ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 38,Issue 3,2012 Table of Contents
2012, 38(3):257-265.
DOI: 10.7519/j.issn.1000-0526.2012.03.001
Abstract:
Studies on the paleoclimate during the last 20-30 years are reviewed. The following hot topics are discussed: snowball Earth and PaleoceneEocene thermal maximum (PETM), glacialinterglacial cycles, paleomonsoon, D/O cycles and H events, Holocene monsoon, abrupt climate change in the Holocene, climate change and associated ancient civilization, and the last 2 ka climate. It is indicated that, the snowball Earth and PETM were caused by the depletion and explosive increasing of CO2 in the atmosphere respectively. However, the change of temperature was preceding that of greenhouse gases in glacialinterglacial cycle, as found in the ice cores in the Antarctica. It is also shown that the changes of temperatures and greenhouse gases were highly correlated before the Quaternary, but changed after that, which might be linked to a differed mechanism. Enhancement of greenhouse effect in the present will, probably to some extent, delay the onset of the next glacial period. In any case, anthropogenic effect on the climate will definitely continue in the 21st century even we turn to reduce the emission of greenhouse gases in some ways. The global warming will remain as a critical issue, which we have to face in near future.
Studies on the paleoclimate during the last 20-30 years are reviewed. The following hot topics are discussed: snowball Earth and PaleoceneEocene thermal maximum (PETM), glacialinterglacial cycles, paleomonsoon, D/O cycles and H events, Holocene monsoon, abrupt climate change in the Holocene, climate change and associated ancient civilization, and the last 2 ka climate. It is indicated that, the snowball Earth and PETM were caused by the depletion and explosive increasing of CO2 in the atmosphere respectively. However, the change of temperature was preceding that of greenhouse gases in glacialinterglacial cycle, as found in the ice cores in the Antarctica. It is also shown that the changes of temperatures and greenhouse gases were highly correlated before the Quaternary, but changed after that, which might be linked to a differed mechanism. Enhancement of greenhouse effect in the present will, probably to some extent, delay the onset of the next glacial period. In any case, anthropogenic effect on the climate will definitely continue in the 21st century even we turn to reduce the emission of greenhouse gases in some ways. The global warming will remain as a critical issue, which we have to face in near future.
2 Dynamic Diagnostic Analysis of the 15 April 2009 Gale Wind over the Bohai Sea and Shandong Province
2012, 38(3):266-273.
DOI: 10.7519/j.issn.1000-0526.2012.03.002
Abstract:
A gale with wind force scale 8 occurred in the Bohai Sea and Shandong Province on 15 April 2009. The gale is severe strong, but lasts only a half day. Wind speed strengthens significantly near the Bohai Sea and Shandong Province. With the conventional surface data and NCEP analysis data, the causes for this gale event are diagnosed. Results show that the gale is affected by the cold front near the surface and the vortex at the upper level. The cold advection spreads downwards from the upper level during the southward moving of the cold air, as a result, the cold advection and the cold air under the 850 hPa both strengthen. When the cold air arrives at the Bohai Sea, the strong cold advection behind and the strong warm advection in front of the cold air at the low level make the frontal zone further strengthening. The downdraft of the secondary circulation is corresponding to the positive allobaric area near the surface. The strong allobaric wind and the large scale baric gradient wind both lead to the abnormal gale together, and the corresponding severe gust wind is probably related to the impulse of the secondary circulation.
A gale with wind force scale 8 occurred in the Bohai Sea and Shandong Province on 15 April 2009. The gale is severe strong, but lasts only a half day. Wind speed strengthens significantly near the Bohai Sea and Shandong Province. With the conventional surface data and NCEP analysis data, the causes for this gale event are diagnosed. Results show that the gale is affected by the cold front near the surface and the vortex at the upper level. The cold advection spreads downwards from the upper level during the southward moving of the cold air, as a result, the cold advection and the cold air under the 850 hPa both strengthen. When the cold air arrives at the Bohai Sea, the strong cold advection behind and the strong warm advection in front of the cold air at the low level make the frontal zone further strengthening. The downdraft of the secondary circulation is corresponding to the positive allobaric area near the surface. The strong allobaric wind and the large scale baric gradient wind both lead to the abnormal gale together, and the corresponding severe gust wind is probably related to the impulse of the secondary circulation.
2012, 38(3):274-280.
