ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 38,Issue 9,2012 Table of Contents
2012, 38(9):1033-1041.
DOI: 10.7519/j.issn.1000-0526.2012.09.001
Abstract:
Temperature differences between GPS/RO dry retrievals, derived from COSMIC Data Analysis and Archival Center (CDAAC), and China’s radiosonde temperature profiles in the Upper Troposphere and Lower Stratosphere (UTLS, from 200 to 30 hPa) are calculated to analyze the radiosonde temperature bias. A simple quality control is carried out first to reduce the effects of outliers. Total mean temperature difference and standard deviation with temporal difference ranging from 1 to 3 hours and spatial distance ranging from 30 to 300 km are calculated to check the affection of collocation methods. Results show that the mean difference between GPS/RO retrieval and radiosonde temperature is independent of the collocation criteria, which mainly affect the standard deviation. Compared to GPS/RO data, China’s radiosonde temperature shows a small warm mean bias in general, and the absolute mean bias and standard deviation in upper troposphere are larger than that in lower stratosphere. Latitudinal comparison results show that bias distribution characteristic agrees well with the temperature lapse rate, which indicates that GPS/RO data have the ability to differentiate the lag errors of radiosonde measurements. The bias is larger in low latitudes than that in high latitudes. Comparison of temperature difference in daytime and nighttime reveals that GPS/RO data can differentiate radiative errors of radiosonde caused by solar radiation. In comparison to the small bias between the new L band electronic radiosonde and GPS/RO profiles, the significant temperature bias between type 59 mechanic radiosonde and GPS/RO data, especially in low latitude area, which may be attributed to large lag errors caused by the large lag index of type 59 radiosonde and lapse rate in low latitude area, demonstrates the ability of GPS/RO data to differentiate the old and new radiosonde type of China and the improvements of temperature precision by the L band radiosonde measurements.
Temperature differences between GPS/RO dry retrievals, derived from COSMIC Data Analysis and Archival Center (CDAAC), and China’s radiosonde temperature profiles in the Upper Troposphere and Lower Stratosphere (UTLS, from 200 to 30 hPa) are calculated to analyze the radiosonde temperature bias. A simple quality control is carried out first to reduce the effects of outliers. Total mean temperature difference and standard deviation with temporal difference ranging from 1 to 3 hours and spatial distance ranging from 30 to 300 km are calculated to check the affection of collocation methods. Results show that the mean difference between GPS/RO retrieval and radiosonde temperature is independent of the collocation criteria, which mainly affect the standard deviation. Compared to GPS/RO data, China’s radiosonde temperature shows a small warm mean bias in general, and the absolute mean bias and standard deviation in upper troposphere are larger than that in lower stratosphere. Latitudinal comparison results show that bias distribution characteristic agrees well with the temperature lapse rate, which indicates that GPS/RO data have the ability to differentiate the lag errors of radiosonde measurements. The bias is larger in low latitudes than that in high latitudes. Comparison of temperature difference in daytime and nighttime reveals that GPS/RO data can differentiate radiative errors of radiosonde caused by solar radiation. In comparison to the small bias between the new L band electronic radiosonde and GPS/RO profiles, the significant temperature bias between type 59 mechanic radiosonde and GPS/RO data, especially in low latitude area, which may be attributed to large lag errors caused by the large lag index of type 59 radiosonde and lapse rate in low latitude area, demonstrates the ability of GPS/RO data to differentiate the old and new radiosonde type of China and the improvements of temperature precision by the L band radiosonde measurements.
2012, 38(9):1042-1052.
DOI: 10.7519/j.issn.1000-0526.2012.09.002
Abstract:
Based on the three different types of precipitation data of Tianjin and Doppler radar observational data, using the radar rainfall estimation grid point field derived from the all valid raingauge calibration as a “true” value, the accuracy of radar rainfall estimates by 14 different raingauge density calibrations is studied, and the contribution of one raingauge to radar rainfall estimates is also analyzed. The conclusion can be drawn as follows: (1) Radar rainfall estimation error is bigger when the raingauge calibration density is lower, then estimation results are not satisfactory. However the estimation accuracy of radar is continuously improved and estimation error is significantly reduced, with the raingauge calibration density increased. (2) Calibration on different types of precipitation needs different raingauge densities, which is related to the nature of precipitation. When the precision of radar estimation is equal to the precision of the “true” value, the raingauge maximum density on calibration radar is required to be one raingauge per 121 km2. (3) Any increased raingauge site, whose precipitation is zero, has no impacts on radar rainfall estimation. When it is not zero, the estimation error would appear around the site (over or under estimate), and the deviation of estimation is closely related to the average precipitation and the distribution of raingauge density around the raingauge site. (4) When randomly increased (decreased) precipitation of single raingauge site, the radar would be over or under estimated the precipitation around the raingauge site, and the degree of over or under estimates and the area of bias are related to the density of the surrounding raingauges and the changes in the size of precipitation, which was unrelated to the type of precipitation and either unrelated to the variation of precipitation over time.
