Volume 33,Issue 2,2005 Table of Contents
2005, 33(2):97-103.
Abstract:
The hydrological models used in Land-surface models are briefly introduced. The physical processes of land-surface hydrological processes and the developing status of land-surface hydrological model studies in China and abroad are briefly summarized. Land-surface hydrological models which are coupled with climate models are reviewed. The weakness and possible solutions in land-surface hydrological process modeling and coupling process studies are pointed out. The developing directions of land-surface hydrological processes are discussed. It is pointed out that more attention should be paid to both infiltration excess, saturation excess and snow models, and the large-scale land surface hydrological model should be developed based on tradition hydrological models.
The hydrological models used in Land-surface models are briefly introduced. The physical processes of land-surface hydrological processes and the developing status of land-surface hydrological model studies in China and abroad are briefly summarized. Land-surface hydrological models which are coupled with climate models are reviewed. The weakness and possible solutions in land-surface hydrological process modeling and coupling process studies are pointed out. The developing directions of land-surface hydrological processes are discussed. It is pointed out that more attention should be paid to both infiltration excess, saturation excess and snow models, and the large-scale land surface hydrological model should be developed based on tradition hydrological models.
2005, 33(2):104-108.
Abstract:
Stratiform clouds are the main precipitation system in most parts of North China. It is necessary to combine the analysis of composite observation data with the new numerical models to study further the characteristics and precipitation mechanisms of stratiform clouds. The categories and characteristics of stratiform clouds are described. The research methods and main findings in researches on microphysical characteristics at home and abroad in such areas as cloud drop spectrum, ice crystal spectrum, snow particle spectrum, raindrop spectrum and total particle spectrum are discussed through analyzing airborne PMS data and surface raindrop data. In addition, the researches methods and main achievements in stratiform cloud precipitation mechanism researches are also introduced, including stratiform cloud precipitation simulation and cold and warm cloud precipitation mechanism researches.
Stratiform clouds are the main precipitation system in most parts of North China. It is necessary to combine the analysis of composite observation data with the new numerical models to study further the characteristics and precipitation mechanisms of stratiform clouds. The categories and characteristics of stratiform clouds are described. The research methods and main findings in researches on microphysical characteristics at home and abroad in such areas as cloud drop spectrum, ice crystal spectrum, snow particle spectrum, raindrop spectrum and total particle spectrum are discussed through analyzing airborne PMS data and surface raindrop data. In addition, the researches methods and main achievements in stratiform cloud precipitation mechanism researches are also introduced, including stratiform cloud precipitation simulation and cold and warm cloud precipitation mechanism researches.
2005, 33(2):109-114119.
Abstract:
A brief review is given of the development history of the Ensemble Kalman Filter (EnKF) assimilation method and its essential theory. A numerical test was conducted using the one-dimensional nonlinear wave equation. Results indicate that the method has advantages of being simple to realize and being able to avoid the computation inaccuracy occurred in the prediction process using the EKF covariance variation equation and the problem of massive data storage resulted from the covariance matrix; moreover, the EnKF can control effectively the augment of the estimated error variance for model variables and improve the prediction precision.
A brief review is given of the development history of the Ensemble Kalman Filter (EnKF) assimilation method and its essential theory. A numerical test was conducted using the one-dimensional nonlinear wave equation. Results indicate that the method has advantages of being simple to realize and being able to avoid the computation inaccuracy occurred in the prediction process using the EKF covariance variation equation and the problem of massive data storage resulted from the covariance matrix; moreover, the EnKF can control effectively the augment of the estimated error variance for model variables and improve the prediction precision.
2005, 33(2):115-119.
Abstract:
An analysis was made of the circulation background and influencing weather systems of 94 short-range heavy rainfall events from 1994 to 2001 in the northern and central Fujian Province,and the synoptic patterns were divided into three types: cold shear (or trough), southwest flow and Subtropical High. The source and enhancing areas and path, evolution and precipitation features of radar echoes under various weather patterns are summarized. Three conceptive models of short-range heavy rains for the northern and central Fujian Province were established,aiming to improve short-range prediction and to combine synoptic maps with radar echoes.
