Volume 38,Issue 2,2010 Table of Contents
2010, 38(2):145-151.
Abstract:
The important physic and chemical phenomena， such as air jets， airplane jolts， the ozonopause and so on， closely relate to the position， intensity and fluctuation of the tropopause; therefore， it is extremely important to investigate the tropopause， which is already a focus in recent several decades. The researches on the tropopause are reviewed in aspects of the characteristics of the distribution and variation of the tropopause and the relation between tropopause and ozone， whereby some key problems encountered during researches are summarized and discussed.
The important physic and chemical phenomena， such as air jets， airplane jolts， the ozonopause and so on， closely relate to the position， intensity and fluctuation of the tropopause; therefore， it is extremely important to investigate the tropopause， which is already a focus in recent several decades. The researches on the tropopause are reviewed in aspects of the characteristics of the distribution and variation of the tropopause and the relation between tropopause and ozone， whereby some key problems encountered during researches are summarized and discussed.
2010, 38(2):152-158.
Abstract:
Considering the impact of initial matching，two groups of numerical experiments （S1 and S2） are made.The predictability of extraseasonal shortterm climate during summer is examined by the statistic crossvalidation method.The results are based on the ensembles of JJA simulation carried out with the BCC Atmospheric General Circulation Model （BCC_AGCM201） developed in the National Climate Center for the years of 1980 to 2006. It is shown that the capability of the model in predicting the seasonalscale atmospheric general circulation in the middle and low latitudes is better than that in high latitude. In general， the results also indicate that the integrated prediction agrees quite well with the observed largescale patterns of rainfall distribution. The effect of initial matching is distinct in the experiment S1 compared with that in S2， especially in the Jianghuai region and Southern China.
Considering the impact of initial matching，two groups of numerical experiments （S1 and S2） are made.The predictability of extraseasonal shortterm climate during summer is examined by the statistic crossvalidation method.The results are based on the ensembles of JJA simulation carried out with the BCC Atmospheric General Circulation Model （BCC_AGCM201） developed in the National Climate Center for the years of 1980 to 2006. It is shown that the capability of the model in predicting the seasonalscale atmospheric general circulation in the middle and low latitudes is better than that in high latitude. In general， the results also indicate that the integrated prediction agrees quite well with the observed largescale patterns of rainfall distribution. The effect of initial matching is distinct in the experiment S1 compared with that in S2， especially in the Jianghuai region and Southern China.
2010, 38(2):159-164.
Abstract:
A cone is used to represent the probable track of the center of a tropical cyclone, which is formed by enclosing the area swept out by a set of circles along the forecast track (at 24, 48 hours, etc). The size of each circle is set so that the entire track of the tropical cyclone can be expected to remain within the cone roughly 60% to 70% of the time. Based on forecasts over the previous 4 years (from 2004 to 2007), the relationship between tropical cyclone track forecast error and their forecast movement speed and direction is used in classification, and the probability circle radiuses are calculated by means of the statistical method as for the forecast valid time of 24, 48, 72 hours, respectively. The old data used operationally since 2007 are replaced with the new results calculated for the western North Pacific basin in order to reduce the forecast uncertainty. Meantime, the subjective forecasts in the recent five years are analyzed in terms of the modified probability circle radius. The characteristics of forecast errors and the causes of great errors in some tropical cyclone forecasting cases are also given from 2004 to 2007. Possibility of improving the calculation method of radius is also discussed.
A cone is used to represent the probable track of the center of a tropical cyclone, which is formed by enclosing the area swept out by a set of circles along the forecast track (at 24, 48 hours, etc). The size of each circle is set so that the entire track of the tropical cyclone can be expected to remain within the cone roughly 60% to 70% of the time. Based on forecasts over the previous 4 years (from 2004 to 2007), the relationship between tropical cyclone track forecast error and their forecast movement speed and direction is used in classification, and the probability circle radiuses are calculated by means of the statistical method as for the forecast valid time of 24, 48, 72 hours, respectively. The old data used operationally since 2007 are replaced with the new results calculated for the western North Pacific basin in order to reduce the forecast uncertainty. Meantime, the subjective forecasts in the recent five years are analyzed in terms of the modified probability circle radius. The characteristics of forecast errors and the causes of great errors in some tropical cyclone forecasting cases are also given from 2004 to 2007. Possibility of improving the calculation method of radius is also discussed.
2010, 38(2):165-169.
Abstract:
The effects of the Tibetan Plateau topography on Eurasian atmospheric circulation are studied. The experiments with and without TP (CTL and NTP Experiments) are performed respectively by using an atmospheric general circulation model (NCAR CAM 3.1). The results suggest: there are anomaly centers of the Rossby wave train from the Mongolia region, via Okhotsk Sea, Aleutian Islands to the west coast of North America in May; because the middle latitude westerly jet moves northward and weakens, and the Plateau diabetic heating is enhanced from May to June, the wavetrainlike height centers slightly changed their positions and weakened in June. Additionally, the wavelike anomaly centers around the Okhotsk Sea and the area off the east coast of Japan are similar to the positivephase OKJ wave train, which can be considered being suppressed by the east section of the positivephase OKJ wave train, strong in May and weak in June.
