ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 44,Issue 3,2018 Table of Contents
2018, 44(3):341-350.
DOI: 10.7519/j.issn.1000-0526.2018.03.001
Abstract:
In this paper, the development of weather forecast technology is reviewed. Owing to people’s creativity and wisdom, the atmospheric evolution processes can be solved by modern mathematical and physical methods of model equations instead of merely judgement based on experience in the past. However, the complicated weather and climate systems still pose challenges to nonlinear uncertainty problems. The artificial intelligence (AI) technologies may contribute to address the challenges. This paper introduces some initial assumptions and development of AI in observation and identification, data processing, shortterm and nowcast forecasting, model parameterization and integrated analysis of forecast products and so on, indicating the way forward of further research and development and their contribution.
In this paper, the development of weather forecast technology is reviewed. Owing to people’s creativity and wisdom, the atmospheric evolution processes can be solved by modern mathematical and physical methods of model equations instead of merely judgement based on experience in the past. However, the complicated weather and climate systems still pose challenges to nonlinear uncertainty problems. The artificial intelligence (AI) technologies may contribute to address the challenges. This paper introduces some initial assumptions and development of AI in observation and identification, data processing, shortterm and nowcast forecasting, model parameterization and integrated analysis of forecast products and so on, indicating the way forward of further research and development and their contribution.
2018, 44(3):351-360.
DOI: 10.7519/j.issn.1000-0526.2018.03.002
Abstract:
In this paper, both CMA and NCEP data are used to analyze the extremely severe rainfall in North China and Beijing which occurred during 19-21 July 2016 and brought the serious damage to people and society. The results are as follows. (1) At the end of the second ten days of July, the subtropical high moved eastwards and then maintained. The short wave trough was stopped and was almost stationary which was very favorable to the occurrence of the severe rainfall. (2) The coupling between the short wave trough in upper troposphere and the warm inverse trough at the surface caused rapid cyclogenesis. (3) The warm conveyor belt as the moisture passage transported very rich water vapor to North China and the obvious interaction between middle and lower latitude systems existed. (4) There were obvious multiscale characteristics in the 20 July 2016 heavy rain and the 21 July 2012 rainstorm, but they are different. The large scale forcing of the former was slight stronger, whereas the convection of the latter was more active. The mechanism and mesoscale systems of the rainstorm in 20 July 2016 need to be investigated in future.
In this paper, both CMA and NCEP data are used to analyze the extremely severe rainfall in North China and Beijing which occurred during 19-21 July 2016 and brought the serious damage to people and society. The results are as follows. (1) At the end of the second ten days of July, the subtropical high moved eastwards and then maintained. The short wave trough was stopped and was almost stationary which was very favorable to the occurrence of the severe rainfall. (2) The coupling between the short wave trough in upper troposphere and the warm inverse trough at the surface caused rapid cyclogenesis. (3) The warm conveyor belt as the moisture passage transported very rich water vapor to North China and the obvious interaction between middle and lower latitude systems existed. (4) There were obvious multiscale characteristics in the 20 July 2016 heavy rain and the 21 July 2012 rainstorm, but they are different. The large scale forcing of the former was slight stronger, whereas the convection of the latter was more active. The mechanism and mesoscale systems of the rainstorm in 20 July 2016 need to be investigated in future.
2018, 44(3):361-371.
DOI: 10.7519/j.issn.1000-0526.2018.03.003
Abstract:
Typhoons Vicente (1208) and Kalmaegi (1415) were successfully simulated by the mesoscale weather research and forecasting (WRF) model using the NCEP (National Centers for Environmental Prediction) final operational global analysis data with the resolution of 1°×1°. The results showed that the simulated track and intensity of the typhoons are in consistence with Japan Meteorological Agency (JMA) best track data. The simulated surface wind nearly coincides with the station observation. Sensitivity experiments were then carried out to test the impact of terrain and land surface characteristics in Hong Kong and Shenzhen on the wind in Shenzhen area. Based on the sensitivity tests, we found that the wind influence on the Midwest Shenzhen induced by typhoons landing in western Guangdong is weakened by the terr-ain of Hong Kong. Hong Kong plays a role of slowering winds and protecting the Midwest Shenzhen from typhoons moving westward. Furthermore, it is found that the wind intensity in Yantian international container terminal is enhanced by the channel effect of Wutong Mountain in Shenzhen.
