Volume 36,Issue 2,2008 Table of Contents
2008, 36(2):129-133.
Abstract:
A number of conventional physical variables and convective parameters are computed with mesoscale numerical weather model AREM (Advanced Regional ηcoordinate). The methods for diagnosing severe storm potential are studied accordingly in combination with the fuzzy logic method. Potential forecast products for the location of hailfall, disastrous gust and thunderstorm are developed. The results show that the method can diagnosis well the type and location of severe convective weather, and is of important value for nowcasting in evaluating severe weather potential.
A number of conventional physical variables and convective parameters are computed with mesoscale numerical weather model AREM (Advanced Regional ηcoordinate). The methods for diagnosing severe storm potential are studied accordingly in combination with the fuzzy logic method. Potential forecast products for the location of hailfall, disastrous gust and thunderstorm are developed. The results show that the method can diagnosis well the type and location of severe convective weather, and is of important value for nowcasting in evaluating severe weather potential.
2008, 36(2):134-138.
Abstract:
Some comparative prediction experiments with different physics parameterization schemes are conducted on precipitation over the middle reaches of the Changjiang River in flood season. The results show that different physic parameterization schemes can lead to different forecasting results, which becomes more evident in predicting highergrade precipitation. In the experiments, the forecasting combined the Grell cumulus parameterization scheme with the Blackadar planetary boundary layer scheme is better than others. However, for a certain case, it is uncertain which scheme is better. The result of ensemble mean prediction is relatively stable and superior to most single predictions. The improvements in precipitation prediction can be seen mainly in the situation with the rainfall being less than 50 mm.
Some comparative prediction experiments with different physics parameterization schemes are conducted on precipitation over the middle reaches of the Changjiang River in flood season. The results show that different physic parameterization schemes can lead to different forecasting results, which becomes more evident in predicting highergrade precipitation. In the experiments, the forecasting combined the Grell cumulus parameterization scheme with the Blackadar planetary boundary layer scheme is better than others. However, for a certain case, it is uncertain which scheme is better. The result of ensemble mean prediction is relatively stable and superior to most single predictions. The improvements in precipitation prediction can be seen mainly in the situation with the rainfall being less than 50 mm.
2008, 36(2):139-144.
Abstract:
The prediction models of droughts and floods in flood season over Zhejiang Province are built based on the Support Vector Machine (SVM) method. By use of rainfall data from 38 observation stations, the indexes of drought and flood intensities are devised, which can represent the overall state of droughts and floods in Zhejiang Province. Taking the indexes as predictands and antecedent atmospheric circulation and SST, which exhibit high correlation with the predictands, as predictors, the prediction models of droughts and floods for Zhejiang based on the and regression method are built, respectively. The comparison between the prediction results by two methods shows that the SVM prediction model could make use of the plentiful predictor’s information and nonlinear projection capability effectively, and shows better performance,which was confirmed by both training and testing samples.
The prediction models of droughts and floods in flood season over Zhejiang Province are built based on the Support Vector Machine (SVM) method. By use of rainfall data from 38 observation stations, the indexes of drought and flood intensities are devised, which can represent the overall state of droughts and floods in Zhejiang Province. Taking the indexes as predictands and antecedent atmospheric circulation and SST, which exhibit high correlation with the predictands, as predictors, the prediction models of droughts and floods for Zhejiang based on the and regression method are built, respectively. The comparison between the prediction results by two methods shows that the SVM prediction model could make use of the plentiful predictor’s information and nonlinear projection capability effectively, and shows better performance,which was confirmed by both training and testing samples.
2008, 36(2):145-149.
Abstract:
The distribution of summerhalf year rainfall in the Pearl River basin is obtained with the monthly rainfall data of April to September from 1954 to 2003 in the basin, the antecedent Pacific SST (Sea Surface Temperature) field and 500 hPa height field, by means of the principalcomponent〖CD*2〗stepwiseregression prediction model. The results show that the first 25 principal components of summer half year rainfall can well describe the variation of summer half year rainfall in the basin. The distribution prediction of summerhalf year rainfall from 2004 to 2006 in the basin shows that the prediction results are similar to the real distribution. The prediction factors taking from the principal components of the 500 hPa height field and the SST field over the North Pacific contain a large amount of useful information for rainfall prediction. The method has certain significance for operational prediction.
The distribution of summerhalf year rainfall in the Pearl River basin is obtained with the monthly rainfall data of April to September from 1954 to 2003 in the basin, the antecedent Pacific SST (Sea Surface Temperature) field and 500 hPa height field, by means of the principalcomponent〖CD*2〗stepwiseregression prediction model. The results show that the first 25 principal components of summer half year rainfall can well describe the variation of summer half year rainfall in the basin. The distribution prediction of summerhalf year rainfall from 2004 to 2006 in the basin shows that the prediction results are similar to the real distribution. The prediction factors taking from the principal components of the 500 hPa height field and the SST field over the North Pacific contain a large amount of useful information for rainfall prediction. The method has certain significance for operational prediction.
