ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 38,Issue 6,2012 Table of Contents
2012, 38(6):641-645.
DOI: 10.7519/j.issn.1000-0526.2012.06.001
Abstract:
Based on the basic meaning of these words related to the typhoon movement and the special horizontal structure of typhoon, we focused on the ambiguous statements of landfall, touch and graze typhoon, and analyzed the location relationship between coastline and the position of typhoon when it moves along or close to the coastline, thus obtained a specific method to identify the landfall and touch typhoon, so as to avoid the possible confusion of wording in operational forecasting.
Based on the basic meaning of these words related to the typhoon movement and the special horizontal structure of typhoon, we focused on the ambiguous statements of landfall, touch and graze typhoon, and analyzed the location relationship between coastline and the position of typhoon when it moves along or close to the coastline, thus obtained a specific method to identify the landfall and touch typhoon, so as to avoid the possible confusion of wording in operational forecasting.
2012, 38(6):646-656.
DOI: 10.7519/j.issn.1000-0526.2012.06.002
Abstract:
A climatology of cyclogenesis frequency of extratropical cyclones in the Northern Hemisphere and East Asia for the years of 1958 to 2001, and the interdecadal variation and possible causes, were analyzed by applying an improved objective detecting and tracking algorithm to the six hourly sea level pressure fields in the European Center for Medium range Weather Forecasts reanalysis data ERA40. The result shows that: (1) major source regions of extratropical cyclones in the Northern Hemisphere are eastern North America (downstream areas of Rocky Mountains), Northwest Atlantic, Greenland Northern Europe, Mongolia and Japan Northwest Pacific. Atmospheric baroclinicity and positive vorticity are apt to intensify and develop in ocean west bank and leeward slope of steep orography, which makes for the formation of ground cyclones. (2) The cyclogenesis number of annual, spring and winter indicated a decrease trend in the region of 30°-60°N and an increase trend in the region of 60°-90°N, which supports the viewpoint of the northward shift of storm tracks in the Northern Hemisphere. The cyclone number also had a negative and positive correlation with Arctic Oscillation index (AO) in the south and north of 60°N respectively, especially for annual, spring and autumn. (3) The annual cyclone number in East Asia from 1958 to 2001 indicated obvious interdecadal variations. The cyclone number increased from 1960s to mid 1980s but reduced after mid 1980s in the region of 40°-60°N, 80°-140°E. This is because atmospheric baroclinicity weakened in this region, while strengthened in the higher latitude region, resulting in the northward shift of cyclone source region. There is a linear increased trend of cyclone numbers in the lower latitude region of 20°-40°N, 110°-160°E, mainly because the North Pacific storm track, located in 40°-55°N, had a shift trend to lower latitudes.
A climatology of cyclogenesis frequency of extratropical cyclones in the Northern Hemisphere and East Asia for the years of 1958 to 2001, and the interdecadal variation and possible causes, were analyzed by applying an improved objective detecting and tracking algorithm to the six hourly sea level pressure fields in the European Center for Medium range Weather Forecasts reanalysis data ERA40. The result shows that: (1) major source regions of extratropical cyclones in the Northern Hemisphere are eastern North America (downstream areas of Rocky Mountains), Northwest Atlantic, Greenland Northern Europe, Mongolia and Japan Northwest Pacific. Atmospheric baroclinicity and positive vorticity are apt to intensify and develop in ocean west bank and leeward slope of steep orography, which makes for the formation of ground cyclones. (2) The cyclogenesis number of annual, spring and winter indicated a decrease trend in the region of 30°-60°N and an increase trend in the region of 60°-90°N, which supports the viewpoint of the northward shift of storm tracks in the Northern Hemisphere. The cyclone number also had a negative and positive correlation with Arctic Oscillation index (AO) in the south and north of 60°N respectively, especially for annual, spring and autumn. (3) The annual cyclone number in East Asia from 1958 to 2001 indicated obvious interdecadal variations. The cyclone number increased from 1960s to mid 1980s but reduced after mid 1980s in the region of 40°-60°N, 80°-140°E. This is because atmospheric baroclinicity weakened in this region, while strengthened in the higher latitude region, resulting in the northward shift of cyclone source region. There is a linear increased trend of cyclone numbers in the lower latitude region of 20°-40°N, 110°-160°E, mainly because the North Pacific storm track, located in 40°-55°N, had a shift trend to lower latitudes.
2012, 38(6):657-668.
