intensity in four flash heavy rainfall events is less than 1.2 mm/5 min,and that for precipitation duration and amount is less than 10 min and 4 mm,respectively.The consistent precipitation exceeds 50 mm for the four events,which is also captured in the model.Overall,the forecast model has good performance and can be used for the short-time forecast of flash heavy rainfall events in Puer area. References | Related Articles | Metrics

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Confidence analysis of rainy and snowy weather diagnosis in Kelan,Shanxi province based on NCEP FNL data CHENG Hu-hua, WANG Yi-bai, WEN Bin, WU Shuai, ZHI Mao-lin, ZHAO Liang 2019, 35 (2):  23-31.  doi: 10.3969/j.issn.1673-503X.2019.02.004 Abstract ( 207 )   PDF (1137KB) ( 54 )   Save Based on the National Centers for Environment Prediction (NCEP) FNL Reanalysis data (1°×1°) and radiosonde data on a total of 1218 rainy and snowy days from 2005 to 2014 in Kelan,Shanxi province,the conventional physical variables (temperature,relative humidity,zonal wind and meridional wind) and diagnostic physical variables (T800-500,Td800 and TTd700) were statistically analyzed based on statistical analysis methods including deviation,absolute difference,correlation coefficient,and the occurrence rates of deviation range.The results showed that among these conventional physical variables,air temperature has the lowest averaged deviation and absolute difference and the highest correlation coefficient,being-0.22 ℃,1.02 ℃,and 0.90,respectively,which means air temperature has the highest reliability.While relative humidity has the lowest reliability with the largest averaged deviation and absolute difference and the smallest correlation coefficient,being 12.31%,19.68%,and 0.63,respectively.The reliability of the zonal wind and meridional wind is close to each other and slightly lower than that of air temperature.For these diagnostic physical variables,the deviations of T800-500,Td800 and TTd700 are -0.08 ℃,1.50 ℃,and 2.79 ℃,respectively,and their absolute difference are 1.21 ℃,3.33 ℃,and 4.14 ℃ with the correlation coefficient of 0.95,0.92,and 0.74,respectively.The occurrence rates of deviation range between-5 and 5 are 98.77%,80.30%,and 75.04%,respectively.The reliability of T800-500 is highest and that of TTd700 is the lowest.The characteristics of the NCEP FNL reanalysis data on rainy and snowy days should be paid attention. References | Related Articles | Metrics

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Ground-based observation of aerosol optical properties in Pengzhou,Chengdu WU Jun-wei, ZHAO Hu-jia, YANG Dong, WEI Yao 2019, 35 (2):  32-39.  doi: 10.3969/j.issn.1673-503X.2019.02.005 Abstract ( 256 )   PDF (863KB) ( 122 )   Save Based on measurements from a ground-based CE318 solar photometer in Pengzhou area of Chengdu in 2017,aerosol optical depth (AOD),Angström exponent (α),and atmospheric turbidity (β) were retrieved and their correlations with the inhalable particulate matters (PM10 and PM2.5) were studied.The results show that the seasonal mean AOD is largest in winter,followed by spring,summer,and autumn.The large AOD values usually occur in winter and spring,and the lower values mostly occur in summer and autumn.The α values vary in a small range throughout the whole year with a monthly average of 1.22±0.19 and are low in spring and high in summer.The monthly variation of AOD is similar to that of α in all seasons except for winter.The AOD has a strong correlation with β and weak positive correlation with PM10 and PM2.5.Aerosol optical property in this area is not greatly affected by dust particles from the north but is significantly influenced by human activities.The primary aerosol type in this region is the urban-industrial aerosols dominated by fine particles. References | Related Articles | Metrics