2008, 36(2):150-154.
Abstract:
Based on the synoptic pattern classification and the principles of the Perfect Prognosis method, the thunder/lightning potential forecasts in Guangzhou are studied by using the lightning positioning data, conventional meteorological observational data, operating numerical model output and NCEP/NCAR reanalysis data during the period of 2000 to 2005. By the method of mosaicization of synoptic situation, the concept of uncertainty,and the statistical and mathematical methods such as regression analysis,the synoptic patterns are classified when thunder/lightning occurred；then the functions between meteorological elements and lightning times for each day are developed;accordingly the probability of thuncler/lighting occurence can be obtained. This operational scheme for thunder/lightning potential forecast is running in real time in Guangzhou Central Meteorological Office,which can provide some valuable references for thunder/lightning forecasing.
Based on the synoptic pattern classification and the principles of the Perfect Prognosis method, the thunder/lightning potential forecasts in Guangzhou are studied by using the lightning positioning data, conventional meteorological observational data, operating numerical model output and NCEP/NCAR reanalysis data during the period of 2000 to 2005. By the method of mosaicization of synoptic situation, the concept of uncertainty,and the statistical and mathematical methods such as regression analysis,the synoptic patterns are classified when thunder/lightning occurred；then the functions between meteorological elements and lightning times for each day are developed;accordingly the probability of thuncler/lighting occurence can be obtained. This operational scheme for thunder/lightning potential forecast is running in real time in Guangzhou Central Meteorological Office,which can provide some valuable references for thunder/lightning forecasing.
2008, 36(2):155-159.
Abstract:
A comparative analysis is made of a hail process at Ninghe County on 15 July 2002 and a heavy precipitation at Tianjin on 16 August 2005 by using of weather maps, cloud images, and Tianjin CINRAD/SA products. The emphasis is put on the echoes of mesoscale systems on the velocity field and the image features on the intensity field. The results indicate that though the influencing systems for the two processes are different, there appeared supercell storms on the radar echo images of both, with the heavy supercell accompanying a heavy rain of 77.5 mm per hour and the weak one having hailstones of about 40 mm in diameter. The characteristics on the velocity chart are different too. The heavy precipitation supercell shows the characteristic of “adverse wind area,” while the weak storm shows the characteristic of mesocyclones. The direction turning of radar echoes is also studied and the analysis shows that radar echoes turned to the area with greater hail diameter the rotational velocity in the mesocyclone.
A comparative analysis is made of a hail process at Ninghe County on 15 July 2002 and a heavy precipitation at Tianjin on 16 August 2005 by using of weather maps, cloud images, and Tianjin CINRAD/SA products. The emphasis is put on the echoes of mesoscale systems on the velocity field and the image features on the intensity field. The results indicate that though the influencing systems for the two processes are different, there appeared supercell storms on the radar echo images of both, with the heavy supercell accompanying a heavy rain of 77.5 mm per hour and the weak one having hailstones of about 40 mm in diameter. The characteristics on the velocity chart are different too. The heavy precipitation supercell shows the characteristic of “adverse wind area,” while the weak storm shows the characteristic of mesocyclones. The direction turning of radar echoes is also studied and the analysis shows that radar echoes turned to the area with greater hail diameter the rotational velocity in the mesocyclone.
2008, 36(2):160-163.
Abstract:
In order to effectively forecast or forewarn squall lines and verify the effectiveness of the nowcasting system, a squall line occurring on 1 August 2006 in Beijing is analyzed by using conventional weather data, automatic weather station data, Doppler radar data, and the nowcasting system. The results suggest that the squall line occurred under the favorable weather conditions. The severe storms on the squall line had large radar reflectivity and high tops of echoes. There was a divergence at lower level, a convergence at middle level, and a divergence at upper level in the velocity cross section of the squall. The VIL (Vertical Integrated Liquid water) of the storms increased rapidly to a large value, which is a good indictor of hailstorm. When the probability of severe hail is larger than 30% according to the hail index products, a hail storm is very likely to happen. The convergence line in the boundary can trigger and intensify convections. The nowcasting system is a good tool for nowcasting severe convections.
In order to effectively forecast or forewarn squall lines and verify the effectiveness of the nowcasting system, a squall line occurring on 1 August 2006 in Beijing is analyzed by using conventional weather data, automatic weather station data, Doppler radar data, and the nowcasting system. The results suggest that the squall line occurred under the favorable weather conditions. The severe storms on the squall line had large radar reflectivity and high tops of echoes. There was a divergence at lower level, a convergence at middle level, and a divergence at upper level in the velocity cross section of the squall. The VIL (Vertical Integrated Liquid water) of the storms increased rapidly to a large value, which is a good indictor of hailstorm. When the probability of severe hail is larger than 30% according to the hail index products, a hail storm is very likely to happen. The convergence line in the boundary can trigger and intensify convections. The nowcasting system is a good tool for nowcasting severe convections.