DOI: 10.7519/j.issn.1000-0526.2012.06.003
Abstract:
Using the output from the run of GRAPES Meso for the six venues during the Vancouver 2010 Winter Olympic and Paralympic Games, its capability to forecast the 2 m temperature, relative humidity, 10 m wind speed and wind direction is evaluated in terms of the forecast accuracy, mean error, mean absolute error and Alpha Index. And also statistics TS, EH, PO, NH, B and ETS are used for the verification of precipitation. The results show that the forecast accuracy of relative humidity is the highest and the forecast performance tends to be steady with the increasing leading time. The model exhibits a cold bias for temperature forecast. As for relative humidity, the forecast experiences a gradual transition from dry bias to wet bias, while wind speed forecast is always larger than observation. Among all the classification for the precipitation, the forecasts of GRAPES Meso for rain or shine have the highest mean TS. And with the increase of precipitation, ETS is gradually close to the TS. At last compared with the other models we found that there are some deficiencies in GRAPES Meso. Through the verification it is found that there is a certain systematic error in the forecasts, and if the error can be effectively reduced then the numerical weather prediction will have a greater improvement.
Using the output from the run of GRAPES Meso for the six venues during the Vancouver 2010 Winter Olympic and Paralympic Games, its capability to forecast the 2 m temperature, relative humidity, 10 m wind speed and wind direction is evaluated in terms of the forecast accuracy, mean error, mean absolute error and Alpha Index. And also statistics TS, EH, PO, NH, B and ETS are used for the verification of precipitation. The results show that the forecast accuracy of relative humidity is the highest and the forecast performance tends to be steady with the increasing leading time. The model exhibits a cold bias for temperature forecast. As for relative humidity, the forecast experiences a gradual transition from dry bias to wet bias, while wind speed forecast is always larger than observation. Among all the classification for the precipitation, the forecasts of GRAPES Meso for rain or shine have the highest mean TS. And with the increase of precipitation, ETS is gradually close to the TS. At last compared with the other models we found that there are some deficiencies in GRAPES Meso. Through the verification it is found that there is a certain systematic error in the forecasts, and if the error can be effectively reduced then the numerical weather prediction will have a greater improvement.
2012, 38(6):669-678.
DOI: 10.7519/j.issn.1000-0526.2012.06.004
Abstract:
In order to study the influence of ice crystal multiplication on non inductive electrification during the development of thunderstorm, a three dimensional numerical model of thunderstorm was used to evaluate the distribution of the variant particles, charge and the electric field in the thunderstorm with an ideal environment. The result shows that there is an ice crystal gathering area in the lower part of the thunderstorm with ice crystal multiplication during its development and mature stage. It makes the number of ice crystals in the case of multiplication increase by 15%-18% and the gathering area become larger compared to the condition without multiplication. And multiplication also makes the number of graupel particles in the condition with multiplication increase about 20%. The positive charged region always occurs nearby the area with high graupel concentration, while the negative charged region always appears in the overlap region with the high ice and graupel concentrations. Multiplication firstly influences the ice and graupel concentration and spacial distribution, then makes the non inductive electrification in thunderstorm more powerful and location change, and even the electrification process in single cell storm starts ahead 5-6 min.
In order to study the influence of ice crystal multiplication on non inductive electrification during the development of thunderstorm, a three dimensional numerical model of thunderstorm was used to evaluate the distribution of the variant particles, charge and the electric field in the thunderstorm with an ideal environment. The result shows that there is an ice crystal gathering area in the lower part of the thunderstorm with ice crystal multiplication during its development and mature stage. It makes the number of ice crystals in the case of multiplication increase by 15%-18% and the gathering area become larger compared to the condition without multiplication. And multiplication also makes the number of graupel particles in the condition with multiplication increase about 20%. The positive charged region always occurs nearby the area with high graupel concentration, while the negative charged region always appears in the overlap region with the high ice and graupel concentrations. Multiplication firstly influences the ice and graupel concentration and spacial distribution, then makes the non inductive electrification in thunderstorm more powerful and location change, and even the electrification process in single cell storm starts ahead 5-6 min.
2012, 38(6):679-687.