The effects of the Tibetan Plateau topography on Eurasian atmospheric circulation are studied. The experiments with and without TP (CTL and NTP Experiments) are performed respectively by using an atmospheric general circulation model (NCAR CAM 3.1). The results suggest: there are anomaly centers of the Rossby wave train from the Mongolia region, via Okhotsk Sea, Aleutian Islands to the west coast of North America in May; because the middle latitude westerly jet moves northward and weakens, and the Plateau diabetic heating is enhanced from May to June, the wavetrainlike height centers slightly changed their positions and weakened in June. Additionally, the wavelike anomaly centers around the Okhotsk Sea and the area off the east coast of Japan are similar to the positivephase OKJ wave train, which can be considered being suppressed by the east section of the positivephase OKJ wave train, strong in May and weak in June.
2010, 38(2):170-174.
Abstract:
The wind shear caused by the passing of a coldfront through the Capital Airport on 11 November 2008 and its predictable time scale are analyzed by means of the NCEP reanalysis data and AMDAR data.It is concluded that while the coldfront passing，there existed several forms of wind shear，including the horizontal wind shear related to an upperlevel trough; the vertical wind shear caused by the upperlevel and midlevel jet axes，temperature inversion before the coldfront，as well as the horizontalwind and crosswind shear on the runway surface while the surfacefront passing.The predictable time scales of these forms of wind shear are also discussed.
The wind shear caused by the passing of a coldfront through the Capital Airport on 11 November 2008 and its predictable time scale are analyzed by means of the NCEP reanalysis data and AMDAR data.It is concluded that while the coldfront passing，there existed several forms of wind shear，including the horizontal wind shear related to an upperlevel trough; the vertical wind shear caused by the upperlevel and midlevel jet axes，temperature inversion before the coldfront，as well as the horizontalwind and crosswind shear on the runway surface while the surfacefront passing.The predictable time scales of these forms of wind shear are also discussed.
2010, 38(2):175-181.
Abstract:
The radar and automatic precipitation station data of 5 to 7 June 2008 from the Guangdong provincial CINRAD network are used, an analysis is carried out of the observation differences of the radar networking system at 3 km over Guangdong Province, and it is discovered that observed values of Guangzhou radar, compared to nearby radar, are generally 1 to 3 dBz higher, and those of Meizhou radar are 1 to 2 dBz lower. With the Z〖CD*2〗R relationship and the optimum interpolation calibrated method, 6minute and 1hour quantitative rainfall estimations are conducted, and a verification is made using the basin average rainfall deviations and the rootmeansquare errors on the estimation effect. It is concluded: in 6minute precipitation estimation, two methods would underestimate precipitation, and the bigger the precipitation, the better the estimation effect is; in 1 hour precipitation estimation, the estimations of the two methods are generally higher, and the results of the radarraingauge estimation method is best, in which progressive accumulation and then calibration are performed; the shorttime precipitation estimation can reflect well the variation in precipitation processes, while the longterm precipitation estimations can estimate the amount of precipitation more accurately.
The radar and automatic precipitation station data of 5 to 7 June 2008 from the Guangdong provincial CINRAD network are used, an analysis is carried out of the observation differences of the radar networking system at 3 km over Guangdong Province, and it is discovered that observed values of Guangzhou radar, compared to nearby radar, are generally 1 to 3 dBz higher, and those of Meizhou radar are 1 to 2 dBz lower. With the Z〖CD*2〗R relationship and the optimum interpolation calibrated method, 6minute and 1hour quantitative rainfall estimations are conducted, and a verification is made using the basin average rainfall deviations and the rootmeansquare errors on the estimation effect. It is concluded: in 6minute precipitation estimation, two methods would underestimate precipitation, and the bigger the precipitation, the better the estimation effect is; in 1 hour precipitation estimation, the estimations of the two methods are generally higher, and the results of the radarraingauge estimation method is best, in which progressive accumulation and then calibration are performed; the shorttime precipitation estimation can reflect well the variation in precipitation processes, while the longterm precipitation estimations can estimate the amount of precipitation more accurately.
2010, 38(2):182-188.
