Table of Content

30 April 2020, Volume 36 Issue 2 Previous Issue    Next Issue

Select

Causes analysis of heavy rainfall in 2018 in Jilin province Xiu-juan WANG, Zhong-bao JIANG, Xiao-hua MA, Xu FENG 2020, 36 (2):  1-8.  doi: 10.3969/j.issn.1673-503X.2020.02.001 Abstract ( 564 )   HTML ( 31 )   PDF (6355KB) ( 435 )   Save Based on the data from the conventional meteorological and automated stations, NCEP (National Centers for Environmental Prediction) 1°×1° reanalysis and satellite black body temperature, formation reasons for a continuous heavy rainfall that occurred in Jilin province on August 13-15, 2018 were analyzed.The results show that "three zones" (westerly zone, subtropical zone and tropical zone circulation) are the large scale circulation backgrounds for the formation of this heavy rainfall.From the water vapor flux throughout the atmosphere, it reveals that an abundant water vapor delivering by the southwest airstream at the periphery of subtropical high and the southeast airstream at the periphery of a typhoon coming from a long distance away is supplied to the heavy rainfall zone.This heavy rainfall process can be divided into two phases.First, a positive moist potential vorticity disturbance existing at the high levels slides along the pseudo-equivalent potential temperature front zone and forms an unstable atmospheric stratification that has adequate water vapor and high unstable energy.Compared with the first phase, the water vapor and thermal conditions are weak, and unstable energy is small in the second phase.From the satellite images, it shows an MCC (Mesoscale Convective Complexes) and meso-scale α convective cloud.When the MCC cloud is in a thriving stage, cyclonic vorticity and meso-scale convergence exist at the low level and anticyclone vorticity and meso-scale divergence exists at the high level.The shear line at 925 hPa and convergence line at the surface are the meso-scale initiation condition for this heavy rainfall. Figures and Tables | References | Related Articles | Metrics

Select

Causes analysis of the formation of an extensive severe convective weather in 2016 in He'nan province Li-man CUI, Ai-fang SU, Yu-xing ZHANG, Chun-xiao WANG, Di WANG 2020, 36 (2):  9-19.  doi: 10.3969/j.issn.1673-503X.2020.02.002 Abstract ( 375 )   HTML ( 13 )   PDF (11033KB) ( 180 )   Save Based on the data from the Himawari-8 satellite, Doppler weather radar, regional automatic and conventional meteorological stations, and ERA-Interim (European Centre for Medium-range Weather Forecasts Interim) reanalysis, the environmental condition, triggering mechanism and evolution of MCS (Mesoscale Convective System) of a large-scale strong storm occurred in He'nan province on June 5, 2016, were analyzed.It shows that under the background of a North China cold vortex, the cold advection at the high level, combined with the development of warm ridge and the surge of the CAPE (Convective Available Potential Energy) values, provides unstable conditions for the development of the MCS.The convergence line at the surface and cold pool is the trigger mechanism.Southwest He'nan province is located in the high-energy area, where air masses with different temperatures and humidity properties meet each other.The intrusion of cold air in the middle and high level and the adiabatic lapse rate of the dry air below the middle level provide the possibility for the hail weather.Central and southern He'nan province is located in the area having a large amount of PW (Precipitable Water), and the deep wet layer and low uplift condensation height are conductive to the production of severe precipitation.The suction of the divergence at the high level and convergence at the low level leads to a strong upward movement over the Southwest He'nan province.The dynamic uplift is enhanced by the variable pressure wind generated by the thunderstorm high pressure.The strong convection echo is developed by the small and medium scale dynamic convergence.Hail weather occurs in the area having large values of TBB (Black Body Temperature) gradient in front of MCSs, and heavy precipitation occurs near the low value center of TBB.The radar product analysis shows that the strong echo drape, TBSS (Three Body Scattering Spike) and the fast-moving bow echo, the gust front and rear inflow jet are good indicators for the early warning of hail and thunderstorm gale.The significant warming zone at 12:00 at 925 hPa, the high-value zone of CAPE and the intersection zone between the cold pool outflow and the warm air are the potential zones for the development of strong convection.The height of wet-bulb temperature with 0 ℃ is closely related to hail. Figures and Tables | References | Related Articles | Metrics