Based on the three different types of precipitation data of Tianjin and Doppler radar observational data, using the radar rainfall estimation grid point field derived from the all valid raingauge calibration as a “true” value, the accuracy of radar rainfall estimates by 14 different raingauge density calibrations is studied, and the contribution of one raingauge to radar rainfall estimates is also analyzed. The conclusion can be drawn as follows: (1) Radar rainfall estimation error is bigger when the raingauge calibration density is lower, then estimation results are not satisfactory. However the estimation accuracy of radar is continuously improved and estimation error is significantly reduced, with the raingauge calibration density increased. (2) Calibration on different types of precipitation needs different raingauge densities, which is related to the nature of precipitation. When the precision of radar estimation is equal to the precision of the “true” value, the raingauge maximum density on calibration radar is required to be one raingauge per 121 km2. (3) Any increased raingauge site, whose precipitation is zero, has no impacts on radar rainfall estimation. When it is not zero, the estimation error would appear around the site (over or under estimate), and the deviation of estimation is closely related to the average precipitation and the distribution of raingauge density around the raingauge site. (4) When randomly increased (decreased) precipitation of single raingauge site, the radar would be over or under estimated the precipitation around the raingauge site, and the degree of over or under estimates and the area of bias are related to the density of the surrounding raingauges and the changes in the size of precipitation, which was unrelated to the type of precipitation and either unrelated to the variation of precipitation over time.
2012, 38(9):1053-1059.
DOI: 10.7519/j.issn.1000-0526.2012.09.003
Abstract:
In this paper we select 10 broad spectrum solar radiation mechanism models widely used in foreign countries and achieved recognitions, and there are separate transmittance formulas in the main atmospheric attenuation process. The transmission (TR，TO，TUM), direct radiation, and diffuse radiation by selected models in relation to the exact spectrum model SMARTS are compared and reviewed strictly in an ideal atmosphere. On this basis, we then selected the model of high precision METSTAT, and corrected its defects and inadequacies regarding optical mass, transmission rate of ozone absorption and uniformly mixed gas absorption transmittance of the model, then an improved solar radiation model METSTAT_M in an ideal atmosphere is obtained. After a rigorous comparison, it is demonstrated that the METSTAT_M model is superior to other models.
In this paper we select 10 broad spectrum solar radiation mechanism models widely used in foreign countries and achieved recognitions, and there are separate transmittance formulas in the main atmospheric attenuation process. The transmission (TR，TO，TUM), direct radiation, and diffuse radiation by selected models in relation to the exact spectrum model SMARTS are compared and reviewed strictly in an ideal atmosphere. On this basis, we then selected the model of high precision METSTAT, and corrected its defects and inadequacies regarding optical mass, transmission rate of ozone absorption and uniformly mixed gas absorption transmittance of the model, then an improved solar radiation model METSTAT_M in an ideal atmosphere is obtained. After a rigorous comparison, it is demonstrated that the METSTAT_M model is superior to other models.
2012, 38(9):1060-1069.