Typhoons Vicente (1208) and Kalmaegi (1415) were successfully simulated by the mesoscale weather research and forecasting (WRF) model using the NCEP (National Centers for Environmental Prediction) final operational global analysis data with the resolution of 1°×1°. The results showed that the simulated track and intensity of the typhoons are in consistence with Japan Meteorological Agency (JMA) best track data. The simulated surface wind nearly coincides with the station observation. Sensitivity experiments were then carried out to test the impact of terrain and land surface characteristics in Hong Kong and Shenzhen on the wind in Shenzhen area. Based on the sensitivity tests, we found that the wind influence on the Midwest Shenzhen induced by typhoons landing in western Guangdong is weakened by the terr-ain of Hong Kong. Hong Kong plays a role of slowering winds and protecting the Midwest Shenzhen from typhoons moving westward. Furthermore, it is found that the wind intensity in Yantian international container terminal is enhanced by the channel effect of Wutong Mountain in Shenzhen.
2018, 44(3):372-381.
DOI: 10.7519/j.issn.1000-0526.2018.03.004
Abstract:
By using the daily reanalysis data of National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP) and daily precipitation data at 20:00 BT from Chinese meteorological stations during 1950-2015, and based on the methods of Morlet wavelet analysis and wave-packet propagation diagnosis (WPD), in this paper, we put emphasis on the research of high frequency baroclinic wave packets distribution and propagation climate characteristics of East Asian subtropical westerly jet (EASJ) in summer (June to August) and their corresponding relationships with the typical rainy season in eastern China. The results show that (1) after filtering out the monthly scale (30 days) cycle signals, highlighted 3-7 d high frequency narrowband signals of the EASJ are obvious in the 200 hPa zonal winds, covering the high frequency narrowband signals of 2-4 d and 5-7 d in South China in the rainy season, 5-7 d in Jianghuai Region in Meiyu season and 2-4 d and 6-8 d in the rainstorms in the northern China from late July to August, which reflects the step changes of summer narrowband signals and the relationship with the typical rainy season in eastern China. (2) The 3-7 d high-frequency baroclinic wave packets corresponding to the East Asian subtropical westerly jet are quasi-zonal distribution, which represents the strong disturbance area, i.e., the dynamic instability zone of the strong west wind shears. The low-value region of the wave packet corresponds to the high pressure in South Asia, which represents the weak perturbation region, i.e., the weak wind pressure stability zone. The distribution characteristics of wave packets during the Meiyu season shows that the two 5-7 d high-frequency baroclinic wave-band and high value zones in the mid latitude and high latitude have a good correspondence with the high energy values of the baroclinic energy dispersive waveguides and the critical areas influencing the precipitation of the Yangtze River and the Meiyu season. (3) The 3-7 d high-frequency baroclinic wave band, located at 40°-55°N, corresponding to the subtropical westerly jet, has the regularity of meridional displacement and intensity changes. Its meridional displacement shows that it falls on the south and rises on the north and then fluctuates, and its intensity gradually weakens and then strengthens. The latitudinal evolution of the zonal winds is divided into two stages, which are characterized by significant differences in the distribution of the wave packets. The first stage has two large wave areas, which are the Black Sea to the Caspian Sea region and the northeast of China to the island of Japan; and the second stage has three large wave areas, including the Black Sea to the Caspian Sea, the west side of the Balkhash Lake and the northeastern region of Japan, of which the disturbance of 3-7 d high frequency baroclinic wave on the west side of the Balkhash Lake has an important contribution to the precipitation in eastern China.