2008, 36(2):164-167.
Abstract:
Precipitable Water (PW) data obtained from retrieving observed data, is used to improve the initial humidity field with the variational assimilation method. The numerical simulation experiments are carried out with MM5 using different initial fields of a heavy rain event happened on 9 to 10 July 2003. The results indicate that the data assimilation of PW has a strong capability of adjusting the initial humidity field; after PW assimilation,the quality of the initial humidity field can be greatly improved,and the accuracy of precipitation forecast can be effectively enhanced.
Precipitable Water (PW) data obtained from retrieving observed data, is used to improve the initial humidity field with the variational assimilation method. The numerical simulation experiments are carried out with MM5 using different initial fields of a heavy rain event happened on 9 to 10 July 2003. The results indicate that the data assimilation of PW has a strong capability of adjusting the initial humidity field; after PW assimilation,the quality of the initial humidity field can be greatly improved,and the accuracy of precipitation forecast can be effectively enhanced.
2008, 36(2):168-173.
Abstract:
The Tibetan Plateau is an important member of the global climatic system. Researches on interdecadal climatic variations over the Plateau based on different substitute data are enumerated systematically and the research progresses on dry, humid, cool and warm features of the plateau environment and the variation of snow cover and heat sources (sinks) are listed in detail. It reveals that it is colder before the 1920s and warmer from the 1920s to the 1950s and after the 1980s. There are same changes occurred over the Tibetan Plateau in accompany with the worldwide warming jumping around the 1980s, which is earlier than that of the North Hemisphere. The precipitation and snow cover over the plateau tend to increase under the context of global warming. There are obvious regional and seasonal climate variations on the plateau. The thermal/mechanical forcing and terrain effect of the plateau and the impacts on the Asian monsoon onset, rainfall in monsoon regions, and regional and global climatic changes are analyzed. Some existing problems in the related researches and research priorities in the future are also discussed.
The Tibetan Plateau is an important member of the global climatic system. Researches on interdecadal climatic variations over the Plateau based on different substitute data are enumerated systematically and the research progresses on dry, humid, cool and warm features of the plateau environment and the variation of snow cover and heat sources (sinks) are listed in detail. It reveals that it is colder before the 1920s and warmer from the 1920s to the 1950s and after the 1980s. There are same changes occurred over the Tibetan Plateau in accompany with the worldwide warming jumping around the 1980s, which is earlier than that of the North Hemisphere. The precipitation and snow cover over the plateau tend to increase under the context of global warming. There are obvious regional and seasonal climate variations on the plateau. The thermal/mechanical forcing and terrain effect of the plateau and the impacts on the Asian monsoon onset, rainfall in monsoon regions, and regional and global climatic changes are analyzed. Some existing problems in the related researches and research priorities in the future are also discussed.
2008, 36(2):174-179.
Abstract:
South Asia High (SAH) is a strong and steady center of atmosphere activity in summer, which exits at the top of the troposphere and the bottom of the stratosphere over the southern Asia. It is an important member of the subtropical high system and has close relationship with the atmosphere circulation in Northern Hemisphere in summer and weather and climate in Asia regions. There has been a great deal of research findings on South Asia High published in recent years, and the significance of the evolution of South Asia High to weather and climate in China and in Northern Hemisphere is recognized gradually. A review is made for the formation causes, structures, seasonal change, interannual change, and longitudinal oscillation of South Asia High and its influences on weather and climate in China. Meanwhile, the advances in Polar Vortex research in recent years and its relation with SAH are discussed briefly. It is important to reinforce the study of the mutual relations, variation rules and abnormal characteristics of South Asia High and Polar Vortex.
South Asia High (SAH) is a strong and steady center of atmosphere activity in summer, which exits at the top of the troposphere and the bottom of the stratosphere over the southern Asia. It is an important member of the subtropical high system and has close relationship with the atmosphere circulation in Northern Hemisphere in summer and weather and climate in Asia regions. There has been a great deal of research findings on South Asia High published in recent years, and the significance of the evolution of South Asia High to weather and climate in China and in Northern Hemisphere is recognized gradually. A review is made for the formation causes, structures, seasonal change, interannual change, and longitudinal oscillation of South Asia High and its influences on weather and climate in China. Meanwhile, the advances in Polar Vortex research in recent years and its relation with SAH are discussed briefly. It is important to reinforce the study of the mutual relations, variation rules and abnormal characteristics of South Asia High and Polar Vortex.
2008, 36(2):180-184.