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Analysis of visibility characteristics and its influencing factors over Chaohu Lake area WU Jie, ZHOU Jian-ping, DENG Xue-liang, WANG Chuan-hui, ZHOU Wen-lin 2019, 35 (2):  40-45.  doi: 10.3969/j.issn.1673-503X.2019.02.006 Abstract ( 213 )   PDF (966KB) ( 130 )   Save Based on the high-density visibility monitoring data from Chaohu Lake area,the spatial and temporal distribution characteristics of visibility were analyzed,and the influence mechanism of the lake and surrounding topography on visibility and fog formation was preliminarily discussed.The results show that the visibility over Chaohu Lake is lower than that of far shore due to the influence of temperature,wind and water vapor.Generally,fog forms first in the far shore area compared with the nearshore area,but the nearshore area fog lasts for a long time and dissipates slowly.Under the action of lacustrine wind or dominant wind,the occurrence and duration of fog on the north and southwest coast of Chaohu Lake are obviously more than those in other areas.Due to the impact of mountains on the southeast coast of Chaohu Lake,dry and cold mountain winds at night improve the visibility on the shore and reduce the occurrence of fog. References | Related Articles | Metrics

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Analysis of ozone pollution characteristics and meteorological factors over Lanzhou city CHEN Pei-zhang, CHEN Dao-jin 2019, 35 (2):  46-54.  doi: 10.3969/j.issn.1673-503X.2019.02.007 Abstract ( 287 )   PDF (695KB) ( 299 )   Save Based on the monitoring data from the four state-controlled stations of Lanlian Hotel,Biological Products Institute,Staff Hospital and Railway Design Institute from 2014 to 2017,this paper analyzed the time distribution characteristics of ozone concentration and the influence of meteorological indicators on ozone concentration over Lanzhou city.The optimal meteorological factor range was obtained by a genetic algorithm to predict the excessive O3_8h concentration.The results show that from 2014 to 2017,the higher ozone pollution over the main city of Lanzhou mainly occurs in the period of April to August during which a high value ranges between 14:00 to 16:00 every day.The meteorological factors that play a leading role in the change of ozone concentration are the net surface solar radiation,height of boundary layer,2 m temperature,westerly wind,relative humidity and vertical velocity at 850 hPa.The range of the optimal meteorological factors obtained by the genetic algorithm is used to identify whether the meteorological conditions are in a high-impact state.At time when the meteorological conditions are in a high-impact state,the probability of O3_8h exceeding the standard value (O3_8h greater than 160 ug·m-3) at the next time is 42.31%,and the probability of O3_8h exceeding 130 ug·m-3 is 99.04%.In contrast,at the time when the meteorological conditions are in a low-impact state,the probability of O3_8h not exceeding the standard at the next time is 99.87%.Therefore,in the main city of Lanzhou,it is necessary to identify the future meteorological conditions first,and then manually control some major meteorological factors or control the concentration of ozone precursors before 09:00 to prevent the rapid rise of ozone concentration at 09:00-14:00 and prevent the ozone concentration from exceeding the standard level. References | Related Articles | Metrics

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Daily maximum height of the atmospheric boundary layer and its response to air quality over Urumqi city JIA Jian, YANG Pei-qi, JIANG Hui-ming 2019, 35 (2):  55-60.  doi: 10.3969/j.issn.1673-503X.2019.02.008 Abstract ( 364 )   PDF (998KB) ( 208 )   Save Based on L-band radar and conventional observation data in Urumqi city from 2007 to 2017,the maximum daily boundary layer height was estimated using the principle of Holzworth dry adiabatic curve,and the corresponding average wind speed and ventilation volume of the boundary layer were calculated.Meanwhile,the air pollution index (AQI) from 2015 to 2017 was used to discuss the relationship between air quality and atmospheric boundary layer parameters.The results show that the average annual height of the maximum daily boundary layer is 1415 m,and demonstrates a downward trend,with an average decline rate of 5.9 m·a-1.In time series,the daily maximum boundary layer height distribution shows obvious periodicity.The monthly data presents a "parabola",with the lowest average height in January (336 m) and the highest average height in June (2400 m).In winter,the average wind speed of the boundary layer is the smallest,with 2.6 m·s-1,and the largest in spring and summer,with 5.6 m·s-1.In a year,the average ventilation volume in January is the smallest,which is 977.0 m2·s-1,and the average ventilation volume in May is the largest,which is 14835.9 m2·s-1.From April to September,the average ventilation volume is 13282.3 m2·s-1.The accumulation of atmospheric pollutants under the conditions of weak wind speed,low boundary layer height,and small ventilation volume is easy to cause moderate pollution.In winter,Urumqi is always located at the rear or bottom of Mongolia high pressure,which is one of the important causes for serious pollution in winter. References | Related Articles | Metrics

