Volume 44,Issue 1,2016 Table of Contents
2016, 44(1):1-6.
Abstract:
Based on mathematical morphology of digital image processing technology, an automatic recognition algorithm of gust fronts is devised. Based on the narrowband shape, velocity convergence, and moving rapidly of gust front, three parameters (difference between reflectivity factors of two adjacent times, velocity shear, and velocity gradient) can be gained. Taking into account of the three parameters, a 2D characteristic quantity field can be obtained. Applying binaryzation, dilation, corrosion, thinning, cutting, and conjunction, a curve corresponds to the skeleton of a gust front is shown as results. To evaluate the algorithm, the dataset of gust fronts (53 volumes) are applied. The results show that the algorithm recognized 39 cases correctly, and meanwhile, 3 cases are recognized falsely, and 11 are missing recognition.
Based on mathematical morphology of digital image processing technology, an automatic recognition algorithm of gust fronts is devised. Based on the narrowband shape, velocity convergence, and moving rapidly of gust front, three parameters (difference between reflectivity factors of two adjacent times, velocity shear, and velocity gradient) can be gained. Taking into account of the three parameters, a 2D characteristic quantity field can be obtained. Applying binaryzation, dilation, corrosion, thinning, cutting, and conjunction, a curve corresponds to the skeleton of a gust front is shown as results. To evaluate the algorithm, the dataset of gust fronts (53 volumes) are applied. The results show that the algorithm recognized 39 cases correctly, and meanwhile, 3 cases are recognized falsely, and 11 are missing recognition.
2016, 44(1):7-13.
Abstract:
Considering the quality of CINRDA/SA weather radar base data, the calibration techniques are studied. Based on the principles of echo intensity calibration, the test methods, procedures and technical requirements are discussed in detail, and the unified calibration methods and operating flows are also formulated for CINRDA/SA, which eliminates human or test errors of radar echo intensity calibration to maximum extent. On account of the uncertainty of radar parameters measured in factory, in Jiangsu Province, the actual length of waveguide and loss in transmission lines are exactly measured. A specialtest waveguide is developed to measure the loss of transmission and reception lines in radar stations. All the correction of loss measured above is applied to echo intensity calibration for CINRDA/SA. The sun considered as a microwave signal source can test the echo intensity of reception lines, which is conducted by combining solar flux density with solar power received by radar. The comparative analysis of radar echo intensity between two or more weather radars provides a reference for radar network systems.
Considering the quality of CINRDA/SA weather radar base data, the calibration techniques are studied. Based on the principles of echo intensity calibration, the test methods, procedures and technical requirements are discussed in detail, and the unified calibration methods and operating flows are also formulated for CINRDA/SA, which eliminates human or test errors of radar echo intensity calibration to maximum extent. On account of the uncertainty of radar parameters measured in factory, in Jiangsu Province, the actual length of waveguide and loss in transmission lines are exactly measured. A specialtest waveguide is developed to measure the loss of transmission and reception lines in radar stations. All the correction of loss measured above is applied to echo intensity calibration for CINRDA/SA. The sun considered as a microwave signal source can test the echo intensity of reception lines, which is conducted by combining solar flux density with solar power received by radar. The comparative analysis of radar echo intensity between two or more weather radars provides a reference for radar network systems.
2016, 44(1):14-18.
Abstract:
Ultrasonic anemometers are suitable to a variety of industries for wind measurement demand because of small start wind speed, nomoving parts, not disturbing the wind field, and high accuracy. However, ultrasound test procedures related to wind measurements have not formalized in China. Selecting the speed test points drawing on the wind cup test procedures, tests are conducted at each point at different angles in the HDF720 lowspeed wind tunnel loop. The test results indicate that ultrasonic wind sensors can be installed in a large wind tunnel for testing, at the same wind speed, the measurement results are slightly different at different angles due to the shadow effect of wind instrument sensors. Moreover, for different wind speeds, the differences are different. Combined with the above test analysis, the measurements must be corrected according to the ultrasonic sensor installation angles when using ultrasonic anemometer to measure wind speed in real time.
Ultrasonic anemometers are suitable to a variety of industries for wind measurement demand because of small start wind speed, nomoving parts, not disturbing the wind field, and high accuracy. However, ultrasound test procedures related to wind measurements have not formalized in China. Selecting the speed test points drawing on the wind cup test procedures, tests are conducted at each point at different angles in the HDF720 lowspeed wind tunnel loop. The test results indicate that ultrasonic wind sensors can be installed in a large wind tunnel for testing, at the same wind speed, the measurement results are slightly different at different angles due to the shadow effect of wind instrument sensors. Moreover, for different wind speeds, the differences are different. Combined with the above test analysis, the measurements must be corrected according to the ultrasonic sensor installation angles when using ultrasonic anemometer to measure wind speed in real time.
2016, 44(1):19-22.
Abstract:
To study characteristics of calibration on meteorological temperature sensors, a statistical analysis is made of the calibration data of meteorological temperature sensors from 2010 to 2013 The results show that the overproof rates of both ZQZTW1 temperature and WZP1 temperature sensors are less than 10% and the values are almost the same in four years; among the unqualified sensors, the overproof rates at -30 ℃ and 50 ℃ are significantly higher than those at the other calibration temperature points； at such calibration temperature points as -10 ℃,0 ℃, and 10 ℃, the possibilities that calibration errors of temperature sensors are out of tolerance have the highest consistence and are highly correlated. The results of analysis have certain guiding significance to the selection of the calibration temperature range and temperature points of temperature sensors, as well as warehouse supply.
