Volume 35,Issue 3,2007 Table of Contents
2007, 35(3):309-316.
Abstract:
This review summarizes some recent research advancements about the orographic influences on surface precipitation. The orographic dynamical and thermodynamical effects and their influences on precipitation and cloud physics are analyzed in detail. Emphasis is put on the orographic influences on the precipitation produced by weather systems of different scales, including climatic scale, synoptic scale, mesoscale convective systems. The existing problems in this field relevant to observation and analysis, climatic statistics, theoretical analysis and model simulation are discussed, and an outlook for this field is given.
This review summarizes some recent research advancements about the orographic influences on surface precipitation. The orographic dynamical and thermodynamical effects and their influences on precipitation and cloud physics are analyzed in detail. Emphasis is put on the orographic influences on the precipitation produced by weather systems of different scales, including climatic scale, synoptic scale, mesoscale convective systems. The existing problems in this field relevant to observation and analysis, climatic statistics, theoretical analysis and model simulation are discussed, and an outlook for this field is given.
2007, 35(3):317-321.
Abstract:
The hydrological principles of applying the flow hydrograph produced by precipitation are introduced, and a flood and waterlogging index calculated only with precipitation data and a quantitative method for forecasting the flood and waterlogging intensity over a river drainage area are presented. The method uses the conventional precipitation data to calculate the effective integrated areal rainfall in the valley (considering different contributions of successive areal rainfall days in the valley during the former period). Through checking the relationship between flood and waterlogging data (such as precipitation, water level, etc.) and the effective integrated areal rainfall, the magnitude of the effective integrated areal rainfall for various levels of flood and waterlogging index in the valley can be determined. In the operational forecasting, the actual and forecasted areal rainfall are used to determine the effective integrated areal rainfall for a certain future day, and then by comparing it with the given effective integrated areal rainfall corresponding to the flood and waterlogging indexes of various levels, the level and intensity of flood and waterlogging can be estimated.
The hydrological principles of applying the flow hydrograph produced by precipitation are introduced, and a flood and waterlogging index calculated only with precipitation data and a quantitative method for forecasting the flood and waterlogging intensity over a river drainage area are presented. The method uses the conventional precipitation data to calculate the effective integrated areal rainfall in the valley (considering different contributions of successive areal rainfall days in the valley during the former period). Through checking the relationship between flood and waterlogging data (such as precipitation, water level, etc.) and the effective integrated areal rainfall, the magnitude of the effective integrated areal rainfall for various levels of flood and waterlogging index in the valley can be determined. In the operational forecasting, the actual and forecasted areal rainfall are used to determine the effective integrated areal rainfall for a certain future day, and then by comparing it with the given effective integrated areal rainfall corresponding to the flood and waterlogging indexes of various levels, the level and intensity of flood and waterlogging can be estimated.
2007, 35(3):322-326.
Abstract:
An uncertainty index (from the uncertainty in measurement, proposed by the International Organization for Standardization) and the instability index (a derived index) are defined to evaluate the forecast performance of Numerical Weather Prediction (NWP) models. The uncertainty index is defined by comparing two mosaicked model fields with same meteorological variables from analysis and prediction, respectively. An operational system based on the two indexes is developed to evaluate the prediction performance for three operational NWP models (ECMWF, JMA and T213) in real time. Results from the operational application of these indexes show that these models can provide objective criteria for forecasters to evaluate NWP models, and be helpful for better use of NWP products.
An uncertainty index (from the uncertainty in measurement, proposed by the International Organization for Standardization) and the instability index (a derived index) are defined to evaluate the forecast performance of Numerical Weather Prediction (NWP) models. The uncertainty index is defined by comparing two mosaicked model fields with same meteorological variables from analysis and prediction, respectively. An operational system based on the two indexes is developed to evaluate the prediction performance for three operational NWP models (ECMWF, JMA and T213) in real time. Results from the operational application of these indexes show that these models can provide objective criteria for forecasters to evaluate NWP models, and be helpful for better use of NWP products.
2007, 35(3):327-329.
Abstract:
The MM5 model system is used widely in meteorological research and weather prediction operation, but for some unknown reasons, it runs usually on the commercial version of Unix and Linux systems and is unamiable to free Unixlike systems. The transplantation of MM5V3 on the highperformance operating system FreeBSD is introduced in detail. FreeBSD is a free Unix system with particularly high performance. The run time on FreeBSD 6.0 is compared with that on RHAS 4 (Red Hat Advanced Server 4), and it is found that FreeBSD's performance is higher obviously than RHAS'. It is of great significance to operational forecasting.
The MM5 model system is used widely in meteorological research and weather prediction operation, but for some unknown reasons, it runs usually on the commercial version of Unix and Linux systems and is unamiable to free Unixlike systems. The transplantation of MM5V3 on the highperformance operating system FreeBSD is introduced in detail. FreeBSD is a free Unix system with particularly high performance. The run time on FreeBSD 6.0 is compared with that on RHAS 4 (Red Hat Advanced Server 4), and it is found that FreeBSD's performance is higher obviously than RHAS'. It is of great significance to operational forecasting.
2007, 35(3):330-334.