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Temporal and spatial distribution characteristics of thunderstorms and its atmospheric circulation background in years with severe thunderstorm in Dalian area WANG Xiu-ping, JIN Wei, WANG Yan, HOU Yan-ze, GAO Lei 2019, 35 (2):  61-68.  doi: 10.3969/j.issn.1673-503X.2019.02.009 Abstract ( 210 )   PDF (2939KB) ( 278 )   Save Based on the daily surface thunderstorm observation data from three stations in Dalian city from 1961 to 2013 and the monthly average NCEP/NCAR (the National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data from 1948 to 2016,the temporal and spatial distribution of the number of thunderstorm days in Dalian city was analyzed using the linear trend estimation and synthetic analysis methods.The background characteristics of the average atmospheric circulation from May to September in the years with severe thunderstorms were discussed.The results show that the thunderstorm events in Dalian have obvious regional characteristics.There are a higher number of thunderstorm days in the northern inland area and a lower one in the southern coastal area.Except in February,thunderstorms can occur in any month,and the number of thunderstorm days reach the peak value in July and August.Thunderstorms mainly occur from May to September.They have a strong seasonality.There is a higher number of thunderstorm days in summer (from June to August),and a lower number of thunderstorm days in winter.The annual average number of thunderstorm days shows a decreasing trend,especially in the northern area.The starting time of thunderstorm mostly appears in April,and the ending day mostly appears in October.The starting day of thunderstorm is more stable than the ending day.Both the starting and ending dates of thunderstorm in the northern inland area are more stable than those in the southern coastal area.The starting dates of thunderstorm are ahead notably,whereas the delay trend in the ending dates of thunderstorm is insignificant.The obvious delay trend of ending date is only in Dalian station.The thresholds of five-day average temperature corresponding to the starting and ending days of thunderstorm in the northern inland area are -1 ℃ and 10 ℃,respectively,those in the southern area (and eastern area) are 6 ℃ (-1 ℃) and 3 ℃ (8 ℃),respectively.In the active thunderstorm years,the Mongolian low vortex at 500 hPa is anomaly strong,the subtropical high is more westward and northward,the southerly wind moisture transport at 850 hPa and the ascending motion of the whole atmosphere layer over Dalian are both abnormally strong.All of these are beneficial to the occurrence of more thunderstorm events.While in the inactive thunderstorm years,the characteristics of weather situation are basically contrary to those in active thunderstorm years. References | Related Articles | Metrics

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A study on the consistency and local characteristics of temperature evolution in Northeast China HOU Yi-ling, LIU Ming-yan, ZHAO Chun-yu, WANG Tao 2019, 35 (2):  69-76.  doi: 10.3969/j.issn.1673-503X.2019.02.010 Abstract ( 241 )   PDF (1358KB) ( 316 )   Save The consistency and local characteristics of the temperature in Northeast China were studied using the surface temperature data from 162 stations in Northeast China from 1961 to 2015.The results show that there is good spatial consistency in the annual average temperature in Northeast China.The region-wide consistent climate pattern is the most important climate pattern of the region.The time coefficient of the first rotation load vector shows an upward trend and there is also a significant 2-7 years periodicity,indicating that the temperature in the northern region is significantly affected by global warming,ENSO (El Niño-Southern Oscillation),and another large-scale climatic background.The temperature increasing rate in the northern region is 0.34 ℃ per decade from 1961 to 2015,which is higher than that of 0.26 ℃ per decade in the southern region,while the increasing trend slows down after 1980.The probability curve of annual average temperature moves to the high-value area with time.Significant warming appears in winter in the northern region,and in both winter and summer in the southern region,which indicates that the length of spring and autumn may be short. References | Related Articles | Metrics

