Table of Content

28 June 2022, Volume 38 Issue 3 Previous Issue    Next Issue

Articles

Select

Observational analysis of EF4 tornadic supercell storm in Kaiyuan of Liaoning province on July 3, 2019 Shi-bo GENG,Kui-zhi CAI,Ying WANG,Fu-ran ZHOU,Guang-liang XIAO,Hai-liang HUANG,Xiao-ling CHAI 2022, 38 (3):  1-10.  doi: 10.3969/j.issn.1673-503X.2022.03.001 Abstract ( 215 )   HTML ( 11 )   PDF (6331KB) ( 184 )   Save Based on the observational data from Doppler radar, ground automatic weather station, wind profile, and ERA5 reanalysis data, the environmental conditions, Doppler radar echo characteristics, and formation mechanism of super monomer storm accompanied by EF4 strong tornado occurred in Kaiyuan of Liaoning province on July 3, 2019 were analyzed.The results indicated that this process occurs under thermal instability, warm wet in the lower layer, and cold and dry in the upper layer.The wet convection is triggered near the ground convergence line formed by the confluence flow field of the ground trunk line and develops into a supercell storm with a tornado.The tornado occurs near the hook echo in the lower layer.The Doppler radar shows the echo characteristics of the classic supercell storm.The strong wind shear in the lower layer converts the horizontal vorticity into the vertical vorticity in the convective storm.The strong upward movement makes the downstream vorticity tilt and stretch.Therefore, the mesocyclone structure appears for the first time when the Doppler radar is at an elevation of 2.4°, i.e., 17 minutes before the tornado.Then, during the movement of the storm, the downdraft behind the storm (RFD) "depresses" the vorticity in the middle and low layers, resulting in the tornado reaching the ground.Therefore, one minute after the tornado, there is also a strong mesocyclone at an elevation of 0.5° with characteristics of tornado-like vortexes (TVS).The maximum rotation speed of the mesocyclone reaches 28 m·s-1 (reaching the strong meso-cyclone standard).Therefore, this tornado conforms to the characteristics of a "top-down" type I tornado.Due to the strong evaporation and cooling of water droplets caused by the entrainment of ambient dry air, a strong cold pool with a temperature drop of 10 ℃ in one hour appears on the ground.An excessively strong cold pool may play a key role in promoting the demise of the tornado, resulting in the demise of the tornado after about 30 minutes. Figures and Tables | References | Related Articles | Metrics

Select

Analysis of the satellite image and radar echo features of the strong tornado in Kaiyuan of Liaoning province Xu-xuan JIA,De-qin LI,Cheng-cheng FENG,Li-peng ZHANG 2022, 38 (3):  11-18.  doi: 10.3969/j.issn.1673-503X.2022.03.002 Abstract ( 319 )   HTML ( 20 )   PDF (8286KB) ( 140 )   Save Based on Himawari-8 satellite data, SC weather radar data in Shenyang, ERA5 reanalysis data, and weather observations, the features of the satellite image, radar echo, and atmospheric circulation of the strong tornado in Kaiyuan of Liaoning province on July 3, 2019 were analyzed.The results show that this strong tornado occurs at the bottom of the northeastern cold vortex.At 850 hPa, the lower layer has warm and humid airflow, forming a vertical structure with wet bottom and dry top.At 17:00, there is a vertical wind shear of 22.8 m·s-1 at 0—6 km and of 7.6 m·s-1 at 0—1 km where the tornado is born.Before the tornado appears, the temperature on the western side of the birthplace is higher than that on the eastern side.There is a ground temperature difference of 2—5 ℃.When the tornado is generated, an obvious cold pool is formed on the eastern side of the tornado's moving path.The lowest temperature is 19 ℃, and the maximum temperature difference on the western side is 11 ℃.When the tornado is generated, the horizontal scale of the cloud anvil of the convective storm on the visible light cloud chart increases significantly.The cloud top rises and the brightness temperature decreases.The evolution characteristics of radar reflectivity show that the development of tornado convective storms has experienced three stages, i.e., from multi-cell non-strong storms to multi-cell strong storms and then to supercell storms.Convective cells merge when the tornado reaches the strongest level.This tornado storm has a mesocyclone in all three stages.At 17:11, the mesocyclone extends down to the lower level, and the reflectivity factor appears as a finger echo. Figures and Tables | References | Related Articles | Metrics