Abstract:
Hail events occurred in Handan on 10 May 2005, 11 and 28 June 2005, 13 July 2005 and 20 June 2004, respectively, are analyzed by means of the conventional observation data and radar echo data to analyze compositely the five hail events from the aspects of weather situation, physical vector fields, and evolution features of radar echoes. The results show that the hail weather appeared under the unstable stratification of convection conditions: the middle or top layer is dry and cold, but the low layer is humid; there existed a mesoscale convergent shear on the ground; the heights of the 0 ℃ layer, -20 ℃ layer and strong vertical wind shear were favorable. The findings conclude that Doppler radar can properly monitor and measure the development and evolution processes of the mesoscale weather systems; the variation of echo intensity, echo top heights, wind speed, the emergence of adverse wind areas, and the sudden increase of OHP (OneHour Precipitation accumulation) and VIL (Vertical Integration of Liquid water) values can be the indicators of hail emergence.
Hail events occurred in Handan on 10 May 2005, 11 and 28 June 2005, 13 July 2005 and 20 June 2004, respectively, are analyzed by means of the conventional observation data and radar echo data to analyze compositely the five hail events from the aspects of weather situation, physical vector fields, and evolution features of radar echoes. The results show that the hail weather appeared under the unstable stratification of convection conditions: the middle or top layer is dry and cold, but the low layer is humid; there existed a mesoscale convergent shear on the ground; the heights of the 0 ℃ layer, -20 ℃ layer and strong vertical wind shear were favorable. The findings conclude that Doppler radar can properly monitor and measure the development and evolution processes of the mesoscale weather systems; the variation of echo intensity, echo top heights, wind speed, the emergence of adverse wind areas, and the sudden increase of OHP (OneHour Precipitation accumulation) and VIL (Vertical Integration of Liquid water) values can be the indicators of hail emergence.
2007, 35(3):335-339.
Abstract:
The clustering analysis method is employed to divide the rainfall field in spring and summer over the ThreeRiver Source region into three areas for predicting the rainfall distribution and rainfall trends for different areas. Based on the correlation relationship of the spring and summer rainfall indexes in the three areas with the Pacific SST in the preceding season, the SST distribution index is defined. When the winter SST over the western Pacific is lower (higher) than normal, the higher (lower) than normal SST distribution in the central and eastern equatorial Pacific is correlated with the decreased (increased) spring rainfall in Areas 1 and 3 of the ThreeRiver Source Region; while the higher (lower) than normal winter SST distribution in the central equatorial Pacific and off the coast of California is correlated with the decreased (increased) summer rainfall in Areas 2 and 3 of the ThreeRiver Source region. Further analyses are conducted of the correlation relationship between the winter SST in Pacific and the spring and summer 500 hPa geopotential height field in the Northern Hemisphere. The results show that when the overall winter Pacific SST index is high (low), the Indian high pressure system, central Siberia trough and Aleutian trough at 500 hPa in spring strengthen (weaken) with increased (decreased) spring rainfall in the ThreeRiver Source region. In contrast, when the overall winter SST index in the central Pacific and off the coast of California is high (low), the Iranian high pressure system and central Siberia ridge in summer strengthen (weaken) with the southward (northward) displacement of the western Pacific subtropical high and decreased (increased) summer rainfall in the ThreeRiver Source region.
The clustering analysis method is employed to divide the rainfall field in spring and summer over the ThreeRiver Source region into three areas for predicting the rainfall distribution and rainfall trends for different areas. Based on the correlation relationship of the spring and summer rainfall indexes in the three areas with the Pacific SST in the preceding season, the SST distribution index is defined. When the winter SST over the western Pacific is lower (higher) than normal, the higher (lower) than normal SST distribution in the central and eastern equatorial Pacific is correlated with the decreased (increased) spring rainfall in Areas 1 and 3 of the ThreeRiver Source Region; while the higher (lower) than normal winter SST distribution in the central equatorial Pacific and off the coast of California is correlated with the decreased (increased) summer rainfall in Areas 2 and 3 of the ThreeRiver Source region. Further analyses are conducted of the correlation relationship between the winter SST in Pacific and the spring and summer 500 hPa geopotential height field in the Northern Hemisphere. The results show that when the overall winter Pacific SST index is high (low), the Indian high pressure system, central Siberia trough and Aleutian trough at 500 hPa in spring strengthen (weaken) with increased (decreased) spring rainfall in the ThreeRiver Source region. In contrast, when the overall winter SST index in the central Pacific and off the coast of California is high (low), the Iranian high pressure system and central Siberia ridge in summer strengthen (weaken) with the southward (northward) displacement of the western Pacific subtropical high and decreased (increased) summer rainfall in the ThreeRiver Source region.
2007, 35(3):340-344.
Abstract:
An analysis is made of the climate variation trend and abrupt climate changes over the source region of the Yangtze River in the last 44 years based on the temperature and precipitation data of 5 stations and 500 hPa dew point data of 2 highaltitude stations. The result shows that the temperature increased over the region, and the variation range is greater in winter, but the tendency is obvious in summer; the annual and summery precipitation decreased, while increased in the other seasons; and the greater range is found in spring, more obvious tendency in winter. The annual average temperature shows a rising trend from the end of the 1960's to the early 1970's; the abrupt change from cold to warm happened in 1986; and the abrupt increasing of precipitation in winter and spring appeared in the 1970's and the 1980's. The signals that the climate becomes warm and humid in the source region of the Yangtze River climate appeared since 1986, and the main causes include the global climate warming, the resulting intensification of the evaporation over the oceans and lands, and the quicker surface water circulation and air moisture transportation.