To study characteristics of calibration on meteorological temperature sensors, a statistical analysis is made of the calibration data of meteorological temperature sensors from 2010 to 2013 The results show that the overproof rates of both ZQZTW1 temperature and WZP1 temperature sensors are less than 10% and the values are almost the same in four years; among the unqualified sensors, the overproof rates at -30 ℃ and 50 ℃ are significantly higher than those at the other calibration temperature points； at such calibration temperature points as -10 ℃,0 ℃, and 10 ℃, the possibilities that calibration errors of temperature sensors are out of tolerance have the highest consistence and are highly correlated. The results of analysis have certain guiding significance to the selection of the calibration temperature range and temperature points of temperature sensors, as well as warehouse supply.
2016, 44(1):23-30.
Abstract:
In order to reduce the uncertainty of homogeneity test results and improve the credibility of homogeneity test conclusion, the possible causes of inhomogeneous temperature time series are discussed based on reliable evidences. The monthly average temperature series of 77 stations in Shaanxi are tested by using TwoPhase Regression (TPR), Penalized Maximal 〖WTBX〗F〖WTBZ〗 test (PMFT), Penalized Maximal t test (PMT). The test results are judged based on the detailed station metadata and satellite remote sensing image data, and the causal analysis of the influence on the homogeneity temperature series is discussed. The results show that station metadata can support 78% of the detected inhomogeneous breakpoints using two methods. In addition to 66.7% of inhomogeneity caused by station migration, the replacement of equipment and calculation method change for daily average temperature are the other reasons, accounting for 22.2% and 11.1%, respectively, in the 78% of the inhomogeneous breakpoints supported by station metadata. Using the land use/cover change (LUCC) distribution image data of the phase at the different time and different buffers obtained by remote sensing (high resolution Landsat images) combined with GIS technology, the panorama view and composite diagram of the observation field, a comprehensive analysis is made of the inhomogeneous breakpoints occurred in 1993 and the 8month average temperature at Tongguan influenced by small environment changes around the station. Finally, due to the satellite remote sensing images can fill the limitations in the aspect of station observation environmental assessment of traditional station metadata. It is suggested that satellite remote sensing images can be the supplement of stations metadata to provide a more intuitive and objective evidences for station observation environmental assessment.
In order to reduce the uncertainty of homogeneity test results and improve the credibility of homogeneity test conclusion, the possible causes of inhomogeneous temperature time series are discussed based on reliable evidences. The monthly average temperature series of 77 stations in Shaanxi are tested by using TwoPhase Regression (TPR), Penalized Maximal 〖WTBX〗F〖WTBZ〗 test (PMFT), Penalized Maximal t test (PMT). The test results are judged based on the detailed station metadata and satellite remote sensing image data, and the causal analysis of the influence on the homogeneity temperature series is discussed. The results show that station metadata can support 78% of the detected inhomogeneous breakpoints using two methods. In addition to 66.7% of inhomogeneity caused by station migration, the replacement of equipment and calculation method change for daily average temperature are the other reasons, accounting for 22.2% and 11.1%, respectively, in the 78% of the inhomogeneous breakpoints supported by station metadata. Using the land use/cover change (LUCC) distribution image data of the phase at the different time and different buffers obtained by remote sensing (high resolution Landsat images) combined with GIS technology, the panorama view and composite diagram of the observation field, a comprehensive analysis is made of the inhomogeneous breakpoints occurred in 1993 and the 8month average temperature at Tongguan influenced by small environment changes around the station. Finally, due to the satellite remote sensing images can fill the limitations in the aspect of station observation environmental assessment of traditional station metadata. It is suggested that satellite remote sensing images can be the supplement of stations metadata to provide a more intuitive and objective evidences for station observation environmental assessment.
2016, 44(1):31-35.
Abstract:
Meteorological station movement often leads to inhomogeneity of climate series. In order to study the homogeneity test and homogenization methods of singlestation temperature series, improve the reliability of temperature data series at Huzhu meteorological station, the homogeneity test and correction are conducted before and after the Huzhu meteorological station movement based on the 〖WTBX〗t〖WTBZ〗test and SHNT methods. The results show that impact of the Huzhu meteorological station movement on the homogeneity of temperature data series is significant. The adjustment results based on different methods (i.e., linear regression, stepwise multiple linear regression, and parallel data of basic stations) are analyzed. The results show that the correction result of the stepwise multiple linear regression based on 15years parallel observation data in basic station is better. The correction is conducted on the temperature data series before moving on the basis of the stepwise multiple linear regression. The climate tendency rate is 031 ℃/10a after correction, and the inhomogeneity of temperature series can be eliminated.
Meteorological station movement often leads to inhomogeneity of climate series. In order to study the homogeneity test and homogenization methods of singlestation temperature series, improve the reliability of temperature data series at Huzhu meteorological station, the homogeneity test and correction are conducted before and after the Huzhu meteorological station movement based on the 〖WTBX〗t〖WTBZ〗test and SHNT methods. The results show that impact of the Huzhu meteorological station movement on the homogeneity of temperature data series is significant. The adjustment results based on different methods (i.e., linear regression, stepwise multiple linear regression, and parallel data of basic stations) are analyzed. The results show that the correction result of the stepwise multiple linear regression based on 15years parallel observation data in basic station is better. The correction is conducted on the temperature data series before moving on the basis of the stepwise multiple linear regression. The climate tendency rate is 031 ℃/10a after correction, and the inhomogeneity of temperature series can be eliminated.
2016, 44(1):36-40.
Abstract:
The automatic recognition of trough lines is essential in automatic synoptic maps analysis, while trough line analysis mainly depends on manual analysis presently. In order to extract trough lines rapidly and accurately with isoline data, a trough point extraction method based on the DouglasPeucker algorithm is proposed. The algorithm extracts curve characteristic points as trough points through DouglasPeucker algorithm, which retains the characters and topology of isolines mostly, then connects trough points to construct candidate curves with the related principles according to isoline topological structure, finally, remove ridge lines in the candidate curves. The results show that this algorithm can realize the automatic recognition of trough lines.