By using the daily reanalysis data of National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP) and daily precipitation data at 20:00 BT from Chinese meteorological stations during 1950-2015, and based on the methods of Morlet wavelet analysis and wave-packet propagation diagnosis (WPD), in this paper, we put emphasis on the research of high frequency baroclinic wave packets distribution and propagation climate characteristics of East Asian subtropical westerly jet (EASJ) in summer (June to August) and their corresponding relationships with the typical rainy season in eastern China. The results show that (1) after filtering out the monthly scale (30 days) cycle signals, highlighted 3-7 d high frequency narrowband signals of the EASJ are obvious in the 200 hPa zonal winds, covering the high frequency narrowband signals of 2-4 d and 5-7 d in South China in the rainy season, 5-7 d in Jianghuai Region in Meiyu season and 2-4 d and 6-8 d in the rainstorms in the northern China from late July to August, which reflects the step changes of summer narrowband signals and the relationship with the typical rainy season in eastern China. (2) The 3-7 d high-frequency baroclinic wave packets corresponding to the East Asian subtropical westerly jet are quasi-zonal distribution, which represents the strong disturbance area, i.e., the dynamic instability zone of the strong west wind shears. The low-value region of the wave packet corresponds to the high pressure in South Asia, which represents the weak perturbation region, i.e., the weak wind pressure stability zone. The distribution characteristics of wave packets during the Meiyu season shows that the two 5-7 d high-frequency baroclinic wave-band and high value zones in the mid latitude and high latitude have a good correspondence with the high energy values of the baroclinic energy dispersive waveguides and the critical areas influencing the precipitation of the Yangtze River and the Meiyu season. (3) The 3-7 d high-frequency baroclinic wave band, located at 40°-55°N, corresponding to the subtropical westerly jet, has the regularity of meridional displacement and intensity changes. Its meridional displacement shows that it falls on the south and rises on the north and then fluctuates, and its intensity gradually weakens and then strengthens. The latitudinal evolution of the zonal winds is divided into two stages, which are characterized by significant differences in the distribution of the wave packets. The first stage has two large wave areas, which are the Black Sea to the Caspian Sea region and the northeast of China to the island of Japan; and the second stage has three large wave areas, including the Black Sea to the Caspian Sea, the west side of the Balkhash Lake and the northeastern region of Japan, of which the disturbance of 3-7 d high frequency baroclinic wave on the west side of the Balkhash Lake has an important contribution to the precipitation in eastern China.
2018, 44(3):382-395.
DOI: 10.7519/j.issn.1000-0526.2018.03.005
Abstract:
Based on the daily mean total cloud amount and precipitation data from 549 meteorological stations in China and NCEP/DOE-2 monthly mean and daily reanalysis data for the period 1980-2015, this paper analyzes the distribution, spatio-temporal variation characteristics of total clouds in China as well as their correlations to north boundary belt of East Asian subtropical summer monsoon, the advance and retreat process over time, and interdecadal change characteristics of their locations. The study sugg-ests that, spring cloud cover in Northwest China is more than that in Northeast while the cloud in summer shows the opposite distribution. Monthly variation of the cloud cover in China is mainly characterized by the increase and decrease in the range and zonal movement of great values. The amount of total cloud cover in monsoon region is stable during the early advancing period of summer monsoon while 〖JP2〗a large interannual〖JP〗 variation of cloud cover appears in the later stage. The variation of cloud cover can be divided into three distribution patterns: same anomaly in whole area, opposite anomalies in the south and north and opposite anomalies in the middle and northern (southern) regions. Besides, the pentad meridional movement of great cloud cover area and the advance and retreat process of subtropical summer monsoon have a consist-ency in time and space. The locations of 50% and 65% monthly mean total cloud lines of July and August correspond respectively to the northern edge and southern edge of the north boundary belt, sharing a synchronous advancing and retreating paces and the interdecadal position variation characteristics. From 1980s to 1990s, the climate of the north boundary belt got drier, but has become wetter since early 21st century.