DOI: 10.7519/j.issn.1000-0526.2012.03.003
Abstract:
Verification results of different precipitation forecast products in the SWAN system and the GZMM model for 4 heavy rain cases in 2010 are discussed. The crossover point of CSI curves in forecast lead time where the model would perform better than the nowcast, is analyzed in particular. Firstly, the radar nowcast for 1hour precipitation forecast exceeding 0.1 mm starts with higher scores than the model, but the skill of the nowcast drops as the forecast lead time increases. The GZMM model performs at a fairly steady level over 3-6 hour period with lower scores at 1 and 2 hours. The CSI scores of 1hour QPF with 0.12°resolution in the SWAN at 1 and 2 hours are 0.504 and 0.442, respectively. At t=3 h, the two CSI curves cross, indicating the skill of the radar extrapolation has decreased to the same level as the model forecast. Secondly, the performance of 1hour precipitation forecast with 3 graded levels is documented. For the 0.1-2 mm rainfall, the CSI score of the model is about 0.23 over the 6hour period, and the GZMM model performs better than the SWAN. For rainfall between 2 and 10 mm, the SWAN product with 0.12°resolution performs better than the GZMM model over 0-3 hour period. At t=4 h, the skill of the radar extrapolation has decreased to the same level as the model forecast. For rainfall over 10 mm, both the SWAN and the GZMM perform not very good. But the skill of the radar nowcast is higher than that of the GZMM model over the 6hour period.
Verification results of different precipitation forecast products in the SWAN system and the GZMM model for 4 heavy rain cases in 2010 are discussed. The crossover point of CSI curves in forecast lead time where the model would perform better than the nowcast, is analyzed in particular. Firstly, the radar nowcast for 1hour precipitation forecast exceeding 0.1 mm starts with higher scores than the model, but the skill of the nowcast drops as the forecast lead time increases. The GZMM model performs at a fairly steady level over 3-6 hour period with lower scores at 1 and 2 hours. The CSI scores of 1hour QPF with 0.12°resolution in the SWAN at 1 and 2 hours are 0.504 and 0.442, respectively. At t=3 h, the two CSI curves cross, indicating the skill of the radar extrapolation has decreased to the same level as the model forecast. Secondly, the performance of 1hour precipitation forecast with 3 graded levels is documented. For the 0.1-2 mm rainfall, the CSI score of the model is about 0.23 over the 6hour period, and the GZMM model performs better than the SWAN. For rainfall between 2 and 10 mm, the SWAN product with 0.12°resolution performs better than the GZMM model over 0-3 hour period. At t=4 h, the skill of the radar extrapolation has decreased to the same level as the model forecast. For rainfall over 10 mm, both the SWAN and the GZMM perform not very good. But the skill of the radar nowcast is higher than that of the GZMM model over the 6hour period.
2012, 38(3):281-290.
DOI: 10.7519/j.issn.1000-0526.2012.03.004
Abstract:
In order to make the sudden rainstorm nowcasting and early warning more timely and accurately， using the detection data including conventional synoptic analysis, Beijing radar regional mosaic and VDRAS (variational Doppler radar analysis system) retrieved wind field, AWS (auto weather stations), wind profile data, and satellite images, we have conducted the comparative analysis on synoptic scale and mesoscale systems of two severe convective rainstorm events, which happened in Beijing area on August 14, 2008 and July 13, 2009, and put the forecast focus in the rainstorm nowcasting and early warning in Beijing area. It shows that the two rainstorm events have many similarities, e.g. in the good synoptic scale conditions, such as moisture condition, the dynamic condition at the middle and low levels, and the intrusion of the cold air, the clear areas between the prestorm southern and northern mesoscale systems of satellite images, the occurrence and development of mesoscale systems being associated with mesoscale convergence below 1 km ASL. And on the other hand, they have many differences in the direction and speed of the movement of the radar echoes, the structures of VDRAS wind fields in the lower troposphere, the structures of vertical wind profiles. It is proved that by the study and analysis, the nowcasting ability of severe convective rainstorm can be promoted using high space resolution detection data and there is important significance to the forecasting service in the main flooding season.
In order to make the sudden rainstorm nowcasting and early warning more timely and accurately， using the detection data including conventional synoptic analysis, Beijing radar regional mosaic and VDRAS (variational Doppler radar analysis system) retrieved wind field, AWS (auto weather stations), wind profile data, and satellite images, we have conducted the comparative analysis on synoptic scale and mesoscale systems of two severe convective rainstorm events, which happened in Beijing area on August 14, 2008 and July 13, 2009, and put the forecast focus in the rainstorm nowcasting and early warning in Beijing area. It shows that the two rainstorm events have many similarities, e.g. in the good synoptic scale conditions, such as moisture condition, the dynamic condition at the middle and low levels, and the intrusion of the cold air, the clear areas between the prestorm southern and northern mesoscale systems of satellite images, the occurrence and development of mesoscale systems being associated with mesoscale convergence below 1 km ASL. And on the other hand, they have many differences in the direction and speed of the movement of the radar echoes, the structures of VDRAS wind fields in the lower troposphere, the structures of vertical wind profiles. It is proved that by the study and analysis, the nowcasting ability of severe convective rainstorm can be promoted using high space resolution detection data and there is important significance to the forecasting service in the main flooding season.
2012, 38(3):291-299.