The automatic recognition of trough lines is essential in automatic synoptic maps analysis, while trough line analysis mainly depends on manual analysis presently. In order to extract trough lines rapidly and accurately with isoline data, a trough point extraction method based on the DouglasPeucker algorithm is proposed. The algorithm extracts curve characteristic points as trough points through DouglasPeucker algorithm, which retains the characters and topology of isolines mostly, then connects trough points to construct candidate curves with the related principles according to isoline topological structure, finally, remove ridge lines in the candidate curves. The results show that this algorithm can realize the automatic recognition of trough lines.
2016, 44(1):41-46.
Abstract:
Based on WebGIS, HTTP communication, and database technologies, the drawbacks of the existing weather warning system are studied. A unified communication protocol is designed, and a oneclick integrated management and releasing platform of weather warning information is developed. The platform enables WebGIS map display, weather data overlay, and the oneclick dissemination, publication and distribution of early warning information. The oneclick publishing technology opens a new approach to the enhancement of meteorological service and warning information publishing capabilities.
Based on WebGIS, HTTP communication, and database technologies, the drawbacks of the existing weather warning system are studied. A unified communication protocol is designed, and a oneclick integrated management and releasing platform of weather warning information is developed. The platform enables WebGIS map display, weather data overlay, and the oneclick dissemination, publication and distribution of early warning information. The oneclick publishing technology opens a new approach to the enhancement of meteorological service and warning information publishing capabilities.
2016, 44(1):47-54.
Abstract:
The economy and urbanization are prosperous in coastal areas, highly dependeod on the changes of weather and climate, and disasters induced by severe convective weather become more serious. This convective weather is closely associated with the sea breeze circulation. Therefore, the study of sea breeze thunderstorm receives increasing and extensive attention, and becomes the major object of meteorology and atmospheric science. The history of observation investigations and numerical studies of sea breeze thunderstorm over the past half century is overviewed; The current research status and important achievements are summarized, that focus on sea breeze thunderstorm structure and characteristics including the thermodynamic and dynamic conditions, the process of evolution and its trigger mechanism. The research directions are discussed and some issues and topics are addressed for future study.
The economy and urbanization are prosperous in coastal areas, highly dependeod on the changes of weather and climate, and disasters induced by severe convective weather become more serious. This convective weather is closely associated with the sea breeze circulation. Therefore, the study of sea breeze thunderstorm receives increasing and extensive attention, and becomes the major object of meteorology and atmospheric science. The history of observation investigations and numerical studies of sea breeze thunderstorm over the past half century is overviewed; The current research status and important achievements are summarized, that focus on sea breeze thunderstorm structure and characteristics including the thermodynamic and dynamic conditions, the process of evolution and its trigger mechanism. The research directions are discussed and some issues and topics are addressed for future study.
2016, 44(1):55-60.
Abstract:
Based on Japan, Germany, and T639 numerical model gridded forecast products of precipitation from May to September 2008 to 2010, using the method of inverse distance interpolation to downscale, the precipitation of each grid numerical model forecast fields is interpolated to four stations: Yanqing, Miyun, Fangshan, Beijing Meteorological Observatory, which are the representative stations of the northwest, northeast, southwest, southeast of Beijing. Precipitation weather in Beijing can be divided into four categories: westerly trough, Northeast vortex, Mongolia vortex, and other systems. The forecasting accuracy rating method is used to calculate weighting coefficients of numerical prediction models. Then the objective precipitation forecast model is set up. Using independent samples to test the model, the test results show that the objective integration precipitation forecast model is superior to the independent model, which has reference value for summer precipitation forecasting and numerical model application.
Based on Japan, Germany, and T639 numerical model gridded forecast products of precipitation from May to September 2008 to 2010, using the method of inverse distance interpolation to downscale, the precipitation of each grid numerical model forecast fields is interpolated to four stations: Yanqing, Miyun, Fangshan, Beijing Meteorological Observatory, which are the representative stations of the northwest, northeast, southwest, southeast of Beijing. Precipitation weather in Beijing can be divided into four categories: westerly trough, Northeast vortex, Mongolia vortex, and other systems. The forecasting accuracy rating method is used to calculate weighting coefficients of numerical prediction models. Then the objective precipitation forecast model is set up. Using independent samples to test the model, the test results show that the objective integration precipitation forecast model is superior to the independent model, which has reference value for summer precipitation forecasting and numerical model application.
2016, 44(1):61-66.
Abstract:
Using the data of rainfall in May from 11 counties in the northwestern Fujian from 1961 to 2014, conventional meteorological observation data, and NCEP 25×25° reanalysis data and so on, the atmospheric circulation characteristics and causes of extralarge May rainfall are analyzed. The results show that in the years of regionally and locally extralarge May rainfall, there were atmospheric circulation anomalies: 500 hPa highlevel Eurasia circulation from west to east shows a wave train distribution of “+-+”; the positive height anomaly zone to the north Okhotsk was stable, which played the role of blocking the eastward cold air; cold air along the northerly flow in the western side of the Ural before the ridge of positive height anomaly center moved southward continually; the negative height anomaly center in the Sayan area deepened, splitting eastwardmoving small troughs frequently at the bottom, which affected the northwestern Fujian; at 925 hPa, there was a stable shear line in the northern South China.The analysis results show the main cause include: at the 500 hPa East Asian trough shifted further east obviously, guiding cold air southward and meeting the southwest warm air on the northwest side of the strong subtropical high over northwestern Fujian; at the 925 hPa, there was a cyclonic convergence zone over the northwestern Fujian, and both north and south branch troughs were very active, moving eastward to affect the northwest Fujian.