Abstract:
Based on the conventional, microwave radiometer,and wind profiler data, the causes of a snowy weather event occurred on 7 February 2007 in Beijing are analyzed. The analysis of the circulation situation shows that the largescale circulation situation was favorable to the snowy weather during the eastward shifting of the middle troposphere convergence system, such as the strong warm southerly airflow and nearsurface conditions, etc, which are similar to the classical model of snowing in Beijing. The causes of the false precipitation prediction for the most part of Beijing include the filling of the inverted trough resulted from the weak southward cold airflow, the weak ascending current in the convergent system in PBL, and the relatively high and thin wet layer. The main reason for the false snowfall prediction is that the location and intensity of weather systems from NWP have obvious bias and longer lead time, and it is difficult for forecasters to judge the weather situation. The precipitation occurred at some stations in the eastern Beijing is mainly induced by the shortterm returning airflow in the condition of abundant vapor while the passing of an upperlevel trough with poor dynamic lifting. Under the favorable condition of abundant vapor provided by the warmwet air flow from south, condensation occurred easily at relatively high altitudes, which is the main reason of snowfall at some highelevation stations over Beijing.
Based on the conventional, microwave radiometer,and wind profiler data, the causes of a snowy weather event occurred on 7 February 2007 in Beijing are analyzed. The analysis of the circulation situation shows that the largescale circulation situation was favorable to the snowy weather during the eastward shifting of the middle troposphere convergence system, such as the strong warm southerly airflow and nearsurface conditions, etc, which are similar to the classical model of snowing in Beijing. The causes of the false precipitation prediction for the most part of Beijing include the filling of the inverted trough resulted from the weak southward cold airflow, the weak ascending current in the convergent system in PBL, and the relatively high and thin wet layer. The main reason for the false snowfall prediction is that the location and intensity of weather systems from NWP have obvious bias and longer lead time, and it is difficult for forecasters to judge the weather situation. The precipitation occurred at some stations in the eastern Beijing is mainly induced by the shortterm returning airflow in the condition of abundant vapor while the passing of an upperlevel trough with poor dynamic lifting. Under the favorable condition of abundant vapor provided by the warmwet air flow from south, condensation occurred easily at relatively high altitudes, which is the main reason of snowfall at some highelevation stations over Beijing.
2010, 38(2):189-192.
Abstract:
From late January to early February in 2008, there occurred rare snowy and freezing weather in the northwestern Fujian. The characteristics of the snowy and freezing weather are analyzed in terms of reflectivity, echo top, radial velocity,and VWP products from Doppler radar. The results indicate: (1) The echo intensity of ice and snow is weaker than that of continuous precipitation. (2) The heights of the echo top and zero layer are relatively low. (3) There exists a structure with a shape of a cow’s eye on the radial velocity chart, which means that there existed a lowlevel jet, and a circularshaped zerovelocity line at the lower level and a Sshaped zerovelocity line at middle and upper levels, which means that there was wind shear in the lowerlayer and cold advection in the middleupper layer. (4) In the VWP chart, there existed southwestern wind at the upper level, northwestern wind at the middle level, southwestern wind at the lower level, and northeastern wind in the surface layer, which means that the “coldwarmcoldwarm” stratification structure (from the near surface to upper level) was beneficial to the formation of freezing weather.
From late January to early February in 2008, there occurred rare snowy and freezing weather in the northwestern Fujian. The characteristics of the snowy and freezing weather are analyzed in terms of reflectivity, echo top, radial velocity,and VWP products from Doppler radar. The results indicate: (1) The echo intensity of ice and snow is weaker than that of continuous precipitation. (2) The heights of the echo top and zero layer are relatively low. (3) There exists a structure with a shape of a cow’s eye on the radial velocity chart, which means that there existed a lowlevel jet, and a circularshaped zerovelocity line at the lower level and a Sshaped zerovelocity line at middle and upper levels, which means that there was wind shear in the lowerlayer and cold advection in the middleupper layer. (4) In the VWP chart, there existed southwestern wind at the upper level, northwestern wind at the middle level, southwestern wind at the lower level, and northeastern wind in the surface layer, which means that the “coldwarmcoldwarm” stratification structure (from the near surface to upper level) was beneficial to the formation of freezing weather.
2010, 38(2):193-196.
Abstract:
The causes of a local extraordinary rainstorm in the northwestern Changde on 24 August 2006, by means of Doppler radar and Lightning data，is analyzed. The results indicate that the continual formation and combination of MCV (Mesoscale Convective Vortex) maintained the life cycle of MCC (Mesoscale Convective Complex), and three MCCs formed an organized MCS (Mesoscale Convective System); this heavy rain was caused mainly by the mesoscale convergence line; the generation and development of radar echoes inclined to the direction of the warmwet airflow; the southeast warm and wet airflow provided sufficient vapor; the beginning of lightning activity indicated the beginning of the heavy rain; the lifting effect of the southtonorth terrain favored the maintenance and reinforcement of the rainstorm and enhanced and prolonged the rainstorm.