Select

Analysis of the tornado weather process of Ewiniar typhoon Jiang-ling ZHI 2020, 36 (2):  20-27.  doi: 10.3969/j.issn.1673-503X.2020.02.003 Abstract ( 332 )   HTML ( 10 )   PDF (5340KB) ( 104 )   Save Based on the data from the conventional and automatic weather stations, Doppler radar, network videos, the disaster investigation and so on, the tornado weather process of No.1804 Ewiniar typhoon was analyzed.The results show that the tornado occurs on the right and rear side of the direction of typhoon Ewiniar after landing, with a strength level of EF1.The favorable circulation background includes the divergence suction at a high level, strong southeasterly jet stack at the middle and low level, and the lifting trigger of the mesoscale convergence line at the ground.The properties of atmosphere convective parameters are weak convective available potential energy and convective inhibitory energy, strong vertical wind shear at a low level, and low elevation condensation height and large relative helicity of a storm.The convective storm that produced the tornado is a low-mass micro-supercell one, and the tornado appears in the weak echo area of hook echo.On the velocity diagram, the meso-cyclone appears about 30 min ahead.The rotation speed of the meso-cyclone increases to the largest level near the occurrence of a tornado.Its size decreases, and its bottom height reaches to the minimum.All of these have a certain indicating effect for the early warning of the tornado. Figures and Tables | References | Related Articles | Metrics

Select

Evolution characteristics and formation mechanism of a hazing process in Chengdu Xin-yi LI, Feng-kai YANG, Yu-lei ZHU, Chang-jian NI 2020, 36 (2):  28-33.  doi: 10.3969/j.issn.1673-503X.2020.02.004 Abstract ( 308 )   HTML ( 7 )   PDF (1949KB) ( 126 )   Save Based on data from the environmental monitoring system, meteorological stations and Lidar stations in Chengdu from January 14 to 28, 2017, the evolution mechanism of a hazing process was analyzed.The results show that the hazing process is closely related to the weather situation.The change in meteorological factors plays an important role in particle diffusion.The correlation coefficients of PM2.5 mass concentration with wind speed, temperature, and relative humidity are -0.36, 0.45 and 0.20, respectively.During the hazing process, the average height of the mixing layer is about 378 m, and it is high in the daytime and low at the night.Trough the correlation analysis between the mixing layer height and the particle mass concentration at the ground in about two hour interval, it shows that the mixing layer height can play a significant role in the diffusion of ground particles.The correlation coefficient increases from -0.47 to -0.63 during the two hour period.This can to some extent indicate the evolution trend of particle mass concentration in the next few hours.In summary, the results obtained in this study can provide a theoretical basis and research reference for the early warning, prediction of local haze process, and pollution prevention and control. Figures and Tables | References | Related Articles | Metrics

Select

Relationship between atmospheric heat source over the Tibetan Plateau in May and midsummer precipitation in Heilongjiang province De-jun LOU, Bo WANG, Ji WANG, Xue-mei ZHANG, Yu-lian LIU, Xian-wei ZHOU 2020, 36 (2):  34-40.  doi: 10.3969/j.issn.1673-503X.2020.02.005 Abstract ( 184 )   HTML ( 4 )   PDF (6870KB) ( 45 )   Save Based on the summer precipitation data of Heilongjiang province and the National Center for Environment Prediction (NCEP) reanalysis data from 1961 to 2017, we studied the relationship between atmospheric heat source over the Tibetan Plateau and midsummer precipitation in Heilongjiang province as well as the possible mechanism using methods of singular value decomposition, correlation analysis, and regression analysis.The results show that the atmospheric heat source over the Tibetan Plateau in May is closely related to the precipitation in Heilongjiang province in July.When the heat source over the eastern Plateau is strong in May, the precipitation in central Heilongjiang province is significantly low in July.In the presence of strong heat source in May and under the influence of the subtropical westerly jet, atmospheric circulation exhibits similar Silk Road teleconnection waves in middle latitudes and similar East Asia-Pacific teleconnection waves in East Asian coastal regions in July, which makes Heilongjiang province under the control of an anti-cyclonic circulation and thus results in low precipitation in this region. Figures and Tables | References | Related Articles | Metrics