Using the data of rainfall in May from 11 counties in the northwestern Fujian from 1961 to 2014, conventional meteorological observation data, and NCEP 25×25° reanalysis data and so on, the atmospheric circulation characteristics and causes of extralarge May rainfall are analyzed. The results show that in the years of regionally and locally extralarge May rainfall, there were atmospheric circulation anomalies: 500 hPa highlevel Eurasia circulation from west to east shows a wave train distribution of “+-+”; the positive height anomaly zone to the north Okhotsk was stable, which played the role of blocking the eastward cold air; cold air along the northerly flow in the western side of the Ural before the ridge of positive height anomaly center moved southward continually; the negative height anomaly center in the Sayan area deepened, splitting eastwardmoving small troughs frequently at the bottom, which affected the northwestern Fujian; at 925 hPa, there was a stable shear line in the northern South China.The analysis results show the main cause include: at the 500 hPa East Asian trough shifted further east obviously, guiding cold air southward and meeting the southwest warm air on the northwest side of the strong subtropical high over northwestern Fujian; at the 925 hPa, there was a cyclonic convergence zone over the northwestern Fujian, and both north and south branch troughs were very active, moving eastward to affect the northwest Fujian.
2016, 44(1):67-75.
Abstract:
Using the hourly meteorological data from Menyuan and Qilian weather stations from 2004 to 2013, the diurnal change characteristics of orographic clouds are analyzed. It is found that the daily changes of total and low cloud amount show a pattern of two peaks in summer clearly, and the daily change of stratocumulus is opposite to that of cumulonimbus, and the occurrence frequency of stratocumulus is the greatest in the morning. The occurrence frequency of stratocumulus is greater in Menyuan than in Qilian, but that of cumulonimbus is greater in Qilian than in Menyuan. The circulation of mountainvalley breeze in both stations shows same variation characteristics: maximum wind velocity in the afternoon and minimum in the early morning, but the wind speed is greater in Qilian than in Menyuan. The dominate time of valley breeze is longer than that of mountain breeze in Menyuan, and vice versa in Qilian. The occurrence time of cumulonimbus is closely related to the occurrence time of maximum mountain breeze or valley breeze, which indicates that the mountainvalley breeze is a key factor in the course of orographic cloud formation. Under the control of a weather system, cumulonimbus maintains much longer with more precipitation; however, under the control of orographic winds and thermal turbulence, it maintains shorter with less precipitation. The formation of stratocumulus is closely related to the circulation of mountainvalley breeze and diurnal change of the boundary layer, and can be distinguished as three types: transformed from altostratus, derived from cumulonimbus when its growth is limited, resulted from the local circulation of mountainvalley breeze.
Using the hourly meteorological data from Menyuan and Qilian weather stations from 2004 to 2013, the diurnal change characteristics of orographic clouds are analyzed. It is found that the daily changes of total and low cloud amount show a pattern of two peaks in summer clearly, and the daily change of stratocumulus is opposite to that of cumulonimbus, and the occurrence frequency of stratocumulus is the greatest in the morning. The occurrence frequency of stratocumulus is greater in Menyuan than in Qilian, but that of cumulonimbus is greater in Qilian than in Menyuan. The circulation of mountainvalley breeze in both stations shows same variation characteristics: maximum wind velocity in the afternoon and minimum in the early morning, but the wind speed is greater in Qilian than in Menyuan. The dominate time of valley breeze is longer than that of mountain breeze in Menyuan, and vice versa in Qilian. The occurrence time of cumulonimbus is closely related to the occurrence time of maximum mountain breeze or valley breeze, which indicates that the mountainvalley breeze is a key factor in the course of orographic cloud formation. Under the control of a weather system, cumulonimbus maintains much longer with more precipitation; however, under the control of orographic winds and thermal turbulence, it maintains shorter with less precipitation. The formation of stratocumulus is closely related to the circulation of mountainvalley breeze and diurnal change of the boundary layer, and can be distinguished as three types: transformed from altostratus, derived from cumulonimbus when its growth is limited, resulted from the local circulation of mountainvalley breeze.
2016, 44(1):76-86.
Abstract:
Based on the conventional observational, automatic meteorological observing station, and the NCEP 1°×1° reanalyzed data, two extreme snowstorms in Shandong on 28 February in 2010 (“2〖DK〗·28” for short) and 19 April in 2013 (“4〖DK〗·19”) are comparatively analyzed. The results show that: (1) Both snowstorms were caused by the 500 hPa upperlevel trough, lowlevel southwest jet, and shear line at 700 hPa. The differences are that the cold air came from northeast before the “228” snowstorm and forced the warm and wet air to climb, which played an active role, while there were northeast winds and a “cold pad” formed before the “4〖DK〗·19”snowstorm, and the warm air clam climbed along the pad, in which the cold air played a passive role. (2) There was an obvious energy frontal zone, inversion layer, and thick wet layer in both snowstorms. The vertical helicity has a distribution characteristic of positive at lower levels and negative at upper levels. The snowstorm area was located in the large water vapor flux area near the left side of the vapor flux divergence center. The difference lied in: comparing with the “4〖DK〗·19”snowstorm, the “2〖DK〗·28”snowstorm has a higher rising height of convergence, stronger ascending motion, and more profound and unstable stratification.