Select

Analysis of rainstorm caused by an explosive cyclone in Northeast China Ning WANG,Liang-chen MA,Ye HUO 2022, 38 (3):  19-28.  doi: 10.3969/j.issn.1673-503X.2022.03.003 Abstract ( 343 )   HTML ( 17 )   PDF (7168KB) ( 115 )   Save Based on the NCEP FNL(National Center for Atmospheric Research Final Analysis) and GDAS(Global Data Assimilation System) 1°×1° reanalysis data, ground observation data from May 2 to 4 in 2016, the rainstorm process in Northeast China caused by the explosive development of the surface cyclone in spring was investigated.The large-scale circulation background, water vapor source and transport, dynamic mechanism, and thermal conditions were analyzed.The results show that the Huang-Huai cyclone locates near 40°N intensified northward and the central pressure drops 24 hPa from 14:00 on February 2 to 14:00 on February 3, exceeding the definition standard of the explosive cyclone.The 500 hPa upper trough is rapidly strengthened and developed into a closed vortex, and the low-level shear line is strengthened and developed into a low-level vortex.The obvious low-level jet forms in the east of the trough, which provides water vapor and heat for the rainstorm area and the rainstorm is typical warm shear precipitation in Northeast China.Isentropic potential vortexes transport downwards from the upper level of 320 K to the lower level of 305 K and gradually move to the southeast.The downward transmission of the upper level positive potential vortexes enhances the development of surface cyclones and the convergence of ascending movement, which is conducive to the increase of rainstorms.The specific humidity above 6 g·kg-1 will be useful for rainstorm forecasts in late spring and early summer in Northeast China.Water vapor mainly comes from the Northwest Pacific Ocean, such as the East China Sea and the Yellow Sea.The rainstorm area is consistent with the negative area of water vapor flux divergence at 850 hPa, the vertical velocity at 700 hPa, and the absolute vorticity large value at 850 hPa.The strong rainfall area corresponds to the dense zone of equivalent potential temperature at 850 hPa and the warm frontogenic area.The precipitation is located in the energy front area and the side of the warm area. Figures and Tables | References | Related Articles | Metrics

Select

Numerical simulation and analysis of the system of embedded convection clouds in Northeast China Tian WEI,Heng DING,Gui-qiang QIU,Rui-rui FAN,Jia-lin YAO 2022, 38 (3):  29-36.  doi: 10.3969/j.issn.1673-503X.2022.03.004 Abstract ( 101 )   HTML ( 4 )   PDF (5468KB) ( 28 )   Save Based on the conventional meteorological observation data, the NCEP FNL(National Center for Atmospheric Research Final Analysis) reanalysis data and the numerical simulation results of the WRF(Weather Research and Forecasting) model, the formation and evolution process and the microphysical characteristics of the embedded convective clouds occurring in Liaoning province on July 1, 2010, were analyzed.The results show that the WRF model performs very well in simulating the convection process.The embedded convective cloud occurs in conditions where there are stratiform clouds in the upper atmosphere and scattered convective bubbles in the lower atmosphere.As the convective bubbles in the lower atmosphere develop and grow continuously, and till extend to the height of stratiform clouds, the embedded convective cloud is formed.With the eastward movement of the stratiform cloud, the embedded convective cells merge and split repeatedly, and the obvious right shift of the convective fluids appears in the splitting process.In the cloud system, there are not only warm cloud precipitation mechanisms that cloud water can be directly converted into the rain, but also cold cloud precipitation mechanisms of seeding-supplying.Both mechanisms are the most active in the mature stage.The intensity of convergence at a low level and divergence at a high level is the strongest in the development stage, which is the most favorable for the development of a cloud system. Figures and Tables | References | Related Articles | Metrics

Select

Causes and characteristics of a persistent rainstorm event in warm front of a cold vortex Li REN,Chen LUAN,Xiao-xue WANG,Yue ZHANG 2022, 38 (3):  37-44.  doi: 10.3969/j.issn.1673-503X.2022.03.005 Abstract ( 255 )   HTML ( 7 )   PDF (7627KB) ( 97 )   Save Based on conventional meteorological observational data, precipitation data from automatic observational stations, and National Centers for Environmental Prediction(NCEP) FNL reanalysis data, we diagnostically analyzed the causes and characteristics of a persistent rainstorm event due to a cold vortex in Northeast China from August 6 to 8, 2019.The results indicated that a warm front that remains stable and makes frontogenesis causes the persistent rainstorm event.Heavy precipitation occurs in the south of the 850 hPa front areas, with a pattern of an east-westward belt, corresponding to the maximum frontal zone.The middle-level atmosphere has weak unstable convection, which favors the maintenance of heavy precipitation.The region with a high value of positive potential vorticity in the upper layer extends down to the lower layer, leading to the increase of the vorticity in the middle and lower layers and the formation of a columnar structure of positive vorticity ahead of the warm front.Moreover, it induces cyclonic circulation in the front area near the surface and promotes the occurrence of low-pressure systems.A strong convergence zone at the low-level frontal area is located on the windward slope.The interaction of frontal convergence and topographic forced uplift makes the low-level strong convergence zone remain in the same area for 3 days.In the weakened stage of the eastward movement of the cold vortex, warm and moist air carried by a typhoon moves northward, resulting in the northward movement of the front area and the maintenance of heavy precipitation.In the stages of formation and maintenance of the cold vortex, T850-500≥25 ℃, K≥35 ℃, and a certain convective effective potential energy are a good indication of the occurrence of heavy precipitation.The water vapor input along the eastern boundary of the rainstorm area is the most critical, accounting for half of the total water vapor input.Although the total water vapor input from the southern boundary is not quite large, it concentrates in the first rainstorm day and contributes most of the water vapor for the rainstorm on August 6, 2019. Figures and Tables | References | Related Articles | Metrics