Based on the daily mean total cloud amount and precipitation data from 549 meteorological stations in China and NCEP/DOE-2 monthly mean and daily reanalysis data for the period 1980-2015, this paper analyzes the distribution, spatio-temporal variation characteristics of total clouds in China as well as their correlations to north boundary belt of East Asian subtropical summer monsoon, the advance and retreat process over time, and interdecadal change characteristics of their locations. The study sugg-ests that, spring cloud cover in Northwest China is more than that in Northeast while the cloud in summer shows the opposite distribution. Monthly variation of the cloud cover in China is mainly characterized by the increase and decrease in the range and zonal movement of great values. The amount of total cloud cover in monsoon region is stable during the early advancing period of summer monsoon while 〖JP2〗a large interannual〖JP〗 variation of cloud cover appears in the later stage. The variation of cloud cover can be divided into three distribution patterns: same anomaly in whole area, opposite anomalies in the south and north and opposite anomalies in the middle and northern (southern) regions. Besides, the pentad meridional movement of great cloud cover area and the advance and retreat process of subtropical summer monsoon have a consist-ency in time and space. The locations of 50% and 65% monthly mean total cloud lines of July and August correspond respectively to the northern edge and southern edge of the north boundary belt, sharing a synchronous advancing and retreating paces and the interdecadal position variation characteristics. From 1980s to 1990s, the climate of the north boundary belt got drier, but has become wetter since early 21st century.
2018, 44(3):396-407.
DOI: 10.7519/j.issn.1000-0526.2018.03.006
Abstract:
In this paper, the characteristics of atmospheric boundary layer for the afternoon graupel process on 29 August 2016 are analyzed by making full use of densified observation data of sounding balloon and reanalysis data from ECMWF’s ERAInterim 0.125°×0.125° and comparing to the typical sunny cases on 26 August 2016. The results show that the temperature zero line increases with time and the stratification of temperature lapse rate is remarkable. The inversion layer is not obvious and the boundary layer has more unstable convection stratifications. Potential temperature increases with height and it presents an increasing trend of 5 K·(2 h)-1 with time. Specific humidity decreases as height increases and the content of water vapor is greater than that in sunny days. Wind speed varies with height. The wind speed in the near surface layer is higher than that at the same altitude in sunny days and the top wind velocity of boundary layer is less than that of sunny boundary layer. The wind direction is always dominated by west wind and it does not fluctuate greatly with height. Cloud coverage before graupel is large and cloud thickness reached 4000 m, there are complex vertical motions. The surface layer is descending while clouds are ascending. There is obvious supercooled water in the boundary layer at 08:00 BT before graupel on 29 August in Nagqu, and the top of the boundary layer fluctuates enormously. The maximum height of 3780 m exists at 08:00 BT while the minimum height of 850 m exists at 10:00 BT. The potential temperature increases with time and the accumulated energy lasts for 6 h. The specific humidity is greater than that in sunny days. The wind speed in boundary layer is larger than that of the sunny days, varying little with altitude and the wind direction is always dominated by west wind. There is deep cloud system which provides moisture. The ascending motion in clouds and descending motion under the clouds are main dynamic mechanism to promote graupel.
In this paper, the characteristics of atmospheric boundary layer for the afternoon graupel process on 29 August 2016 are analyzed by making full use of densified observation data of sounding balloon and reanalysis data from ECMWF’s ERAInterim 0.125°×0.125° and comparing to the typical sunny cases on 26 August 2016. The results show that the temperature zero line increases with time and the stratification of temperature lapse rate is remarkable. The inversion layer is not obvious and the boundary layer has more unstable convection stratifications. Potential temperature increases with height and it presents an increasing trend of 5 K·(2 h)-1 with time. Specific humidity decreases as height increases and the content of water vapor is greater than that in sunny days. Wind speed varies with height. The wind speed in the near surface layer is higher than that at the same altitude in sunny days and the top wind velocity of boundary layer is less than that of sunny boundary layer. The wind direction is always dominated by west wind and it does not fluctuate greatly with height. Cloud coverage before graupel is large and cloud thickness reached 4000 m, there are complex vertical motions. The surface layer is descending while clouds are ascending. There is obvious supercooled water in the boundary layer at 08:00 BT before graupel on 29 August in Nagqu, and the top of the boundary layer fluctuates enormously. The maximum height of 3780 m exists at 08:00 BT while the minimum height of 850 m exists at 10:00 BT. The potential temperature increases with time and the accumulated energy lasts for 6 h. The specific humidity is greater than that in sunny days. The wind speed in boundary layer is larger than that of the sunny days, varying little with altitude and the wind direction is always dominated by west wind. There is deep cloud system which provides moisture. The ascending motion in clouds and descending motion under the clouds are main dynamic mechanism to promote graupel.