An analysis was made of the circulation background and influencing weather systems of 94 short-range heavy rainfall events from 1994 to 2001 in the northern and central Fujian Province,and the synoptic patterns were divided into three types: cold shear (or trough), southwest flow and Subtropical High. The source and enhancing areas and path, evolution and precipitation features of radar echoes under various weather patterns are summarized. Three conceptive models of short-range heavy rains for the northern and central Fujian Province were established,aiming to improve short-range prediction and to combine synoptic maps with radar echoes.
2005, 33(2):120-123.
Abstract:
By means of the fuzzy grading method, the ensemble area rainfall forecast and the three prediction models used in the area rainfall prediction over the Three Gorges Reservoir Valley (analogy forecast, MM5 model and T213) are assessed comprehensively. The results show that the prediction accuracy of the analogy forecast method is about the same as those of MM5 model and T213 rainfall prediction, and the prediction accuracy in winter is better than in summer for all the three prediction models. In practice, the dynamically weighted coefficient method is adopted in the integration of the three prediction models, to make full play of their advantages. The integrated forecast performed better than the three methods. It is proved that the fuzzy assessment method of drainage area rainfall can be used in quantitative rainfall forecast assessment because it can reflect objectively the difference between predicted and actual rainfall.
By means of the fuzzy grading method, the ensemble area rainfall forecast and the three prediction models used in the area rainfall prediction over the Three Gorges Reservoir Valley (analogy forecast, MM5 model and T213) are assessed comprehensively. The results show that the prediction accuracy of the analogy forecast method is about the same as those of MM5 model and T213 rainfall prediction, and the prediction accuracy in winter is better than in summer for all the three prediction models. In practice, the dynamically weighted coefficient method is adopted in the integration of the three prediction models, to make full play of their advantages. The integrated forecast performed better than the three methods. It is proved that the fuzzy assessment method of drainage area rainfall can be used in quantitative rainfall forecast assessment because it can reflect objectively the difference between predicted and actual rainfall.
2005, 33(2):124-127.
Abstract:
A comparison was made between the two 30-year climatic averages of meteorological elements from 1971 to 2000 and 1961 to 1990 from 39 meteorological stations used in Shaanxi climate prediction. The results show that the climate in the 1990s is drier and wormer than that in the 1960s in most areas, and some elements are especially obvious. Compared it with the 1961-1990 average, the 1971-2000 annual mean temperature and the days of sunny day increase, while the annual mean precipitation and the rainy days, overcast days, etc, decrease. The annual sunshine duration and the days of strong wind, sandstorm, and thunderstorm, etc, also decrease. For various long-range data series, the difference between the two averages is most obvious for the latest several (five to six) 30-year averages during the period from the 1920s to the 1990s. The difference of the two averages has certain impacts on the operation of climatic analysis and climatic prediction.
A comparison was made between the two 30-year climatic averages of meteorological elements from 1971 to 2000 and 1961 to 1990 from 39 meteorological stations used in Shaanxi climate prediction. The results show that the climate in the 1990s is drier and wormer than that in the 1960s in most areas, and some elements are especially obvious. Compared it with the 1961-1990 average, the 1971-2000 annual mean temperature and the days of sunny day increase, while the annual mean precipitation and the rainy days, overcast days, etc, decrease. The annual sunshine duration and the days of strong wind, sandstorm, and thunderstorm, etc, also decrease. For various long-range data series, the difference between the two averages is most obvious for the latest several (five to six) 30-year averages during the period from the 1920s to the 1990s. The difference of the two averages has certain impacts on the operation of climatic analysis and climatic prediction.
2005, 33(2):128-132.