An analysis is made of the climate variation trend and abrupt climate changes over the source region of the Yangtze River in the last 44 years based on the temperature and precipitation data of 5 stations and 500 hPa dew point data of 2 highaltitude stations. The result shows that the temperature increased over the region, and the variation range is greater in winter, but the tendency is obvious in summer; the annual and summery precipitation decreased, while increased in the other seasons; and the greater range is found in spring, more obvious tendency in winter. The annual average temperature shows a rising trend from the end of the 1960's to the early 1970's; the abrupt change from cold to warm happened in 1986; and the abrupt increasing of precipitation in winter and spring appeared in the 1970's and the 1980's. The signals that the climate becomes warm and humid in the source region of the Yangtze River climate appeared since 1986, and the main causes include the global climate warming, the resulting intensification of the evaporation over the oceans and lands, and the quicker surface water circulation and air moisture transportation.
2007, 35(3):345-350.
Abstract:
The snow disaster variation and its circulation characteristics in the early winter are analyzed by use of the meteorological data of air temperature, precipitation and snow cover in the early winter over the southern Qinghai Province from 1961 to 2004. The result shows that snowfall over the southern Qinghai Province had been decreasing; the averaged snow cover had a slight decreasing trend comparing with other seasons, which was negatively correlated with air temperature, but positively correlated with snowfall. The principal synoptic systems of impacting snowfall in the early winter were the combinations of the westerly and southtonorth trough, moving plateau trough, plateau low pressure, plateau shear line, Bangladesh Bay storm; the configuration of the 850 hPa temperature anomaly field of the southern and middle Asia in the typical snowabundant/scarce year on the plateau was “positive in the south and negative in the north”, while the anomaly distribution of 500 hPa on the plateau and the eastern coastal area was “low in the west and high in the east”.
The snow disaster variation and its circulation characteristics in the early winter are analyzed by use of the meteorological data of air temperature, precipitation and snow cover in the early winter over the southern Qinghai Province from 1961 to 2004. The result shows that snowfall over the southern Qinghai Province had been decreasing; the averaged snow cover had a slight decreasing trend comparing with other seasons, which was negatively correlated with air temperature, but positively correlated with snowfall. The principal synoptic systems of impacting snowfall in the early winter were the combinations of the westerly and southtonorth trough, moving plateau trough, plateau low pressure, plateau shear line, Bangladesh Bay storm; the configuration of the 850 hPa temperature anomaly field of the southern and middle Asia in the typical snowabundant/scarce year on the plateau was “positive in the south and negative in the north”, while the anomaly distribution of 500 hPa on the plateau and the eastern coastal area was “low in the west and high in the east”.
2007, 35(3):351-354.
Abstract:
The mesoscale characteristics of heavy rainfall events over the northern Fujian Province are studied by using of the hourly precipitation of 49 heavy rainfall events on 129 heavy rain days in flood senson at 10 stations of Nanping, Fujiang Province from 1980 to 2005. The spatial and temporal distribution, moving features, precipitation processes, influencing systems of rain clusters and severe rain clusters on heavy rain days in flood season, and topographic effect are analyzed. Some features and movement regularities of mesoscale precipitation systems in Nanping are described. The result is useful to forecasters.
The mesoscale characteristics of heavy rainfall events over the northern Fujian Province are studied by using of the hourly precipitation of 49 heavy rainfall events on 129 heavy rain days in flood senson at 10 stations of Nanping, Fujiang Province from 1980 to 2005. The spatial and temporal distribution, moving features, precipitation processes, influencing systems of rain clusters and severe rain clusters on heavy rain days in flood season, and topographic effect are analyzed. Some features and movement regularities of mesoscale precipitation systems in Nanping are described. The result is useful to forecasters.
2007, 35(3):355-358.
Abstract:
The distribution and the climate characteristics of fog in Shangqiu are analyzed by use of fog data from eight weather stations in Shangqiu from 1961 to 2004. The results indicate that fog days occurred more frequently in the west part such as Suixian and Ningilng than in the south part such as Zhecheng and Xiayi. There was an increasing annual tendency in foggy days and a Vshaped monthly variation feature with the maximum in fall and minimum in summer. The fogs occurred generally in early morning, and dissipated most likely at seven to eight o'clock after sunrise. The duration of fog was mostly less than 3 hours and there was no fog maintaining more than 24 hours. Based on the weather maps from 1999 to 2004, the surface synoptic patterns favorable for foggy days can be classified to four kinds: continental anticyclone, warm zone in front of cold front, uniform pressure field, and low pressure with an inverted trough.