DOI: 10.7519/j.issn.1000-0526.2012.03.005
Abstract:
After the extreme freezing catastrophe in year 2008, Guizhou Province experienced another rare freezing weather at the beginning of 2011. Analysis based on the conventional observational data as well as the NCEP reanalysis data indicates that the Ural blocking high and the height departure distribution of “negative in the south and positive in the north” are the key causes for the maintenance of lowtemperature. Meanwhile, the quasistationary front in Guizhou and Yunnan plays an important role during the freezing days; the deep trough over Indian Ocean and abundant water vapor are very favorable to the vast area stricken by snow and freezing rain. The extent of calamity is weaker than that of 2008, especially in the eastern Guizhou, as it lacks for the continuous transportation of moisture. The route of cold air mass is also different from 2008. Moreover, the two strong processes are discussed, and they have different configuration in Tlogp diagram. In addition, research on the relation among the maximum frozen rain diameter, the daily average surface temperature, lowest temperature, daily total rainfall, the daily mean surface velocity, and the daily average temperature shows a better correlation with freezing development when there has compatible precipitation.
After the extreme freezing catastrophe in year 2008, Guizhou Province experienced another rare freezing weather at the beginning of 2011. Analysis based on the conventional observational data as well as the NCEP reanalysis data indicates that the Ural blocking high and the height departure distribution of “negative in the south and positive in the north” are the key causes for the maintenance of lowtemperature. Meanwhile, the quasistationary front in Guizhou and Yunnan plays an important role during the freezing days; the deep trough over Indian Ocean and abundant water vapor are very favorable to the vast area stricken by snow and freezing rain. The extent of calamity is weaker than that of 2008, especially in the eastern Guizhou, as it lacks for the continuous transportation of moisture. The route of cold air mass is also different from 2008. Moreover, the two strong processes are discussed, and they have different configuration in Tlogp diagram. In addition, research on the relation among the maximum frozen rain diameter, the daily average surface temperature, lowest temperature, daily total rainfall, the daily mean surface velocity, and the daily average temperature shows a better correlation with freezing development when there has compatible precipitation.
2012, 38(3):300-306.
DOI: 10.7519/j.issn.1000-0526.2012.03.006
Abstract:
In this paper we choose the SVM (support vector machine) method for forecasting 2min average wind speed four times daily (00, 06, 12 and 18 UTC) when it is affected by landfalling tropical cyclones. First we select related factors based on the intensity of the tropical cyclones during 2002-2007, the landform and the environment element variables at lowlevel and upperlevel around the station. And then we establish numerical weather prediction models. The standard deviation of the wind speed fitting error in Model 4 is 1.591 m·s-1. By testing with 8 landfalling tropical cyclones in 2008 as independent samples, the difference of the actual average absolute wind speed from the forecast one is 1.75 m·s-1, and the standard deviation is 2.367 m·s-1. The precision of wind speed forecast in 48 h can be better when the SVM method is used under conditions of selecting appropriate forecast factors and sample truncation.
In this paper we choose the SVM (support vector machine) method for forecasting 2min average wind speed four times daily (00, 06, 12 and 18 UTC) when it is affected by landfalling tropical cyclones. First we select related factors based on the intensity of the tropical cyclones during 2002-2007, the landform and the environment element variables at lowlevel and upperlevel around the station. And then we establish numerical weather prediction models. The standard deviation of the wind speed fitting error in Model 4 is 1.591 m·s-1. By testing with 8 landfalling tropical cyclones in 2008 as independent samples, the difference of the actual average absolute wind speed from the forecast one is 1.75 m·s-1, and the standard deviation is 2.367 m·s-1. The precision of wind speed forecast in 48 h can be better when the SVM method is used under conditions of selecting appropriate forecast factors and sample truncation.
2012, 38(3):307-313.
DOI: 10.7519/j.issn.1000-0526.2012.03.007
Abstract:
In order to investigate the characteristics of shortterm heavy rainfall in Guizhou Province, the hourly rainfall data from 84 stations in Guizhou through 1991-2009 are analyzed, with defined a threshold value for each station by the method of threshold value. The distribution of threshold value shows that there are two heavy precipitation high value centers, the stronger one is in Wangmo, southwest in Guizhou, while the other one is in northwest of Guizhou. The precipitation event frequency increases gradually during April to June, maintains in July and begins to reduce during August to September. Precipitation often occurs during the three time periods of 23:00-02:00 BT, 05:00-08:00 BT, and 17:00-20:00 BT, there is very little precipitation event during daytime. Most of the heavy precipitation events occur in the evening in northwest Guizhou, while in the middle of Guizhou, heavy rainfall is concentrated in the time period of 23:00-02:00 BT, and then in 05:00-08:00 BT in the southeast Guizhou.