Abstract:
By using the global temperature, height, and wind data of 40 years from 1960 to 2000, the anomalous features of global circulation in spring in cold/warm years in Northeast China were analyzed. It is concluded: in cold spring years, radial circulation prevailed in the troposphere; the Mongolia high and the Aleutian low strengthened at the lower-level, and cold air systems were more active; above the mid-level, there was a blocking high or warm ridge in the high-latitude region. The variation of the East-Asia Trough Index has a close relation with spring temperature. The variation of vertical temperature distribution extended up to the tropopause in cold/warm years. In cold spring year over Northeast China, north winds prevailed and the westerly was relatively strong; a negative temperature anomaly center extended from surface to tropopause, while a positive zonal wind area lay across Northeast China. In warm spring year, vice versa.
By using the global temperature, height, and wind data of 40 years from 1960 to 2000, the anomalous features of global circulation in spring in cold/warm years in Northeast China were analyzed. It is concluded: in cold spring years, radial circulation prevailed in the troposphere; the Mongolia high and the Aleutian low strengthened at the lower-level, and cold air systems were more active; above the mid-level, there was a blocking high or warm ridge in the high-latitude region. The variation of the East-Asia Trough Index has a close relation with spring temperature. The variation of vertical temperature distribution extended up to the tropopause in cold/warm years. In cold spring year over Northeast China, north winds prevailed and the westerly was relatively strong; a negative temperature anomaly center extended from surface to tropopause, while a positive zonal wind area lay across Northeast China. In warm spring year, vice versa.
2005, 33(2):133-135141.
Abstract:
The main hail-fallout zones and their annual variation in rent years in Jilin Province are different from the past. An analysis was made of the statistical characteristics of the annual distribution and variation, daily change and main routes of hails, as well as the number of hailing days, in 51 meteorological stations in Jilin Province from April to October, 1990 to 1999. Comparing the recent 14 years with the past 30 years, there is no difference in daily and annual variation, but there are differences in the number of hailing days and the main hailing routes. The analysis indicates that there are nine hail fallout zones, most of which are in the NW-SE direction, and two in the SW-NE direction cross the central part of Jilin Province.
The main hail-fallout zones and their annual variation in rent years in Jilin Province are different from the past. An analysis was made of the statistical characteristics of the annual distribution and variation, daily change and main routes of hails, as well as the number of hailing days, in 51 meteorological stations in Jilin Province from April to October, 1990 to 1999. Comparing the recent 14 years with the past 30 years, there is no difference in daily and annual variation, but there are differences in the number of hailing days and the main hailing routes. The analysis indicates that there are nine hail fallout zones, most of which are in the NW-SE direction, and two in the SW-NE direction cross the central part of Jilin Province.
2005, 33(2):136-141.
Abstract:
Summer precipitation data in Northeast China from 1960 to 2000 was used to study the temporal and spatial features of summer rainfall. The results show that summer rainfall in Northeast China exhibited a downward trend with variation periods of 14 years and 2 to 4 years. Two abrupt summer rainfall changes occurred in 1964 and 1988/1989. The variations of summer precipitation in Northeast China can be divided into 5 types: southwest, southeast, northeast, northwest, and central Northeast China. Difference variation tendencies were found in different areas. Rainfall significantly decreased in the southeast of Northeast China and increased in the southwest of Northeast China. Meanwhile, the precipitation over different areas exhibited different periods and different occurring time of abrupt change. There is a 16-18 year cycle period in rainfall variation in the northeast of Northeast China and a 10-14 year period over the others areas. The abrupt changes took place in the 1960's and 1980's.
Summer precipitation data in Northeast China from 1960 to 2000 was used to study the temporal and spatial features of summer rainfall. The results show that summer rainfall in Northeast China exhibited a downward trend with variation periods of 14 years and 2 to 4 years. Two abrupt summer rainfall changes occurred in 1964 and 1988/1989. The variations of summer precipitation in Northeast China can be divided into 5 types: southwest, southeast, northeast, northwest, and central Northeast China. Difference variation tendencies were found in different areas. Rainfall significantly decreased in the southeast of Northeast China and increased in the southwest of Northeast China. Meanwhile, the precipitation over different areas exhibited different periods and different occurring time of abrupt change. There is a 16-18 year cycle period in rainfall variation in the northeast of Northeast China and a 10-14 year period over the others areas. The abrupt changes took place in the 1960's and 1980's.
2005, 33(2):142-146.