2018, 44(3):408-415.
DOI: 10.7519/j.issn.1000-0526.2018.03.007
Abstract:
Using the minutely data including visibility, relative humidity, temperature and wind speed of 36 automatic weather stations along the Yangtze River in Jiangsu Province during 2010-2013, the characteristics of river fogs are analyzed. The results show that river fog mainly occurs in June, November and January, formed from 19:00 BT to the next 07:00 BT, during which the fog is the thickest in 02:00-04:00 BT and gets to end from 06:00 BT to 12:00 BT, so the fog duration is 3-9 h. When fog occurs, relative humidity is 85% or higher, temperature is 5-19℃ in spring, 18-26℃ in summer, 7-23℃ in autumn and 0-11℃ in winter. As for the wind speed, it is below 5 m·s-1 in spring, summer, autumn, and about 6 m·s-1 in winter. Specifically, the fog tends to occur with the wind direction of NNE-E and wind speed 1-2 m·s-1 in spring, the wind direction of NNE-ESE and wind speed 0.3-1 m·s-1 in summer, the wind direction of NNE-NE and E-ESE, wind speed 0.3-2 m·s-1 in autumn, and the wind direction of NNE-NE and WNW, wind speed 1-2 m·s-1 in winter. In addition, by analyzing the visibility changes of the first station in the fog, we found that there are obvious “trunklike” characteristics before river fogs develop. Such features could provide the basis for the operation of early warning and forecasting of river fogs.
Using the minutely data including visibility, relative humidity, temperature and wind speed of 36 automatic weather stations along the Yangtze River in Jiangsu Province during 2010-2013, the characteristics of river fogs are analyzed. The results show that river fog mainly occurs in June, November and January, formed from 19:00 BT to the next 07:00 BT, during which the fog is the thickest in 02:00-04:00 BT and gets to end from 06:00 BT to 12:00 BT, so the fog duration is 3-9 h. When fog occurs, relative humidity is 85% or higher, temperature is 5-19℃ in spring, 18-26℃ in summer, 7-23℃ in autumn and 0-11℃ in winter. As for the wind speed, it is below 5 m·s-1 in spring, summer, autumn, and about 6 m·s-1 in winter. Specifically, the fog tends to occur with the wind direction of NNE-E and wind speed 1-2 m·s-1 in spring, the wind direction of NNE-ESE and wind speed 0.3-1 m·s-1 in summer, the wind direction of NNE-NE and E-ESE, wind speed 0.3-2 m·s-1 in autumn, and the wind direction of NNE-NE and WNW, wind speed 1-2 m·s-1 in winter. In addition, by analyzing the visibility changes of the first station in the fog, we found that there are obvious “trunklike” characteristics before river fogs develop. Such features could provide the basis for the operation of early warning and forecasting of river fogs.
2018, 44(3):416-424.
DOI: 10.7519/j.issn.1000-0526.2018.03.008
Abstract:
Using the data detected by the W-band ground radar developed by China, the physical process of a cloud system with light rain in Hefei was analyzed, and the microphysical parameters in the water cloud and cirrus cloud were retrieved preliminarily based on the data from two different regions detected by the ground and airborne W-band radars. The results showed that: (1) The corresponding height where the echo intensity increased, and the Doppler velocity, linear depolarization ratio (LDR) and spectral width suddenly increased was the top of melting layer, then the thickness of melting layer was initially estimated according the LDR bright band. (2) Using empirical relations, the ice and liquid water content of cirrus cloud and water cloud were retrieved, and the effective radius of ice crystal cloud particles were also obtained using the derived formula. (3) Using bin-by-bin correction method in the groups, the echo intensity of water cloud was corrected, then the liquid water content was retrieved based on the corrected echo intensity, so the retrieval errors were reduced.