The distribution and the climate characteristics of fog in Shangqiu are analyzed by use of fog data from eight weather stations in Shangqiu from 1961 to 2004. The results indicate that fog days occurred more frequently in the west part such as Suixian and Ningilng than in the south part such as Zhecheng and Xiayi. There was an increasing annual tendency in foggy days and a Vshaped monthly variation feature with the maximum in fall and minimum in summer. The fogs occurred generally in early morning, and dissipated most likely at seven to eight o'clock after sunrise. The duration of fog was mostly less than 3 hours and there was no fog maintaining more than 24 hours. Based on the weather maps from 1999 to 2004, the surface synoptic patterns favorable for foggy days can be classified to four kinds: continental anticyclone, warm zone in front of cold front, uniform pressure field, and low pressure with an inverted trough.
2007, 35(3):359-362.
Abstract:
In order to describe quantitatively the relation between subtropical high variation and summer precipitation in Jixing, a subtropicalhigh index is defined by selecting a specified key area on 500 hPa. The analysis of the index indicates that there existed very good relation between subtropicalhigh index and summer precipitation with interdecadal variation periods of more than 45 years and about 9 to 16 years, as well 4 years and quasi2 years. The index can be used in operational precipitation forecasting. There occurred a synchronous interdecadal jump in summer precipitation in Jiaxing and Northwest Pacific Ocean tropical high around 1980. Before 1980, the tropical high intensity was weaker and farther eastern than normal, while the precipitation in Jiaxing was less than normal; and after 1980, vice versa.
In order to describe quantitatively the relation between subtropical high variation and summer precipitation in Jixing, a subtropicalhigh index is defined by selecting a specified key area on 500 hPa. The analysis of the index indicates that there existed very good relation between subtropicalhigh index and summer precipitation with interdecadal variation periods of more than 45 years and about 9 to 16 years, as well 4 years and quasi2 years. The index can be used in operational precipitation forecasting. There occurred a synchronous interdecadal jump in summer precipitation in Jiaxing and Northwest Pacific Ocean tropical high around 1980. Before 1980, the tropical high intensity was weaker and farther eastern than normal, while the precipitation in Jiaxing was less than normal; and after 1980, vice versa.
2007, 35(3):363-367.
Abstract:
The influencing systems and the developing process of a hail event occurred on 30 May 2005 in Gansu are analyzed with cloud and radar echo images in detail in combination with the actual weather situation, circulation pattern, and environmental fields. The characteristics of hail cloud echoes, velocity echoes and satellite cloud images are obtained. The findings conclude that the event w as caused by a mesoβscale convective system rather than a zonal hail cloud system. Some quantitative indexes are also achieved, which is meaningful to the operational hail forecast.
The influencing systems and the developing process of a hail event occurred on 30 May 2005 in Gansu are analyzed with cloud and radar echo images in detail in combination with the actual weather situation, circulation pattern, and environmental fields. The characteristics of hail cloud echoes, velocity echoes and satellite cloud images are obtained. The findings conclude that the event w as caused by a mesoβscale convective system rather than a zonal hail cloud system. Some quantitative indexes are also achieved, which is meaningful to the operational hail forecast.
2007, 35(3):368-373.
Abstract:
The characteristics of the largescale circulation background and mesoscale systems of the North China heavy rain storm occurred on 16 August 2005 are studied on the basis of the NCEP reanalysis data, surface hourly precipitation data, Doppler data and ShumanShapiro filter method. Results show that the heavy rainfall event occurred under the favorable environmental conditions, resulted fro m the interaction of midand lowlatitude systems. The mesoscale convergence and the mesoscale low triggered the occurrence of the heavy rainfall. Rain clusters bringing the heavy rainfall were related to mesoβ systems. The mesoβ mesoscale rain clusters appeared to the north of the cyclone center on 1000 hPa after filtering and to the south of the mesoα convergence line on 850 hPa.
The characteristics of the largescale circulation background and mesoscale systems of the North China heavy rain storm occurred on 16 August 2005 are studied on the basis of the NCEP reanalysis data, surface hourly precipitation data, Doppler data and ShumanShapiro filter method. Results show that the heavy rainfall event occurred under the favorable environmental conditions, resulted fro m the interaction of midand lowlatitude systems. The mesoscale convergence and the mesoscale low triggered the occurrence of the heavy rainfall. Rain clusters bringing the heavy rainfall were related to mesoβ systems. The mesoβ mesoscale rain clusters appeared to the north of the cyclone center on 1000 hPa after filtering and to the south of the mesoα convergence line on 850 hPa.
2007, 35(3):374-378.
Abstract:
The mechanism analysis of a floodinducing heavy rainfall occurred in June 2005 Guangdong Province is diagnosed by analyzing the circulation situation, moisture, dynamical mechanism, vertical helicity, and so on based on the conventional observation data, radar echo, satellite image and NCEP grid data. The results show that the causes of the heavy rainfall include the farther south and weakerthannormal ridge position of the West Pacific subtropical high and the interaction between the southwest warm and wet airflow to the north of the subtropical high and the cold air in front of the westerly trough; the lowlevel jet stream provides enough moisture; the divergence in high level and the convergence in low level resulted in strong updraft; the vertical helicity is two orders of magnitude greater than normal with the long axis of the positive vertical helicity area having the same direction with the movement of the shear convergence line on 700 hPa. During the heavy flooding rainfall, there was an enclosed negative center of vertical helicity at the middle level and an enclosed positive center at the upper level, spreading obviously down to the lower level.