Abstract:
The features of correlation between SST and summer precipitation in East China and its interannual/interdecadal variation were investigated by using NCEP/NCAR reanalysis SST data and precipitation data provided by the national meteorological center. The main results show that there exists obvious synchronous correlation between SST in the Nino 3 region and annual summer rainfall over East China, and the interannual correlation show apparent features of interdecadal variation. It is found by using running correlation technology that interannual correlation between SST in the Nino 3 region and summer rainfall over East China had abrupt changes, which can be described by three periods: before 1972, 1973 to 1983, and after 1984, corresponding to the precipitation pattern changes: east to west, south to north, and south to north.
The features of correlation between SST and summer precipitation in East China and its interannual/interdecadal variation were investigated by using NCEP/NCAR reanalysis SST data and precipitation data provided by the national meteorological center. The main results show that there exists obvious synchronous correlation between SST in the Nino 3 region and annual summer rainfall over East China, and the interannual correlation show apparent features of interdecadal variation. It is found by using running correlation technology that interannual correlation between SST in the Nino 3 region and summer rainfall over East China had abrupt changes, which can be described by three periods: before 1972, 1973 to 1983, and after 1984, corresponding to the precipitation pattern changes: east to west, south to north, and south to north.
2005, 33(2):147-151.
Abstract:
The climate characteristics of the occurrence frequency of abnormal high temperature from May to July in Hainan were analyzed, and their influential factors,sea temperature over the South China Sea and the Northern Hemisphere 500 hPa height field,were analyzed. It is indicated that the occurrence frequency of abnormal high temperature had a 3.8-year period in May, but a 5-year period in June; the sea area around the middle South China Sea was the key area influencing the frequency of abnormal high temperature in the corresponding periods. In the abnormal year, the circulation characteristics over the Eurasia Continent at the 500 hPa were the blocking high in the middle latitudes, the southward westerly trough, and the subtropical high over the western Pacific Ocean inclined westward and southward for a long time.
The climate characteristics of the occurrence frequency of abnormal high temperature from May to July in Hainan were analyzed, and their influential factors,sea temperature over the South China Sea and the Northern Hemisphere 500 hPa height field,were analyzed. It is indicated that the occurrence frequency of abnormal high temperature had a 3.8-year period in May, but a 5-year period in June; the sea area around the middle South China Sea was the key area influencing the frequency of abnormal high temperature in the corresponding periods. In the abnormal year, the circulation characteristics over the Eurasia Continent at the 500 hPa were the blocking high in the middle latitudes, the southward westerly trough, and the subtropical high over the western Pacific Ocean inclined westward and southward for a long time.
2005, 33(2):152-155.
Abstract:
利用新疆1959～2000年夏季溫度資料，采用滑動平均、最大熵譜、經驗正交、線性回歸方法，分析天山山區近42年來夏季溫度變化的基本特征，并與南疆、北疆進行比較。結果表明：①天山山區在夏季溫度的冷暖變化階段以及最炎熱、最涼爽年出現的年份與南疆和北疆不同；②夏季溫度空間分布的同向性變化北疆最大，天山山區居中，南疆最??；夏季溫度空間反向變化南疆和天山山區較大，北疆較?。虎巯募緶囟鹊哪甏H變化趨勢不同，天山山區持續增溫，北疆波動增溫，南疆變化穩定；④三種夏季增溫的覆蓋范圍以最低溫度為最廣，其增溫率天山山區最大，南疆最小，北疆居中。
利用新疆1959～2000年夏季溫度資料，采用滑動平均、最大熵譜、經驗正交、線性回歸方法，分析天山山區近42年來夏季溫度變化的基本特征，并與南疆、北疆進行比較。結果表明：①天山山區在夏季溫度的冷暖變化階段以及最炎熱、最涼爽年出現的年份與南疆和北疆不同；②夏季溫度空間分布的同向性變化北疆最大，天山山區居中，南疆最??；夏季溫度空間反向變化南疆和天山山區較大，北疆較?。虎巯募緶囟鹊哪甏H變化趨勢不同，天山山區持續增溫，北疆波動增溫，南疆變化穩定；④三種夏季增溫的覆蓋范圍以最低溫度為最廣，其增溫率天山山區最大，南疆最小，北疆居中。
2005, 33(2):156-159.