The causes of a local extraordinary rainstorm in the northwestern Changde on 24 August 2006, by means of Doppler radar and Lightning data，is analyzed. The results indicate that the continual formation and combination of MCV (Mesoscale Convective Vortex) maintained the life cycle of MCC (Mesoscale Convective Complex), and three MCCs formed an organized MCS (Mesoscale Convective System); this heavy rain was caused mainly by the mesoscale convergence line; the generation and development of radar echoes inclined to the direction of the warmwet airflow; the southeast warm and wet airflow provided sufficient vapor; the beginning of lightning activity indicated the beginning of the heavy rain; the lifting effect of the southtonorth terrain favored the maintenance and reinforcement of the rainstorm and enhanced and prolonged the rainstorm.
2010, 38(2):197-200.
Abstract:
A detailed analysis is made of a singlepoint rainstorm on 11 September 2008 over the northwestern plateau of Yunnan Province through Lijiang (CINRAD/CC) Doppler radar data, in combination with the weather background and local topography. The results indicate: on the echo intensity field, there was a mixed precipitation echo composed by cumulus in the front and stratocumulus in the rear; there was an adverse wind area on the velocity field, around the moving path of which heavy precipitation occurred; cold advection characteristics are found at 5.2 km on the VWP map. The subtropical high is relatively strong on 500 hPa, and under the influence of a southward cold air from North China, a shear line moved southeastward on 700 hPa, resulting in the heavy precipitation. The dynamic lifting on the windward slope forced by the special terrain, combined with the wind field on 11 September 2008, is another important cause of the rainstorm.
A detailed analysis is made of a singlepoint rainstorm on 11 September 2008 over the northwestern plateau of Yunnan Province through Lijiang (CINRAD/CC) Doppler radar data, in combination with the weather background and local topography. The results indicate: on the echo intensity field, there was a mixed precipitation echo composed by cumulus in the front and stratocumulus in the rear; there was an adverse wind area on the velocity field, around the moving path of which heavy precipitation occurred; cold advection characteristics are found at 5.2 km on the VWP map. The subtropical high is relatively strong on 500 hPa, and under the influence of a southward cold air from North China, a shear line moved southeastward on 700 hPa, resulting in the heavy precipitation. The dynamic lifting on the windward slope forced by the special terrain, combined with the wind field on 11 September 2008, is another important cause of the rainstorm.
2010, 38(2):201-204.
Abstract:
The interdecadal variation of spring dust storm frequency (SDSF) in China and its possible affecting factors are examined on the basis of landsurface air temperature (SAT) and NCEP/NCAR reanalyzed datasets from 1954 to 2007. The results suggest that SDSF is negatively correlated with the SAT significantly around Lake Baikal, where the maximum correlation coefficient is -0.8. The warming around Lake Baikal can reduce the frequency of Mongolian cyclones and resulted in the decrease of SDSF in China over the past decades. It is found that the winter temperature at 850 hPa is positively correlated with the spring SAT significantly around Lake Baikal; therefore, a linear regression model between averaged winter air temperature index over the region of 80°〖KG-*9〗E to 140°〖KG-*9〗E, 40°〖KG-*9〗N to 70°〖KG-*9〗N and SDSF is constructed during a training period of 1954 to 1983. The verification for the hindcast period from 1984 to 2005 suggests that the forecasted DSF is positively correlated with the observation with a maximum correlation coefficient of +0.4; the average Anomaly Correlation Coefficient (ACC) is +0.4 with the root mean square error (RMS) being 1 to 2. Such a result implies that this statistical model has a potential capability in the operational seasonal forecasting of SDSF.
The interdecadal variation of spring dust storm frequency (SDSF) in China and its possible affecting factors are examined on the basis of landsurface air temperature (SAT) and NCEP/NCAR reanalyzed datasets from 1954 to 2007. The results suggest that SDSF is negatively correlated with the SAT significantly around Lake Baikal, where the maximum correlation coefficient is -0.8. The warming around Lake Baikal can reduce the frequency of Mongolian cyclones and resulted in the decrease of SDSF in China over the past decades. It is found that the winter temperature at 850 hPa is positively correlated with the spring SAT significantly around Lake Baikal; therefore, a linear regression model between averaged winter air temperature index over the region of 80°〖KG-*9〗E to 140°〖KG-*9〗E, 40°〖KG-*9〗N to 70°〖KG-*9〗N and SDSF is constructed during a training period of 1954 to 1983. The verification for the hindcast period from 1984 to 2005 suggests that the forecasted DSF is positively correlated with the observation with a maximum correlation coefficient of +0.4; the average Anomaly Correlation Coefficient (ACC) is +0.4 with the root mean square error (RMS) being 1 to 2. Such a result implies that this statistical model has a potential capability in the operational seasonal forecasting of SDSF.
2010, 38(2):205-208.