The mechanism analysis of a floodinducing heavy rainfall occurred in June 2005 Guangdong Province is diagnosed by analyzing the circulation situation, moisture, dynamical mechanism, vertical helicity, and so on based on the conventional observation data, radar echo, satellite image and NCEP grid data. The results show that the causes of the heavy rainfall include the farther south and weakerthannormal ridge position of the West Pacific subtropical high and the interaction between the southwest warm and wet airflow to the north of the subtropical high and the cold air in front of the westerly trough; the lowlevel jet stream provides enough moisture; the divergence in high level and the convergence in low level resulted in strong updraft; the vertical helicity is two orders of magnitude greater than normal with the long axis of the positive vertical helicity area having the same direction with the movement of the shear convergence line on 700 hPa. During the heavy flooding rainfall, there was an enclosed negative center of vertical helicity at the middle level and an enclosed positive center at the upper level, spreading obviously down to the lower level.
2007, 35(3):379-382.
Abstract:
A mesoscale analysis is performed of the regional heavy rain in the early summer of 2006 in Shaanxi Province with the rainfall data of automatic precipitation stations, FY2C satellite TBB, DopplerRadar data, etc. The results indicate that the regional heavy rain occurred under the effect of mesoscale convergence line and mesoβ convective cloud clusters together. The mesoscale system s corresponding to the heavy rain centers can be clearly seen from the stream field after filtering. It can be seen that the severe heavy rainfall is closely connected with the strong radar reflectivity, adverse wind area, lowlevel jet, and warm advection.
A mesoscale analysis is performed of the regional heavy rain in the early summer of 2006 in Shaanxi Province with the rainfall data of automatic precipitation stations, FY2C satellite TBB, DopplerRadar data, etc. The results indicate that the regional heavy rain occurred under the effect of mesoscale convergence line and mesoβ convective cloud clusters together. The mesoscale system s corresponding to the heavy rain centers can be clearly seen from the stream field after filtering. It can be seen that the severe heavy rainfall is closely connected with the strong radar reflectivity, adverse wind area, lowlevel jet, and warm advection.
2007, 35(3):383-386.
Abstract:
A comparative analysis is made of two severe convective weather events occurred over the Zhoushan islands in 2004 by means of the data from new generation Doppler weather radar. One has extreme rainfall, while the other has extreme gales. The reflectivity, radial velocity and other secondary radar products of the two cases are analyzed, and some similarities and differences are found out. Both cases have seen organized strong echoes, strong wind areas in radial velocity pictures, vertical wind shear, high echo tops, and large VIL (Vertical Integrated Liquid water). Heavy rainfall happened when the echoes moved slowly while strong gales happened when the echoes moved quickly. The case of extreme gales had higher echo top, greater reflectivity and VIL. The wind convergence, mesoscale cyclone and vertical wind shear at lower levels may produce heavy rainfall. The mesoscale cyclone and vertical wind shear at middle and upper levels may produce strong downburst or hails.
A comparative analysis is made of two severe convective weather events occurred over the Zhoushan islands in 2004 by means of the data from new generation Doppler weather radar. One has extreme rainfall, while the other has extreme gales. The reflectivity, radial velocity and other secondary radar products of the two cases are analyzed, and some similarities and differences are found out. Both cases have seen organized strong echoes, strong wind areas in radial velocity pictures, vertical wind shear, high echo tops, and large VIL (Vertical Integrated Liquid water). Heavy rainfall happened when the echoes moved slowly while strong gales happened when the echoes moved quickly. The case of extreme gales had higher echo top, greater reflectivity and VIL. The wind convergence, mesoscale cyclone and vertical wind shear at lower levels may produce heavy rainfall. The mesoscale cyclone and vertical wind shear at middle and upper levels may produce strong downburst or hails.
2007, 35(3):387-392.
Abstract:
The version 7 and version 8 of TOMS (Total Ozone Mapping Spectrometer) ozone data sets are most widely used at present. The TOMS data of version 7 and version 8 are compared and the features and distribution of the differences between the data of version 7 and version 8 are discussed. By means of the two version ozone data of TOMS from November 1978 to December 2001, the spatialte mporal variation of the differences between two version ozone data are analyzed in detail. Results show that though quite good relationship exists between two versions data sets, there are significant spatialtemporal differences in magnitude, especially over two polar areas.
The version 7 and version 8 of TOMS (Total Ozone Mapping Spectrometer) ozone data sets are most widely used at present. The TOMS data of version 7 and version 8 are compared and the features and distribution of the differences between the data of version 7 and version 8 are discussed. By means of the two version ozone data of TOMS from November 1978 to December 2001, the spatialte mporal variation of the differences between two version ozone data are analyzed in detail. Results show that though quite good relationship exists between two versions data sets, there are significant spatialtemporal differences in magnitude, especially over two polar areas.
2007, 35(3):393-399.