Abstract:
Based on the monthly precipitation data of 52 observational stations in June, July and August from 1961 to 2000, the features of summer precipitation in Guizhou Province were analyzed by means of abrupt change analysis and wavelet analysis techniques. A prediction model was developed and the prediction experiment of summer precipitation in Guizhou Province was conducted with the mean generating function. The results indicate that summer precipitation in Guizhou increased obviously in recent 40 years and its inter-annual variation was remarkable with varying periods: 8-10, 4-6, 4, and 2 years. Abrupt change mainly occurred in 1971 and 1994, and precipitation began to decrease from l994. The result shows that the mean generating function has good prediction capability for short-range climate changes, especially for extreme precipitation events.
Based on the monthly precipitation data of 52 observational stations in June, July and August from 1961 to 2000, the features of summer precipitation in Guizhou Province were analyzed by means of abrupt change analysis and wavelet analysis techniques. A prediction model was developed and the prediction experiment of summer precipitation in Guizhou Province was conducted with the mean generating function. The results indicate that summer precipitation in Guizhou increased obviously in recent 40 years and its inter-annual variation was remarkable with varying periods: 8-10, 4-6, 4, and 2 years. Abrupt change mainly occurred in 1971 and 1994, and precipitation began to decrease from l994. The result shows that the mean generating function has good prediction capability for short-range climate changes, especially for extreme precipitation events.
2005, 33(2):160-162166.
Abstract:
With the 40-year hail and thunderstorm data from meteorological stations over Northwest China, an analysis was made of the distribution characteristics of hails, and the relation with altitude, topography and concomitant thunderstorms. The causes of frequently occurring hails in Northwest China are discussed. The result indicates that hails in this area are concentrated mainly around three areas; the occurrence of hails is highly correlated with thunderstorms and altitude with the correlation coefficients being 0.78 and 0.84; and in the last 10 years hail disasters decreased greatly. Considering meteorological factors and topography, five source areas of hails are pointed out.
With the 40-year hail and thunderstorm data from meteorological stations over Northwest China, an analysis was made of the distribution characteristics of hails, and the relation with altitude, topography and concomitant thunderstorms. The causes of frequently occurring hails in Northwest China are discussed. The result indicates that hails in this area are concentrated mainly around three areas; the occurrence of hails is highly correlated with thunderstorms and altitude with the correlation coefficients being 0.78 and 0.84; and in the last 10 years hail disasters decreased greatly. Considering meteorological factors and topography, five source areas of hails are pointed out.
2005, 33(2):163-166.
Abstract:
Based on the upper-level radiosonde observation data of seven stations from 1970 to 2001 in Qinghai Province, the abrupt change and abnormality analysis of 500 hPa temperature and height were analyzed by the statistical method, and the basic facts and regulations were found. The changes of height and temperature at 500 hPa, especially the effects of abnormal changes on surface air temperature and precipitation and their mutual relation, are discussed. The results show that there were abrupt changes from low (cold) to high (warm) at 500 hPa in height and temperature at most stations in the middle 1980s; since 1987, there have been an increasing trend in positive abnormality and a decreasing trend in negative abnormality for height and temperature, which were correlated with the surface air temperature change.
Based on the upper-level radiosonde observation data of seven stations from 1970 to 2001 in Qinghai Province, the abrupt change and abnormality analysis of 500 hPa temperature and height were analyzed by the statistical method, and the basic facts and regulations were found. The changes of height and temperature at 500 hPa, especially the effects of abnormal changes on surface air temperature and precipitation and their mutual relation, are discussed. The results show that there were abrupt changes from low (cold) to high (warm) at 500 hPa in height and temperature at most stations in the middle 1980s; since 1987, there have been an increasing trend in positive abnormality and a decreasing trend in negative abnormality for height and temperature, which were correlated with the surface air temperature change.