DOI: 10.7519/j.issn.1000-0526.2012.06.005
Abstract:
The circulation background and characteristics of meteorological element distribution are analyzed on a wide spread radiation fog that occurred in January 2010 over the Central China area. Observation and simulation of the wide spread radiation fog over Hunan are investigated by using a new generation of high resolution Weather Research and Forecasting (WRF) Model. The results show that there are two obvious inversion layers occurring in the evolution process of the radiation fog. One is the subsidence inversion formed by the high altitude systemic northerly airstream, which is located near 700 hPa with the stable atmospheric stratification, and thus low level water vapor can not be propagated upward, and therefore provides high humidity conditions for the fog formation. The other is the radiation inversion formed from the surface cooling effect of radiation, which is the main factor for the formation and development of this fog. However, for the dissipation of the fog the main cause is the surface heating by solar shortwave radiation after sunrise and heat transportation. In addition, it shows that there are better simulation results by using WRF model when T213 data are used as the initial conditions instead of NCEP reanalysis. The overlap zone of the maximum U value below 900 m with large inversion ≥ 5℃ corresponds well with the fog. At the north of the rivers and lakes, moreover after high ridge changed into high rear sector near the surface, the advection fog appears likely due to the effect of water vapor transport by low level southerly flow. There is a gap of the near surface layer of elements between the simulation from WRF model and observations, and the assimilation of observation data must be considered in the simulation.
The circulation background and characteristics of meteorological element distribution are analyzed on a wide spread radiation fog that occurred in January 2010 over the Central China area. Observation and simulation of the wide spread radiation fog over Hunan are investigated by using a new generation of high resolution Weather Research and Forecasting (WRF) Model. The results show that there are two obvious inversion layers occurring in the evolution process of the radiation fog. One is the subsidence inversion formed by the high altitude systemic northerly airstream, which is located near 700 hPa with the stable atmospheric stratification, and thus low level water vapor can not be propagated upward, and therefore provides high humidity conditions for the fog formation. The other is the radiation inversion formed from the surface cooling effect of radiation, which is the main factor for the formation and development of this fog. However, for the dissipation of the fog the main cause is the surface heating by solar shortwave radiation after sunrise and heat transportation. In addition, it shows that there are better simulation results by using WRF model when T213 data are used as the initial conditions instead of NCEP reanalysis. The overlap zone of the maximum U value below 900 m with large inversion ≥ 5℃ corresponds well with the fog. At the north of the rivers and lakes, moreover after high ridge changed into high rear sector near the surface, the advection fog appears likely due to the effect of water vapor transport by low level southerly flow. There is a gap of the near surface layer of elements between the simulation from WRF model and observations, and the assimilation of observation data must be considered in the simulation.
2012, 38(6):688-694.
DOI: 10.7519/j.issn.1000-0526.2012.06.006
Abstract:
A case of sustained low horizontal visibility occurred in Tianjin during January 2009. From the perspective of the meteorological factors, the evolution process of air pollution and air backward trajectory, this event was mainly caused by fine particles in haze weather conditions. The result indicated that fine particle mass concentration was the main influence factor of horizontal visibility. The increase of the ratio of PM2.5 to PM10 resulted in the persistent air pollution and the continuous declined visibility, which was affected in the calm weather conditions under the control of southwest warm and moist air flow. Simulations of the backward trajectory model HYSPLIT have indicated that the aerosol pollutions come from southwestern region and surrounding areas, and cold waves are the important clearance mechanism of regional fine particle pollution in Tianjin. The cyclical change of visibility is caused by the enrichment of fine particle and the quick removal of air pollution, and is also affected by the periodic weather systems.
A case of sustained low horizontal visibility occurred in Tianjin during January 2009. From the perspective of the meteorological factors, the evolution process of air pollution and air backward trajectory, this event was mainly caused by fine particles in haze weather conditions. The result indicated that fine particle mass concentration was the main influence factor of horizontal visibility. The increase of the ratio of PM2.5 to PM10 resulted in the persistent air pollution and the continuous declined visibility, which was affected in the calm weather conditions under the control of southwest warm and moist air flow. Simulations of the backward trajectory model HYSPLIT have indicated that the aerosol pollutions come from southwestern region and surrounding areas, and cold waves are the important clearance mechanism of regional fine particle pollution in Tianjin. The cyclical change of visibility is caused by the enrichment of fine particle and the quick removal of air pollution, and is also affected by the periodic weather systems.
2012, 38(6):695-700.