Abstract:
Dust storms that impact China mostly happen in spring, seldom in summer. The dust aerosol model (GRAPESDAM) is applied to simulate a group of dust severe storms occurred in Hexi Corridor in July 2005. By means of the case simulation and analysis, the feasibility of summer severe dust storm predictions is discussed. The simulation shows that the model can simulate successfully the dust storms, including the surface wind, the spreading area, and the movement of the dust storms. For summer clustering severe dust storms, in condition of exact numerical prediction of the synoptic pattern and meteorological fields, the dust aerosol model is able to make meaningful prediction of this kind of dust storms.
Dust storms that impact China mostly happen in spring, seldom in summer. The dust aerosol model (GRAPESDAM) is applied to simulate a group of dust severe storms occurred in Hexi Corridor in July 2005. By means of the case simulation and analysis, the feasibility of summer severe dust storm predictions is discussed. The simulation shows that the model can simulate successfully the dust storms, including the surface wind, the spreading area, and the movement of the dust storms. For summer clustering severe dust storms, in condition of exact numerical prediction of the synoptic pattern and meteorological fields, the dust aerosol model is able to make meaningful prediction of this kind of dust storms.
2007, 35(3):400-403.
Abstract:
The effects of climate warming on plant phonological changes from 1983 to 2004 in Guangdong are studied by use of the plant phenological data and temperature data of 10 Agrometeorological stations in Guangdong of the same time. The models for relationship between phenological periods and temperature are constructed. The responses of the phenological period to climate change are ana lyzed. The results show that the phenological periods of ligneous plants occurred earlier with increasing temperature in spring; on the contrary, the ligneous plant phenological periods delayed with decreasing temperature. The response of plant phenological periods to climate change is nonlinear. In the context of the same range of temperature rise or fall, the range of phonological period postpone as a result of the temperature fall is greater than that of phonological period advance as a result of temperature rise.
The effects of climate warming on plant phonological changes from 1983 to 2004 in Guangdong are studied by use of the plant phenological data and temperature data of 10 Agrometeorological stations in Guangdong of the same time. The models for relationship between phenological periods and temperature are constructed. The responses of the phenological period to climate change are ana lyzed. The results show that the phenological periods of ligneous plants occurred earlier with increasing temperature in spring; on the contrary, the ligneous plant phenological periods delayed with decreasing temperature. The response of plant phenological periods to climate change is nonlinear. In the context of the same range of temperature rise or fall, the range of phonological period postpone as a result of the temperature fall is greater than that of phonological period advance as a result of temperature rise.
2007, 35(3):404-406.
Abstract:
The winter negative accumulated temperatures of all stations are statistically calculated based on the average daily air temperature of 11 meteorological observation stations in Tangshan from 1961 to 2005, and the spatial variations are analyzed. The results show: (1) The spatial distribution of the winter negative accumulated temperature in Tangshan decreased from northwest to southeast. (2) The interannual variation of winter negative accumulated temperature can be denoted in three periods of time: cold winters from the middle 1960s to the early 1970s; the transitional period of alternate cold and worm winters from the middle 1970s to the late 1980s; worm winters in the 1990s. (3) There existed a variation trend of winter warming: “North > South > central part.” The potential im pacts of these variation features are discussed.
The winter negative accumulated temperatures of all stations are statistically calculated based on the average daily air temperature of 11 meteorological observation stations in Tangshan from 1961 to 2005, and the spatial variations are analyzed. The results show: (1) The spatial distribution of the winter negative accumulated temperature in Tangshan decreased from northwest to southeast. (2) The interannual variation of winter negative accumulated temperature can be denoted in three periods of time: cold winters from the middle 1960s to the early 1970s; the transitional period of alternate cold and worm winters from the middle 1970s to the late 1980s; worm winters in the 1990s. (3) There existed a variation trend of winter warming: “North > South > central part.” The potential im pacts of these variation features are discussed.
2007, 35(3):407-410.
Abstract:
The principles of GPSbased water vapor remote sensing are introduced. The atmospheric integrated water vapor content over Harbin was retrieved by means of the measurements of the Harbin GPS station in June 2004, and the results with the error being 2.7 mm (comparing with the computed water content by radiosonde data) were obtained. The errors and the influence degree on the precipitable water vapor results are analyzed. Comparison is conducted between retrieved and observed, as well as the radiosonde data. The findings conclude that the retrieved results are applicable.
The principles of GPSbased water vapor remote sensing are introduced. The atmospheric integrated water vapor content over Harbin was retrieved by means of the measurements of the Harbin GPS station in June 2004, and the results with the error being 2.7 mm (comparing with the computed water content by radiosonde data) were obtained. The errors and the influence degree on the precipitable water vapor results are analyzed. Comparison is conducted between retrieved and observed, as well as the radiosonde data. The findings conclude that the retrieved results are applicable.
2007, 35(3):411-413.
Abstract:
The difference between the results from the precisely predicted ephemeris and precise ephemeris is very small in the water vapor monitoring network, so the precisely predicted ephemeris can be used to detect water vapor in real time. Because the ionospheric delay has great effect on water vapor, it should be eliminated. The derivation processes of three methods (Klobuchar model, dualfr equency measurements and linearly combined double frequency measurements without ionospheric delay) are described. The effects of ionospheric delay eliminated by these three methods are compared, and the results indicate that the combined method is the best.