Using the data detected by the W-band ground radar developed by China, the physical process of a cloud system with light rain in Hefei was analyzed, and the microphysical parameters in the water cloud and cirrus cloud were retrieved preliminarily based on the data from two different regions detected by the ground and airborne W-band radars. The results showed that: (1) The corresponding height where the echo intensity increased, and the Doppler velocity, linear depolarization ratio (LDR) and spectral width suddenly increased was the top of melting layer, then the thickness of melting layer was initially estimated according the LDR bright band. (2) Using empirical relations, the ice and liquid water content of cirrus cloud and water cloud were retrieved, and the effective radius of ice crystal cloud particles were also obtained using the derived formula. (3) Using bin-by-bin correction method in the groups, the echo intensity of water cloud was corrected, then the liquid water content was retrieved based on the corrected echo intensity, so the retrieval errors were reduced.
2018, 44(3):425-433.
DOI: 10.7519/j.issn.1000-0526.2018.03.009
Abstract:
Based on the hourly observation of automatic weather stations in Beijing area during 2008-2015, the fine spatiotemporal distribution characteristics of local circulation are studied. The analysis results are as follows. Firstly, the local wind pattern in Beijing is affected by the combined effect of the mountainvalley wind and the urban heat island. Wind speed is basically distributed along the topographic gradient. In the western and northern mountains, the wind speed is greater than that in the plains and urban areas. Local circulation in Beijing area occurs through the whole year, although it varies seasonally. Averagely, the strength of the local wind in eastwest direction is 0.16 m·s-1 and in southnorth direction is 0.07 m·s-1. Secondly, local wind speed has seasonal changes. In summer, it is the maximum, followed by winds in spring and autumn, and in winter, it is the minimum. Its diurnal variation shows a bimodal structure, with peak value appearing at about 09:00 BT and 16:00 BT. Finally, there are significant differences with diurnal amplitude and positive or negative duration of anomaly between zonal local circulation component and meridional local circulation component. Analyses of the wind and temperature in Beijing area show that the local circulation presents diurnal variation obviously due to the mountainvalley and urban temperature differences.
Based on the hourly observation of automatic weather stations in Beijing area during 2008-2015, the fine spatiotemporal distribution characteristics of local circulation are studied. The analysis results are as follows. Firstly, the local wind pattern in Beijing is affected by the combined effect of the mountainvalley wind and the urban heat island. Wind speed is basically distributed along the topographic gradient. In the western and northern mountains, the wind speed is greater than that in the plains and urban areas. Local circulation in Beijing area occurs through the whole year, although it varies seasonally. Averagely, the strength of the local wind in eastwest direction is 0.16 m·s-1 and in southnorth direction is 0.07 m·s-1. Secondly, local wind speed has seasonal changes. In summer, it is the maximum, followed by winds in spring and autumn, and in winter, it is the minimum. Its diurnal variation shows a bimodal structure, with peak value appearing at about 09:00 BT and 16:00 BT. Finally, there are significant differences with diurnal amplitude and positive or negative duration of anomaly between zonal local circulation component and meridional local circulation component. Analyses of the wind and temperature in Beijing area show that the local circulation presents diurnal variation obviously due to the mountainvalley and urban temperature differences.
2018, 44(3):434-441.
DOI: 10.7519/j.issn.1000-0526.2018.03.010
Abstract:
This article selects some weather processes including heavy rainfall and general rainfall, using statistical method to contrast Parsivel precipitation particle spectrometer data and pluviometer data from five stations in Nanjing. The results show that the particle spectrometer data are close to the pluviometer data in rainfall processes. When the rain intensity is between 10-20 mm·h-1, the particle spectrometer data have the largest difference from the pluviometer data. However, the particle spectrometer data are bigger than the pluviometer data as a whole when the rain intensity is either larger than 20 mm·h-1 or between 0 and 1 mm·h-1, or when the rainfall particle diameter is bigger than 2 mm.The result is opposite when the rain intensity is between 1 and 20 mm·h-1, or when the particle diameter is smaller than 2 mm.