2005, 33(2):167-172.
Abstract:
Based on the synthetical analysis of lightning data and Doppler radar echoes from a severe storm event in Henan Province on 19 June 2003, relationship is found between lightning frequency and radar echo intensity. In the different phases of the radar echo variation, lightning location is sometimes consistent with the position of strong radar echo, and at some other times away from the position of strong radar echo; sometimes even no lightning occurs. Through analyzing velocity echo data, it can be seen that under the adverse lower-level wind field, precipitation radar echoes dissipated gradually while moving toward the station, and at the same time the lightning frequency decreased gradually.
Based on the synthetical analysis of lightning data and Doppler radar echoes from a severe storm event in Henan Province on 19 June 2003, relationship is found between lightning frequency and radar echo intensity. In the different phases of the radar echo variation, lightning location is sometimes consistent with the position of strong radar echo, and at some other times away from the position of strong radar echo; sometimes even no lightning occurs. Through analyzing velocity echo data, it can be seen that under the adverse lower-level wind field, precipitation radar echoes dissipated gradually while moving toward the station, and at the same time the lightning frequency decreased gradually.
2005, 33(2):173-177.
Abstract:
The features of spatial-temporal distribution of air pollutants in the urban area of Hohhot were analyzed using the monitoring data of pollutant density such as TSP, SO 2 and NOx in the urban area from 1990 to 2002 to study the relationship between pollutant density and meteorological conditions. Results show that the dominant pollutant in Hohhot is smoke; pollution is more serious in spring and winter than in summer and fall, similarly more serious in the heating period than in the non-heating period. The air pollution in the central Hohhot is most serious. The amount of pollutant emission and the atmosphere stability state are major factors that influence air pollutants in the urban area. The weather change is the dominant factor of the urban air pollution density change. The local circulation is also a key factor influencing pollutant distribution. Therefore, the variations in exhaust gas in different seasons along with weather conditions constitute the basis of Hohhot air pollution prediction.
The features of spatial-temporal distribution of air pollutants in the urban area of Hohhot were analyzed using the monitoring data of pollutant density such as TSP, SO 2 and NOx in the urban area from 1990 to 2002 to study the relationship between pollutant density and meteorological conditions. Results show that the dominant pollutant in Hohhot is smoke; pollution is more serious in spring and winter than in summer and fall, similarly more serious in the heating period than in the non-heating period. The air pollution in the central Hohhot is most serious. The amount of pollutant emission and the atmosphere stability state are major factors that influence air pollutants in the urban area. The weather change is the dominant factor of the urban air pollution density change. The local circulation is also a key factor influencing pollutant distribution. Therefore, the variations in exhaust gas in different seasons along with weather conditions constitute the basis of Hohhot air pollution prediction.
18 Climatic Conditions for Sandstorm Occurrence and Resulting Air Pollution over Heilongjiang Province
2005, 33(2):178-181.
Abstract:
The climatic conditions and weather patterns of seven typical sandstorms from 2000 to 2003 over Heilongjiang Province, as well as the resulting air pollution, especially particle pollutants, were analyzed. It was concluded that the climatic conditions for sandstorm occurrence include high temperature, strong winds in spring and persistent rainless periods; there are four kinds of weather patterns favorable to the occurrence of air pollution during sandstorm weather. Furthermore, the conditions of air pollution, especially the particle pollution in Harbin were analyzed. Under the effect of sandstorm weather, the particulate concentration increases rapidly, and as a result, the medium to serious air pollution events occur in Harbin.
The climatic conditions and weather patterns of seven typical sandstorms from 2000 to 2003 over Heilongjiang Province, as well as the resulting air pollution, especially particle pollutants, were analyzed. It was concluded that the climatic conditions for sandstorm occurrence include high temperature, strong winds in spring and persistent rainless periods; there are four kinds of weather patterns favorable to the occurrence of air pollution during sandstorm weather. Furthermore, the conditions of air pollution, especially the particle pollution in Harbin were analyzed. Under the effect of sandstorm weather, the particulate concentration increases rapidly, and as a result, the medium to serious air pollution events occur in Harbin.