Based on the conventional observational, automatic meteorological observing station, and the NCEP 1°×1° reanalyzed data, two extreme snowstorms in Shandong on 28 February in 2010 (“2〖DK〗·28” for short) and 19 April in 2013 (“4〖DK〗·19”) are comparatively analyzed. The results show that: (1) Both snowstorms were caused by the 500 hPa upperlevel trough, lowlevel southwest jet, and shear line at 700 hPa. The differences are that the cold air came from northeast before the “228” snowstorm and forced the warm and wet air to climb, which played an active role, while there were northeast winds and a “cold pad” formed before the “4〖DK〗·19”snowstorm, and the warm air clam climbed along the pad, in which the cold air played a passive role. (2) There was an obvious energy frontal zone, inversion layer, and thick wet layer in both snowstorms. The vertical helicity has a distribution characteristic of positive at lower levels and negative at upper levels. The snowstorm area was located in the large water vapor flux area near the left side of the vapor flux divergence center. The difference lied in: comparing with the “4〖DK〗·19”snowstorm, the “2〖DK〗·28”snowstorm has a higher rising height of convergence, stronger ascending motion, and more profound and unstable stratification.
2016, 44(1):87-94.
Abstract:
In order to promote the levels of shortterm forecasting and nowcasting of severe convective weather, the extremes of WPR (Wind Profiler Radar) data observed ahead of the occurrence of severe convective rainfall during rainy season from 2008 to 2012 in Dali are analyzed on the basis of large sample of related data. The results show: The maximum detection height of WPR reached its maximum 0 to 1 hours ahead of the appearance of heavy rainfall. The intensity of severe convective rainfall was positively associated with the maximum detection height and its increased range. Meanwhile, the negative vertical speed increased to maximum and its corresponding height decreased to the lowest 1 hour prior to the beginning of strong rainfall. The greater the negative vertical speed, the bigger the intensity of heavy rainfall was. Furthermore, the peak value of the extreme SNR (Signal to Noise Ratio) appeared 1 hour ahead of the appearance of strong rainfall. The intensity of strong rainfall was positively correlated with the peak value. The mesoscale lowlevel jet appeared 3 to 4 hours ahead of the occurrence of strong rainfall.
In order to promote the levels of shortterm forecasting and nowcasting of severe convective weather, the extremes of WPR (Wind Profiler Radar) data observed ahead of the occurrence of severe convective rainfall during rainy season from 2008 to 2012 in Dali are analyzed on the basis of large sample of related data. The results show: The maximum detection height of WPR reached its maximum 0 to 1 hours ahead of the appearance of heavy rainfall. The intensity of severe convective rainfall was positively associated with the maximum detection height and its increased range. Meanwhile, the negative vertical speed increased to maximum and its corresponding height decreased to the lowest 1 hour prior to the beginning of strong rainfall. The greater the negative vertical speed, the bigger the intensity of heavy rainfall was. Furthermore, the peak value of the extreme SNR (Signal to Noise Ratio) appeared 1 hour ahead of the appearance of strong rainfall. The intensity of strong rainfall was positively correlated with the peak value. The mesoscale lowlevel jet appeared 3 to 4 hours ahead of the occurrence of strong rainfall.
2016, 44(1):95-103.
Abstract:
The characteristics of vertical distribution of aerosols are analyzed with the data observed by airborne instruments in three dust weather events in Beijing. The results show that the vertical distribution of dust particles is influenced by the thermal inversion layer. The spectral distribution is monotone decreasing; within the boundary layer, the diameters of particles for blowing sand, dust and sand storms are concentrated between 01 and 03 μm, while another peak of the size distribution for the blowing sand event is about 08 μm and 65 μm for the dust storm and 28 and 65 μm for the sand storm. The effective diameter of fine particles in the dust event is 4 to 10 times as big as particles from anthropogenic sources. During dust weather the whole particle spectrum width from the nearground layer decreased with height, with maximum at 3000 m, associated with air transportation. The particle distribution for the dust storm shows that in the surface layer, the number of concentration or spectral width in the particle spectrum of ＞50 μm was significantly higher than that of the dust storm and sandstorm, which was related the local high winds. The sandstorm alone reached the maximum spectrum width near the bottom of the clouds, which indicates that big particles were carried up to a certain height, associated with the upward movement of Mongolia cyclone structures.
The characteristics of vertical distribution of aerosols are analyzed with the data observed by airborne instruments in three dust weather events in Beijing. The results show that the vertical distribution of dust particles is influenced by the thermal inversion layer. The spectral distribution is monotone decreasing; within the boundary layer, the diameters of particles for blowing sand, dust and sand storms are concentrated between 01 and 03 μm, while another peak of the size distribution for the blowing sand event is about 08 μm and 65 μm for the dust storm and 28 and 65 μm for the sand storm. The effective diameter of fine particles in the dust event is 4 to 10 times as big as particles from anthropogenic sources. During dust weather the whole particle spectrum width from the nearground layer decreased with height, with maximum at 3000 m, associated with air transportation. The particle distribution for the dust storm shows that in the surface layer, the number of concentration or spectral width in the particle spectrum of ＞50 μm was significantly higher than that of the dust storm and sandstorm, which was related the local high winds. The sandstorm alone reached the maximum spectrum width near the bottom of the clouds, which indicates that big particles were carried up to a certain height, associated with the upward movement of Mongolia cyclone structures.
2016, 44(1):104-110.
Abstract:
The temporal and spatial distributions of road icing are analyzed on the basis of hourly meteorological data from automatic weather stations along the main road over Qinghai from 2004 to 2012, and the linear relationship between road icing and surface/air temperature, snow depth, and maximum temperature is discussed. The results show that road icing gradually reduced from southeast to northwest and mainly occurred from January to April. Analyses suggest that there exists a robust linear relationship between surface and air temperature, snow depth, and maximum ground temperature; therefore, surface temperature and snow depth can be predicted based on those linear models, which can be used for the warning of road icing. The impact of road icing on traffic safty, deponding on the duration of road icing, are divided into 4 grades: extremely severe, serious, relatively serious, and slightly icing.