Select

Fine analysis of causes of an early-morning abnormal temperature rise in Shenyang in 2019 Han LIANG,Qi YAN,Shuang LI,Chen-he ZHANG,Ya-xin YU,Ge HUANG,Hong-yu SUN,Ming-gang SANG 2022, 38 (3):  45-51.  doi: 10.3969/j.issn.1673-503X.2022.03.006 Abstract ( 238 )   HTML ( 6 )   PDF (4363KB) ( 151 )   Save Air temperature observed at a national weather station in Shenyang increased by 6.5℃ in an hour at 01:00 on December 2, 2019.We accurately analyzed the causes of this abnormal temperature-increase process from the aspects of system configuration, thermodynamic diagnosis, and urban heat island effect, using regular and encrypted observation data, National Centers for Environment Prediction (NCEP) reanalysis data, and wind profiler radar data in Shenyang.The results indicated that a warm ridge between extremely low altitudes and near the surface passes by during the abnormal temperature-increase period, which is the major reason for the increase of air temperature at the midnight over most regions of Liaoning province.The national weather station is located in the southeastern region of Shenyang.In the presence of the northwesterly surface winds, air flows move from warm urban regions to cold suburb regions in Shenyang.This results in the increase in air temperature observed at all weather stations in the southern part of Shenyang, increasing by 3-4℃ in comparison with stations in northern suburbs.Therefore, the urban heat island center moving to the leeward is another reason for the abnormal temperature-increase event.Moreover, the base value of air temperature before temperature rise can affect the temperature-increase degree.The lower the basic temperature is, the greater the temperature-increase degree is. Figures and Tables | References | Related Articles | Metrics

Select

Simulation on impacts of aerosol number concentration on physical characteristics of warm clouds during different growth stages Guo-hang YU,Su-ying YANG,Cheng-rong HU,Xuan-xuan LIU,Ya-ru LI,Zhi-yi LONG 2022, 38 (3):  52-64.  doi: 10.3969/j.issn.1673-503X.2022.03.007 Abstract ( 188 )   HTML ( 7 )   PDF (12385KB) ( 53 )   Save Based on the TAU2D cloud model with complete cloud microphysical processes, cloud microphysical characteristics of warm clouds generated by thermal turbulence under different aerosol concentrations(Na) were simulated.The results showed that with higher Na, cloud droplets radius becomes smaller, the collision coalescence of cloud droplets occurs later, and the broadening of cloud droplet spectral due to the collision-coalescence effect becomes weak, which results in narrower cloud droplet spectral with smaller standard deviation, slower development and longer life time of clouds, and later occurrence of precipitation.Otherwise, the larger size of cloud droplets tends to generate earlier collision-coalescence growth, distinct broadening of cloud droplet spectral with larger standard deviation, longer cloud life time, and earlier occurrence of precipitation.In the presence of high Na, the cloud droplet spectral exhibits a wider range during the collision-coalescence stage than in the condensation growth stage.During the deposition stage, the evaporation of clouds reduces small cloud droplets and thus makes the cloud droplet spectral slightly wider than that during the collision-coalescence stage.During the condensation growth stage, there is a positive correlation between cloud droplet number concentration (N) and relative dispersion degree(ε) under low Na conditions, while a negative correlation between them occurs under high Na conditions.During the collision-coalescence stage, there is a negative correlation between N and ε, and such a negative correlation is weakened with the increase of Na.In the deposition stage, there is a negative correlation between N and ε. Figures and Tables | References | Related Articles | Metrics