2005, 33(2):182-184.
Abstract:
An analysis was made of the soil water data from the Henan Provincial soil water database from July 1997 to June 2003, and the variation regularities of soils water for various types of soils are discussed. The results show that the available soil water is the greatest for loam, the second for clay and the least for sandy soil. The soil water is influenced by underground water greatly. The areas with lower underground water level are less attacked by droughts. Based on the soil water data, the correction coefficients of soil water and the distributions of field capacities for various types of soils over Henan Province were determined, which were used a the forecast model of soil water.
An analysis was made of the soil water data from the Henan Provincial soil water database from July 1997 to June 2003, and the variation regularities of soils water for various types of soils are discussed. The results show that the available soil water is the greatest for loam, the second for clay and the least for sandy soil. The soil water is influenced by underground water greatly. The areas with lower underground water level are less attacked by droughts. Based on the soil water data, the correction coefficients of soil water and the distributions of field capacities for various types of soils over Henan Province were determined, which were used a the forecast model of soil water.
2005, 33(2):185-188192.
Abstract:
選取河北省西部地區30個國家基本站30年年平均氣溫作為樣本，通過對總體樣本、分區樣本的偏度系數、峰度系數的分析，研究了各站點組成的空間序列，年平均氣溫以及地理參數(海拔高度、經度、緯度)的正態性。研究發現：總體樣本的年平均氣溫、海拔高度不遵從正態分布，而經度、緯度能較好的遵從正態分布；按照經緯度跨度不大于1．5，盡量多選取山區站；或既要多選山區站，又要使同一分區的站點具有相同的氣候特點兩種原則，對站點進行分區，能使分區樣本的年平均氣溫和地理參數均遵從正態分布。
選取河北省西部地區30個國家基本站30年年平均氣溫作為樣本，通過對總體樣本、分區樣本的偏度系數、峰度系數的分析，研究了各站點組成的空間序列，年平均氣溫以及地理參數(海拔高度、經度、緯度)的正態性。研究發現：總體樣本的年平均氣溫、海拔高度不遵從正態分布，而經度、緯度能較好的遵從正態分布；按照經緯度跨度不大于1．5，盡量多選取山區站；或既要多選山區站，又要使同一分區的站點具有相同的氣候特點兩種原則，對站點進行分區，能使分區樣本的年平均氣溫和地理參數均遵從正態分布。
2005, 33(2):189-192.
Abstract:
Based on the data of precipitation in spring from 1995 to 2001 in Henan, a new method was developed combining numerical prediction and statistical analysis techniques to evaluate the effectiveness of precipitation enhancement by airplane seeding. The basic idea is that the numerical forecasts for historical raining processes were formulated and a series of precipitation forecasts were obtained in terms of the MM5 V3 numerical model in the same evaluation area, which was partitioned based on the climatic rainfall characteristics. The statistical equations between precipitation forecasts for non-seeding precipitation processes and observed precipitation were established. The rainfall of the seeded precipitation processes was predicted with the above model and compared with the observation. The effectiveness of precipitation enhancement was finally gained. The results show that the average effectiveness of precipitation enhancement in spring from 1995 to 2001 is 16.7% in the northern Henan and 19.3% in the eastern Henan, respectively.
Based on the data of precipitation in spring from 1995 to 2001 in Henan, a new method was developed combining numerical prediction and statistical analysis techniques to evaluate the effectiveness of precipitation enhancement by airplane seeding. The basic idea is that the numerical forecasts for historical raining processes were formulated and a series of precipitation forecasts were obtained in terms of the MM5 V3 numerical model in the same evaluation area, which was partitioned based on the climatic rainfall characteristics. The statistical equations between precipitation forecasts for non-seeding precipitation processes and observed precipitation were established. The rainfall of the seeded precipitation processes was predicted with the above model and compared with the observation. The effectiveness of precipitation enhancement was finally gained. The results show that the average effectiveness of precipitation enhancement in spring from 1995 to 2001 is 16.7% in the northern Henan and 19.3% in the eastern Henan, respectively.
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