The temporal and spatial distributions of road icing are analyzed on the basis of hourly meteorological data from automatic weather stations along the main road over Qinghai from 2004 to 2012, and the linear relationship between road icing and surface/air temperature, snow depth, and maximum temperature is discussed. The results show that road icing gradually reduced from southeast to northwest and mainly occurred from January to April. Analyses suggest that there exists a robust linear relationship between surface and air temperature, snow depth, and maximum ground temperature; therefore, surface temperature and snow depth can be predicted based on those linear models, which can be used for the warning of road icing. The impact of road icing on traffic safty, deponding on the duration of road icing, are divided into 4 grades: extremely severe, serious, relatively serious, and slightly icing.
2016, 44(1):111-117.
Abstract:
Using the fog data of expressway in Sichuan and meteorological data from 2006 to 2013, the characteristics of dense fogs which made the expressway in Sichuan close and the corresponding causes are analyzed. The main conclusions are as follows: dense fogs leading to road closure mainly occur from November to the following January, mostly starting in the period of 05:00 to 08:00 in the early morning, usually ending from 08:00 to 11:00 in the morning, with the duration of road closure basically being 0 to 9 hours. There is generally an evenly distributed pressure field while dense fog occurs, and the low levels are controlled by high pressure circulation. The upperlevel circulation conditions of dense fogs can be classified into two patterns: northwest flow and straight westerly flow. The meteorological conditions beneficial to the formation of dense fogs include significant radiation cooling at night, weak wind and high humidity from the ground to the near surface layer, and temperature inversion at the surface layer.
Using the fog data of expressway in Sichuan and meteorological data from 2006 to 2013, the characteristics of dense fogs which made the expressway in Sichuan close and the corresponding causes are analyzed. The main conclusions are as follows: dense fogs leading to road closure mainly occur from November to the following January, mostly starting in the period of 05:00 to 08:00 in the early morning, usually ending from 08:00 to 11:00 in the morning, with the duration of road closure basically being 0 to 9 hours. There is generally an evenly distributed pressure field while dense fog occurs, and the low levels are controlled by high pressure circulation. The upperlevel circulation conditions of dense fogs can be classified into two patterns: northwest flow and straight westerly flow. The meteorological conditions beneficial to the formation of dense fogs include significant radiation cooling at night, weak wind and high humidity from the ground to the near surface layer, and temperature inversion at the surface layer.
2016, 44(1):118-122.
Abstract:
According to the daily data of conventional surface observation from 1981 to 2010, the API and meteorological observation data of the same period in 2014 in Xingtai, using the method of the corrected Pasquill and the national standards, the atmospheric stability and the mixed layer thickness are calculated. The results show that in recent 30 years, atmospheric instable type shows growth trend and neutral type assumes drop tendency in Xingtai, with the change rates of 116% and -140% per 10 years, respectively. The diurnal variation of atmospheric stability under the influence of solar radiation is obvious, and the monthly change for neutral and stability types had the highest frequency. The wind is the important factor to determine the atmospheric thickness. The average thickness is 46009 m, and the monthly change shows a unimodal distribution. The daily variation of thickness has the characteristics: spring > winter > autumn > summer. The verification indicates that the mixed layer thickness and the occurrence frequency of various stability grades are the important factors affecting the air quality.
According to the daily data of conventional surface observation from 1981 to 2010, the API and meteorological observation data of the same period in 2014 in Xingtai, using the method of the corrected Pasquill and the national standards, the atmospheric stability and the mixed layer thickness are calculated. The results show that in recent 30 years, atmospheric instable type shows growth trend and neutral type assumes drop tendency in Xingtai, with the change rates of 116% and -140% per 10 years, respectively. The diurnal variation of atmospheric stability under the influence of solar radiation is obvious, and the monthly change for neutral and stability types had the highest frequency. The wind is the important factor to determine the atmospheric thickness. The average thickness is 46009 m, and the monthly change shows a unimodal distribution. The daily variation of thickness has the characteristics: spring > winter > autumn > summer. The verification indicates that the mixed layer thickness and the occurrence frequency of various stability grades are the important factors affecting the air quality.
19 Water Requirement Characteristics and Meteorological Impact Factors of Winter Wheat in Shijiazhuang
2016, 44(1):123-129.
Abstract:
Based on the meteorological data of 9 stations in Shijiazhuang, the water requirements of winter wheat at different growth stages from 1964 to 2012 are calculated by using the PenmanMonteith equation and crop coefficient equation, and the water requirements and the influence factors in each growth stage are analyzed by using the linear trend, variation coefficients, 5years moving average, Morlet wave, and Pearson coefficient methods. The results show that the water requirement trends at various stages generally declined obviously: decline more obviously at the stages of sowing to overwintering, heading to ripening, and the whole growth period from 1965 to 1987, rose obviously from 1988 to 2012 at the stage of returning green to elongation, and varied unnoticeably at the other growth stages and in the whole growth period. There was oscillation of over 4year period at various growth stages in 48 years; the spatial distribution of the water requirement increased from northeast to southwest, and the trend of water requirement decreased from north to south in the whole growth period and various growth stages. The correlation analysis indicates that sunshine is positively correlated to the water requirement of the winter wheat most obviously, and the humidity is negatively correlated with that most obviously at growth stages.