In order to investigate the characteristics of shortterm heavy rainfall in Guizhou Province, the hourly rainfall data from 84 stations in Guizhou through 1991-2009 are analyzed, with defined a threshold value for each station by the method of threshold value. The distribution of threshold value shows that there are two heavy precipitation high value centers, the stronger one is in Wangmo, southwest in Guizhou, while the other one is in northwest of Guizhou. The precipitation event frequency increases gradually during April to June, maintains in July and begins to reduce during August to September. Precipitation often occurs during the three time periods of 23:00-02:00 BT, 05:00-08:00 BT, and 17:00-20:00 BT, there is very little precipitation event during daytime. Most of the heavy precipitation events occur in the evening in northwest Guizhou, while in the middle of Guizhou, heavy rainfall is concentrated in the time period of 23:00-02:00 BT, and then in 05:00-08:00 BT in the southeast Guizhou.
2012, 38(3):314-321.
DOI: 10.7519/j.issn.1000-0526.2012.03.008
Abstract:
In regard to the strong convection clouds from afternoon to night on 8 August 2008 in the northwest, west and southwest of Beijing area, weather modification activities were conducted to find out the changes of the surface humidity leeward after the largescale operations. In this paper, by means of the data obtained from 215 automatic as well as nonautomatic weather stations， the precipitation distribution was studied. Especially, by means of the data obtained from 108 weather stations with the humidity detection, the ground water vapor pressure every 5 min is calculated and analyzed, taking aim at the experimentation evidence for the largescale modification operations. The study shows that the leading airflow in the evening was southwest to northeast, and the weather system moved basically along the direction of southwest to northeast. Largescale weather modification operation was conducted in the southwest part of Beijing area. After the operation, in the zonal belt of the operation, the ground water vapor pressure changed with time abruptly (it suddently diminished after lasted about 25 min). The break change weakened from southeast to northwest and the start time of the change postponed. In the axis line of the zonal belt, the break change was smallest. Farther away from the axis line, the smaller the break was. Outside the zonal belt, such phenomenon did not occur. It was as if a dry air column moving from southwest to northeast. Without the weather modification activities on 8 August 2008, there would be no such phenomenon in the rain band backward position. Meanwhile, the causes for the above phenomena are analyzed, and some useful operational instructions are obtained.
In regard to the strong convection clouds from afternoon to night on 8 August 2008 in the northwest, west and southwest of Beijing area, weather modification activities were conducted to find out the changes of the surface humidity leeward after the largescale operations. In this paper, by means of the data obtained from 215 automatic as well as nonautomatic weather stations， the precipitation distribution was studied. Especially, by means of the data obtained from 108 weather stations with the humidity detection, the ground water vapor pressure every 5 min is calculated and analyzed, taking aim at the experimentation evidence for the largescale modification operations. The study shows that the leading airflow in the evening was southwest to northeast, and the weather system moved basically along the direction of southwest to northeast. Largescale weather modification operation was conducted in the southwest part of Beijing area. After the operation, in the zonal belt of the operation, the ground water vapor pressure changed with time abruptly (it suddently diminished after lasted about 25 min). The break change weakened from southeast to northwest and the start time of the change postponed. In the axis line of the zonal belt, the break change was smallest. Farther away from the axis line, the smaller the break was. Outside the zonal belt, such phenomenon did not occur. It was as if a dry air column moving from southwest to northeast. Without the weather modification activities on 8 August 2008, there would be no such phenomenon in the rain band backward position. Meanwhile, the causes for the above phenomena are analyzed, and some useful operational instructions are obtained.
2012, 38(3):322-328.
DOI: 10.7519/j.issn.1000-0526.2012.03.009
Abstract:
In order to analyze the relationship between meteorological elements and heating, the daily average air temperature, relative humidity, the wind speed and total daily solar radiation during the 2009 heating season in Beijing Meteorological Observatory are selected as the meteorological elements; the supply water temperature, return water temperature and difference between supply and return water temperature in the Beijing Haiyuan Heating Department are regarded as the heating temperature; and these factors are correlatively analyzed. The results show that the daily average temperatures and supplyreturn water temperatures have an obvious negative correlation. Their correlation coefficients are -0.75 and -0.62, respectively. The correlation coefficients between the daily average relative humidity and supplyreturn water temperatures are smaller, they are -0.41 and -0.47, respectively. and the correlation coefficients between the daily average wind speed and the above supplyreturn water temperatures are the least. In addition, the relationships between the various meteorological elements and supply water temperature, return water temperature and the difference between supply and return water temperature are analyzed. A table about the relationships between various meteorological elements and supply water temperature, return water temperature and difference between supply and return water temperature is set up. Based on the table of supplyreturn water temperature of daily average meteorological elements, the heating departments can directly control the supply heating under the different weather conditions and adjust supplyreturn water temperatures.