This article selects some weather processes including heavy rainfall and general rainfall, using statistical method to contrast Parsivel precipitation particle spectrometer data and pluviometer data from five stations in Nanjing. The results show that the particle spectrometer data are close to the pluviometer data in rainfall processes. When the rain intensity is between 10-20 mm·h-1, the particle spectrometer data have the largest difference from the pluviometer data. However, the particle spectrometer data are bigger than the pluviometer data as a whole when the rain intensity is either larger than 20 mm·h-1 or between 0 and 1 mm·h-1, or when the rainfall particle diameter is bigger than 2 mm.The result is opposite when the rain intensity is between 1 and 20 mm·h-1, or when the particle diameter is smaller than 2 mm.
11 Preparation of Pure AgI Nano-Aerosol and Its Efficiency of
Ice Nucleation in Laboratory Experiment
2018, 44(3):442-448.
DOI: 10.7519/j.issn.1000-0526.2018.03.011
Abstract:
The 100 mg pure AgI powder was placed in a vaporization tube of an electrical heating furnace and heated to 1600℃ for gasification. Then, the gaseous AgI was burst into a 2 m3 metal container by high-pressure air, and AgI aerosols were formed after suddenly cooled afterward. AgI aerosols were sampled by natural sedimentation using the formvar stabilized with carbon support films. The results indica-ted that the aerosol composition maintains pure AgI and the size spectrum width is 0.84-34.6 nm with 2.17 nm peaking diameter. The ice nucleation efficiency of the quantitative pure AgI nano-aerosol was detected by a 15 L mixed cloud chamber, with and without fog, respectively. The preliminary results were that the efficiency of ice nucleation is little more than 1.1×1011 g-1 under the condition of -10℃ with cold fog, and 3.4×1010 g-1 without cold fog.
The 100 mg pure AgI powder was placed in a vaporization tube of an electrical heating furnace and heated to 1600℃ for gasification. Then, the gaseous AgI was burst into a 2 m3 metal container by high-pressure air, and AgI aerosols were formed after suddenly cooled afterward. AgI aerosols were sampled by natural sedimentation using the formvar stabilized with carbon support films. The results indica-ted that the aerosol composition maintains pure AgI and the size spectrum width is 0.84-34.6 nm with 2.17 nm peaking diameter. The ice nucleation efficiency of the quantitative pure AgI nano-aerosol was detected by a 15 L mixed cloud chamber, with and without fog, respectively. The preliminary results were that the efficiency of ice nucleation is little more than 1.1×1011 g-1 under the condition of -10℃ with cold fog, and 3.4×1010 g-1 without cold fog.
2018, 44(3):449-454.
DOI: 10.7519/j.issn.1000-0526.2018.03.012
Abstract:
Haze has become a major environmental problem in Guanzhong Region of Shaanxi Province. Aerosol is one of the most uncertain factors in the climate change study, and many observations and researches worldwide have paid much attention to its climate effect. The overall design and observation content of the aerosol observation platform of atmospheric laboratory test base in Qinling Mountains are introduced in this paper. This platform has the ability of field data collection, remote monitoring, data transmission, humancomputer interaction, data storage and quality inspection, data inversion, product display and other functions. It integrates observation, calculation and query, which can provide data support for the research and development of environmental and meteorological service technology.
Haze has become a major environmental problem in Guanzhong Region of Shaanxi Province. Aerosol is one of the most uncertain factors in the climate change study, and many observations and researches worldwide have paid much attention to its climate effect. The overall design and observation content of the aerosol observation platform of atmospheric laboratory test base in Qinling Mountains are introduced in this paper. This platform has the ability of field data collection, remote monitoring, data transmission, humancomputer interaction, data storage and quality inspection, data inversion, product display and other functions. It integrates observation, calculation and query, which can provide data support for the research and development of environmental and meteorological service technology.
2018, 44(3):455-462.