DOI: 10.7519/j.issn.1000-0526.2012.06.007
Abstract:
Forecast errors for different typhoon types, typhoon landfall position and time, typhoon locating in different position from coastline, typhoon landfall in East China and South China are issued based on typhoon track operational forecast data and best track data in the western North Pacific (the South China Sea is included) provided by China Meteorological Administration (CMA) from 2005 to 2009. The results show that typhoon track forecast during 2005-2009 is more skillful than from 1999 to 2003. Average typhoon forecast bias in the South China Sea (SCS) is larger than in western North Pacific (WNP).Unusual typhoon track mainly occurred in the SCS and their forecast errors are smaller than usual typhoon tracks for 24 h, 48 h and 72 h forecast periods. The forecast error is the largest during typhoon approaching coastline period among typhoon far away from coastline, approaching coastline and landfall later periods and it is larger for typhoon landfall in South China than in East China during same period. The average forecast errors are 71.1 km, 122.6 km and 210.6 km of typhoon landfall position for 24 h, 48 h and 72 h forecast periods, respectively. Timing errors of 70% landfall typhoons demonstrate an early bias of 8 h and 12 h against forecast landfall for 48 h and 72 h forecast periods. Compared with large scale steering flow to typhoon movement and 24 h forecast errors, the results also show that there are different bias between large scale steering flow and typhoon movement among three typical landfall typhoon tracks and relationships between these biases and 24 h typhoon forecast track errors. Parabolic typhoon movements in the SCS have the largest bias between the steering flow and typhoon movement, but have the smallest forecast errors; the largest forecast error for west to northwestward moving typhoon is not corresponding to its smaller bias between steering flow and typhoon movement, which may be related to low skillful forecast of large scale circulation. The forecast error of typhoon landfall in East China is smaller than in South China, which is consistent with the bias of the former between steering flow and typhoon movement being smaller than the latter.
Forecast errors for different typhoon types, typhoon landfall position and time, typhoon locating in different position from coastline, typhoon landfall in East China and South China are issued based on typhoon track operational forecast data and best track data in the western North Pacific (the South China Sea is included) provided by China Meteorological Administration (CMA) from 2005 to 2009. The results show that typhoon track forecast during 2005-2009 is more skillful than from 1999 to 2003. Average typhoon forecast bias in the South China Sea (SCS) is larger than in western North Pacific (WNP).Unusual typhoon track mainly occurred in the SCS and their forecast errors are smaller than usual typhoon tracks for 24 h, 48 h and 72 h forecast periods. The forecast error is the largest during typhoon approaching coastline period among typhoon far away from coastline, approaching coastline and landfall later periods and it is larger for typhoon landfall in South China than in East China during same period. The average forecast errors are 71.1 km, 122.6 km and 210.6 km of typhoon landfall position for 24 h, 48 h and 72 h forecast periods, respectively. Timing errors of 70% landfall typhoons demonstrate an early bias of 8 h and 12 h against forecast landfall for 48 h and 72 h forecast periods. Compared with large scale steering flow to typhoon movement and 24 h forecast errors, the results also show that there are different bias between large scale steering flow and typhoon movement among three typical landfall typhoon tracks and relationships between these biases and 24 h typhoon forecast track errors. Parabolic typhoon movements in the SCS have the largest bias between the steering flow and typhoon movement, but have the smallest forecast errors; the largest forecast error for west to northwestward moving typhoon is not corresponding to its smaller bias between steering flow and typhoon movement, which may be related to low skillful forecast of large scale circulation. The forecast error of typhoon landfall in East China is smaller than in South China, which is consistent with the bias of the former between steering flow and typhoon movement being smaller than the latter.
2012, 38(6):701-711.
DOI: 10.7519/j.issn.1000-0526.2012.06.008
Abstract:
The climate system is nonlinear and non stationary, in addition, it is also hierarchic, thus it is a multi level structure formed by many different spatio temporal scales, and each spatio temporal scale has different predictability and stability respectively. When we research a meteorological drought index, we generally consider the precipitation, temperature, relative moisture of soil and other essential factors in certain period of time. By taking account of the climatic characteristics of different regions, the comentropy method is first used to obtain the two intrinsic scales of zonal precipitation i.e. the homogeneous state intrinsic scale and the variational state intrinsic scale because of the conception that the climate system is nonlinear, non stationary and hierarchic, then a new meteorological drought index named MSPI is developed. Afterwards, the appearance, development, continuance and alleviation of the severe meteorological drought in the middle and lower reaches of the Changjiang River in 2011 are taken as an example to examine the ability of MSPI to monitor the meteorological drought. The result shows that MSPI can monitor meteorological drought at different grades and can distinguish the course of meteorological drought perfectly. Taking all factors into consideration, we think that the MSPI is an efficacious meteorological drought index which can meet the demands to monitor and detect meteorological drought. In practice, the MSPI could be as a useful complement to other meteorological drought indices.