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Variation of vegetation NDVI and its response to climate change in the Greater Khingan Range QU Xue-bin, ZHANG Xu-ming, SUN Zhuo 2019, 35 (2):  77-83.  doi: 10.3969/j.issn.1673-503X.2019.02.011 Abstract ( 171 )   PDF (1579KB) ( 72 )   Save Vegetation NDVI series from 2000 to 2016 in the Greater Khingan Range was reconstructed using the S-G filter method.The variations of vegetation NDVI during the growing season and their responses to climate were analyzed considering the factors of elevation,slope orientation,slope angle,temperature,and precipitation.The results show that the average of vegetation NDVI during growing season increased by 0.029 per decade.The vegetation NDVI decreased slowly first,then increased rapidly with the increase of elevation.The vegetation NDVI showed an increasing trend with the increase of the slope.The variation of vegetation NDVI showed no obvious regularity with the change of slope orientation.The averaged of vegetation NDVI during growing season showed a significant positive correlation with precipitation of one year and two years ago,indicating that NDVI had obvious hysteresis compared to precipitation.There was a significant positive correlation between the vegetation NDVI at different elevations with the air temperature in the early days of vegetation restoration.There is a significant difference for correlation between vegetation NDVI and precipitation within a year in the vertical direction. References | Related Articles | Metrics

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Climatic potential productivity and population carrying capacity in China from 1961 to 2010 XU Yu-qing, ZHOU Bo-tao, YU Li, XU Ying 2019, 35 (2):  84-91.  doi: 10.3969/j.issn.1673-503X.2019.02.012 Abstract ( 238 )   PDF (1294KB) ( 211 )   Save Climatic potential productivity (CPP) was calculated and population carrying capacity was evaluated for China using Thornthwaite Memorial model and annual temperature and precipitation data from a new gridded daily dataset (CN05.1),in order to further enhance the understanding of the impact of climate change and the greatest possible supporting capacity of climate resources.The results show that the annual CPP increased dramatically,and the mutation point was in 1987,with a minimum of 689.18 g·m-2·a-1,a maximum of 814.56 g·m-2·a-1 and a mean of 744.05 g·m-2·a-1 from 1961 to 2010.The CPP varied in different regions with a zonal distribution of gradually increasing from northwest to southeast of China.Regions with the CPP larger than 1800 g·m-2·a-1 were distributed in most areas of South China,with the highest value of 2103.56 g·m-2·a-1.Regions with the CPP lower than 300 g·m-2·a-1 were mainly distributed in western and northern China,with the lowest value of 39.28 g·m-2·a-1.The area with an increasing of the CPP (82%) was larger than that with a decreasing of the CPP (17%) over 2001-2010,relative to 1961-2010.However,the magnitude of variations in most areas in China was very small relative to 1961- 2010,with relatively greater variations distributed in the western and northern China.The climatic potential population carrying capacities of croplands in China ranged from 46 to 2180 persons/km2 from 1995 to 2010,with annual average values of no less than 1130 persons/km2.The actual population ranged from 0 to 49729 persons/km2,with annual average value of no more than 137 persons/km2.The ratio of actual total population to climatic potential population carrying capacities was in the range of 58%-65%.The actual productivity of croplands was less than climatic potential productivity,and the actual population was not beyond the scope of climatic potential population carrying capacities in most areas of China.Therefore,there is a certain potential for climatic potential productivity to be developed.The actual population has exceeded the climatic potential population carrying capacities in Qinghai,Guangdong,Zhejiang,Beijing,Tianjin and Shanghai and much attention should be paid to these areas. References | Related Articles | Metrics

BULLETINS

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Research on forecast method of maximum and minimum air temperature in mountainous scenic spot WANG Xin-wei, ZHANG Yu-xing, WEI Fang-fang 2019, 35 (2):  92-96.  doi: 10.3969/j.issn.1673-503X.2019.02.013 Abstract ( 211 )   PDF (498KB) ( 152 )   Save Based on the ECMWF grid data and the observation data,the temperature forecast for mountainous scenic spot using SVM and Kalman methods was investigated.The results show that the accuracy of the single SVM method is relatively high and stable,while that of the Kalman method is not sufficiently available especially for long-time forecast.The performance of integration solution of the two methods is better than that of the single one of them.More specifically,the forecasting accuracies of maximum and minimum air temperature decrease with the increasing prediction time for each method.The analysis also shows that the absolute error of forecasted maximum air temperature is smaller than that of minimum air temperature. References | Related Articles | Metrics