Abstract:
The droughts in Zhejiang Province since 1952 are analyzed by method of colligation drought index and wavelet analysis. There were evident interdecadal variations in droughts in Zhejiang Province. The severe droughts were concentrated around the 1950’s, 1960’s and 2003 to 2004, and often occurred in two successive years. There was a sudden obvious change from drought to wetness in the late 1970’s and a weak climatic fluctuation from wetness to drought in the early 2000’s.
The droughts in Zhejiang Province since 1952 are analyzed by method of colligation drought index and wavelet analysis. There were evident interdecadal variations in droughts in Zhejiang Province. The severe droughts were concentrated around the 1950’s, 1960’s and 2003 to 2004, and often occurred in two successive years. There was a sudden obvious change from drought to wetness in the late 1970’s and a weak climatic fluctuation from wetness to drought in the early 2000’s.
2008, 36(2):185-189.
Abstract:
The abnormality of temperature in Beijing, the corresponding atmospheric circulation characteristics, and the relation with the antecedent SST over Northern Pacific are analyzed with the data of temperature in Beijing, 500 hPa geopotential heights over the Northern Hemisphere, sealevel pressure and sea surface temperature (SST) over the North Pacific from 1951 to 2005. The winter temperature in Beijing had the following variation: lower in the 1950s and 1960s, gradually increasing since the 1970s, and remained high since the 1990s. The 500 hPa circulation characteristics in the previous and present periods are quite different. The intensities of the Northern Hemispheric Subtropical High and the relevant subtropical high cells can well reflect the winter temperature in Beijing. The abnormal SST variations on the westerly driftage area and the Southern equatorial ocean current area in the previous spring can be a signal to the abnormal low (high) temperature in Beijing. When SST on the Southern equatorial ocean current area in the previous spring is abnormally high, it is advantageous to the buildup of the favorable circulation for Beijing warm winter. When SST in the westerly driftage area in previous spring is abnormally low, it is favorable to the formation of the coldwinter circulation pattern in Beijing.
The abnormality of temperature in Beijing, the corresponding atmospheric circulation characteristics, and the relation with the antecedent SST over Northern Pacific are analyzed with the data of temperature in Beijing, 500 hPa geopotential heights over the Northern Hemisphere, sealevel pressure and sea surface temperature (SST) over the North Pacific from 1951 to 2005. The winter temperature in Beijing had the following variation: lower in the 1950s and 1960s, gradually increasing since the 1970s, and remained high since the 1990s. The 500 hPa circulation characteristics in the previous and present periods are quite different. The intensities of the Northern Hemispheric Subtropical High and the relevant subtropical high cells can well reflect the winter temperature in Beijing. The abnormal SST variations on the westerly driftage area and the Southern equatorial ocean current area in the previous spring can be a signal to the abnormal low (high) temperature in Beijing. When SST on the Southern equatorial ocean current area in the previous spring is abnormally high, it is advantageous to the buildup of the favorable circulation for Beijing warm winter. When SST in the westerly driftage area in previous spring is abnormally low, it is favorable to the formation of the coldwinter circulation pattern in Beijing.
2008, 36(2):190-196.
Abstract:
The causes of a disastrous rainstorm in Shandong Peninsula on 27 July 2006 are analyzed. It is shown that the rainstorm was resulted from four mesoβ convective cloud clusters. The inverse trough of the tropical cyclone “Kaemi,” the westerly trough at high level and the subtropical high interacted mutually. The southerly jet formed between tropical low and subtropical high, and the water vapor channel into the rainstorm area was set up. The warm and wet air transportation increased the temperature and humidity in the lowlevel atmosphere over the heavy rain area, so the atmosphere became convectively instable. On the left front of the lowlevel southerly jet, the convergence, positive vorticity, and upward movement developed so that positive khelicity increased. On the right backside of the southwesterly jet in the front of the high level trough, the divergence and negative vorticity developed so that the negative khelicity increased tempestuously, which produced pumping effect to the lowlevel atmosphere, resulting in the convergence and increased upward movement at low levels. The convective instability energy was triggered and released, so that the mesoscale convective cloud clusters were produced and rainstorms occurred.
The causes of a disastrous rainstorm in Shandong Peninsula on 27 July 2006 are analyzed. It is shown that the rainstorm was resulted from four mesoβ convective cloud clusters. The inverse trough of the tropical cyclone “Kaemi,” the westerly trough at high level and the subtropical high interacted mutually. The southerly jet formed between tropical low and subtropical high, and the water vapor channel into the rainstorm area was set up. The warm and wet air transportation increased the temperature and humidity in the lowlevel atmosphere over the heavy rain area, so the atmosphere became convectively instable. On the left front of the lowlevel southerly jet, the convergence, positive vorticity, and upward movement developed so that positive khelicity increased. On the right backside of the southwesterly jet in the front of the high level trough, the divergence and negative vorticity developed so that the negative khelicity increased tempestuously, which produced pumping effect to the lowlevel atmosphere, resulting in the convergence and increased upward movement at low levels. The convective instability energy was triggered and released, so that the mesoscale convective cloud clusters were produced and rainstorms occurred.