Abstract:
The trends of day/night precipitation distribution are analyzed by using the hourtohour precipitation data of 18 stations in Tibet from 1961 to 2006. The results show that the rate of night precipitation showed a decreasing trend and that of day precipitation an increasing trend in most parts of Tibet during recent 46 years; the days of night precipitation increased in winter half year in all regions, as well as in summer half year and all year in the northeastern and northwestern parts of Tibet, but decreased in the other regions; the days of seasonal and annual day precipitation increased in most parts of Tibet. The interdecadal variability of day and night rain frequency was large and has no obvious increasing trend, but had great difference between different decades in different regions.The rate of day rain was much less than normal in all year and summer half year, but greater in winter half year. The night rain days were less than normal in the eastern Tibetan and more in the central and western Tibet in summer half year. The day rain days were more than normal on the southern Tibet and North Tibet, and less in the other regions. The rate of day rain is depended on the intensity of precipitation in all year and season, but not the frequency of rains.
The trends of day/night precipitation distribution are analyzed by using the hourtohour precipitation data of 18 stations in Tibet from 1961 to 2006. The results show that the rate of night precipitation showed a decreasing trend and that of day precipitation an increasing trend in most parts of Tibet during recent 46 years; the days of night precipitation increased in winter half year in all regions, as well as in summer half year and all year in the northeastern and northwestern parts of Tibet, but decreased in the other regions; the days of seasonal and annual day precipitation increased in most parts of Tibet. The interdecadal variability of day and night rain frequency was large and has no obvious increasing trend, but had great difference between different decades in different regions.The rate of day rain was much less than normal in all year and summer half year, but greater in winter half year. The night rain days were less than normal in the eastern Tibetan and more in the central and western Tibet in summer half year. The day rain days were more than normal on the southern Tibet and North Tibet, and less in the other regions. The rate of day rain is depended on the intensity of precipitation in all year and season, but not the frequency of rains.
2010, 38(2):209-213.
Abstract:
A study is conducted of the characteristics of climatic change at Tianchi in the Tianshan Mountains， based on the climatic statistic data of the Tianchi station in the Tianshan Mountains from 1959 to 2007， by means of the linear trend estimation， power spectrum analysis， the moving〖WTBX〗 t〖WTBZ〗 test techniques， and anomaly standard deviation contrastive analysis.The results indicate that climatic change at Tianchi had obvious multirange oscillation characteristic， and possessed obvious annual change; a sudden change of air temperature occurred around 1996， but there was no such a sudden change in precipitation.Air temperature and precipitation changes were in agreement with the warmwet change pattern in the mountainous areas of the Tianshan Mountains.The minimum temperature increase contributed most greatly to the warming of Tianchi， and the most obvious humidity increase trend appeared in spring and winter; summer precipitation kept unchanged but the rainy days decreased. Extreme weather such as severe precipitation increased in summer.
A study is conducted of the characteristics of climatic change at Tianchi in the Tianshan Mountains， based on the climatic statistic data of the Tianchi station in the Tianshan Mountains from 1959 to 2007， by means of the linear trend estimation， power spectrum analysis， the moving〖WTBX〗 t〖WTBZ〗 test techniques， and anomaly standard deviation contrastive analysis.The results indicate that climatic change at Tianchi had obvious multirange oscillation characteristic， and possessed obvious annual change; a sudden change of air temperature occurred around 1996， but there was no such a sudden change in precipitation.Air temperature and precipitation changes were in agreement with the warmwet change pattern in the mountainous areas of the Tianshan Mountains.The minimum temperature increase contributed most greatly to the warming of Tianchi， and the most obvious humidity increase trend appeared in spring and winter; summer precipitation kept unchanged but the rainy days decreased. Extreme weather such as severe precipitation increased in summer.
2010, 38(2):214-221.
Abstract:
The principles of CINRAD velocity measurement are addressed in detail and systemically，and the questions of velocity ambiguity，as well as their reasons，are discussed.Based on these analyses，two methods for correcting ambiguity are introduced：theoretical value through velocity demarcation and true value displayed while velocity ambiguity occurring.Several precision test methods of different types of CINRAD are introduced and compared mutually， and their merits and demerits are given，which can be used in the technical assurance for CINRAD.
The principles of CINRAD velocity measurement are addressed in detail and systemically，and the questions of velocity ambiguity，as well as their reasons，are discussed.Based on these analyses，two methods for correcting ambiguity are introduced：theoretical value through velocity demarcation and true value displayed while velocity ambiguity occurring.Several precision test methods of different types of CINRAD are introduced and compared mutually， and their merits and demerits are given，which can be used in the technical assurance for CINRAD.
2010, 38(2):222-225.
Abstract:
To apply multichannel remote sensing technology to cloud remote sensing based on groundbased infrared sensors，the SBDART model is used to calculate the atmospheric downward infrared radiation of double bands（103 to 113 μm，115 to 125 μm），from which the characteristics of the brightness temperature difference are analyzed and the influences of the different visibilities and sky statuses on brightness temperature difference are discussed.The simulation results are compared with that in the real sky status. It is shown that in the perfect visibility situation，the change of the radiance at the zenith is more evident than that at the horizon，and the different characteristics of the brightness temperature difference in the different sky statuses can be adopted to identify clouds under higher visibility within a certain range of zenith angle.