Select

Impact of tropical cyclones on precipitation and characteristics of circulation anomalies in Hu'nan province during 1951-2017 Yu-fang LIAO, Jian-ming ZHANG, Ling-yao GUO 2020, 36 (2):  41-48.  doi: 10.3969/j.issn.1673-503X.2020.02.006 Abstract ( 153 )   HTML ( 3 )   PDF (3505KB) ( 98 )   Save Understanding on the precipitation patterns influenced by tropical cyclones in Hu'nan province can provide technical support for precipitation forecast in relation to tropical cyclones in this region.Using tropical cyclone data in recent 67 years, we statistically analyzed the impact of tropical cyclones on precipitation in Hu'nan province and the characteristics of circulation anomalies.The results indicate that precipitation in relation to tropical cyclones in Hu'nan province mainly occurs from July to September.Tropical cyclones landing in coastal areas of Guangdong and Fujian provinces have the most frequent and severest effects on precipitation in Hu'nan province, and those landing in Zhejiang and Fujian provinces contribute to the widest precipitation area in Hu'nan province.These precipitation events mainly concentrate in the southeast Hu'nan province, and the heavy precipitation events have exhibited an increase in area and intensity in the past 67 years.Atmospheric circulation in relation to tropical cyclones landing in coastal regions of Guangdong and Fujian provinces is characterized by a strong South Asia High, with its location more east- and northwards, and thus a strong West Pacific Subtropical High, with its location more west- and northwards.The two high-pressure systems contribute to the convergence of southeasterly flows on the southern side of the West Pacific Subtropical High and southwesterly winds over the South China Sea and the eastern Philippine Ocean, and thus the formation of a monsoon trough.Finally, southeasterly flow over southern and eastern China favors the landing of tropical cyclones and then precipitation in these regions.Tropical cyclones landing in Fujian province, in comparison with those landing in Guangdong province, are usually accompanied with South Asia High and the West Pacific Subtropical High located further northward and the monsoon trough more eastward, which can result in a cyclonic circulation and substantial precipitation in most regions in Hu'nan province.However, tropical cyclones landing in Guangdong province were mostly controlled by a cyclonic circulation and substantial precipitation in the southeastern region of Hu'nan province. Figures and Tables | References | Related Articles | Metrics

Select

Assessment of air temperature simulation and threshold-crossing times of 2 ℃ warmings by CMIP5 models in Liaoning province Tao WANG, Yi-shu WANG, Yu-min SHEN, Yan WANG, Lian-wei ZHAO, Xiao-tao WANG, Li-du SHEN 2020, 36 (2):  49-61.  doi: 10.3969/j.issn.1673-503X.2020.02.007 Abstract ( 179 )   HTML ( 4 )   PDF (7762KB) ( 38 )   Save Using the 19 global climate models, ensemble models in conjunction with the observational data in Liaoning province, we evaluated the accuracy and credibility of air temperature simulated by different models under different typical concentration paths.The results indicate that the optimal model simulation performs better and has higher credibility than ensemble simulation.With the increase in emissions and concentrations of carbon dioxide, the change rate and credibility in simulated air temperature tend to show an increasing trend, and the beginning years when the temperature increment is beyond 2 ℃ for the first time, occur before 2011 at most stations.The later the beginning year is, the higher the temperature increments, and vice versa.The beginning years with temperature increment of stably by 2 ℃ occur before 2022 at most stations, and the ending years occur between 2019 and 2016, with a duration of less than 13 years.The beginning years occur earlier in the western region than in the eastern region in Liaoning province, while the ending years and duration time distribute more even.With the increase in global emissions and concentrations of carbon dioxide, the warming rate increases.Occurrence time and variation trend of the maximum, minimum, and average temperatures in different regions under different typical concentration paths are basically consistent with each other. Figures and Tables | References | Related Articles | Metrics