2008, 36(2):197-201.
Abstract:
The atmospheric circulation pattern, atmospheric stability and radar data of a severe continuous rainfall event on 6 and 7 June 2006 in Nanping, Fujian Province are analyzed. The results show that the greater the meridionality of the weather system was, the stronger the weather system was; the greater the instability of the atmosphere, the stronger of the precipitation. Under the control of a certain weather system, the merging of radar echoes from different directions foreshowed strong rains. The differences in the intrusion of cold air and the outburst of warm advection on two days were related with different precipitation intensities. The precipitation amount was well corresponding to K and SI indexes in the two cases. The greater the indexes, the stronger the precipitation. The accuracy of the refined weather forecasting can be improved by use of radiosonde data from single station and radar data.
The atmospheric circulation pattern, atmospheric stability and radar data of a severe continuous rainfall event on 6 and 7 June 2006 in Nanping, Fujian Province are analyzed. The results show that the greater the meridionality of the weather system was, the stronger the weather system was; the greater the instability of the atmosphere, the stronger of the precipitation. Under the control of a certain weather system, the merging of radar echoes from different directions foreshowed strong rains. The differences in the intrusion of cold air and the outburst of warm advection on two days were related with different precipitation intensities. The precipitation amount was well corresponding to K and SI indexes in the two cases. The greater the indexes, the stronger the precipitation. The accuracy of the refined weather forecasting can be improved by use of radiosonde data from single station and radar data.
2008, 36(2):202-205.
Abstract:
The agriculture climate resources for 11 counties in Tangshan are analyzed by using the DTOPSIS (Dynamic Technique for Order Preference by Similarity to Ideal Solution) method based on the nine meteorological elements of Tangshan from 1971 to 2000. The results show that Tangshan can be divided into four agricultural climate resource zones (northwestern hilly area, central plain, southern coast, and the others); the agricultural climate resources condition is better in the high latitude areas than that in the low latitude areas and better in the plain areas than in coast areas, and meanwhile, the agricultural climate resources in the northwestern plain superior to those in the central plain and that in the central plain superior to those in coast areas.
The agriculture climate resources for 11 counties in Tangshan are analyzed by using the DTOPSIS (Dynamic Technique for Order Preference by Similarity to Ideal Solution) method based on the nine meteorological elements of Tangshan from 1971 to 2000. The results show that Tangshan can be divided into four agricultural climate resource zones (northwestern hilly area, central plain, southern coast, and the others); the agricultural climate resources condition is better in the high latitude areas than that in the low latitude areas and better in the plain areas than in coast areas, and meanwhile, the agricultural climate resources in the northwestern plain superior to those in the central plain and that in the central plain superior to those in coast areas.
2008, 36(2):206-209.
Abstract:
The regularity of climate change during the growing period of spring rape is analyzed, taking the Mengyuan county as an example. The result shows that the temperature is rising during the growing period of spring rape in Mengyuan, and precipitation is dropping at a rate of 1.64 of 20.70 mm per 10 years from April to August and rising at a rate of 20.16 mm per 10 years in September. The climate warming advances the seeding date and the mature stage of spring rape, lengthens the growth season, improves the use efficiency of climate resources, and enhances the output per unit in average. The influence of climate warming at each growth stage varies, and all growth stages are postponed except the seedling stage. The climatic yields are influenced mainly by temperature of April and June, annual mean temperature, and precipitation of June.
The regularity of climate change during the growing period of spring rape is analyzed, taking the Mengyuan county as an example. The result shows that the temperature is rising during the growing period of spring rape in Mengyuan, and precipitation is dropping at a rate of 1.64 of 20.70 mm per 10 years from April to August and rising at a rate of 20.16 mm per 10 years in September. The climate warming advances the seeding date and the mature stage of spring rape, lengthens the growth season, improves the use efficiency of climate resources, and enhances the output per unit in average. The influence of climate warming at each growth stage varies, and all growth stages are postponed except the seedling stage. The climatic yields are influenced mainly by temperature of April and June, annual mean temperature, and precipitation of June.
2008, 36(2):210-214.
Abstract:
The national landuse GIS database is used to identify forest fires and determine the positions of fires during the crossing of NOAA satellites, but its cost is high and the database cannot be updated yearly. MODIS is very different from NOAA, has the ability to identify 17 types of land surface with its VISNIRSWIR multichannel spectral bands (wavelength 400 to 2500 nm). By analyzing the MODIS land cover (LC) products, a new forestfire pixel identification method based on MODIS land IGBP types is devised, and its reliability is discussed. The total confidence of the forest fire identification based on MODIS LC is about 96.5%. A nearrealtime forest fire detection and monitoring system is constructed with an operational MODIS direct broadcast station.