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Study on the forecast of cloud landscape in Huangshan Mountain in winter half-year DING Guo-xiang, LIU An-ping, YANG Bin 2019, 35 (2):  97-101.  doi: 10.3969/j.issn.1673-503X.2019.02.014 Abstract ( 245 )   PDF (548KB) ( 69 )   Save In order to improve the forecast accuracy of cloud landscape in mountainous scenic spot,the temporal change and the vertical distribution characteristics of some meteorological elements such as temperature,humidity and so on were first analyzed based on the observed cloud data from the Huangshan weather station and the NCEP/NCAR reanalysis data during 2004-2014.Then,the forecast factors reflecting the cloud landscape weather features were selected,and their thresholds and negative indexes were determined by analyzing the distribution characteristics of the forecast factors.Finally,the forecast model of cloud landscape at 08:00 during winter half-year was developed with index accumulation method and its total forecasting accuracy and TS grade was 88% and 31%,respectively.In addition,the model was further verified using the data from 2015 to 2016.As a result,the forecast accuracy of cloud landscape is 88% and the total TS grade is 36%.Specifically,TS grades in March and October are 44% and that in January is 38%.In conclusion,the model simulation results can provide available reference to the forecast of cloud landscape in Huangshan Mountain in winter half-year. References | Related Articles | Metrics

SCIENTIFIC NOTES

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Responses of main physiological parameters and yield of spring maize to drought stress after flowering MA Yong-zhong, CAI Fu, ZHAO Xian-li, WANG Yang 2019, 35 (2):  102-106.  doi: 10.3969/j.issn.1673-503X.2019.02.015 Abstract ( 193 )   PDF (618KB) ( 47 )   Save For understanding the response characteristics of physiological process and yield of spring maize to drought stress,a field experiment with continuous no-water complementing was conducted from filling to mature stage of spring maize "Danyu 39".In the meantime,main variables associated with photosynthesis including net photosynthetic rate (Pn) and transpiration rate (Tr),photo response parameter,water use efficiency (WUE) and yield factors were observed and calculated as well as their response characteristics to drought stress were investigated.The results indicate that Pn,Tr,WUE and maximum net photosynthetic rate (Pnmax) are decreasing with the duration of drought prolonging after flowering.During the 15th to 27th day of water controlling,the decrement rates for Pn and Tr vary from 50.0% to 75.1% and 71.7% to 83.6% under the light intensity of 1200 μmol·m-2·s-1,and those for WUE and Pnmax expand from 21.7% to 47.9% and 50.9% to 73.2%,respectively.In addition,the drought stress also induces significant decreases of 11.6% and 23.2% for hundred-grain and stalk weight of maize.However,the length and thickness of maize cluster as well as the ratio of grain to stalk do not vary significantly,while the radio of bare-tip and plant grain weight demonstrate a non-significant increasing and decreasing trend,respectively.Besides,a reduction rate of 11.7% for maize yield is caused by the drought during the studied period. References | Related Articles | Metrics

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Potential source analysis of heavy pollution weather in Haikou ZHANG Ying-ying, CHEN Ming, CHEN Li-ying 2019, 35 (2):  107-111.  doi: 10.3969/j.issn.1673-503X.2019.02.016 Abstract ( 199 )   PDF (1059KB) ( 95 )   Save After entering the winter half year,pollution weather of Haikou is easily caused by the weak cold air or downdraft.Using cluster analysis,PSCF and CWT methods,the potential source of heavy pollution weather from October to January during 2013-2015 was analyzed.The result shows that Haikou's air quality is mainly influenced by the northeast air stream from south china and east china during the studied period.The analysis results of PSCF and CWT methods indicate that the most areas of Guangdong,Fujian and Jiangxi province as well as the east of Hunan and Guangxi province are potential areas contributing pollutant for the pollution weather of Haikou.In addition,the main weather system causing air pollution,the exotic impacting from the key area and the accumulation condition of local pollutant should be considered in pollution forecast. References | Related Articles | Metrics