DOI: 10.7519/j.issn.1000-0526.2012.09.004
Abstract:
Based on TBB data, Doppler radar, AWS data, NCEP data and conventional observation data, the mesoscale convective system which caused the short time torrential rain in Nanjing on July 7, 2009 is studied. The results show that under the favorable weather background situation, multiple mesoscale convective systems mergered in Nanjing, and produced a new mesoscale convection system, which has strong convection and moving slowly, thus caused a short time torrential rain. The short time torrential rain’s mesoscale characteristics reflected in TBB data are that the convective clouds after mergering intensified and low temperature region obviously increased, moving slowly. The big value area of TBB gradient stayed in Nanjing for a long time. The mesoscale characteristics reflected in the surface wind field are that the combineation of the southward ground wind convergence line and the convergence center locally generated in Nanjing caused the surface convergence obviously increased. The mesoscale characteristics reflected in radar data are that the convergence in Nanjing obviously increased which is caused by the convective cell continuously mergered, high precipitation efficiency of low centroid muti cell strom and the misoscale cells passing by Nanjing along the same direction. Additionally, the shear line and the low level jet stream are the impotant influence system of the he short time torrential rain. Using Doppler radar may identify and analyze this development, and lay the basis of the short time torrential rain’s nowcasting.
Based on TBB data, Doppler radar, AWS data, NCEP data and conventional observation data, the mesoscale convective system which caused the short time torrential rain in Nanjing on July 7, 2009 is studied. The results show that under the favorable weather background situation, multiple mesoscale convective systems mergered in Nanjing, and produced a new mesoscale convection system, which has strong convection and moving slowly, thus caused a short time torrential rain. The short time torrential rain’s mesoscale characteristics reflected in TBB data are that the convective clouds after mergering intensified and low temperature region obviously increased, moving slowly. The big value area of TBB gradient stayed in Nanjing for a long time. The mesoscale characteristics reflected in the surface wind field are that the combineation of the southward ground wind convergence line and the convergence center locally generated in Nanjing caused the surface convergence obviously increased. The mesoscale characteristics reflected in radar data are that the convergence in Nanjing obviously increased which is caused by the convective cell continuously mergered, high precipitation efficiency of low centroid muti cell strom and the misoscale cells passing by Nanjing along the same direction. Additionally, the shear line and the low level jet stream are the impotant influence system of the he short time torrential rain. Using Doppler radar may identify and analyze this development, and lay the basis of the short time torrential rain’s nowcasting.
2012, 38(9):1070-1077.
DOI: 10.7519/j.issn.1000-0526.2012.09.005
Abstract:
This paper primarily discusses the synoptic and climatic characters in heavy rain during Meiyu flood period (June-July) based on the thirty year (1981-2010) observational data at 46 stations and the reanalysis dataset from 1981 to 2010. Main circulation characters and impacting systems of heavy rain in Jiang Huai Basin at 500 hPa and wind distribution characters at 850 hPa are summarized by integratively analyzing abundant historical examples. A conceptual model of heavy rain and study respects of medium range forecast are put forward. Ten durative heavy rain weather processes in the last thirty years are discussed, and the results show that the easterly propagation of Rossby wave is in favor of occurrence of the durative heavy rain weather processes in Jiang Huai Basin. The downstream development of Rossby wave provides some new ideas for medium range forecast.
This paper primarily discusses the synoptic and climatic characters in heavy rain during Meiyu flood period (June-July) based on the thirty year (1981-2010) observational data at 46 stations and the reanalysis dataset from 1981 to 2010. Main circulation characters and impacting systems of heavy rain in Jiang Huai Basin at 500 hPa and wind distribution characters at 850 hPa are summarized by integratively analyzing abundant historical examples. A conceptual model of heavy rain and study respects of medium range forecast are put forward. Ten durative heavy rain weather processes in the last thirty years are discussed, and the results show that the easterly propagation of Rossby wave is in favor of occurrence of the durative heavy rain weather processes in Jiang Huai Basin. The downstream development of Rossby wave provides some new ideas for medium range forecast.
2012, 38(9):1078-1086.
DOI: 10.7519/j.issn.1000-0526.2012.09.006
Abstract:
Using the radar and automatic weather station (AWS) data, and the Tianjin corrected sounding data, the rules and synoptic scale meteorological conditions for three types of thunderstorms initiation and intensification associated with sea breeze fronts in the Bohai Bay from 2004 to 2009 are investigated. Based on VDRAS (variational Doppler radar analysis system) data, the thermal and dynamical structures of the third type thunderstorm were analyzed. The results show that： (1) Under the strong instable environment, thunderstorm is initiated and intensified when it moves along the sea breeze fronts. (2) The location, the rate of intensification, and the intensity are distinct for different types. (3) For type Ⅰ〖KG-*4〗, the dynamical is better than the other two types, and convection weather is stronger. For type Ⅲ〖KG-*7〗, the thermal, dynamical and vapour are better than the other two types, while CIN (convection inhibition) is small. (4) A mesoscale convergence line is formed at low level by sea breeze front. Vertical updrafts along the sea breeze front extend from the ground to the height of 3 km. Strong centers appear at the height of 1.5-3.0 km, and the maximum velocity is up to 1.9 m·s-1.