The difference between the results from the precisely predicted ephemeris and precise ephemeris is very small in the water vapor monitoring network, so the precisely predicted ephemeris can be used to detect water vapor in real time. Because the ionospheric delay has great effect on water vapor, it should be eliminated. The derivation processes of three methods (Klobuchar model, dualfr equency measurements and linearly combined double frequency measurements without ionospheric delay) are described. The effects of ionospheric delay eliminated by these three methods are compared, and the results indicate that the combined method is the best.
2007, 35(3):414-417.
Abstract:
The compress principle of FM94 BUFR codes and the information structure and software structure of the BUFR encoder/decoder software are discussed in accordance with the globe exchange requirement of meteorological observation data in the development of FY2 (02) Application System Project. Taking the encoding of the wind field data derived from FY2C satellite cloud images as an example, the detail information of Section 3 and Section 4 of FY2C atmospheric motion vectors is introduced. The encoded results indicate that the BUFR encoder has considerable high data compression ratio and is suitable for data transmission.
The compress principle of FM94 BUFR codes and the information structure and software structure of the BUFR encoder/decoder software are discussed in accordance with the globe exchange requirement of meteorological observation data in the development of FY2 (02) Application System Project. Taking the encoding of the wind field data derived from FY2C satellite cloud images as an example, the detail information of Section 3 and Section 4 of FY2C atmospheric motion vectors is introduced. The encoded results indicate that the BUFR encoder has considerable high data compression ratio and is suitable for data transmission.
2007, 35(3):418-422.
Abstract:
The calibration technology of radar reflectivity is directly related to the precision of radar quantitative measurement, being the fundamental factor for radar observation. Taking CINRAD/CC radar as an example, the principles of automatic calibration technology, the DDS (Direct Digital Synthesis) technique, which is used in calibration, and the implementation procedures are described in detail. The precision of automatic echo intensity calibration was measured and the testing results are given. The findings conclude that CINRAD/CC can ensure the precision less than 1 dB while the transmitter power and receiver gain change. The factors influencing the precision of automatic calibration are also analyzed.
The calibration technology of radar reflectivity is directly related to the precision of radar quantitative measurement, being the fundamental factor for radar observation. Taking CINRAD/CC radar as an example, the principles of automatic calibration technology, the DDS (Direct Digital Synthesis) technique, which is used in calibration, and the implementation procedures are described in detail. The precision of automatic echo intensity calibration was measured and the testing results are given. The findings conclude that CINRAD/CC can ensure the precision less than 1 dB while the transmitter power and receiver gain change. The factors influencing the precision of automatic calibration are also analyzed.
2007, 35(3):423-428.
Abstract:
The carbon humidity sensor's resistance is significantly influenced by temperature, resulting in upperair relative humidity sounding data errors. Through static tests on the sensors in the temperaturehumidity controlled chamber, the testing of the resistance changes was conducted under different temperatures. Based on the analysis and calculation on these lab data, the correction data of relative humidity and temperature were obtained, and the relative humidity correction equation was established, which can effectively correct the errors caused by temperature correspondingly. The comparison and analysis of correction on re al upperair relative humidity sounding data indicates that not only the accuracy of relative humidity data is improved after correction, but also the detailed variations in relative humidity at the upper atmosphere during the lower humidity period can be clearly manifested, which cannot be seen before correction.
The carbon humidity sensor's resistance is significantly influenced by temperature, resulting in upperair relative humidity sounding data errors. Through static tests on the sensors in the temperaturehumidity controlled chamber, the testing of the resistance changes was conducted under different temperatures. Based on the analysis and calculation on these lab data, the correction data of relative humidity and temperature were obtained, and the relative humidity correction equation was established, which can effectively correct the errors caused by temperature correspondingly. The comparison and analysis of correction on re al upperair relative humidity sounding data indicates that not only the accuracy of relative humidity data is improved after correction, but also the detailed variations in relative humidity at the upper atmosphere during the lower humidity period can be clearly manifested, which cannot be seen before correction.
2007, 35(3):429-431.
Abstract:
The upgrading and reconstructing of the calibrating system based on the Model500 windtunnel used widely in the provincial/prefecturallevel meteorological instrument calibration departments is introduced. The overall design scheme and philosophy are based on a computer, and the data collector and motor control circuit are developed to digitize all physical quantity involved in the process of calibration. The computer reads in data from the asynchronous serial port of the collector to realize the automation of AWS (Automatic Weather Station) wind speed sensor calibration and meanwhile to have the capability of calibrating semiautomatically conventional windfinding instruments. The calibration data are put into the LAN server, and the remote processing, printing, and sharing of data are realized. The software is based on the Windows platform written by VB 6.0. This system has been put into operation, and the practice of more than one year proves that it is steady, reliable, and easy to use. The competent authorities plan to popularize the system in the meteorological instrument calibration agencies across China.
The upgrading and reconstructing of the calibrating system based on the Model500 windtunnel used widely in the provincial/prefecturallevel meteorological instrument calibration departments is introduced. The overall design scheme and philosophy are based on a computer, and the data collector and motor control circuit are developed to digitize all physical quantity involved in the process of calibration. The computer reads in data from the asynchronous serial port of the collector to realize the automation of AWS (Automatic Weather Station) wind speed sensor calibration and meanwhile to have the capability of calibrating semiautomatically conventional windfinding instruments. The calibration data are put into the LAN server, and the remote processing, printing, and sharing of data are realized. The software is based on the Windows platform written by VB 6.0. This system has been put into operation, and the practice of more than one year proves that it is steady, reliable, and easy to use. The competent authorities plan to popularize the system in the meteorological instrument calibration agencies across China.