In order to analyze the relationship between meteorological elements and heating, the daily average air temperature, relative humidity, the wind speed and total daily solar radiation during the 2009 heating season in Beijing Meteorological Observatory are selected as the meteorological elements; the supply water temperature, return water temperature and difference between supply and return water temperature in the Beijing Haiyuan Heating Department are regarded as the heating temperature; and these factors are correlatively analyzed. The results show that the daily average temperatures and supplyreturn water temperatures have an obvious negative correlation. Their correlation coefficients are -0.75 and -0.62, respectively. The correlation coefficients between the daily average relative humidity and supplyreturn water temperatures are smaller, they are -0.41 and -0.47, respectively. and the correlation coefficients between the daily average wind speed and the above supplyreturn water temperatures are the least. In addition, the relationships between the various meteorological elements and supply water temperature, return water temperature and the difference between supply and return water temperature are analyzed. A table about the relationships between various meteorological elements and supply water temperature, return water temperature and difference between supply and return water temperature is set up. Based on the table of supplyreturn water temperature of daily average meteorological elements, the heating departments can directly control the supply heating under the different weather conditions and adjust supplyreturn water temperatures.
2012, 38(3):329-335.
DOI: 10.7519/j.issn.1000-0526.2012.03.010
Abstract:
Since the year 2000, continuous heatwave events have some new characteristics, such as high frequency, long duration, broad influence, strong intensity and high extreme temperature. Analyzed the four times of continuous heatwave weather by use of the NCEP data and synoptic meteorology method, it was found that continuous heatwave weather over north area of Hangzhou Bay seems to appear under the intense warming by descending drafts and clear sky radiation, which is due to the powerful control of the subtropical high with ridge line strengthened up to 30°N, and high and low altitude negative vorticities have a vertical superimposition when the South Asian high moves eastwards, or in the influence of typhoon periphery circulation, and the advection warming, also synthesizing the earlier period continuous high temperature factors. In the 21st century, during the heatwave days, the hightemperature hours and extremely hot hours are both growing up, and the latter grows up more. Although the sunshine hours decreased, the temperature still quickly elevated, maybe it is connected with the urban heat island effect (UHIE) which is caused by the development of cities. Nowadays, this effect of cities over the north area of Hangzhou Bay is already extended to the temperature difference relations among cities.
Since the year 2000, continuous heatwave events have some new characteristics, such as high frequency, long duration, broad influence, strong intensity and high extreme temperature. Analyzed the four times of continuous heatwave weather by use of the NCEP data and synoptic meteorology method, it was found that continuous heatwave weather over north area of Hangzhou Bay seems to appear under the intense warming by descending drafts and clear sky radiation, which is due to the powerful control of the subtropical high with ridge line strengthened up to 30°N, and high and low altitude negative vorticities have a vertical superimposition when the South Asian high moves eastwards, or in the influence of typhoon periphery circulation, and the advection warming, also synthesizing the earlier period continuous high temperature factors. In the 21st century, during the heatwave days, the hightemperature hours and extremely hot hours are both growing up, and the latter grows up more. Although the sunshine hours decreased, the temperature still quickly elevated, maybe it is connected with the urban heat island effect (UHIE) which is caused by the development of cities. Nowadays, this effect of cities over the north area of Hangzhou Bay is already extended to the temperature difference relations among cities.
11 Comparative Analysis of Boundary Layer Convergence Lines Triggering Convective Storm in Bohai Bay
2012, 38(3):336-343.
DOI: 10.7519/j.issn.1000-0526.2012.03.011
Abstract:
Boundary layer convergence lines caused convective storms in Bohai Bay during 2008-2009 were analyzed. The results showed that: (1) In the hightemperature and high humidity environments under instable conditions of atmospheric stratification, a single landsea breeze convergence line is able to produce a weak convective storm in its endpoint. (2) The three cases that landsea breeze convergence line intersects the weak cold front, or two landsea breeze convergence lines intersect, or outflow boundary of thunderstorm meets with the boundary layer convergence line in coastal could produce strong convective storm. (3) Boundary layer convergence line triggering the convective storm in the Bohai Bay often occurs in July-August every year. Meanwhile, in the subtropical high eastward withdrawal process in the Bohai Bay, this atmospheric stratification maintains a high temperature, high humidity and instable condition. And then convergence line triggers convective storm, which moves along the convergence line, and its direction of movement depends on the dominant wind direction on both sides of convergence line. (4) Boundary layer convergence line triggering convective storm has its features of sudden, strong, and short duration. By analyzing the movement and evolution of landsea breeze convergence line, we may improve the nowcasting and warning of strong convective storm and reduce disasters.
Boundary layer convergence lines caused convective storms in Bohai Bay during 2008-2009 were analyzed. The results showed that: (1) In the hightemperature and high humidity environments under instable conditions of atmospheric stratification, a single landsea breeze convergence line is able to produce a weak convective storm in its endpoint. (2) The three cases that landsea breeze convergence line intersects the weak cold front, or two landsea breeze convergence lines intersect, or outflow boundary of thunderstorm meets with the boundary layer convergence line in coastal could produce strong convective storm. (3) Boundary layer convergence line triggering the convective storm in the Bohai Bay often occurs in July-August every year. Meanwhile, in the subtropical high eastward withdrawal process in the Bohai Bay, this atmospheric stratification maintains a high temperature, high humidity and instable condition. And then convergence line triggers convective storm, which moves along the convergence line, and its direction of movement depends on the dominant wind direction on both sides of convergence line. (4) Boundary layer convergence line triggering convective storm has its features of sudden, strong, and short duration. By analyzing the movement and evolution of landsea breeze convergence line, we may improve the nowcasting and warning of strong convective storm and reduce disasters.