Articles

Select

Inversion of ground-based microwave radiometer measurements using radial basis function neural network Xu FAN,Ying HUANG,Wen-nan LENG,Bei-dou ZHANG,Wen-yu ZHANG,Guo-yin WANG 2020, 36 (2):  62-69.  doi: 10.3969/j.issn.1673-503X.2020.02.008 Abstract ( 186 )   HTML ( 7 )   PDF (1052KB) ( 102 )   Save Using observational data from a ground-based microwave radiometer at the Semi-Arid Climate and Environment Observatory (SACOL) of Lanzhou University and radiosonde data from the Yuzhong station in 2009 and 2010, a radial basis function neural network (RBFNN) algorithm was established for the inversion of air temperature, relative humidity, and water vapor density, and the application of this algorithm was explored throughout comparing the inversion results with the original products of the microwave radiometer.The results show that the maximum mean square root error is 2.72 K for air temperature, 22.32% for relative humidity, and 0.73 g·m-3 for water vapor density, respectively, derived using the RBFNN method.The RBFNN inversion performs better than the original products of microwave radiometer at all observational heights and significantly improves profiles of air temperature at 2-10 km, relative humidity at 0-3 km, and water vapor at 1-7 km, respectively.Therefore, the RBFNN algorithm is recommended for the local inversion of meteorological variables based on a ground-based microwave radiometer. Figures and Tables | References | Related Articles | Metrics

Select

A study on rainfall trend during the crop growing season in Heilongjiang province based on Hurst exponent method Li-xia JIANG,Liang-liang WANG,Jia-jia LV,Ming GAO,Ping WANG,Qiu-jing WANG,Li-juan GONG,Hui-ying ZHAO 2020, 36 (2):  70-77.  doi: 10.3969/j.issn.1673-503X.2020.02.009 Abstract ( 157 )   HTML ( 5 )   PDF (2708KB) ( 87 )   Save Based on daily precipitation data from the 78 meteorological stations in Heilongjiang province from 1971 to 2016, this paper analyzed the historical and future trends of precipitation change during the crop growing season (from May to September) in Heilongjiang province by using the methods of Mexican-hat wavelet transform and Hurst exponent.The results show that there are the major quasi-periods of 7 years, 14 years and 7 years in the growing season, May and June, respectively, and the first quasi-periods of 2 years, 3 years and 7 years as well as the second quasi-periods of 6 years, 11 years and 21 years in July, August and September, respectively, for precipitation in Heilongjiang province during 1971-2016.Meanwhile, the precipitation in each month shows an increasing trend in recent years.The precipitation in growing season shows a fluctuant interannual variation and the change amplitudes are relatively large in July and August.In addition, the precipitation experiences an interdecadal change of increase-decrease-increase pattern.Specifically, the precipitation is above the normal level in the 1980s and 1990s and sharply increases since 2010.The Hurst exponent of each month is above 0.5 at each station, which means that there is an obvious Hurst Phenomenon for precipitation.Precipitation mainly occurs in summer, especially in July.The facts that the precipitation increases and concentrates abnormally in July in recent several years as well as persistently increases in main river basins in July in the future are worthy of attention in agricultural disaster prevention and mitigation. Figures and Tables | References | Related Articles | Metrics