Using the radar and automatic weather station (AWS) data, and the Tianjin corrected sounding data, the rules and synoptic scale meteorological conditions for three types of thunderstorms initiation and intensification associated with sea breeze fronts in the Bohai Bay from 2004 to 2009 are investigated. Based on VDRAS (variational Doppler radar analysis system) data, the thermal and dynamical structures of the third type thunderstorm were analyzed. The results show that： (1) Under the strong instable environment, thunderstorm is initiated and intensified when it moves along the sea breeze fronts. (2) The location, the rate of intensification, and the intensity are distinct for different types. (3) For type Ⅰ〖KG-*4〗, the dynamical is better than the other two types, and convection weather is stronger. For type Ⅲ〖KG-*7〗, the thermal, dynamical and vapour are better than the other two types, while CIN (convection inhibition) is small. (4) A mesoscale convergence line is formed at low level by sea breeze front. Vertical updrafts along the sea breeze front extend from the ground to the height of 3 km. Strong centers appear at the height of 1.5-3.0 km, and the maximum velocity is up to 1.9 m·s-1.
2012, 38(9):1087-1095.
DOI: 10.7519/j.issn.1000-0526.2012.09.007
Abstract:
We analyzed space and time distributed characteristics of poor visibility frequency and the changing situation of its interrelated meteorological factors by using the ground station data as well as the upper air and the earth’s surface data in the region of Bohai Rim. The results have shown that the characteristics in the interannual change of poor visibility present a weak upward trend and periodic oscillations, with main periods of 2 a， 4 a and 6-8 a.The frequency of poor visibility has two peaks in a year and one peak in a day at local time 08 h. The spatial distribution of low visibility’s frequency exists a great inconformity. According to the different spatial distribution in the seasonal frequency of poor visibility, the whole region can be divided into three areas. It seemed that high humidity and light wind are the main meteorological conditions prone to produce low visibility. While the early or the same time as the appearance of poor visibility, these conditions maintain an inversion or isothermal layer and wet layer in the lower atmosphere.
We analyzed space and time distributed characteristics of poor visibility frequency and the changing situation of its interrelated meteorological factors by using the ground station data as well as the upper air and the earth’s surface data in the region of Bohai Rim. The results have shown that the characteristics in the interannual change of poor visibility present a weak upward trend and periodic oscillations, with main periods of 2 a， 4 a and 6-8 a.The frequency of poor visibility has two peaks in a year and one peak in a day at local time 08 h. The spatial distribution of low visibility’s frequency exists a great inconformity. According to the different spatial distribution in the seasonal frequency of poor visibility, the whole region can be divided into three areas. It seemed that high humidity and light wind are the main meteorological conditions prone to produce low visibility. While the early or the same time as the appearance of poor visibility, these conditions maintain an inversion or isothermal layer and wet layer in the lower atmosphere.
2012, 38(9):1096-1102.
DOI: 10.7519/j.issn.1000-0526.2012.09.008
Abstract:
To research the pollution characteristics of aerosols during low visibility weather in Tianjin, the observational data of visibility, PM10 and PM2.5 mass concentrations and meteorological factors in the autumn and winter of 2009 were studied. At the same time a case of low visibility was analyzed to find out the evolvement processes and vertical distributions of atmospheric aerosol mass concentrations. The results have indicated that most of low visibility weather cases are in haze, accounting for half of the samples or more. Analysis of the typical low visibility process has shown that PM2.5 follows a uniform distribution in haze days with significant regional pollution characteristics. The aerosol mass concentration is increased first and then decreased in foggy days because of both hygroscopic growth of aerosols and wet clearing due to the dissolution of soluble components. PM2.5 mass concentrations in the surface layer are more than those in higher layers, depending on the vertical variation of RH and the inversion layer height.