2012, 38(3):344-348.
DOI: 10.7519/j.issn.1000-0526.2012.03.012
Abstract:
Based on the observation data at 11 stations from 1974 to 2009 in Tangshan and upperair observation data from 1999 to 2009 and Doppler radar data of hail from 2006 to 2009, the spatial and temporal distributions and climate characteristics and radar echo features of the hail were analyzed. Using different analytical methods of mutation, we analyzed sudden changes of hail. The results show that the hail mainly occurs in mountainous and semimountainous areas north of Tangshan. The annual hail days reached the peak in the 1980s, and then show a decreasing trend from the 1990s. A sudden change spot of annual hail days occurred in the early 1990s. After the change spot, the annual hail days reduced obviously. The release of the strong instability energy will be conducive to the formation of hail in unstable region. The height of hail zero layer is at 3.4 km， the height of -20℃ layer is at 6.3 km. Most of the strong hail’s radar echo centers are more than 60 dBz. The vertical sections are all characterized by slantwise echo structure. The top of echo is more than 8 km. The most vertical integrated liquid water content is more than 25 kg·m-2. There is a convergence feature on the basic radial velocity images.
Based on the observation data at 11 stations from 1974 to 2009 in Tangshan and upperair observation data from 1999 to 2009 and Doppler radar data of hail from 2006 to 2009, the spatial and temporal distributions and climate characteristics and radar echo features of the hail were analyzed. Using different analytical methods of mutation, we analyzed sudden changes of hail. The results show that the hail mainly occurs in mountainous and semimountainous areas north of Tangshan. The annual hail days reached the peak in the 1980s, and then show a decreasing trend from the 1990s. A sudden change spot of annual hail days occurred in the early 1990s. After the change spot, the annual hail days reduced obviously. The release of the strong instability energy will be conducive to the formation of hail in unstable region. The height of hail zero layer is at 3.4 km， the height of -20℃ layer is at 6.3 km. Most of the strong hail’s radar echo centers are more than 60 dBz. The vertical sections are all characterized by slantwise echo structure. The top of echo is more than 8 km. The most vertical integrated liquid water content is more than 25 kg·m-2. There is a convergence feature on the basic radial velocity images.
2012, 38(3):349-352.
DOI: 10.7519/j.issn.1000-0526.2012.03.013
Abstract:
The spatiotemporal distributive characteristics of power grid disasters during 1996-2009 in Beijing are investigated based on the disaster cases of power grid supplied by Beijing Electric Power Testing Research Institute. The results showed that lightning disaster (hereafter, it means the power grid disaster caused by lightning) is the main disaster in this area, accounting for 71.3% of the total power grid disasters. Adding with the relative important contribution of wind damage and icing disaster, the contribution can reach to 92.1%. And power grid disasters present significant regional distribution and seasonal character in Beijing; high incidence areas are located in Yanqing District, Changping District and Miyun District which are mainly centralized in the north of Beijing while the low incidence areas are concentrated in the south of Beijing including Daxing District, Tongzhou District. The seasonal distribution of power grid disasters is mainly concentrated in the period of June to September. Furthermore, through analysis some advices are given for improving the power network.
The spatiotemporal distributive characteristics of power grid disasters during 1996-2009 in Beijing are investigated based on the disaster cases of power grid supplied by Beijing Electric Power Testing Research Institute. The results showed that lightning disaster (hereafter, it means the power grid disaster caused by lightning) is the main disaster in this area, accounting for 71.3% of the total power grid disasters. Adding with the relative important contribution of wind damage and icing disaster, the contribution can reach to 92.1%. And power grid disasters present significant regional distribution and seasonal character in Beijing; high incidence areas are located in Yanqing District, Changping District and Miyun District which are mainly centralized in the north of Beijing while the low incidence areas are concentrated in the south of Beijing including Daxing District, Tongzhou District. The seasonal distribution of power grid disasters is mainly concentrated in the period of June to September. Furthermore, through analysis some advices are given for improving the power network.
14 The Characteristic Analysis of Thunderstorm Gale The Characteristic Analysis of Thunderstorm Gale
2012, 38(3):353-357.
DOI: 10.7519/j.issn.1000-0526.2012.03.014
Abstract:
By using the gale disaster data in Hebei Province from 1983 to 2008, the characteristics of wind disasters leading to power system security incidents in time and space are analyzed. Results showed that: (1) The high winds of 7 to 12 scales are main factors for the electrical network security accident; (2) Windinduced power disasters (WIPD) have significant changes yearly, the most disasters can be up to 43 cases in a year, and the least only 2 cases; (3) Monthly distribution of WIPD presents a remarkable unimodal pattern, power disasters are mainly concentrated in the summer halfyear, the 97.8% of total disasters happened in April to October; (4) The spatial distribution of WIPD is extremely uneven, the electrical network disaster accidents were relatively more in Tangshan, Baoding and Cangzhou, but there were relatively few in Zhangjiakou and Chengde region. On this basis, through the case analysis and causation analysis， the prevention measures were proposed, which provided the reference to strengthening the entire province meteorological service， and the disaster prevention and reduction.