DOI: 10.7519/j.issn.1000-0526.2018.03.013
Abstract:
Statistical analysis was performed on 404 samples of threebody scatter spike (TBSS) in 18 storm cells of 10 severe hailstorm processes in Changde and the surrounding areas, and the causes influencing TBSS observation were analyzed in detail. The conclusions can be drawn as follows. (1) Reflectivity intensity is the key factor for TBSS. As a factor causes TBSS features, the minimum reflectivity intensity should be 58 dBz. The more it is above this critical value, the easier TBSS will come into being. (2) The peak of TBSS can be reached under the following conditions: at altitude of 4 km or so, 1.5° elevation, distance of 90 km or so, and the vertical distribution of the storm core echo intensity is a predominant impact factor during this process. (3) The frequency of TBSS is the most from 180° to 360°. Usually, longer length echo area in the leeward direction of wind storms can cause TBSS to be covered. This is the basic factor affecting the TBSS observation. The storm cells relative to the position and moving direction of radar usually decide whether there are echoes influencing TBSS observations in the radial outer side. (4) If intensity of TBSS echo and storm radial outer side weak echo are quite strong, the TBSS features can be identified from the storm radial outer side weak echo.
Statistical analysis was performed on 404 samples of threebody scatter spike (TBSS) in 18 storm cells of 10 severe hailstorm processes in Changde and the surrounding areas, and the causes influencing TBSS observation were analyzed in detail. The conclusions can be drawn as follows. (1) Reflectivity intensity is the key factor for TBSS. As a factor causes TBSS features, the minimum reflectivity intensity should be 58 dBz. The more it is above this critical value, the easier TBSS will come into being. (2) The peak of TBSS can be reached under the following conditions: at altitude of 4 km or so, 1.5° elevation, distance of 90 km or so, and the vertical distribution of the storm core echo intensity is a predominant impact factor during this process. (3) The frequency of TBSS is the most from 180° to 360°. Usually, longer length echo area in the leeward direction of wind storms can cause TBSS to be covered. This is the basic factor affecting the TBSS observation. The storm cells relative to the position and moving direction of radar usually decide whether there are echoes influencing TBSS observations in the radial outer side. (4) If intensity of TBSS echo and storm radial outer side weak echo are quite strong, the TBSS features can be identified from the storm radial outer side weak echo.
2018, 44(3):463-468.
DOI: 10.7519/j.issn.1000-0526.2018.03.014
Abstract:
The main characteristics of the general atmospheric circulation in December 2017 are as follows. There were two polar vortex centers in the Northern Hemisphere. The circulation presented the trough-ridge-trough pattern in the middle-high latitudes of Eurasia. The south branch trough was located near 70°E, obviously more westward than that in the same period of normal years. Therefore, the location of the south branch trough was not favorable for the water vapor transport to eastern China. The subtropical high was located more westward than that in normal years. The monthly mean precipitation over China was 5.9 mm, which is 44.8% less than the normal value (10.8 mm), especially for northern China, where precipitation amount decreased by 40%-80% of the normal. The monthly mean temperature over China was -2.2℃, 1℃ higher than the normal (-3.2℃). However, the temperature over northeastern China and the mid-eastern of Inner Mongolia was lower by 1-3℃ because of the strong east major trough. There were five cold air processes, which were not as strong as the normal events but more active than the normal. These active cold airs led to less fog-haze weather, and only one fog-haze period which occurred from 28 to 30 December 2017.
The main characteristics of the general atmospheric circulation in December 2017 are as follows. There were two polar vortex centers in the Northern Hemisphere. The circulation presented the trough-ridge-trough pattern in the middle-high latitudes of Eurasia. The south branch trough was located near 70°E, obviously more westward than that in the same period of normal years. Therefore, the location of the south branch trough was not favorable for the water vapor transport to eastern China. The subtropical high was located more westward than that in normal years. The monthly mean precipitation over China was 5.9 mm, which is 44.8% less than the normal value (10.8 mm), especially for northern China, where precipitation amount decreased by 40%-80% of the normal. The monthly mean temperature over China was -2.2℃, 1℃ higher than the normal (-3.2℃). However, the temperature over northeastern China and the mid-eastern of Inner Mongolia was lower by 1-3℃ because of the strong east major trough. There were five cold air processes, which were not as strong as the normal events but more active than the normal. These active cold airs led to less fog-haze weather, and only one fog-haze period which occurred from 28 to 30 December 2017.
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ISSN:1000-0526 CN:11-2282/P