To research the pollution characteristics of aerosols during low visibility weather in Tianjin, the observational data of visibility, PM10 and PM2.5 mass concentrations and meteorological factors in the autumn and winter of 2009 were studied. At the same time a case of low visibility was analyzed to find out the evolvement processes and vertical distributions of atmospheric aerosol mass concentrations. The results have indicated that most of low visibility weather cases are in haze, accounting for half of the samples or more. Analysis of the typical low visibility process has shown that PM2.5 follows a uniform distribution in haze days with significant regional pollution characteristics. The aerosol mass concentration is increased first and then decreased in foggy days because of both hygroscopic growth of aerosols and wet clearing due to the dissolution of soluble components. PM2.5 mass concentrations in the surface layer are more than those in higher layers, depending on the vertical variation of RH and the inversion layer height.
2012, 38(9):1103-1109.
DOI: 10.7519/j.issn.1000-0526.2012.09.009
Abstract:
The fog is a kind of special weather phenomenon and is closely related with structures of the atmospheric boundary layer. Based on the Tianjin boundary gradient observation system, we have analyzed a fog process from November 28 to December 2, 2010, which can be divided into two episodes, fogⅠ and fogⅡ. The results showed that: first the condensation of water was found from 80 to 100 m heights during fog Ⅰ and then vapor was transported downward during fogⅡ. There was obvious inversion temperature before fog Ⅰ and unstable atmosphere before fog Ⅱ.While fog Ⅱ happened, the atmospheric status was tending to be neutral, and there was a strong inversion temperature at the top of fog. Analysis on characteristics of radiation and pollution during fog process shows that， there was a long wave radiation equilibrium, an inhibition effect to the photochemical smog, and an accumulated effect of small particle and NOX during fog.
The fog is a kind of special weather phenomenon and is closely related with structures of the atmospheric boundary layer. Based on the Tianjin boundary gradient observation system, we have analyzed a fog process from November 28 to December 2, 2010, which can be divided into two episodes, fogⅠ and fogⅡ. The results showed that: first the condensation of water was found from 80 to 100 m heights during fog Ⅰ and then vapor was transported downward during fogⅡ. There was obvious inversion temperature before fog Ⅰ and unstable atmosphere before fog Ⅱ.While fog Ⅱ happened, the atmospheric status was tending to be neutral, and there was a strong inversion temperature at the top of fog. Analysis on characteristics of radiation and pollution during fog process shows that， there was a long wave radiation equilibrium, an inhibition effect to the photochemical smog, and an accumulated effect of small particle and NOX during fog.
2012, 38(9):1110-1114.
DOI: 10.7519/j.issn.1000-0526.2012.09.010
Abstract:
Critical precipitation is an important indicator for forecasting mountain torrents. According to the features of mountain torrents in Jiangxi Province, the relation between precipitation, occurrence time of mountain torrents, and basin parameters has been studied. The results indicate that precipitation and torrents have a close relation. The correlation between precipitation and basin parameters is considerable. Critical precipitation amounts within 1 h, 3 h, 6 h and 24 h were calculated in the 11 small basins by using mountain torrents and meteorological data of these small basins during 1950 to 2002. A statistical model concerning critical precipitation, basin area, main river length, and main river slope has been built. Moreover, the critical precipitation amounts for the other 1045 small basins have been calculated by using the model. The tests have indicated that the model has good effect in the application to a typical mountain torrent event in Ganzhou City during 2-3 July 2009.
Critical precipitation is an important indicator for forecasting mountain torrents. According to the features of mountain torrents in Jiangxi Province, the relation between precipitation, occurrence time of mountain torrents, and basin parameters has been studied. The results indicate that precipitation and torrents have a close relation. The correlation between precipitation and basin parameters is considerable. Critical precipitation amounts within 1 h, 3 h, 6 h and 24 h were calculated in the 11 small basins by using mountain torrents and meteorological data of these small basins during 1950 to 2002. A statistical model concerning critical precipitation, basin area, main river length, and main river slope has been built. Moreover, the critical precipitation amounts for the other 1045 small basins have been calculated by using the model. The tests have indicated that the model has good effect in the application to a typical mountain torrent event in Ganzhou City during 2-3 July 2009.
2012, 38(9):1115-1120.