By using the gale disaster data in Hebei Province from 1983 to 2008, the characteristics of wind disasters leading to power system security incidents in time and space are analyzed. Results showed that: (1) The high winds of 7 to 12 scales are main factors for the electrical network security accident; (2) Windinduced power disasters (WIPD) have significant changes yearly, the most disasters can be up to 43 cases in a year, and the least only 2 cases; (3) Monthly distribution of WIPD presents a remarkable unimodal pattern, power disasters are mainly concentrated in the summer halfyear, the 97.8% of total disasters happened in April to October; (4) The spatial distribution of WIPD is extremely uneven, the electrical network disaster accidents were relatively more in Tangshan, Baoding and Cangzhou, but there were relatively few in Zhangjiakou and Chengde region. On this basis, through the case analysis and causation analysis， the prevention measures were proposed, which provided the reference to strengthening the entire province meteorological service， and the disaster prevention and reduction.
2012, 38(3):358-364.
DOI: 10.7519/j.issn.1000-0526.2012.03.015
Abstract:
The following are the main characteristics of the general circulation of atmosphere in December 2011: There is one polar vortex center in the Northern Hemisphere with a slightly stronger strength than normal years. The circulation presents a fourwave pattern in middlehigh latitudes. The west European major trough is stronger and the East Asian major trough is weaker than the same period of normal years. The positions of the south branch trough and the northeast subtropical high are approaching to those at the same period of normal years， but the strength is weaker. This kind of situation is not favorable for the transportation of water vapor. There are two cold surge processes affecting China, and the monthly mean temperature is -3.8℃， which is slightly higher than that (-3.9℃) at the same period of normal years. In this month, the mean precipitation (7.5 mm) is 23.5% less than normal. The precipitation amounts of Liaoning Province, west of Jilin Province, southeast of Inner Mongolia, Guangdong Province, west of Qinghai Province, and middle of the Tibet Autonomous Region are all 80% less than the same period of normal years.
The following are the main characteristics of the general circulation of atmosphere in December 2011: There is one polar vortex center in the Northern Hemisphere with a slightly stronger strength than normal years. The circulation presents a fourwave pattern in middlehigh latitudes. The west European major trough is stronger and the East Asian major trough is weaker than the same period of normal years. The positions of the south branch trough and the northeast subtropical high are approaching to those at the same period of normal years， but the strength is weaker. This kind of situation is not favorable for the transportation of water vapor. There are two cold surge processes affecting China, and the monthly mean temperature is -3.8℃， which is slightly higher than that (-3.9℃) at the same period of normal years. In this month, the mean precipitation (7.5 mm) is 23.5% less than normal. The precipitation amounts of Liaoning Province, west of Jilin Province, southeast of Inner Mongolia, Guangdong Province, west of Qinghai Province, and middle of the Tibet Autonomous Region are all 80% less than the same period of normal years.
2012, 38(3):365-370.
DOI: 10.7519/j.issn.1000-0526.2012.03.016
Abstract:
Current national ground meteorological observation net consists of the benchmark, basic and general stations (counting up to 2416 stations), of which about 65.8% the general stations didn’t observe at night time. According to Specification of Surface Meteorological Observation， the average daily temperature must be calculated through mathematical methods, giving a replacement value for 02 BT’s temperature. This process virtually brings about calculation errors. Using the timing temperature data of 19 national basic stations in Shaanxi from 1961 to 2009, the assignment errors are analyzed and evaluated quantitatively through various schemes comparison, and a new assignment (or interpolation) method is raised. The results show that: (1) The replacement value of 02 BT’s given by traditional method is higher than the observed temperature, the average difference at 19 stations is 0.77℃. (2) Radiation intensity caused by stations in place of latitude, season and weather conditions conducting to assigned variable (20 BT’s temperature the day before) magnifies obviously 02 BT’s temperature assignment error. (3) Using stepwise regression analysis method to adjust the traditional weighted average as multifactor asymmetric weighting method can reduce significantly the weighting coefficient of 20 BT’s temperature the day before and reduce the influence caused by the intensity of radiation, thus making the assignment closer to the observed one. The average difference at 19 stations is approximately zero. New regression equations have certain correction effect on the monthly and yearly average temperature, and the annual average temperature can be decreased by 0.1 to 0.4℃, the monthly average temperature even by 0.5℃.