The climate system is nonlinear and non stationary, in addition, it is also hierarchic, thus it is a multi level structure formed by many different spatio temporal scales, and each spatio temporal scale has different predictability and stability respectively. When we research a meteorological drought index, we generally consider the precipitation, temperature, relative moisture of soil and other essential factors in certain period of time. By taking account of the climatic characteristics of different regions, the comentropy method is first used to obtain the two intrinsic scales of zonal precipitation i.e. the homogeneous state intrinsic scale and the variational state intrinsic scale because of the conception that the climate system is nonlinear, non stationary and hierarchic, then a new meteorological drought index named MSPI is developed. Afterwards, the appearance, development, continuance and alleviation of the severe meteorological drought in the middle and lower reaches of the Changjiang River in 2011 are taken as an example to examine the ability of MSPI to monitor the meteorological drought. The result shows that MSPI can monitor meteorological drought at different grades and can distinguish the course of meteorological drought perfectly. Taking all factors into consideration, we think that the MSPI is an efficacious meteorological drought index which can meet the demands to monitor and detect meteorological drought. In practice, the MSPI could be as a useful complement to other meteorological drought indices.
2012, 38(6):712-721.
DOI: 10.7519/j.issn.1000-0526.2012.06.009
Abstract:
As we well know that, it is meaningful if we obtain the exact altitude of the melting layer, its depth and much more other information about cloud, and we could utilize them in retrieving cloud microphysics, weather modification, cloud parameterization of numerical modeling and its evaluation. In order to acquaint the definite location of the metling layer in a cloud, in this paper, first of all we have analyzed 456 cases observed at Guangdong, Hebei and Jilin by our could radar during recent three years, and there are 34 cases in which appear notable metling features. Secondly we take account of the macroscopic parameters’ characteristics, such as the depth of melting layer, the variation of the radar reflectivity at the melting layer. And then one method is proposed which makes use of the vertical profile of radar reflectivity and linear depolarization ratio to identify the altitude and depth of the melting layer. Afterwards, we select and use the rawinsonde data at the same time for the same case to make comparative experiments, which show that the results of the two kinds of data are very closer， the result by inversion method is nearly below the 0° line of the rawinsonde data, and the linear depolarization ratio indicates more sensitive than the radar reflectivity to the melting layer.
As we well know that, it is meaningful if we obtain the exact altitude of the melting layer, its depth and much more other information about cloud, and we could utilize them in retrieving cloud microphysics, weather modification, cloud parameterization of numerical modeling and its evaluation. In order to acquaint the definite location of the metling layer in a cloud, in this paper, first of all we have analyzed 456 cases observed at Guangdong, Hebei and Jilin by our could radar during recent three years, and there are 34 cases in which appear notable metling features. Secondly we take account of the macroscopic parameters’ characteristics, such as the depth of melting layer, the variation of the radar reflectivity at the melting layer. And then one method is proposed which makes use of the vertical profile of radar reflectivity and linear depolarization ratio to identify the altitude and depth of the melting layer. Afterwards, we select and use the rawinsonde data at the same time for the same case to make comparative experiments, which show that the results of the two kinds of data are very closer， the result by inversion method is nearly below the 0° line of the rawinsonde data, and the linear depolarization ratio indicates more sensitive than the radar reflectivity to the melting layer.
2012, 38(6):722-727.
DOI: 10.7519/j.issn.1000-0526.2012.06.010
Abstract:
In order to get a relatively objective assessment for the storm cell identification and tracking (SCIT) and the mesocyclone detection algorithm (MDA) products’ application in China, and then to provide reference of the products for future use, the performance evaluation of two kinds of products on the current business has been done based on the 2007—2008 disaster weather case archives offered by CMA Meteorological Observation Centre. The results of the evaluation are compared with the United States’ and show that the SCIT products can meet the basic needs of nowcasting, but the leak detection and error tracking exist, and when the lead time exceeds 30 min, the location prediction error can be big. The performance evaluation of MDA products can be considered similar to the United States’, and basically can automatically identify the storm vortex, but there are still some missings, and the false alarm rate is high.