Select

Transport and case study of heavy air pollution in Luohe during autumn and winter using backward trajectory analysis Wei WU,Tie-liang SHAN 2022, 38 (3):  65-74.  doi: 10.3969/j.issn.1673-503X.2022.03.008 Abstract ( 156 )   HTML ( 8 )   PDF (4073KB) ( 103 )   Save Based on conventional meteorological data, particulate matter observation data, global atmospheric assimilation system(GDAS) data, and reanalysis data from the National Center for Environment Prediction(NCEP) and ERA5, we analyzed the characteristics, pollutant transport, and potential source areas of heavy air pollution in Luohe during autumn and winter from 2015 to 2019, using methods of mathematical statistics, trajectory cluster analysis, and synoptic analysis.We also conducted an evaluation using a typical heavy pollution event.The results showed that heavy air pollution events have exhibited high occurrence frequency, long duration, and heavy pollution intensity in Luohe during autumn and winter in the past 5 years.The variation trends of air quality index(AQI) and PM2.5 are not obvious, while the PM10 concentration reduces significantly.Meanwhile, the ratio of PM2.5/PM10 increases year by year, and PM2.5 is the primary air pollutant in Luohe.There are six air mass transport paths in Luohe during autumn and winter.The northeast path and the east path are major transport channels for heavy air pollution, characterized by short trajectory, slow movement, low height, and obvious transport in the near-surface layer.The northwest path with long-distance transport and deposition and the southwest path with short-distance transport contribute less to heavy air pollution in Luohe, with a low AQI and low probability for heavy pollution on average.The potential sources of air pollutants in Luohe are complex, with a wide range and strong intensity.They are mainly distributed in the middle and eastern regions of He'nan province, especially in the northeast region, corresponding to air mass trajectories such as the northeast path and the east path.Northerly winds prevail near the surface during heavy air pollution events, especially for the northerly and northeasterly flows with speeds between 2-4 m·s-1.Two regional transport events indicate that the near-surface transport along the north or northeast paths is the main reason for the maintenance and development of AQI peaks. Figures and Tables | References | Related Articles | Metrics

Select

Spatio-temporal changes and influencing factors of ozone in the central area of Dalian during 2013-2018 Rui-feng MA,Jing-hong XV,Liang-zheng YAN 2022, 38 (3):  75-84.  doi: 10.3969/j.issn.1673-503X.2022.03.009 Abstract ( 137 )   HTML ( 6 )   PDF (2906KB) ( 89 )   Save Based on the O3 monitoring data and meteorological data in the central area of Dalian from 2013 to 2018, the temporal and spatial characteristics of O3 pollution in this area and its responses to the meteorological influencing factors were analyzed.The results indicated that O3 has gradually become one of the most important air pollutants in the central city of Dalian during the past 6 years, and its annual average concentration rises from 66.66 μg·m-3 in 2013 to 101.62 μg·m-3 in 2018.In terms of temporal changes, the concentration of O3 is higher in autumn and summer than in winter and spring and is highest in May, June, and September.In addition, the O3 concentration begins to rise at 08:00.and maintains a peak during 14:00-16:00, showing an obvious single peak shape on a daily time scale and is higher in the daytime than in nighttime.In terms of spatial distribution, O3 pollutants spread from the southwest to the northeast from 2013 to 2017.Moreover, O3 in the study area has a negative correlation with the other 5 air pollutants to different degrees and is significantly and positively correlated with temperature and slightly correlated with relative humidity, air pressure, and wind speed.The optimal meteorological conditions for O3 pollution are mainly air temperature above 30 ℃, relative humidity below 80 %, wind speed between 1.5 to 2.0 m·s-1, north wind direction, and long sunshine duration.High pollution days are probably induced by high temperatures and increasing local emissions. Figures and Tables | References | Related Articles | Metrics

Select

The impact of concentration change of PM2.5 on air temperature in China during 1998-2016 Yuan-jun XIAO,Bao-shan LI,Wen-dan SONG,Yong-xiang CHENG,Jing-feng HUANG 2022, 38 (3):  85-92.  doi: 10.3969/j.issn.1673-503X.2022.03.010 Abstract ( 101 )   HTML ( 2 )   PDF (2927KB) ( 58 )   Save Based on daily maximum temperature, daily minimum temperature, and daily average temperature data from 1951 to 2017 from China's 822 weather stations, remote sensing image data for annual average PM2.5 concentrations in China, surface solar radiation data, annual energy consumption, GDP (gross domestic product) and the night lights index data during 1998-2016, using the slope trend analysis and correlation analysis, the changing trend of PM2.5 concentrations in China and its impact factors were analyzed.The results show that the PM2.5 concentrations in the Huang-Huai-Hai region and the northeastern part of China have the largest increase rates i.e.1.42 μg·m-2·a-1 and 1.44 μg·m-2·a-1 from 1998 to 2016, respectively, while those in the other regions have no obvious change.The average PM2.5 concentration in the Huang-Huai-Hai region is high, which reduces the local surface solar radiation and significantly inhibits the local annual maximum temperature, but has no obvious influence on the annual average and minimum temperatures.In northeast China, the annual average PM2.5 concentration despite showing a relatively large increase rate is far lower than that in the Huang-Huai-Hai region, and a high hydrothermal coordination degree induces an inconspicuous inhibition effect of PM2.5 on the annual maximum temperature.Besides, the total energy consumption is positively correlated with PM2.5 concentration. Figures and Tables | References | Related Articles | Metrics