To apply multichannel remote sensing technology to cloud remote sensing based on groundbased infrared sensors，the SBDART model is used to calculate the atmospheric downward infrared radiation of double bands（103 to 113 μm，115 to 125 μm），from which the characteristics of the brightness temperature difference are analyzed and the influences of the different visibilities and sky statuses on brightness temperature difference are discussed.The simulation results are compared with that in the real sky status. It is shown that in the perfect visibility situation，the change of the radiance at the zenith is more evident than that at the horizon，and the different characteristics of the brightness temperature difference in the different sky statuses can be adopted to identify clouds under higher visibility within a certain range of zenith angle.
2010, 38(2):226-229.
Abstract:
The curve fitting of XGH02 macromolecule carbon hygristor used in digital sondes is studied, based on the model of RBF (Radial Basis Function) neural network. Compared with the traditional method of curve fitting, a more precise model of sensor and error calibration is presented. The training and testing of the RBF neural network the model with training and testing samples indicates that the model of the RBF neural network can improve the accuracy of humidity resistance effectively, and the maximum error of measurement is 2.0298% (RH), which is smaller than that of the existing formula.
The curve fitting of XGH02 macromolecule carbon hygristor used in digital sondes is studied, based on the model of RBF (Radial Basis Function) neural network. Compared with the traditional method of curve fitting, a more precise model of sensor and error calibration is presented. The training and testing of the RBF neural network the model with training and testing samples indicates that the model of the RBF neural network can improve the accuracy of humidity resistance effectively, and the maximum error of measurement is 2.0298% (RH), which is smaller than that of the existing formula.
2010, 38(2):230-234.
Abstract:
The characteristics of phased array weather radar and the structure of a NetCDF (Network Common Data Form) file, and the data and product generation of phasedarray weather radar by uploading the NetCDFstored data are discussed, with emphasis on the file structure and uploading procedures of NetCDF data. The uploading of NetCDF data and the product display are realized on the on the VC++ platform. The NetCDF data comes from an synchronous observation experiment in 2004, in which the USA’s new modified phasedarray weather radar of and Doppler radar are used. By means of the product, the comparison and analysis are conducted of the characteristics of two radar sets respectively through a specific application example.
The characteristics of phased array weather radar and the structure of a NetCDF (Network Common Data Form) file, and the data and product generation of phasedarray weather radar by uploading the NetCDFstored data are discussed, with emphasis on the file structure and uploading procedures of NetCDF data. The uploading of NetCDF data and the product display are realized on the on the VC++ platform. The NetCDF data comes from an synchronous observation experiment in 2004, in which the USA’s new modified phasedarray weather radar of and Doppler radar are used. By means of the product, the comparison and analysis are conducted of the characteristics of two radar sets respectively through a specific application example.
2010, 38(2):235-238.
Abstract:
Using the parallel observation data of 135 stations with AWS (Automatic Weather Station) and manual pressure measurements in Sichuan, the differences between the two sorts of data are analyzed and discussed. The results show that the daily difference does not satisfy the normal distribution pattern, and the average daily pressure observed by manual way is 0.35 hPa greater than that by AWS. The correlation coefficient of average daily pressure is 099 with the significant level being 0.01； about 3/4 of manual measurements are greater than those from AWS’s. The monthly average difference between automatic and manual measurements is larger in the first half year with the largest difference in June. The annual mean difference is smallest in 2004 and greatest in 2006. There are about 90% stations in the whole province with negative difference values.
Using the parallel observation data of 135 stations with AWS (Automatic Weather Station) and manual pressure measurements in Sichuan, the differences between the two sorts of data are analyzed and discussed. The results show that the daily difference does not satisfy the normal distribution pattern, and the average daily pressure observed by manual way is 0.35 hPa greater than that by AWS. The correlation coefficient of average daily pressure is 099 with the significant level being 0.01； about 3/4 of manual measurements are greater than those from AWS’s. The monthly average difference between automatic and manual measurements is larger in the first half year with the largest difference in June. The annual mean difference is smallest in 2004 and greatest in 2006. There are about 90% stations in the whole province with negative difference values.
2010, 38(2):239-242.
Abstract:
The differences are compared and analyzed between soil relative humidity measurements from HYASF AWS (Automatic Weather Station) and conventional observation at Nancheng Station from 8 September 2005 to 28 January 2007 by means of the difference probability and correlation analysis methods. The results show that data consistency is best at 40 cm and 50 cm, and worst at 5 cm and 10 cm; automatic humidity values are higher than manual ones as the whole, and differences in rainless periods or dry season are often less than those in rainy periods, but there is still significant correlation between them in all layers. The results can provide an objective basis for evaluating the monitoring capability of HYASF automatic stations.