Select

Inspection and analysis of the effect of aircraft precipitation enhancement based on CA-FCM method Xiu-zhu SHA,Zhen-ping SHAO,Yan-hua LIU,Shan-hai WANG 2020, 36 (2):  78-84.  doi: 10.3969/j.issn.1673-503X.2020.02.010 Abstract ( 134 )   HTML ( 3 )   PDF (1575KB) ( 25 )   Save Using the data of aircraft precipitation enhancement (APE) from 2013 to 2017 in He'nan province, the rationality and applicability of CA-FCM method in the APE effect inspection was investigated, and the relationships between the relative precipitation enhancement rate (RPER) and season, the physical quantity of inspection, vertical integrated liquid water were analyzed.The result shows that the application of CA-FCM in APE effect inspection in He'nan province can obtain a quantitative and reasonable effect.The RPERs of most operations range from 0% to 40%, and few operations make rain reduced.The RPERs in spring, summer, and autumn are 20.8%, 22.4%, and -22.6%, respectively.The APE effects in spring and summer are obviously better than that in autumn, and the half of autumn APEs generate precipitation reduction effect, which is probably related to cloud condition.The cloud availabilities for APE in spring and summer are superior to that in autumn.The significance test result shows that 65% of APE effects are significant.The higher vertical integrated liquid water content is in the APE area, the more the RPERs increase significantly.In addition, the APE conducted under the conditions of pre-operation echo ranging from 30 to 50 dBz and the large scale operation cloud, easily achieves certain precipitation enhancement effect, while that with operation cloud echo of 20-30 dBz is easy to produce precipitation reduction effect.Besides, the maintenance or enhancement of echo intensity and the area plays a significant role in increasing the APE effect. Figures and Tables | References | Related Articles | Metrics

Bulletins

Select

Effects of continuous shading stress on flower-fruit, yield and fruit quality of greenhouse tomato Ji-bo ZHANG,Xiao-ping XUE,Nan LI,Hong-yi LI,Meng-yuan JIANG 2020, 36 (2):  85-91.  doi: 10.3969/j.issn.1673-503X.2020.02.011 Abstract ( 190 )   HTML ( 1 )   PDF (714KB) ( 51 )   Save In this study, tomato variety of "Golden Crown No.5" was taken as the experiment material.Different radiations (photosynthetically active radiation, PAR < 200 μmol·m-2·s-1) and durations (0, 1, 3, 5, 7, 9 d) in the greenhouse by using shading nets and a recovery treatment under normal sunshine conditions were carried out to study the effects of shading stress on flower-fruit, yield formation and fruit quality of greenhouse tomato.The results show that continuous shading stress delays the florescence, reduces the number of flowers and fruits on a single panicle as well as decreases the fruit-setting rate.Shading stress lasting more than 7 days causes the date of tomato flowering delaying about one week.Shading stress also results in the decrease of single fruit weight, yield per plant, fruit diameter and the increase of non-commercial fruit rate.Under the condition of 9-day continuous shading stress, the single fruit weight, yield per plant and fruit diameter are lower than CK (no shading stress) by 0.04 kg, 1.8 kg and 1.1 cm, respectively.The non-commercial fruit rate is higher than CK by 3.1%.Under shading stress, the yield per plant of tomato positively correlates with the photosynthetic parameters such as leaf number, stomatal conductance, transpiration rate and photosynthetic rate significantly, while negatively correlates with intercellular CO2 concentration.The content of vitamin C, soluble sugar and soluble protein in tomato fruit decrease with the increase of duration of shading stress.In opposite, the ascorbic acid content, organic acid content and total acidity of tomato fruit increase with the longer duration of shading stress.The conclusions from this study can provide a basis for quantitative evaluation of the effects of continuous shading stress on flower-fruit, yield formation and fruit quality of greenhouse tomato. Figures and Tables | References | Related Articles | Metrics