The national landuse GIS database is used to identify forest fires and determine the positions of fires during the crossing of NOAA satellites, but its cost is high and the database cannot be updated yearly. MODIS is very different from NOAA, has the ability to identify 17 types of land surface with its VISNIRSWIR multichannel spectral bands (wavelength 400 to 2500 nm). By analyzing the MODIS land cover (LC) products, a new forestfire pixel identification method based on MODIS land IGBP types is devised, and its reliability is discussed. The total confidence of the forest fire identification based on MODIS LC is about 96.5%. A nearrealtime forest fire detection and monitoring system is constructed with an operational MODIS direct broadcast station.
2008, 36(2):215-218.
Abstract:
In order to understand the regularity of air PWV (Precipitable Water Vapor ) variation after rocket cloud seeding, by means of the observation data obtained by the singlestation groundbased GPS at Qinhuangdao, Hebei Province, two cases of rocket precipitation enhancement operations in upwind of the GPS station are analyzed. It is found that the air PWV over the GPS station decreased while the rainfall intensity increased 1 to 3 hours after each rocket seeding operation. The PWV rose again and was compensated faster when seeding at the early stage of weather system development than seeding at the late stage, and seeding effectiveness is more significant. The observation results are compared with some early and new numerical simulation conclusions.
In order to understand the regularity of air PWV (Precipitable Water Vapor ) variation after rocket cloud seeding, by means of the observation data obtained by the singlestation groundbased GPS at Qinhuangdao, Hebei Province, two cases of rocket precipitation enhancement operations in upwind of the GPS station are analyzed. It is found that the air PWV over the GPS station decreased while the rainfall intensity increased 1 to 3 hours after each rocket seeding operation. The PWV rose again and was compensated faster when seeding at the early stage of weather system development than seeding at the late stage, and seeding effectiveness is more significant. The observation results are compared with some early and new numerical simulation conclusions.
2008, 36(2):219-222.
Abstract:
The landuse classification charts in 1997 and 2004 are acquired by means of the remote sensing,GIS, and supervised classification methods for the hilly and gully area (Baota district) in Yan’an. Combined with the local DEM (digital elevation model) slope data, an analysis is made of the landuse distribution variation and differentiation with the data of the slope farmland, slope woodland, slope pasture and slope orchard for the years of 1997 and 2004, respectively. The results show that: (1) During the six years from 1997 to 2003, farmland decreased by 33.1%, woodland increased by 10.1%, pasture increased by 20.6%, orchard increased by 33.3% and the ecological environment of the studied area is improved generally. (2) The slope farmland decrease is mostly obvious, with the 55.5% of decrease occurred in the area of >35° and 51.2% in 25° to 35°. The decreased slope farmland was mainly converted into slope woodland, slope orchard, and mostly the slope pasture. However, the proportion of the irrigable farmland to total farmlands increased while the total farmland decreased. Analysis shows that the preliminary achievements are attributed to the execution of the government’s forestation project.
The landuse classification charts in 1997 and 2004 are acquired by means of the remote sensing,GIS, and supervised classification methods for the hilly and gully area (Baota district) in Yan’an. Combined with the local DEM (digital elevation model) slope data, an analysis is made of the landuse distribution variation and differentiation with the data of the slope farmland, slope woodland, slope pasture and slope orchard for the years of 1997 and 2004, respectively. The results show that: (1) During the six years from 1997 to 2003, farmland decreased by 33.1%, woodland increased by 10.1%, pasture increased by 20.6%, orchard increased by 33.3% and the ecological environment of the studied area is improved generally. (2) The slope farmland decrease is mostly obvious, with the 55.5% of decrease occurred in the area of >35° and 51.2% in 25° to 35°. The decreased slope farmland was mainly converted into slope woodland, slope orchard, and mostly the slope pasture. However, the proportion of the irrigable farmland to total farmlands increased while the total farmland decreased. Analysis shows that the preliminary achievements are attributed to the execution of the government’s forestation project.
2008, 36(2):223-227.
Abstract:
Some basic requirements about measuring differential reflectivity factor are discussed concerning the dualpolarization Doppler weather radar operated under the mode of simultaneous transmission and reception of horizontally and vertically polarized waves. Three kinds of factors, which may induce errors during measuring differential reflectivity factor, are described: (1) the basic requirements for radar measuring cannot be met; (2) echo power fluctuation may result from receiver noises and the relative motion of scatter particles; (3) the attenuations for horizontally and vertically polarized waves differ. Various factors and their weights for influencing the measuring errors of differential reflectivity factor are studied in detail.
Some basic requirements about measuring differential reflectivity factor are discussed concerning the dualpolarization Doppler weather radar operated under the mode of simultaneous transmission and reception of horizontally and vertically polarized waves. Three kinds of factors, which may induce errors during measuring differential reflectivity factor, are described: (1) the basic requirements for radar measuring cannot be met; (2) echo power fluctuation may result from receiver noises and the relative motion of scatter particles; (3) the attenuations for horizontally and vertically polarized waves differ. Various factors and their weights for influencing the measuring errors of differential reflectivity factor are studied in detail.