DOI: 10.7519/j.issn.1000-0526.2012.09.011
Abstract:
In the paper the K means clustering of the improved algorithm, the principal component analysis (PCA) and other methods are used to establish the interpretation forecasting model of thunderstorm by the least squares support vector machine (LS_SVM) and linear programming support vector machine (LP_SVM) based on MOS theory monthly in terms of AREM prediction products and conventional observation data during 2002 to 2006. And use the data at Haikou Station for testing from May to August 2007. The results show that, combining with SVM and AREM products to interpret the forecast products is feasible. The PCA also plays a positive role in improving the forecast accuracy.
In the paper the K means clustering of the improved algorithm, the principal component analysis (PCA) and other methods are used to establish the interpretation forecasting model of thunderstorm by the least squares support vector machine (LS_SVM) and linear programming support vector machine (LP_SVM) based on MOS theory monthly in terms of AREM prediction products and conventional observation data during 2002 to 2006. And use the data at Haikou Station for testing from May to August 2007. The results show that, combining with SVM and AREM products to interpret the forecast products is feasible. The PCA also plays a positive role in improving the forecast accuracy.
2012, 38(9):1121-1128.
DOI: 10.7519/j.issn.1000-0526.2012.09.012
Abstract:
Homogenization of climate observations remains a challenge to climate change research. To examine the influence of metadata on homogenizing climate data, the authors applied many test methods including SHNT (standard normal homogeneity test), Buishand test, Pettitt test, MASH (multiple analysis of series for homogenization), TPR (two phase regression), and Von Neumann ratio test to the Sichuan annual temperature series during 1960-2009. The results show that there are 42 stations existing discontinuity, about 40%; in the inhomogeneous stations, 29 were caused by station migration, and 19 caused by the replacement of equipment. The heterogeneity of the station was increasing during 1960s-1970s, 1980s-1990s and after 2000, and most breakpoints were caused by migration. Analyzing and assessing the sensitivity and applicability of the test methods show that, 48.6% of the SNHT test results were consistent with Buishand and Pettitt, and TPR method which does not involve adjacent stations was consistent with other methods in a low rate. In reference to the topography of Sichuan, it is found that SNHT makes the breakpoint being revealed with the highest rate in the basin and mountain stations, reaching 67.6% and 57.1%, and the missed rate and false positives were low. SNHT and Buishand methods make the breakpoint being revealed with the highest rate in plateau stations, and the missed rate and false positives were low with Buishand. Therefore, in view of reducing dependence on metadata, the homogenization test with the integrated application of variety test methods should contribute to climate change research effectively.
Homogenization of climate observations remains a challenge to climate change research. To examine the influence of metadata on homogenizing climate data, the authors applied many test methods including SHNT (standard normal homogeneity test), Buishand test, Pettitt test, MASH (multiple analysis of series for homogenization), TPR (two phase regression), and Von Neumann ratio test to the Sichuan annual temperature series during 1960-2009. The results show that there are 42 stations existing discontinuity, about 40%; in the inhomogeneous stations, 29 were caused by station migration, and 19 caused by the replacement of equipment. The heterogeneity of the station was increasing during 1960s-1970s, 1980s-1990s and after 2000, and most breakpoints were caused by migration. Analyzing and assessing the sensitivity and applicability of the test methods show that, 48.6% of the SNHT test results were consistent with Buishand and Pettitt, and TPR method which does not involve adjacent stations was consistent with other methods in a low rate. In reference to the topography of Sichuan, it is found that SNHT makes the breakpoint being revealed with the highest rate in the basin and mountain stations, reaching 67.6% and 57.1%, and the missed rate and false positives were low. SNHT and Buishand methods make the breakpoint being revealed with the highest rate in plateau stations, and the missed rate and false positives were low with Buishand. Therefore, in view of reducing dependence on metadata, the homogenization test with the integrated application of variety test methods should contribute to climate change research effectively.
2012, 38(9):1129-1134.
DOI: 10.7519/j.issn.1000-0526.2012.09.013
Abstract:
Some features of raindrop spectrum in stratiform clouds in spring 2003 of Shaanxi were observed and analyzed in this paper, which are closely associated with precipitating weather systems. The precipitating mixed clouds with deeper cold and warm cloud layers have an appropriate level configuration, and their raindrop number concentrations are bigger up to 103 m-3 and the spectra of raindrops are wider up to 0.32 cm. Conversely, the stable clouds have a smaller number concentration (102 m-3) and a narrower spectrum width (0.22 cm). The raindrops under 0.1 cm in diameter accounted for more than 80% of the total concentration, while the contribution to rainfall intensity is less than 20%. Actually, the 0.1-0.2 cm across raindrop is a major component of rainfall intensity, which accounted for an average 48%-77%. The majority of raindrops had a non monotonic decreased spectral distribution, and the three parameter fitting formula n(Di)=n0Dαe-λD is better than the exponential distribution n(Di)=n0e-λD.