In order to get a relatively objective assessment for the storm cell identification and tracking (SCIT) and the mesocyclone detection algorithm (MDA) products’ application in China, and then to provide reference of the products for future use, the performance evaluation of two kinds of products on the current business has been done based on the 2007—2008 disaster weather case archives offered by CMA Meteorological Observation Centre. The results of the evaluation are compared with the United States’ and show that the SCIT products can meet the basic needs of nowcasting, but the leak detection and error tracking exist, and when the lead time exceeds 30 min, the location prediction error can be big. The performance evaluation of MDA products can be considered similar to the United States’, and basically can automatically identify the storm vortex, but there are still some missings, and the false alarm rate is high.
2012, 38(6):728-732.
DOI: 10.7519/j.issn.1000-0526.2012.06.011
Abstract:
The relation of annual thunderstorm days and annual mean lightning density is researched by statistical analysis in different radius areas from the meteorological stations, based on the cloud ground lightning data detected by the Hubei ADTD lightning position determination and monitoring system from 2007 to 2010 and the thunderstorm days of the 28 meteorological stations where lightning monitoring detection efficiency is above 95%. The results have indicated that, in the 18-20 km radius region, the correlation coefficient is obviously increased. When the radius is 18 km, the correlation coefficient reaches a maximum value of 0.8521. Thus we can consider that generally observers only can hear thunderclap in the 18-20 km radius region. The relations of annual thunderstorm days and annual mean lightning density is formulated by statistical fitting: NG=0.029Td1.5, and this equation even surpasses the standard equation (Ng=0.024Td1.3) obviously through the verification of the data in 2011.
The relation of annual thunderstorm days and annual mean lightning density is researched by statistical analysis in different radius areas from the meteorological stations, based on the cloud ground lightning data detected by the Hubei ADTD lightning position determination and monitoring system from 2007 to 2010 and the thunderstorm days of the 28 meteorological stations where lightning monitoring detection efficiency is above 95%. The results have indicated that, in the 18-20 km radius region, the correlation coefficient is obviously increased. When the radius is 18 km, the correlation coefficient reaches a maximum value of 0.8521. Thus we can consider that generally observers only can hear thunderclap in the 18-20 km radius region. The relations of annual thunderstorm days and annual mean lightning density is formulated by statistical fitting: NG=0.029Td1.5, and this equation even surpasses the standard equation (Ng=0.024Td1.3) obviously through the verification of the data in 2011.
PANG Wenbao
,
BAI Guangbi
,
LI Jianke
,
YANG Yanchao
,
SONG Hong
,
CHEN Leihua
,
WANG Xiaoning
,
FENG Xiaoxu
2012, 38(6):733-739.
DOI: 10.7519/j.issn.1000-0526.2012.06.012
Abstract:
Based on wire icing observations at Huashan Meteorological Station from 1980 to 2007 and convention observational data at 95 meteorological stations in Shaanxi Province, the correlations of wire icing thickness with convention meteorological data were analyzed. On this basis, we calculated the standard wire icing thickness at 10 m height above the ground level over the years, estimated the extreme wire icing thickness with a recurrence period of 30 years and of 50 years by means of the method of extreme value type I distribution. According to the design experience of the Shaanxi Electric Power Design Institution, the present situation in Shaanxi Province Electric Power System and historical electrical network icing accident investigations, an elementary grid icing division is made. The results are presented as follows，the biggest icing thickness has positive relationships with annual rime days and annual glaze days. Six different regions of wire icing were separated across the province, and wire icing maps of 1 to 500000 scales with a recurrence period of 30 years and of 50 years were drawn. This result has been used as important basis for wire icing thickness design in the Shaanxi Province electric power construction.
Based on wire icing observations at Huashan Meteorological Station from 1980 to 2007 and convention observational data at 95 meteorological stations in Shaanxi Province, the correlations of wire icing thickness with convention meteorological data were analyzed. On this basis, we calculated the standard wire icing thickness at 10 m height above the ground level over the years, estimated the extreme wire icing thickness with a recurrence period of 30 years and of 50 years by means of the method of extreme value type I distribution. According to the design experience of the Shaanxi Electric Power Design Institution, the present situation in Shaanxi Province Electric Power System and historical electrical network icing accident investigations, an elementary grid icing division is made. The results are presented as follows，the biggest icing thickness has positive relationships with annual rime days and annual glaze days. Six different regions of wire icing were separated across the province, and wire icing maps of 1 to 500000 scales with a recurrence period of 30 years and of 50 years were drawn. This result has been used as important basis for wire icing thickness design in the Shaanxi Province electric power construction.
2012, 38(6):740-744.