Select

Analysis of variation characteristics of atmospheric self-purification capability in the main urban area of Zhengzhou from 1961 to 2020 Mei LIU,Xing-jie JI,Li TIAN,Ya-lei DING,Xuan ZUO 2022, 38 (3):  93-100.  doi: 10.3969/j.issn.1673-503X.2022.03.011 Abstract ( 118 )   HTML ( 0 )   PDF (1187KB) ( 48 )   Save Based on the meteorological observation data from 1961 to 2020 and the air quality monitoring data from 2014 to 2018 in the main urban area of Zhengzhou, the long-term trend and influencing factors of atmospheric self-purification capacity(ASPC) index in this area were analyzed, and the relationship between the ASPC and PM2.5 was studied.The results show that from 1981 to 2010, the ASPC index has an average value of 4.42 t·(d·km2)-1, the largest value of 5.2 t·(d·km2)-1 in spring, and the smallest value of 3.88 t·(d·km2)-1 in autumn, which is disadvantage to the removal of air pollutants.From 1961 to 2020, the ASPC in the study region shows a significant weakening trend with a maximum value of 6.85 t·(d·km2)-1 in 1969 and a minimum value of 3.06 t·(d·km2)-1 in 2020.The mixing layer thickness is positively correlated with the ASPC index.The number of days with daily mean wind speed ≥2.5 m·s-1 and light wind days are significantly positively and negatively correlated with the ASPC, respectively.Furthermore, the ASPC index is significantly correlated with the number of precipitation days.Specifically, the increase in the number of heavy precipitation days after 2015 has a certain influence on the enhancement of ASPC in the same period.In addition, the study also shows that there was a significantly negative correlation between ASPC and PM2.5 concentration in the main urban area, indicating that the stronger ASPC is, the lower the corresponding PM2.5 concentration is, and the better the ambient air quality is. Figures and Tables | References | Related Articles | Metrics

Select

Research on vertical observation and correction method of environmental and meteorological elements in ABL using rotorcraft UAV Jia-ping XU,Tian-liang ZHAO,Yan CHEN,Yong-qing BAI,Xiao-yun SUN,Song WANG,Chang CAO 2022, 38 (3):  101-111.  doi: 10.3969/j.issn.1673-503X.2022.03.012 Abstract ( 183 )   HTML ( 7 )   PDF (1716KB) ( 357 )   Save The observation of the atmospheric boundary layer (ABL) using rotorcraft Unmanned Aerial Vehicle (UAV) can provide a new approach with high temporal and spatial analysis ability for studying the vertical structure of meteorological elements and atmospheric pollutants, which is also helpful for the in-depth understanding of the physical and chemical mechanism of lower-layer atmosphere.This article systematically summarized the rotorcraft UAV-based ABL observational experiments and their advantages.The impact of rotorcraft UAV on meteorological and environmental observation and its suitable boarding scheme were illustrated by placing sensors at different positions of self-developed ABL UAV observation platform and conducting comparative observation experiments among rotorcraft UAV, air sounding balloons, and high observation tower.The experiment of vertical observation in ABL from 0-1000 m under a heavy pollution condition was carried out in Hubei province and suitable correction schemes for vertical observation of meteorological elements and pollutants in ABL combing with UAV's attitude data were also developed.The results show that a set of high-quality atmospheric profile data with a vertical resolution of 2 m to 10 m is acquired based on the above-mentioned experiments, which can finely capture the vertical change characteristics of some elements such as the heights of ABL and its temperature inversion layer as well as pollutants concentration.This research aims to provide an available observation method with feasible technical solutions and robust data for the scientific application of observation using rotorcraft UAV. Figures and Tables | References | Related Articles | Metrics