Some features of raindrop spectrum in stratiform clouds in spring 2003 of Shaanxi were observed and analyzed in this paper, which are closely associated with precipitating weather systems. The precipitating mixed clouds with deeper cold and warm cloud layers have an appropriate level configuration, and their raindrop number concentrations are bigger up to 103 m-3 and the spectra of raindrops are wider up to 0.32 cm. Conversely, the stable clouds have a smaller number concentration (102 m-3) and a narrower spectrum width (0.22 cm). The raindrops under 0.1 cm in diameter accounted for more than 80% of the total concentration, while the contribution to rainfall intensity is less than 20%. Actually, the 0.1-0.2 cm across raindrop is a major component of rainfall intensity, which accounted for an average 48%-77%. The majority of raindrops had a non monotonic decreased spectral distribution, and the three parameter fitting formula n(Di)=n0Dαe-λD is better than the exponential distribution n(Di)=n0e-λD.
2012, 38(9):1135-1139.
DOI: 10.7519/j.issn.1000-0526.2012.09.014
Abstract:
Based on the daily mean air temperature from 1971 to 2000 observed by more than 2000 national surface stations in China, a standardized method was employed to carry out missing data estimation experiment, and the results were verified by cross validation. Two schemes, the relation optimal scheme and the closest station scheme, which were both used to pick up the adjacent stations, were compared. It showed that the relation optimal scheme was better than the other, and only 4 adjacent stations that are most closely related to the estimated station were necessary for estimation. The results indicated that estimate values in average deviate from true values by 0.42℃. The absolute mean error and root mean square error between the estimation and the actural measurements and the sample ratio with the differences falling in ±0.5℃ were all shown good exponential relationships with the average adjacent station distance.
Based on the daily mean air temperature from 1971 to 2000 observed by more than 2000 national surface stations in China, a standardized method was employed to carry out missing data estimation experiment, and the results were verified by cross validation. Two schemes, the relation optimal scheme and the closest station scheme, which were both used to pick up the adjacent stations, were compared. It showed that the relation optimal scheme was better than the other, and only 4 adjacent stations that are most closely related to the estimated station were necessary for estimation. The results indicated that estimate values in average deviate from true values by 0.42℃. The absolute mean error and root mean square error between the estimation and the actural measurements and the sample ratio with the differences falling in ±0.5℃ were all shown good exponential relationships with the average adjacent station distance.
2012, 38(9):1140-1144.
DOI: 10.7519/j.issn.1000-0526.2012.09.015
Abstract:
Meteorological disaster risk assessment is involved with multi source, multi dimensional, multi scale spatial data and socio economic statistical data. Key technologies of evaluating agriculture meteorological disaster risk with GIS MCE are introduced, including establishing evaluation criteria and weights by Delphi method, obtaining the spatial distribution of factors of the meteorological disasters by diffusing spatial attribute value and implementing evaluation by spatial overlay calculation. The results indicated that the technology of GIS MCE can combine multiple source information associating with agriculture meteorological disaster risk and achieve measurable results. As an example, evaluation on meteorological disaster risk with GIS MCE is shown in the article.
Meteorological disaster risk assessment is involved with multi source, multi dimensional, multi scale spatial data and socio economic statistical data. Key technologies of evaluating agriculture meteorological disaster risk with GIS MCE are introduced, including establishing evaluation criteria and weights by Delphi method, obtaining the spatial distribution of factors of the meteorological disasters by diffusing spatial attribute value and implementing evaluation by spatial overlay calculation. The results indicated that the technology of GIS MCE can combine multiple source information associating with agriculture meteorological disaster risk and achieve measurable results. As an example, evaluation on meteorological disaster risk with GIS MCE is shown in the article.
2012, 38(9):1145-1149.