DOI: 10.7519/j.issn.1000-0526.2012.06.013
Abstract:
By using clinical data from Central Hospital of Baishan City, Jilin Province and meteorological data， the relationship between colds and weather conditions is analyzed. It indicates that the incidence of colds is closely related with the previous weather changes. A significant weather change process does not correspond with a single high incidence day, but a sustained high incidence stage. The impacts of meteorological environment on the incidence of colds in different population are different. For adults, higher incidence happens when autumn turns into winter and summer turns into autumn; for infants, it happens in midsummer and midwinter due to their poor adaptability to seasonal and weather change and apparent response to cold and hot weather; for children, the feature of incidence is the same as infants in spring and summer, and close to adults in autumn and winter. A discriminant equation to forecast the colds index is established on the basis of correlation analysis between the numbers of colds inpatients among different people and meteorological elements, and proved to have a good prediction level by prediction test.
By using clinical data from Central Hospital of Baishan City, Jilin Province and meteorological data， the relationship between colds and weather conditions is analyzed. It indicates that the incidence of colds is closely related with the previous weather changes. A significant weather change process does not correspond with a single high incidence day, but a sustained high incidence stage. The impacts of meteorological environment on the incidence of colds in different population are different. For adults, higher incidence happens when autumn turns into winter and summer turns into autumn; for infants, it happens in midsummer and midwinter due to their poor adaptability to seasonal and weather change and apparent response to cold and hot weather; for children, the feature of incidence is the same as infants in spring and summer, and close to adults in autumn and winter. A discriminant equation to forecast the colds index is established on the basis of correlation analysis between the numbers of colds inpatients among different people and meteorological elements, and proved to have a good prediction level by prediction test.
2012, 38(6):745-750.
DOI: 10.7519/j.issn.1000-0526.2012.06.014
Abstract:
Based on the data of dew and frost from 2009 to 2010 recorded by automatic weather station(AWS), manual observation data in Miyun and Dianbai National Reference Climatological Stations and the AWS records and the weather observation data of Pinggu Ordinary Climatological Station from December 2010 to May 2011, the relationships between surface meteorological factors and dew or frost were analyzed. The results show that: the grass temperature and the difference between grass temperature and dew point temperature can be an indicator of dew and frost; 95.0% dews occur in the conditions of the difference being <1.1℃ in Dianbai Station, and 95.0% dews and 95.0% frosts occur when the difference is <1.2℃ and <1.3℃ respectively in Miyun Station. Dew mainly occurs when the minimum grass temperature is -0.5℃, from the analysis of automatic present weather observation data in Pinggu Station, it can be seen that dew occurs when the temperature is above zero, while frost occurs when the temperature is below zero. In many cases, the water vapor content of atmosphere at the height of thermometer screen is not saturated, while the water vapor content of groud hugging (or close to the surface features) atmosphere is saturated. In the conditions of the difference between the minimum grass temperature and the dew point temperature in a day being <3.1℃, the proportion of no dew and frost is 16.8% and 11.7% in the two stations. The proportion of positive difference between grass temperature and dew point temperature in the South China is larger than that in the North China because the soil moisture in the South China is larger than that in the North China.
Based on the data of dew and frost from 2009 to 2010 recorded by automatic weather station(AWS), manual observation data in Miyun and Dianbai National Reference Climatological Stations and the AWS records and the weather observation data of Pinggu Ordinary Climatological Station from December 2010 to May 2011, the relationships between surface meteorological factors and dew or frost were analyzed. The results show that: the grass temperature and the difference between grass temperature and dew point temperature can be an indicator of dew and frost; 95.0% dews occur in the conditions of the difference being <1.1℃ in Dianbai Station, and 95.0% dews and 95.0% frosts occur when the difference is <1.2℃ and <1.3℃ respectively in Miyun Station. Dew mainly occurs when the minimum grass temperature is -0.5℃, from the analysis of automatic present weather observation data in Pinggu Station, it can be seen that dew occurs when the temperature is above zero, while frost occurs when the temperature is below zero. In many cases, the water vapor content of atmosphere at the height of thermometer screen is not saturated, while the water vapor content of groud hugging (or close to the surface features) atmosphere is saturated. In the conditions of the difference between the minimum grass temperature and the dew point temperature in a day being <3.1℃, the proportion of no dew and frost is 16.8% and 11.7% in the two stations. The proportion of positive difference between grass temperature and dew point temperature in the South China is larger than that in the North China because the soil moisture in the South China is larger than that in the North China.