Select

Estimation of area for single-season rice based on remote sensing of GF-1 satellite Tao SHI,An-wei ZHANG,Tai-ming YANG,Shu-qing YE,Jia-wen LI,Yuan-jian YANG 2020, 36 (2):  92-97.  doi: 10.3969/j.issn.1673-503X.2020.02.012 Abstract ( 144 )   HTML ( 3 )   PDF (1153KB) ( 28 )   Save GF-1 satellite, which can provide high-resolution earth observation information, is one of the major members in the high-resolution earth observation system of China.In this study, Hefei city was selected as a case study area.Based on the two GF-1 images at late-May and early-August in 2017, the remote-sensing estimation model for the area of single-season rice was built using the variations of characteristics for different vegetation covers and the blue shift information of rice at maturity.Then, the planting area of the single-season rice in Hefei was estimated based on the model.The estimation accuracy was 93.2%, which were validated by the planting area in the field survey.While the accuracy of estimation of the single-season rice area using the method of the confusion matrix and the Kappa coefficient were 83.7% and 0.84, respectively.In summary, it is feasible that the single-season rice area can be estimated by the remote-sensing model constructed in this study. Figures and Tables | References | Related Articles | Metrics

Scientific Notes

Select

Air pollution forecast in winter based on machine learning method in Chengdu Su-qi SUN,Shi-gong WANG,Bin LUO,Yun-song DU,Wei ZHANG 2020, 36 (2):  98-104.  doi: 10.3969/j.issn.1673-503X.2020.02.013 Abstract ( 218 )   HTML ( 1 )   PDF (1241KB) ( 126 )   Save In this paper, based on the PM2.5, PM10, SO2, NO2, CO, O3 pollutant concentration data from 8 environmental monitoring stations of Chengdu and the T639 global medium-term numerical forecast model products from March of 2014 to February of 2017, the forecast model for the five of the above-mentioned six pollutant except O3 in winter in Chengdu was built by using the recursive feature elimination (RFE) and the random forest method which are superior to the traditional statistical method, and its forecasting performance was assessed.The results show that the mean squared error (MSE) of the values of five pollutants forecasted by the RFE model are 47.58 μg·m-3, 72.10 μg·m-3, 8.87 μ·m-3, 0.59 mg·m-3, 19.84 μg·m-3, and those by the random forest model are 23.94 μg·m-3, 20.98 μg·m-3, 2.40 μg·m-3, 0.16 mg·m-3, 8.09 μg·m-3, which proves that the performance of the random forest model is better than that of the RFE model in the pollutant concentration forecast, indicating that the random forest method has a good performance and can provide the technical support for the air quality forecast business and the basis for the air pollution prevention and control in winter in Chengdu. Figures and Tables | References | Related Articles | Metrics

Select

Modelling and analysis of the total cloud amount using the least square method based on FY-2G product in Jiangxi province Ya-nan LIU,Hai-bo ZOU,Qiong WU 2020, 36 (2):  105-111.  doi: 10.3969/j.issn.1673-503X.2020.02.014 Abstract ( 184 )   HTML ( 3 )   PDF (1904KB) ( 213 )   Save Based on the hourly total cloud amount (TCA) product provided by FY-2G satellite and ground observation data of 26 observation stations in Jiangxi province from January of 2016 to December of 2018, the spatio-temporal distribution characteristics of correlation between two types of data were analyzed.The result shows that the TCAs based on FY-2G satellite and the observation data have good consistency in value and change trend with a population correlation coefficient of above 0.60.However, the spatial correlation is unevenly distributed.Specifically, the correlation coefficient in the vicinity of large water bodies (Poyang Lake and Zhelin Lake), is relatively small and less than 0.45, and that in southern Jiangxi province is less than 0.50.In addition, the correction coefficient of two TCA data in time is unevenly distributed and is the largest at 14 o'clock.Besides, based on the FY-2G satellite TCA product, the regression model of TCA with surface observation is established by using the least square method with segment modelling.As a result, the TCA and its change trend simulated by the model are closer to those of the ground-based observations. Figures and Tables | References | Related Articles | Metrics