Select

Low visibility classification based on CART decision tree in Hebei province Qi YOU,Xiao-li QU,Zeng-bao ZHAO,Jie WANG,Di ZHANG,Lin-han YANG 2022, 38 (3):  112-118.  doi: 10.3969/j.issn.1673-503X.2022.03.013 Abstract ( 128 )   HTML ( 7 )   PDF (1766KB) ( 33 )   Save Based on the hourly observation data of 142 national weather stations in Hebei province from 2016 to 2019, a visibility forecast model was constructed for low visibility and high-frequency areas using Empirical Orthogonal Function and CART decision tree classification and regression methods, and a fitting test was carried out.The results show that except in Zhangjiakou, Chengde, and Qinhuangdao, fog days most appear in the areas south of 40°N, with the average peak of annual fog days more than 50 days.The relative humidity, surface temperature, wind speed, and other meteorological factors are significantly correlated with visibility.High correlation factors act as input variables to the forecast model, which is proved to have a good effect on the winter forecast with high accuracies.In summer, the false alarm rates are lower and the differences between day and night are less obvious, with little differences between the three indexes.Whereas in winter, the accuracy rates and false alarm rates are significantly superior to those in the daytime, and the missing alarm rates are slightly higher.The fitting results of three heavy fog processes on December 7-10, 2019, at Shijiazhuang station are good without any fogy time missed. Figures and Tables | References | Related Articles | Metrics

Select

Predictive temperature deviation correction in winter half year based on multimodal integration Duo QI,Song-tao LIU,Guang-na ZHAO,Meng-zhu GAO 2022, 38 (3):  119-126.  doi: 10.3969/j.issn.1673-503X.2022.03.014 Abstract ( 129 )   HTML ( 0 )   PDF (3424KB) ( 38 )   Save The corrections using Kalman filter decreases average method can effectively improve the prediction accuracies of modal predictive temperature, however, they can also cause significant negative corrections which make the results inferior to the original model outputs.Based on the bias removed ensemble mean (BREM), October of 2019 to April of 2020 in the optimal sliding training period is chosen to make integration predictions using the results of ECMWF (EC), corrections by Kalman filter decreases average method (EC_COR), and the data of national meteorological center forecast (SCMOC), respectively.The corrected results of BREM on EC_COR predictions are evaluated as well.It is shown that the accuracies in various predictions all appear worse in winter and at night, with a systematic higher temperature deviation from November to the next January.BREM can effectively prevent the negative corrections of EC_COR on EC with better effects than those of any other single method before integration, significantly improving the predictions.In addition, the integration of high-quality predictive productions, which is not limited to the model output predictions or forecast corrections, can obtain better results than a single forecast. Figures and Tables | References | Related Articles | Metrics

Select

Analysis of actinic flux and its influence factors in Yinchuan based on TUV model Xiao-yu YAN,Yuan-yuan YANG,Xiao-hui GOU,Jian-jun LIU,Zhan-sheng SU,Bao-guo WU,Xiao-li GONG 2022, 38 (3):  127-136.  doi: 10.3969/j.issn.1673-503X.2022.03.015 Abstract ( 78 )   HTML ( 0 )   PDF (1248KB) ( 13 )   Save Based on the TUV (tropospheric ultraviolet-visible radiation) model, the variation characteristics of actinic flux in Yinchuan were calculated and analyzed, and the influence of cloud, aerosol, column concentration of ozone, and NO2 on actinic flux was further discussed.The results show that the monthly average actinic flux of Yinchuan from July to September of 2019 was 6.5E+16 quanta·cm-2·s-1, 5.6E+16 quanta·cm-2·s-1, and 4.7E+16 quanta·cm-2·s-1, respectively, with daily maximum appearing at 13:00.The actinic flux rises slowly with the increase of wavelength when the wavelength is less than 325 nm, and it rises rapidly when the wavelength is between 325 nm and 480 nm, whereas it changes slightly with the increase of wavelength when the wavelength is above 480 nm.The variations appear more significantly around noon than in the morning and evening.The attenuation effects of cloud optical thickness and aerosol optical depth on actinic flux have obvious "U"-shaped diurnal characteristics.Comparatively speaking, the "U"-shaped waveform of the attenuation effect of aerosol optical thickness on actinic flux is wider than that of aerosol optical thickness.The decay rate of actinic flux is more sensitive to the changes in lower cloud optical thickness.The variability of actinic flux decreasing with the increase of aerosol optical depth is smaller than that with the increase of cloud optical thickness.Actinic flux is more sensitive to the change of strong scattering aerosol with single scattering albedo greater than 0.6, and the larger the aerosol optical thickness is, the more obvious this characteristic is.The influence of wavelength exponent on actinic flux is relatively small. Figures and Tables | References | Related Articles | Metrics