Based on the meteorological data of 9 stations in Shijiazhuang, the water requirements of winter wheat at different growth stages from 1964 to 2012 are calculated by using the PenmanMonteith equation and crop coefficient equation, and the water requirements and the influence factors in each growth stage are analyzed by using the linear trend, variation coefficients, 5years moving average, Morlet wave, and Pearson coefficient methods. The results show that the water requirement trends at various stages generally declined obviously: decline more obviously at the stages of sowing to overwintering, heading to ripening, and the whole growth period from 1965 to 1987, rose obviously from 1988 to 2012 at the stage of returning green to elongation, and varied unnoticeably at the other growth stages and in the whole growth period. There was oscillation of over 4year period at various growth stages in 48 years; the spatial distribution of the water requirement increased from northeast to southwest, and the trend of water requirement decreased from north to south in the whole growth period and various growth stages. The correlation analysis indicates that sunshine is positively correlated to the water requirement of the winter wheat most obviously, and the humidity is negatively correlated with that most obviously at growth stages.
2016, 44(1):130-135.
Abstract:
According to temperature and phenological data of the latest 2 years from different altitudes of the Guifeng mountain, Macheng of Hubei Province, in combination with the previous phenology, the accumulated temperature conditions at different heights and different times for different elements are studied. The result shows that the critical temperature for ancient azaleas bloom is ≥10 ℃ stably ; and the indicators (active accumulated temperature) for full bloom are devised. Further analysis indicates that the two factors are closely related with flowering dates. Taking the above two factors as predicting factors, for the period from the end of March to the end of April, once every 5 days,seven flowering forecast formulas with high accuracy are established. The accumulated temperature indicators can be used, combined with the regression equation, to make rolling and fine forecast of ancient azaleas flowering time.
According to temperature and phenological data of the latest 2 years from different altitudes of the Guifeng mountain, Macheng of Hubei Province, in combination with the previous phenology, the accumulated temperature conditions at different heights and different times for different elements are studied. The result shows that the critical temperature for ancient azaleas bloom is ≥10 ℃ stably ; and the indicators (active accumulated temperature) for full bloom are devised. Further analysis indicates that the two factors are closely related with flowering dates. Taking the above two factors as predicting factors, for the period from the end of March to the end of April, once every 5 days,seven flowering forecast formulas with high accuracy are established. The accumulated temperature indicators can be used, combined with the regression equation, to make rolling and fine forecast of ancient azaleas flowering time.
2016, 44(1):136-141.
Abstract:
In order to accurately diagnose the degradation degree of ZnO varistor, a new method，return voltage measurement， is presented. Samples of ZnO varistors were impacted by impulse currents, and various diagnostic techniques are employed to investigate the degradation degree of those samples. It is proved that the conclusions drawn from return voltage measurement are consistent with the traditional varistor voltage〖WTBX〗 〖WTBZ〗(〖WTBX〗U〖WTBZ〗1mA) and residual voltage method. Besides, two main parameters getting from the return voltage measurement appear to decrease sharply after the impacting process, which is also consistent with SEM experimental results: the average grain size decreases and the conductivity increases. The experimental results further prove the correctness of return voltage measurement, which has a certain reference value for improving the accuracy of ZnO varistor diagnosis.
In order to accurately diagnose the degradation degree of ZnO varistor, a new method，return voltage measurement， is presented. Samples of ZnO varistors were impacted by impulse currents, and various diagnostic techniques are employed to investigate the degradation degree of those samples. It is proved that the conclusions drawn from return voltage measurement are consistent with the traditional varistor voltage〖WTBX〗 〖WTBZ〗(〖WTBX〗U〖WTBZ〗1mA) and residual voltage method. Besides, two main parameters getting from the return voltage measurement appear to decrease sharply after the impacting process, which is also consistent with SEM experimental results: the average grain size decreases and the conductivity increases. The experimental results further prove the correctness of return voltage measurement, which has a certain reference value for improving the accuracy of ZnO varistor diagnosis.
2016, 44(1):142-147.
Abstract:
Based on the analysis of the development status of lightning risk assessment technology and the features of lightning risk assessment of large chemical factories and building groups, a girding lightning risk assessment model is established based on GIS technology, which contains height potential and its gradient, soil resistivity and its gradient, lightning density, lightning protection efficiency, electrical and electronic equipment lightning risk, lightning explosion risk, and population density factor. A chemical factory is taken as an example to show the application of the model.
Based on the analysis of the development status of lightning risk assessment technology and the features of lightning risk assessment of large chemical factories and building groups, a girding lightning risk assessment model is established based on GIS technology, which contains height potential and its gradient, soil resistivity and its gradient, lightning density, lightning protection efficiency, electrical and electronic equipment lightning risk, lightning explosion risk, and population density factor. A chemical factory is taken as an example to show the application of the model.
2016, 44(1):148-151.
Abstract:
Ensuring the separation distance of independent lightning protection device plays a significant role in lightning protection activities. In order to make the separation distance calculating suitable for the actual situation and improve the safety, based on the formation mechanisms of lightning counterattack, the separation distance formulas for defending the lightning counterattack damage of the first positive lightning, the first lightning after the first negative lightning, and the first negative lightning are derived, and then develops the common separation distance formula that can defend simultaneously the lightning counterattack damage of all these three typical lightning by solving the common solution of those formulas. Comparing with these formulas, it is found that there are problems in the related design standards of lightning protection for buildings. The analysis indicates that those formulas are more reasonable and safe.
Ensuring the separation distance of independent lightning protection device plays a significant role in lightning protection activities. In order to make the separation distance calculating suitable for the actual situation and improve the safety, based on the formation mechanisms of lightning counterattack, the separation distance formulas for defending the lightning counterattack damage of the first positive lightning, the first lightning after the first negative lightning, and the first negative lightning are derived, and then develops the common separation distance formula that can defend simultaneously the lightning counterattack damage of all these three typical lightning by solving the common solution of those formulas. Comparing with these formulas, it is found that there are problems in the related design standards of lightning protection for buildings. The analysis indicates that those formulas are more reasonable and safe.