2012, 38(6):751-757.
DOI: 10.7519/j.issn.1000-0526.2012.06.015
Abstract:
The following are the main characteristics of the general circulation of atmosphere in March 2012. There are multi polar vortex centers in the Northern Hemisphere with slightly stronger strength than normal years. The circulation presents a four wave pattern in middle high latitudes. The south branch trough is slightly stronger than normal years and the situation is favorable for the transportation of water vapor. The strength of the Western Pacific subtropical high is weaker than normal years. The monthly mean temperature is 3.5℃， which is lower than the same period of normal years. The mean precipitation (31.4 mm) is 8.7% more than normal. There are 3 cold surge processes affecting China in this month, the first sand and dust weather process appeared in northern China, and the continuous low temperature and rainy weather occurred in southern China for a long time.
The following are the main characteristics of the general circulation of atmosphere in March 2012. There are multi polar vortex centers in the Northern Hemisphere with slightly stronger strength than normal years. The circulation presents a four wave pattern in middle high latitudes. The south branch trough is slightly stronger than normal years and the situation is favorable for the transportation of water vapor. The strength of the Western Pacific subtropical high is weaker than normal years. The monthly mean temperature is 3.5℃， which is lower than the same period of normal years. The mean precipitation (31.4 mm) is 8.7% more than normal. There are 3 cold surge processes affecting China in this month, the first sand and dust weather process appeared in northern China, and the continuous low temperature and rainy weather occurred in southern China for a long time.
2012, 38(6):758-763.
DOI: 10.7519/j.issn.1000-0526.2012.06.016
Abstract:
In this paper, a new application manner by on line analyses for the stacked spectral plots (SSP) in the control & dwell display window of boundary wind profiler (BWP) obtained during the rainfall time periods has been introduced. The paper has described the principle and method of BWP on line analyses in detail, and by combined with some typical cases of precipitation SSP analyses, the evidences of potential parameters extracted from SSP have been presented. The advantages and benefits for implementation on line analyses on SSP of precipitation, including extension application fields of BWP from clear air to rainfall weather, mitigation current BWP’s application bottle neck, as well as indirect verification of the standpoint for non constant interval distance in BWP networking, have been indicated. It is believed that during the precipitation time sections BWP will be a very important tool for the weather stations to carry out detailed weather surveillance and forecast/service with the manner application and expansion of on line analyses of BWP.
In this paper, a new application manner by on line analyses for the stacked spectral plots (SSP) in the control & dwell display window of boundary wind profiler (BWP) obtained during the rainfall time periods has been introduced. The paper has described the principle and method of BWP on line analyses in detail, and by combined with some typical cases of precipitation SSP analyses, the evidences of potential parameters extracted from SSP have been presented. The advantages and benefits for implementation on line analyses on SSP of precipitation, including extension application fields of BWP from clear air to rainfall weather, mitigation current BWP’s application bottle neck, as well as indirect verification of the standpoint for non constant interval distance in BWP networking, have been indicated. It is believed that during the precipitation time sections BWP will be a very important tool for the weather stations to carry out detailed weather surveillance and forecast/service with the manner application and expansion of on line analyses of BWP.
2012, 38(6):764-768.
DOI: 10.7519/j.issn.1000-0526.2012.06.017
Abstract:
In order to satisfy the needs of agrometeorological observation, a soil moisture detection system using frequency domain reflectometry (FDR) was designed. It includes FDR sensors, data acquisition and remote data management. The FDR measurement is based on transmission theory and resonance circuit, and data acquisition part takes full account of signals anti interference ability and error correction methods. Data measured are transferred to central database in wireless communication mode first, and then are sent back to local stations through Internet. Results show that this system can run continuously and stably. Data revised are close to that from drying method. Errors less than 2% tell that this system can totally meet the needs of agrometeorological observation.
In order to satisfy the needs of agrometeorological observation, a soil moisture detection system using frequency domain reflectometry (FDR) was designed. It includes FDR sensors, data acquisition and remote data management. The FDR measurement is based on transmission theory and resonance circuit, and data acquisition part takes full account of signals anti interference ability and error correction methods. Data measured are transferred to central database in wireless communication mode first, and then are sent back to local stations through Internet. Results show that this system can run continuously and stably. Data revised are close to that from drying method. Errors less than 2% tell that this system can totally meet the needs of agrometeorological observation.
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ISSN:1000-0526 CN:11-2282/P