2008, 36(2):228-232.
Abstract:
The products of CINRADSA Doppler Radar located at Xinle, Hebei Province are used to analyze 8 hail processes in the midsouth part of Heibei Province. Some characteristic indexes of Doppler radar echoes for hail weather are summed up. Hailfall is likely to occur when the echo intensify is above 50 dBz, echo top is greater than 10 km, and vertically integral liquid water (VIL) is above 35 kg/m2. The diameter of hail is bigger when VIL is larger. During the initial stage of echo development, about 2 to 3 volume scanning, the value of VIL increases rapidly. Generally, it is a feature of hailfall that echo intensity for each of volume scanning increases about 10 to 30 kg/m2.
The products of CINRADSA Doppler Radar located at Xinle, Hebei Province are used to analyze 8 hail processes in the midsouth part of Heibei Province. Some characteristic indexes of Doppler radar echoes for hail weather are summed up. Hailfall is likely to occur when the echo intensify is above 50 dBz, echo top is greater than 10 km, and vertically integral liquid water (VIL) is above 35 kg/m2. The diameter of hail is bigger when VIL is larger. During the initial stage of echo development, about 2 to 3 volume scanning, the value of VIL increases rapidly. Generally, it is a feature of hailfall that echo intensity for each of volume scanning increases about 10 to 30 kg/m2.
2008, 36(2):233-236.
Abstract:
Based on Doppler radar scan data and automatic weather station data from 2002 and 2003 and the statistical analysis method，the Z〖KG-*8〗〖CD*2〗〖KG*9〗〖KG-*9〗I relation formulas for different regions and different sorts of rainfall in the northern and central Fujian Province are obtained．Precipitation processes in 2005 and 2006 are calibrated by means of the relation formulas．The variational method and optimum Kalman Filter method (in combination with Kalman Filter and optimum interpolation) are used to calibrate the estimated rainfall with realtime data, and the calibrated rainfall is tested with the raingauge data from the Jiuquxi Valley of Wuyishan Mountain. Results for the methods are compared and analyzed．The analysis shows that the smallest error results are from the optimum Kalman Filter method and optimization method from 0 to 100 km, and the greatest error is resulted from the relation of Z=300I1. 4．
Based on Doppler radar scan data and automatic weather station data from 2002 and 2003 and the statistical analysis method，the Z〖KG-*8〗〖CD*2〗〖KG*9〗〖KG-*9〗I relation formulas for different regions and different sorts of rainfall in the northern and central Fujian Province are obtained．Precipitation processes in 2005 and 2006 are calibrated by means of the relation formulas．The variational method and optimum Kalman Filter method (in combination with Kalman Filter and optimum interpolation) are used to calibrate the estimated rainfall with realtime data, and the calibrated rainfall is tested with the raingauge data from the Jiuquxi Valley of Wuyishan Mountain. Results for the methods are compared and analyzed．The analysis shows that the smallest error results are from the optimum Kalman Filter method and optimization method from 0 to 100 km, and the greatest error is resulted from the relation of Z=300I1. 4．
2008, 36(2):237-239.
Abstract:
The advanced operational software of the Lband upperair meteorological sounding software system is introduced, including the balloonreleasing program and the sounding data processing program. The system is programmed using the Borland C++ language under the Windows platform with an operational graphic interface according with the upperair operational criterion and is the backbone operational software system in the upperair meteorological sounding network of China Meteorological Administration (CMA). The longterm operational use of the software system shows that the software system is convenient to operate, has a userfriendly interface and strong functions, and has realized the automation from data sampling to data processing. The basic and exceptional processing functions of the software system and some typical troubleshooting examples are described. The future improvement of the software system, the design of the standard data interface, and the programming of the network software system are discussed.
The advanced operational software of the Lband upperair meteorological sounding software system is introduced, including the balloonreleasing program and the sounding data processing program. The system is programmed using the Borland C++ language under the Windows platform with an operational graphic interface according with the upperair operational criterion and is the backbone operational software system in the upperair meteorological sounding network of China Meteorological Administration (CMA). The longterm operational use of the software system shows that the software system is convenient to operate, has a userfriendly interface and strong functions, and has realized the automation from data sampling to data processing. The basic and exceptional processing functions of the software system and some typical troubleshooting examples are described. The future improvement of the software system, the design of the standard data interface, and the programming of the network software system are discussed.
2008, 36(2):240-243.