Select

Distributions of lightning current amplitude and cumulative probability in the Tianjin area Nan-nan SONG,Yong LIU,Xia LI,Hua-ning LI,Meng LI,Feng YIN 2022, 38 (3):  137-143.  doi: 10.3969/j.issn.1673-503X.2022.03.016 Abstract ( 144 )   HTML ( 4 )   PDF (1017KB) ( 317 )   Save To reveal the characteristics of lightning current amplitude in Tianjin, ADTD lightning location data from 2008 to 2018 were used to study the characteristics of temporal variations and cumulative probabilities of lightning current amplitudes.The results show that the lightning flashes add up to 106 474 over Tianjin during the 11 years, with the ratio of negative flashes of 89.26%, much higher than that of positive flashes.The amplitudes of lightning current are mainly concentrated in 2-100 kA, accounting for 97.76% of the total number of lightning.There are fewer lightning times in the range of 160-200 kA, and the average positive flash current intensity is significantly greater than the negative flash current intensity.Lightning current intensity appears significant seasonal characteristics.The positive lightning current intensity has a bimodal distribution, whereas the negative lightning current intensity is relatively uniform.The positive lightning current appears more frequently in spring, followed by fall.The negative flashing appears frequently in summer whereas flashing is less active in winter which most appears as positive flashing.When the lightning current is higher than 25 kA, the cumulative probability of positive flash current amplitude is significantly higher than that of a negative one, and when the lightning current is lower than 25 kA, the cumulative probability of negative flash current amplitude is higher than that of a positive one.The cumulative probability distribution of the negative flash current amplitude is closer to the total, with significant differences from the cumulative probability distribution of the positive flash current amplitude.The cumulative probability distribution of the total lightning current is mainly affected by the negative flash.Through comparison, it is found that the cumulative probability distribution function recommended by the IEEE working group (Institute of Electrical and Electronics Engineers) can objectively reflect the probability distribution characteristics of lightning current amplitude in Tianjin, especially when the lightning current amplitude is in the range of 25-55 kA, and the cumulative probability is the same as the recommended formula.The cumulative probability formula of lightning current amplitude in the Tianjin area is tried to be used in the lightning disaster risk assessment, which can provide an effective reference for accurately determining the value of the lightning disaster risk assessment parameter (PB) and accurately calculating the loss risk of lightning strikes. Figures and Tables | References | Related Articles | Metrics

Select

Analysis of characteristics of ground flash in Chongqing based on ADTD lightning location data Zhao-huan REN,Wei-ping LI,Yu ZENG,Jing HE,Bin-quan QIN,Wei XU 2022, 38 (3):  144-149.  doi: 10.3969/j.issn.1673-503X.2022.03.017 Abstract ( 182 )   HTML ( 3 )   PDF (1108KB) ( 172 )   Save To master the law of lightning activity in Chongqing, the ADTD lightning location data from 2008 to 2019 were analyzed in detail by using the mathematical statistics method and ArcGIS software.The temporal and spatial distribution characteristics of lightning frequency in Chongqing, the distribution characteristics of lightning current amplitude and steepness, and the cumulative probability distribution function were obtained.The results showed that the average annual occurrence of ground lightning in Chongqing is 208000 times, of which negative ground lightning accounts for 95.7%.The inter-annual variation of ground lightning frequency is large, with a maximum of 3.04×105 times per year and a minimum of 1.27×105 times per year.The monthly distribution is unimodal, and the high incidence period of lightning is from July to August, accounting for 57.9% of the whole year.The diurnal variation is bimodal, the negative lightning reaches the peak at 03:00 and 17:00.The peak time of positive lightning appears 1-2 hours later than that of negative lightning, and the peak value in the afternoon is much smaller than that at night.The spatial distribution of lightning density is closely related to topography, and the high-value area is mainly located at the intersection of mountains and the transition zone from the plateau hills to mountains.From the north of Jiangjin to the central urban area of Chongqing, the south of Kaizhou to the north of Wanzhou, the south of Zhongxian to the west of Shizhu, the south of Yongchuan, and from Rongchang to the west of Dazu are the areas with high ground flash density.The density is generally greater than 3 times·km-2·a-1, and locally greater than 6 times·km-2·a-1.The average lightning current amplitude of total lightning is 37.9 kA, of which the part of 10-50 kA accounts for 80.1%, and the probability peak value appears at 28 kA.The average steepness of total lightning is 10.1 kA·μs-1, of which 5-20 kA·μs-1 accounts for 92%, and the probability peak value appears at 8 kA·μs-1.The cumulative probability distribution function of the total flash amplitude and steepness was obtained by regression fitting with the least square method.The observed value and fitted value were basically consistent, and the fitting effect was good. Figures and Tables | References | Related Articles | Metrics