DOI: 10.7519/j.issn.1000-0526.2012.09.016
Abstract:
Out of the 76 sites’ daily temperature data in 1961-2009 in Hubei Province, the 33 sites were chosen as a research object by homogenization test. The occurrence frequency of extreme high temperature in Hubei Province, intensity changes and response to the regional warming were analyzed. The results show that, the frequency of extreme high temperature is correlated well with the altitude, and that frequency of extreme high temperature displays decreasing in east and west directions and increasing in central. The spatial distribution in the frequency of extreme high temperature shows better consistency, and extreme high temperature events are prone to take place in Jianghan Plain and its northeast. The frequency of extreme high temperature events is positively responding to the summer mean temperature, and in relation to the western, the northeast response is more significant.
Out of the 76 sites’ daily temperature data in 1961-2009 in Hubei Province, the 33 sites were chosen as a research object by homogenization test. The occurrence frequency of extreme high temperature in Hubei Province, intensity changes and response to the regional warming were analyzed. The results show that, the frequency of extreme high temperature is correlated well with the altitude, and that frequency of extreme high temperature displays decreasing in east and west directions and increasing in central. The spatial distribution in the frequency of extreme high temperature shows better consistency, and extreme high temperature events are prone to take place in Jianghan Plain and its northeast. The frequency of extreme high temperature events is positively responding to the summer mean temperature, and in relation to the western, the northeast response is more significant.
2012, 38(9):1150-1154.
DOI: 10.7519/j.issn.1000-0526.2012.09.017
Abstract:
There are less precipitaion, higher temperature and more high temperature days than normal all over China in summer 2011. Meanwhile, stage and regional drought and flood disasters occur and their transformations are quickly. The loss caused by typhoon is lighter, because the typhoon strength of landing China is weaker than normal in 2011. Based on analysis of causes for the weather and climate anomaly characters in summer 2011, the summer climate prediction in 2011 is reviewed. In general, the prediction catched the main characters mentioned above, but the forecast of precipitation over the middle and lower reaches of the Yangtze River is underestimated.
There are less precipitaion, higher temperature and more high temperature days than normal all over China in summer 2011. Meanwhile, stage and regional drought and flood disasters occur and their transformations are quickly. The loss caused by typhoon is lighter, because the typhoon strength of landing China is weaker than normal in 2011. Based on analysis of causes for the weather and climate anomaly characters in summer 2011, the summer climate prediction in 2011 is reviewed. In general, the prediction catched the main characters mentioned above, but the forecast of precipitation over the middle and lower reaches of the Yangtze River is underestimated.
2012, 38(9):1155-1160.
DOI: 10.7519/j.issn.1000-0526.2012.09.018
Abstract:
The following are the main characteristics of the general circulation of atmosphere in June 2012: there is only one polar vortex center in the Northern Hemisphere with stronger strength in relation to normal years. More troughs occur in middle high latitudes, and lead to cold air to influence China. The subtropical high is near climatological normal. The south branch trough at 90°E is slightly stronger than normal years. The monthly mean temperature averaged over China is 20.2℃， which is 0.4℃ higher than the same period of normal years. The mean precipitation (108.5 mm) is 11.2% more than normal (97.4 mm). The precipitation occurs frequently in South China, while the rainfall is more than normal in North China. More than 25 provinces (regions) are attacked by the hail disaster, such as Xinjiang, Shandong, Gansu and so on. Drought sustains in Jianghuai and Huanghuai areas. The strong tropical storms “Talim” and “Doksuri” have successively affected China.
The following are the main characteristics of the general circulation of atmosphere in June 2012: there is only one polar vortex center in the Northern Hemisphere with stronger strength in relation to normal years. More troughs occur in middle high latitudes, and lead to cold air to influence China. The subtropical high is near climatological normal. The south branch trough at 90°E is slightly stronger than normal years. The monthly mean temperature averaged over China is 20.2℃， which is 0.4℃ higher than the same period of normal years. The mean precipitation (108.5 mm) is 11.2% more than normal (97.4 mm). The precipitation occurs frequently in South China, while the rainfall is more than normal in North China. More than 25 provinces (regions) are attacked by the hail disaster, such as Xinjiang, Shandong, Gansu and so on. Drought sustains in Jianghuai and Huanghuai areas. The strong tropical storms “Talim” and “Doksuri” have successively affected China.
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ISSN:1000-0526 CN:11-2282/P