2007, 35(3):432-434.
Abstract:
Some calibration methods needing improving and adjustment methods of overproof sensors in the AWS are discussed. The various overproof sensors were adjusted while the calibration methods have been improved in the recent 2 years in 74 calibration cases of various sensors, such as temperature and humidity, wind direction and velocity, pressure, rainfall,and evaporation sensors. The result shows that it is necessary to improve the temperature, wind direction and velocity sensors and reduce the overproof errors by adjusting various sensors.
Some calibration methods needing improving and adjustment methods of overproof sensors in the AWS are discussed. The various overproof sensors were adjusted while the calibration methods have been improved in the recent 2 years in 74 calibration cases of various sensors, such as temperature and humidity, wind direction and velocity, pressure, rainfall,and evaporation sensors. The result shows that it is necessary to improve the temperature, wind direction and velocity sensors and reduce the overproof errors by adjusting various sensors.
2007, 35(3):435-438.
Abstract:
Exploration is made of the solution for computing the protection coverage of multiple unequalheight discharging rods by means of a mathematical method, and the mathematical solution to the problem is presented, which set the theoretical basis for computer programming for solving the problem. The establishment of the mathematic model for computing the position of the virtual ball supported by three unequalheight discharging rods is the key to the problem. Because the position of the rod tips is known, the quadratic equations with three variables are established according to the related geomorphic principles to obtain the protection coverage of discharging rods. A brief analysis is also made of the computation of the mounting height of the lightning protection belt according to the principles of the rollingball method.
Exploration is made of the solution for computing the protection coverage of multiple unequalheight discharging rods by means of a mathematical method, and the mathematical solution to the problem is presented, which set the theoretical basis for computer programming for solving the problem. The establishment of the mathematic model for computing the position of the virtual ball supported by three unequalheight discharging rods is the key to the problem. Because the position of the rod tips is known, the quadratic equations with three variables are established according to the related geomorphic principles to obtain the protection coverage of discharging rods. A brief analysis is also made of the computation of the mounting height of the lightning protection belt according to the principles of the rollingball method.
2007, 35(3):439-441.
Abstract:
The meteorological station history data is important background information of meteorological records and essential reference for the understanding, management, and application of meteorological data. In order to meet the needs of the data management modernization and data sharing service and to realize the standardization of meteorological station history file compilation, the File Format of Meteorological Station History was formulated. The standards are in accordance with the requirements of the World Meteorological Organization, covers generally the related meteorological station history information, and has certain international versatility.
The meteorological station history data is important background information of meteorological records and essential reference for the understanding, management, and application of meteorological data. In order to meet the needs of the data management modernization and data sharing service and to realize the standardization of meteorological station history file compilation, the File Format of Meteorological Station History was formulated. The standards are in accordance with the requirements of the World Meteorological Organization, covers generally the related meteorological station history information, and has certain international versatility.
2007, 35(3):442-444.
Abstract:
The contents and formats of meteorological station history files of Chinese and abroad are introduced. The standards of the China Meteorological Administration File Format of Meteorological Station History are analyzed and compared with the contents of the Global Climate Observation System and the National Climate Data Center of USA. The results indicate that the contents and formats of our meteorological station history files, fully using other countries' relevant files for reference, can meet not only the needs of international data exchange in sophistication and versatility, but also the needs of meteorological data analysis application.
The contents and formats of meteorological station history files of Chinese and abroad are introduced. The standards of the China Meteorological Administration File Format of Meteorological Station History are analyzed and compared with the contents of the Global Climate Observation System and the National Climate Data Center of USA. The results indicate that the contents and formats of our meteorological station history files, fully using other countries' relevant files for reference, can meet not only the needs of international data exchange in sophistication and versatility, but also the needs of meteorological data analysis application.
2007, 35(3):445-447.
Abstract:
The system has the functions of meteorological data error checking, data packing and so on based on the SCO Unix operating system and the modularized programming technique, combining data processing and sending on one platform, which greatly improves the efficiency of data transmission and reduces the workload of network maintenance and the FTP server load of the National Information Center. Furthermore, it can perform the error checking, data packing, and transmitting of special data (named by long file names) based on the SCO Unix operating system. The system fills up the gaps of Project 9210: the provinciallevel conventional weather data packing and long file name data transmission.
The system has the functions of meteorological data error checking, data packing and so on based on the SCO Unix operating system and the modularized programming technique, combining data processing and sending on one platform, which greatly improves the efficiency of data transmission and reduces the workload of network maintenance and the FTP server load of the National Information Center. Furthermore, it can perform the error checking, data packing, and transmitting of special data (named by long file names) based on the SCO Unix operating system. The system fills up the gaps of Project 9210: the provinciallevel conventional weather data packing and long file name data transmission.
2007, 35(3):448-450.
Abstract:
2007, 35(3):451-452.
Abstract:
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.