Select

Study on temperature prediction in Harbin based on slow feature analysis method De-jun LOU,Xin-nong PAN,Ji WANG,Xue-mei ZHANG,Zhen-duo GAO 2022, 38 (3):  150-155.  doi: 10.3969/j.issn.1673-503X.2022.03.018 Abstract ( 97 )   HTML ( 2 )   PDF (829KB) ( 55 )   Save Slow feature analysis (SFA) is an effective method to extract slowly varying information from known non-stationary time series.In this paper, the ability of the SFA method to extract slow feature information was first tested by using the Logistic non-stationary time series model, and then the slow feature signals extraction and prediction of monthly temperature anomalies series were carried out at Harbin station as a representative station in Heilongjiang province.The results showed that the SFA method can effectively extract the slow feature signals from the temperature anomalies series in Harbin.The extracted slow feature signals can reflect the trend, extreme value, and other information of the original temperature series.Fitting and prediction experiments show that the temperature prediction model after the introduction of SFA signals can improve the prediction ability, compared with the stationary model.The same conclusion is obtained for the independent sample predictions for the latest 48 months. Figures and Tables | References | Related Articles | Metrics

Bulletins

Select

Analysis of prediction and assessment of climate change and its impact on runoff in the Liaohe river basin Feng-hua SUN,Ming-yan LIU,Qing-fei ZHAI 2022, 38 (3):  156-161.  doi: 10.3969/j.issn.1673-503X.2022.03.019 Abstract ( 211 )   HTML ( 6 )   PDF (730KB) ( 173 )   Save The Liaohe river basin is a region with significant climate warming, and the warming amplitude is higher than that over the whole world and China.At the same time, it is also an area with relatively scarce water resources and large demand, so the impact of climate change on water resources is more worthy of attention.Based on long-term historical observational meteorological and hydrological data and climate change forecast data under different scenarios, the relationship between climate change and runoff was established, and the possible impact of future climate change on runoff was estimated, providing the scientific basis for the decision-making of coping with climate change in Liaohe river basin.The results showed that air temperature has a continuous upward trend, and precipitation has no obvious trend of increase or decrease, but there are periodic changes from 1961 to 2020.There is a good correlation between precipitation and runoff in Liaohe river basin, and with relatively consistent long-term trends and characteristics, the correlation between annual precipitation and runoff can reach more than 0.6.The correlation analysis between daily precipitation and runoff shows that the correlation coefficient between the two can be as high as 0.85 on the next day after the occurrence of precipitation and the heavy rain grade (i.e.daily precipitation ≥25 mm).The results of the sensitivity test and model simulation test show that runoff has an obvious response to climate change, and the increase (decrease) of runoff is most obvious when precipitation increases (decreases) and temperature decreases (increases).Under the RCP8.5 emission scenario, the temperature increase trend is the most obvious, and the future runoff also has a significant increasing trend.Under the RCP2.6 emission scenario, the temperature increase is the smallest, and the future runoff also shows no obvious increase or decrease trend.Under the RCP4.5 scenario, the temperature increase is in the middle, and the future runoff is in a decreasing trend. Figures and Tables | References | Related Articles | Metrics

Select

Evaluation of Tibet national meteorological parks based on AHP-fuzzy method Cuo-mu SILANG,Ya-jun XIONG,Zhuo-ga LUOSANG,Sang-deng LUOSONG,Jiang-cun BIANBA,Ke-zhu DANZENG 2022, 38 (3):  162-168.  doi: 10.3969/j.issn.1673-503X.2022.03.020 Abstract ( 99 )   HTML ( 1 )   PDF (699KB) ( 24 )   Save In this study, based on the national meteorological park evaluation index system issued by China Meteorological Administration, the hierarchical analysis method(AHP) was used to construct a meteorological park evaluation system applicable to the plateau under full consideration of the cultural characteristics of the plateau.The results showed that in the criterion layer, weather landscape>human meteorological landscape>environmental protection>scientific, the weight values are 45.94%, 32.48%, 14.91%, and 6.67% respectively.In the factor layer, rarity>human value>climate characteristics>scientificity, the weight values are 25.80%, 17.20%, 9.70% and 5.00% respectively.On this basis, the fuzzy comprehensive evaluation analysis of Namco, Yamzho Yumco and Mansarovar show that the comprehensive evaluation of all factors in Namco is excellent, that in Yamzho Yumco is good, and that in Mansarovar is also good.Therefore, based on limited economic conditions, it is considered that it is the best choice to have Namco developed into a national meteorological park.The results of this study can provide decision-making reference for environmental planning and other related departments and industries. Figures and Tables | References | Related Articles | Metrics