2016, 44(1):152-156.
Abstract:
With the rapid development of the economy, the surrounding environment of artillery operation points has changed greatly, in order to further enhance the security of weather modification operations, a set of safety demonstration methods are proposed referring to the characteristics of artillery operation. The method for calculating the external trajectories of artillery for weather modification is derived. On this basis, a more accurate safety assessment method is given in combination with the safety shootingarea method and GIS, and an example is given to demonstrate the feasibility of the represented method. The danger coefficient method for weather modification safety assessment is proposed. The definition of danger coefficient is given, and an example of safety assessment is provided by the safety assessment system developed by the method, which proves the feasibility of the methods.
With the rapid development of the economy, the surrounding environment of artillery operation points has changed greatly, in order to further enhance the security of weather modification operations, a set of safety demonstration methods are proposed referring to the characteristics of artillery operation. The method for calculating the external trajectories of artillery for weather modification is derived. On this basis, a more accurate safety assessment method is given in combination with the safety shootingarea method and GIS, and an example is given to demonstrate the feasibility of the represented method. The danger coefficient method for weather modification safety assessment is proposed. The definition of danger coefficient is given, and an example of safety assessment is provided by the safety assessment system developed by the method, which proves the feasibility of the methods.
2016, 44(1):157-163.
Abstract:
The typhoon disasters have been a major obstacle to economic and social development in the coastal areas of China, and the study of typhoon disasters often focus on the influence of traditional disastercausing factors and the disaster breeding environment on disasters. Studies show that the vulnerability of the hazard bearing bodies in the society and economy has an important influence on typhoon disasters. Therefore, through the collection and processing of the economic and social data from 11 cities in Zhejiang Province, the vulnerability evaluation index for the hazard bearing bodies of typhoon disasters is established by using the statistics method, and the vulnerability degrees of various prefecturallevel cities in Zhejiang Province are compared and analyzed. The results shows that typhoon vulnerability degrees in Hangzhou and the Zhejiang coastal areas are higher, the middle level in the central Zhejiang, lower in Huzhou, Zhoushan, Quzhou, and Lishui. Comparative analysis shows that the evaluation results are reasonable, which can be used as the basis of the scientific and comprehensive assessment of typhoon disasters.
The typhoon disasters have been a major obstacle to economic and social development in the coastal areas of China, and the study of typhoon disasters often focus on the influence of traditional disastercausing factors and the disaster breeding environment on disasters. Studies show that the vulnerability of the hazard bearing bodies in the society and economy has an important influence on typhoon disasters. Therefore, through the collection and processing of the economic and social data from 11 cities in Zhejiang Province, the vulnerability evaluation index for the hazard bearing bodies of typhoon disasters is established by using the statistics method, and the vulnerability degrees of various prefecturallevel cities in Zhejiang Province are compared and analyzed. The results shows that typhoon vulnerability degrees in Hangzhou and the Zhejiang coastal areas are higher, the middle level in the central Zhejiang, lower in Huzhou, Zhoushan, Quzhou, and Lishui. Comparative analysis shows that the evaluation results are reasonable, which can be used as the basis of the scientific and comprehensive assessment of typhoon disasters.
2016, 44(1):164-166.
Abstract:
There occurred many faults in the antenna servo systems since CINRAD/SA put into operation. As the main part of the antenna servo system, the DC azimuth motor is also one of components with frequent faults. A continuous locking fault occurred in DC azimuth motor at Changle radar station in 2014, leading to radar shutdown and tachometer performance degradation, in which the instability of antenna rotational speed resulted in abnormal PUPC in the process of major weather guarantee. The causes of the problem are analyzed by using the test program RDASOT (radar data acquisition system operability), measuring the resistance of the DC azimuth motor, and the feedback voltage of the tachometer according to the controlling process of antenna signals. The results are useful for the maintenance and operation of radar DC motors.
There occurred many faults in the antenna servo systems since CINRAD/SA put into operation. As the main part of the antenna servo system, the DC azimuth motor is also one of components with frequent faults. A continuous locking fault occurred in DC azimuth motor at Changle radar station in 2014, leading to radar shutdown and tachometer performance degradation, in which the instability of antenna rotational speed resulted in abnormal PUPC in the process of major weather guarantee. The causes of the problem are analyzed by using the test program RDASOT (radar data acquisition system operability), measuring the resistance of the DC azimuth motor, and the feedback voltage of the tachometer according to the controlling process of antenna signals. The results are useful for the maintenance and operation of radar DC motors.
2016, 44(1):167-170.
Abstract:
A new monitoring system is proposed based on Baidu Maps JavaScript API for automatic weather stations. Though such techniques as region redrawing, icon customization, and elements switching, the Web page can display intuitively the status and the realtime data of automatic weather stations which provide great convenience to users. In order to improve the loading speed, the AJAX technology is used to access the remote SQL database, and the third API function is used to strengthen the display effect. This monitoring Web page has been applied successfully in the comprehensive atmospheric monitoring platform of the Guangdong Meteorological Observatory.
A new monitoring system is proposed based on Baidu Maps JavaScript API for automatic weather stations. Though such techniques as region redrawing, icon customization, and elements switching, the Web page can display intuitively the status and the realtime data of automatic weather stations which provide great convenience to users. In order to improve the loading speed, the AJAX technology is used to access the remote SQL database, and the third API function is used to strengthen the display effect. This monitoring Web page has been applied successfully in the comprehensive atmospheric monitoring platform of the Guangdong Meteorological Observatory.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.