Current national ground meteorological observation net consists of the benchmark, basic and general stations (counting up to 2416 stations), of which about 65.8% the general stations didn’t observe at night time. According to Specification of Surface Meteorological Observation， the average daily temperature must be calculated through mathematical methods, giving a replacement value for 02 BT’s temperature. This process virtually brings about calculation errors. Using the timing temperature data of 19 national basic stations in Shaanxi from 1961 to 2009, the assignment errors are analyzed and evaluated quantitatively through various schemes comparison, and a new assignment (or interpolation) method is raised. The results show that: (1) The replacement value of 02 BT’s given by traditional method is higher than the observed temperature, the average difference at 19 stations is 0.77℃. (2) Radiation intensity caused by stations in place of latitude, season and weather conditions conducting to assigned variable (20 BT’s temperature the day before) magnifies obviously 02 BT’s temperature assignment error. (3) Using stepwise regression analysis method to adjust the traditional weighted average as multifactor asymmetric weighting method can reduce significantly the weighting coefficient of 20 BT’s temperature the day before and reduce the influence caused by the intensity of radiation, thus making the assignment closer to the observed one. The average difference at 19 stations is approximately zero. New regression equations have certain correction effect on the monthly and yearly average temperature, and the annual average temperature can be decreased by 0.1 to 0.4℃, the monthly average temperature even by 0.5℃.
2012, 38(3):371-376.
DOI: 10.7519/j.issn.1000-0526.2012.03.017
Abstract:
A realtime weather monitoring and prediction operation oriented software for quality control over automatic weather station (AWS) observation data is introduced. The software makes comprehensive use of data quality control method and instantmessaging technology, brings data quality control into meteorological information operation flow and thus a provincecitycounty three level realtime quality control operation flow over AWS observation data is built. The observation data from 89 national AWS and 1531 regional AWS in Jiangxi Province are under realtime quality control. The adverse effect on weather monitoring and prediction casued by AWS questionable data is effectively reduced.
A realtime weather monitoring and prediction operation oriented software for quality control over automatic weather station (AWS) observation data is introduced. The software makes comprehensive use of data quality control method and instantmessaging technology, brings data quality control into meteorological information operation flow and thus a provincecitycounty three level realtime quality control operation flow over AWS observation data is built. The observation data from 89 national AWS and 1531 regional AWS in Jiangxi Province are under realtime quality control. The adverse effect on weather monitoring and prediction casued by AWS questionable data is effectively reduced.
2012, 38(3):377-380.
DOI: 10.7519/j.issn.1000-0526.2012.03.018
Abstract:
Aiming at the status that the diagrams for visibility marker’s are handdrawn at the national weather stations, an automatic mapping system for visibility marker’s diagram was developed, achieving the function of automated making of visibility marker’s diagram for any distance. The system has the functions of observation station information management, target management, mapping panel management, and image output. The user can set the image size, the circle factor and the radius of the circle according to operational requirements. The visibility marker’s diagrams for 1000 m and 50000 m can be synthesized in one diagram, meeting the operation needs of the current minimum visibility observation. The system is highly automated, easy to operate, with high practicability. Widely use of the system will decrease obviously the workload of operational staff.
Aiming at the status that the diagrams for visibility marker’s are handdrawn at the national weather stations, an automatic mapping system for visibility marker’s diagram was developed, achieving the function of automated making of visibility marker’s diagram for any distance. The system has the functions of observation station information management, target management, mapping panel management, and image output. The user can set the image size, the circle factor and the radius of the circle according to operational requirements. The visibility marker’s diagrams for 1000 m and 50000 m can be synthesized in one diagram, meeting the operation needs of the current minimum visibility observation. The system is highly automated, easy to operate, with high practicability. Widely use of the system will decrease obviously the workload of operational staff.
2012, 38(3):381-384.
DOI: 10.7519/j.issn.1000-0526.2012.03.019
Abstract:
There are two soil surface temperature measurement methods at present: One is the foursensorcombination mode and the other is the single sensor mode. Through the analysis on the measurement mode of soil surface temperature sensor and the signal acquisition principle, the authors discuss a measuring technique of using the single temperature sensor to substitute four temperature sensors. Besides, the improvement of measurement mode meets requirement of the groundbased weather observation standard of 2003 edition issued by the China Meteorological Administration. It has guaranteed uniformity and commensurability of the measurement mode of soil surface temperature. Meanwhile it cuts down the breakdown probability of temperature sensor and reduces the maintenance cost of AWS, which is easy to promote the application.
There are two soil surface temperature measurement methods at present: One is the foursensorcombination mode and the other is the single sensor mode. Through the analysis on the measurement mode of soil surface temperature sensor and the signal acquisition principle, the authors discuss a measuring technique of using the single temperature sensor to substitute four temperature sensors. Besides, the improvement of measurement mode meets requirement of the groundbased weather observation standard of 2003 edition issued by the China Meteorological Administration. It has guaranteed uniformity and commensurability of the measurement mode of soil surface temperature. Meanwhile it cuts down the breakdown probability of temperature sensor and reduces the maintenance cost of AWS, which is easy to promote the application.
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