The differences are compared and analyzed between soil relative humidity measurements from HYASF AWS (Automatic Weather Station) and conventional observation at Nancheng Station from 8 September 2005 to 28 January 2007 by means of the difference probability and correlation analysis methods. The results show that data consistency is best at 40 cm and 50 cm, and worst at 5 cm and 10 cm; automatic humidity values are higher than manual ones as the whole, and differences in rainless periods or dry season are often less than those in rainy periods, but there is still significant correlation between them in all layers. The results can provide an objective basis for evaluating the monitoring capability of HYASF automatic stations.
20 Spatial and Temporal Characteristics of Potential Climatic Productivity of Maize in Northeast China
2010, 38(2):243-247.
Abstract:
The methods such as Rotated Empirical Orthogonal Function (REOF) and Power Spectrum are used to analyze the typical spatial and temporal characteristics of potential photothermal productivity and potential climatic productivity of maize from 1961 to 2007 in Northeast China. The results indicate that the photothermal potential productivity shows a significant increasing trend in recent years, while the potential climatic productivity shows a decreasing trend. Both of the two types of productivity have distinct interannual change, and the main variation period is about 7 to 9 years. Besides that, the potential climate productivity of maize also has the periods of 3 and 5 years. The change of photothermal potential productivity of maize in the southwestern part is opposite to that in the northeastern part. Most parts of Liaoning Province, the western Jilin Province, and the southwestern Heilongjiang Province have high photothermal potential productivity, while in the eastern Northeast China the photothermal potential productivity is relatively low. The areas with high potential climate productivity of maize are in the southeastern Northeast China, and the areas with low productivity are in the western Northeast China.
The methods such as Rotated Empirical Orthogonal Function (REOF) and Power Spectrum are used to analyze the typical spatial and temporal characteristics of potential photothermal productivity and potential climatic productivity of maize from 1961 to 2007 in Northeast China. The results indicate that the photothermal potential productivity shows a significant increasing trend in recent years, while the potential climatic productivity shows a decreasing trend. Both of the two types of productivity have distinct interannual change, and the main variation period is about 7 to 9 years. Besides that, the potential climate productivity of maize also has the periods of 3 and 5 years. The change of photothermal potential productivity of maize in the southwestern part is opposite to that in the northeastern part. Most parts of Liaoning Province, the western Jilin Province, and the southwestern Heilongjiang Province have high photothermal potential productivity, while in the eastern Northeast China the photothermal potential productivity is relatively low. The areas with high potential climate productivity of maize are in the southeastern Northeast China, and the areas with low productivity are in the western Northeast China.
21 Variation of Safe FullHeading Period for DoubleCropping Late Rice in Recent 40 Years in Wenzhou
2010, 38(2):248-252.
Abstract:
An analysis is made of the dates of last days for daily mean temperature being stably greater than 22 ℃ in use of the data from various stations of Wenzhou, and the variation characteristics and trends are obtained. To judge the objectivity of the variation, a significance test is conducted with SPSS (Statistical Product and Service Solutions). The results show that the dates of the last days for daily mean temperature being stably greater than 22 ℃ at some stations varied obviously after the 1990s. Under the condition of 80% assurance rate, the dates of the last days before and after 1990 are studied. The safe fullheading periods are determined, and the sowing dates are derived. The suggestions of sowing dates for doublecropping late rice are presented, which can be used as references for the better utilization of agricultural climatic resources.
An analysis is made of the dates of last days for daily mean temperature being stably greater than 22 ℃ in use of the data from various stations of Wenzhou, and the variation characteristics and trends are obtained. To judge the objectivity of the variation, a significance test is conducted with SPSS (Statistical Product and Service Solutions). The results show that the dates of the last days for daily mean temperature being stably greater than 22 ℃ at some stations varied obviously after the 1990s. Under the condition of 80% assurance rate, the dates of the last days before and after 1990 are studied. The safe fullheading periods are determined, and the sowing dates are derived. The suggestions of sowing dates for doublecropping late rice are presented, which can be used as references for the better utilization of agricultural climatic resources.
2010, 38(2):253-258.
Abstract:
The relationship between red tide disasters in the coastal area of Fujian Province and meteorological conditions is studied，and the circulation patterns for forecasting red tide disasters meteorologically is summed up. The red tide disaster data from 2001 to 2008 in the coastal area of Fujian Province and meteorological data of the corresponding period are used to seek the meteorological factors correlated with red tide disasters，so to analyze meteorological situations on the surface and at different levels during red tide disasters and to study the relationship between Southern Oscillation Index and occurrence of red tide disasters. Results show that meteorological factors such as wind，temperature，humidity， sunshine, and pressure in the coast area of Fujian are correlated well with red tide disasters， but the major factors vary in the different sea areas. The circulation situation at 850 hPa and on surface can better reflect the meteorological background during red tide disasters. Results also show good corresponding relation, with the correlation coefficient being -0.745, between Southern Oscillation index and the occurrence days of red tides next year.