Abstract:
The uncertainty of calibration results for secondclass standard mercury thermometers directly influences the delivered results of temperature quantity values. According to the related standards of temperature instruments, the uncertainty of calibration results for a set of standard thermometers is evaluated by the method of JJF10591999 (Evaluation and Expression of Uncertainty in Measurement), on the basis of temperature measuring principles, calibration methods, components of the uncertainty, and the calibration data of the secondclass standard mercury thermometers in 2007. Based on the calibration results, a set of error analyzing procedures and methods are devised, which provide an example of error analysis for provincelevel metrological service.
The uncertainty of calibration results for secondclass standard mercury thermometers directly influences the delivered results of temperature quantity values. According to the related standards of temperature instruments, the uncertainty of calibration results for a set of standard thermometers is evaluated by the method of JJF10591999 (Evaluation and Expression of Uncertainty in Measurement), on the basis of temperature measuring principles, calibration methods, components of the uncertainty, and the calibration data of the secondclass standard mercury thermometers in 2007. Based on the calibration results, a set of error analyzing procedures and methods are devised, which provide an example of error analysis for provincelevel metrological service.
2008, 36(2):244-248.
Abstract:
Urbanization has exerted great influence on the observation environment of national meteorological observation stations. The observation environmental assessment and new location selection are especially necessary and urgent in building national climatic observation stations. The observation environment must be considered in the selection of the locations for national climatic observation stations, at which measurements must be well representative of the characteristics of local meteorological elements in a large extent and can avoid the influence of local topography, barrier and artificial factors. It is propitious to reflect the actual situation when the surface of an observing station is consistent with the typical surface of local areas, but in some cases, as agricultural activities may influence the observation of some meteorological factors, some special measures must be taken according to specific situation. For the meteorological stations affected by urbanization, a good choice is to retain the original station and meanwile to construct a new one.
Urbanization has exerted great influence on the observation environment of national meteorological observation stations. The observation environmental assessment and new location selection are especially necessary and urgent in building national climatic observation stations. The observation environment must be considered in the selection of the locations for national climatic observation stations, at which measurements must be well representative of the characteristics of local meteorological elements in a large extent and can avoid the influence of local topography, barrier and artificial factors. It is propitious to reflect the actual situation when the surface of an observing station is consistent with the typical surface of local areas, but in some cases, as agricultural activities may influence the observation of some meteorological factors, some special measures must be taken according to specific situation. For the meteorological stations affected by urbanization, a good choice is to retain the original station and meanwile to construct a new one.
2008, 36(2):249-252.
Abstract:
The soil relative humidity measurements from the agrometeorological automatic station and manual observation of the Juxian Meteorological Bureau at the same time in a natural state of nonirrigation from 21 September 2005 to 18 December 2006 are compared and analyzed by means of the difference contrast, difference probability, and correlation methods. The results show that the measurements from the automatic station are unsatisfactory in the layers of 0-5 cm and 0-10 cm but satisfactory in the layers of 10-20 cm and 40-50 cm. It is concluded that the 0-10 cm sensor parameter must be adjusted and replaced, and the design of the sensor must consider the influence of frozen earth. The variation of 90-100 cm depth data is steady, so it is suggested to cancel the sensors at the two levels of 90-100 cm and 170-180 cm.
The soil relative humidity measurements from the agrometeorological automatic station and manual observation of the Juxian Meteorological Bureau at the same time in a natural state of nonirrigation from 21 September 2005 to 18 December 2006 are compared and analyzed by means of the difference contrast, difference probability, and correlation methods. The results show that the measurements from the automatic station are unsatisfactory in the layers of 0-5 cm and 0-10 cm but satisfactory in the layers of 10-20 cm and 40-50 cm. It is concluded that the 0-10 cm sensor parameter must be adjusted and replaced, and the design of the sensor must consider the influence of frozen earth. The variation of 90-100 cm depth data is steady, so it is suggested to cancel the sensors at the two levels of 90-100 cm and 170-180 cm.
2008, 36(2):253-256.
Abstract:
The operational platform of weather forecast for Changzhou is devised with Visual Basic 6.0 language along with Microsoft FrontPage, Microsoft Access, Java, Photoshop, etc. It uses the climatic data of Changzhou Station from 1952 to 2003. The synoptic models are revised by the empirical indexes based on the knowledge of wellexperienced forecasters, and the working flow is standardized based on the Project 9210 and available interconnected network systems. The application of the system shows that the platform is very convenient to search, analyze, produce and distribute all kinds of meteorological information, allowing humancomputer interaction.
The operational platform of weather forecast for Changzhou is devised with Visual Basic 6.0 language along with Microsoft FrontPage, Microsoft Access, Java, Photoshop, etc. It uses the climatic data of Changzhou Station from 1952 to 2003. The synoptic models are revised by the empirical indexes based on the knowledge of wellexperienced forecasters, and the working flow is standardized based on the Project 9210 and available interconnected network systems. The application of the system shows that the platform is very convenient to search, analyze, produce and distribute all kinds of meteorological information, allowing humancomputer interaction.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.