The relationship between red tide disasters in the coastal area of Fujian Province and meteorological conditions is studied，and the circulation patterns for forecasting red tide disasters meteorologically is summed up. The red tide disaster data from 2001 to 2008 in the coastal area of Fujian Province and meteorological data of the corresponding period are used to seek the meteorological factors correlated with red tide disasters，so to analyze meteorological situations on the surface and at different levels during red tide disasters and to study the relationship between Southern Oscillation Index and occurrence of red tide disasters. Results show that meteorological factors such as wind，temperature，humidity， sunshine, and pressure in the coast area of Fujian are correlated well with red tide disasters， but the major factors vary in the different sea areas. The circulation situation at 850 hPa and on surface can better reflect the meteorological background during red tide disasters. Results also show good corresponding relation, with the correlation coefficient being -0.745, between Southern Oscillation index and the occurrence days of red tides next year.
2010, 38(2):259-262.
Abstract:
Atmospheric particles have many adverse influences on the environment, climate and human health due to their physical and chemical properties, such as adsorption, moisture and light absorption and scattering. Along with the development of electron and computer technology, the observation of the microstructure of atmospheric particles and the microstructural analysis of elements are made possible by ESEM and Xray Energy Dispersive Microanalysis (EDS). An introduction is conducted on the basic principles and functions of ESEM, and the application of ESEM in meteorological service. Taking the atmospheric particles produced by pyrotechnics in weather modification operation as an example, the microstructure and chemical properties of atmospheric particles is studied.
Atmospheric particles have many adverse influences on the environment, climate and human health due to their physical and chemical properties, such as adsorption, moisture and light absorption and scattering. Along with the development of electron and computer technology, the observation of the microstructure of atmospheric particles and the microstructural analysis of elements are made possible by ESEM and Xray Energy Dispersive Microanalysis (EDS). An introduction is conducted on the basic principles and functions of ESEM, and the application of ESEM in meteorological service. Taking the atmospheric particles produced by pyrotechnics in weather modification operation as an example, the microstructure and chemical properties of atmospheric particles is studied.
2010, 38(2):263-269.
Abstract:
The occurrence and development regularity of geologic disasters over the QinlingBashan areas are studied statistically by using the geologic disaster and precipitation data from 1955 to 2007, as well as the data from intensive observation， AWS (automatic weather station), and hydrological stations. The formation mechanisms of geologic disasters and relation with the intensity and duration of precipitation are investigated and the critical precipitation indexes for various disasterprone areas are devised. An automatic refined operational forecasting and warning system of geologic disasters is thus established, in combination with the existing operational refined geologic disaster forecasting procedures of the China Meteorological Administration. The application experiment in 2008 proved that its forecasting accuracy is better than that of the original GIScoupled model.
The occurrence and development regularity of geologic disasters over the QinlingBashan areas are studied statistically by using the geologic disaster and precipitation data from 1955 to 2007, as well as the data from intensive observation， AWS (automatic weather station), and hydrological stations. The formation mechanisms of geologic disasters and relation with the intensity and duration of precipitation are investigated and the critical precipitation indexes for various disasterprone areas are devised. An automatic refined operational forecasting and warning system of geologic disasters is thus established, in combination with the existing operational refined geologic disaster forecasting procedures of the China Meteorological Administration. The application experiment in 2008 proved that its forecasting accuracy is better than that of the original GIScoupled model.
2010, 38(2):270-273.
Abstract:
Because of the scarcity of serious lightning samples，statistical methods cannot be used in analysis.Taking Fujian Province as an example，analyzed is the variation tendency of lightning disasters from 2000 to 2006， aiming to predict serious lightning disasters using the information diffusion technique.The results show that the total frequency of lightning disasters presented an increasing tendency， but the frequency of serious lightning disasters did not change obviously.There usually are 27 to 40 serious lightning disasters each year in Fujian Province， and the probability of the accumulated frequency being less than 20 times or more than 45 times is almost negligible.The occurrence probability of serious lightning disasters being more than 34 times is about once every two years，and that of more than 42 times lightning disaster and once every ten years.
Because of the scarcity of serious lightning samples，statistical methods cannot be used in analysis.Taking Fujian Province as an example，analyzed is the variation tendency of lightning disasters from 2000 to 2006， aiming to predict serious lightning disasters using the information diffusion technique.The results show that the total frequency of lightning disasters presented an increasing tendency， but the frequency of serious lightning disasters did not change obviously.There usually are 27 to 40 serious lightning disasters each year in Fujian Province， and the probability of the accumulated frequency being less than 20 times or more than 45 times is almost negligible.The occurrence probability of serious lightning disasters being more than 34 times is about once every two years，and that of more than 42 times lightning disaster and once every ten years.
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.