ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 32,Issue 2,2006 Table of Contents
2006, 32(2):3-8.
DOI: 10.7519/j.issn.1000-0526.2006.02.001
Abstract:
With MM5V3 and its adjoint system, the bogus vortex and the method of 4DVAR are used to generate an optimal initial condition of the typhoon Ma-on, compared with the initialization schemes of traditional Bogussing and Nudging. The results show that the optimal initial field produced by BDA scheme is closer to the observations and the forecast accuracy for both track and intensity is improved effectively.
With MM5V3 and its adjoint system, the bogus vortex and the method of 4DVAR are used to generate an optimal initial condition of the typhoon Ma-on, compared with the initialization schemes of traditional Bogussing and Nudging. The results show that the optimal initial field produced by BDA scheme is closer to the observations and the forecast accuracy for both track and intensity is improved effectively.
2006, 32(2):9-13.
DOI: 10.7519/j.issn.1000-0526.2006.2.002
Abstract:
SBDART radiative model and libRadtran software package are introduced. Cirrus reflectance changes with ice crystal properties are analyzed. These properties include ice effective radius, ice content and ice shape, etc. Simulations show that cirrus reflectance is different when it is made of different ice crystals. In all, the results are that cirrus reflectance increases with increases ice content and decreases ice effective radius for the cloud which consists of any kind of ice crystals.
SBDART radiative model and libRadtran software package are introduced. Cirrus reflectance changes with ice crystal properties are analyzed. These properties include ice effective radius, ice content and ice shape, etc. Simulations show that cirrus reflectance is different when it is made of different ice crystals. In all, the results are that cirrus reflectance increases with increases ice content and decreases ice effective radius for the cloud which consists of any kind of ice crystals.
2006, 32(2):14-18.
DOI: 10.7519/j.issn.1000-0526.2006.2.003
Abstract:
Based on the definition of rapidly intensified offshore tropical cyclone (RIO-TC), statistics of the characteristics is made for the 46 RIO-TC cases close to South China coast from 1949 to 2004, and some valuable facts are found. The general circulation of the cases is studied statistically and found the RIO-TCs occur in three patterns of high-east-low-west, high-north-low-south and weak environmental flow, and the inducing systems are mainly southwest monsoon, cross-equatorial flow, easterly wave, weak cold-air and westerly trough under the different patterns.
Based on the definition of rapidly intensified offshore tropical cyclone (RIO-TC), statistics of the characteristics is made for the 46 RIO-TC cases close to South China coast from 1949 to 2004, and some valuable facts are found. The general circulation of the cases is studied statistically and found the RIO-TCs occur in three patterns of high-east-low-west, high-north-low-south and weak environmental flow, and the inducing systems are mainly southwest monsoon, cross-equatorial flow, easterly wave, weak cold-air and westerly trough under the different patterns.
2006, 32(2):19-22.
DOI: 10.7519/j.issn.1000-0526.2006.2.004
Abstract:
An application of satellite quantitative data to heavy rain and flood monitoring during June 21 to July 10, Huaihe rainfall period in 2003 is introduced. The main contents and conclusions are as follow. ① The rain belt overlaps with lower OLR value band which is from 170W·m-2 to 220W·m-2 , and moves northward or southward together. ②Lower OLR value band position corresponds commendably to four vapor transportation paths during rainfall period. ③ The analysis of the relationship between cross-equatorial flows, monsoon and vapor transportation is made with QuickScat data. ④ The probable position of mesoscale convective precipitation is analyzed with AMSU data. These analyses provide some new ideas for more accurate prediction of the heavy rain.
An application of satellite quantitative data to heavy rain and flood monitoring during June 21 to July 10, Huaihe rainfall period in 2003 is introduced. The main contents and conclusions are as follow. ① The rain belt overlaps with lower OLR value band which is from 170W·m-2 to 220W·m-2 , and moves northward or southward together. ②Lower OLR value band position corresponds commendably to four vapor transportation paths during rainfall period. ③ The analysis of the relationship between cross-equatorial flows, monsoon and vapor transportation is made with QuickScat data. ④ The probable position of mesoscale convective precipitation is analyzed with AMSU data. These analyses provide some new ideas for more accurate prediction of the heavy rain.
5 Relationship between Frequency of Moving Direction of Southwest Vortex and Rainfall in Flood Season
2006, 32(2):23-27.
DOI: 10.7519/j.issn.1000-0526.2006.2.005
Abstract:
By using the data of Southwest vortex in Sichuan Basin during June to August from 1960 to 1999, the synchro-correlative analysis is done between the frequence of southwest vortex and the rainfall of these stations.Two groups of the data which have passed the significance level test of α=0.05 are analyzed with Mexican Hat wavelet. The results show that more than half of southwest vortex during June to August in the 40 years occurred and died out in Sichuan Basin, southwest vortex that can move onward chiefly takes the eastern route. The relationship between northeast route ones and the rainfall of Taiyuan, Shijiazhuang, between east vortex and the rainfall of Hankou, and between the sum of the moving of southwest vortex and the rainfall of Neijiang are much better. By the results of wavelet analysis, it is showed that there lies much better corresponding relationship in the frequency distribution between the times of northeast or east-moving vortex and the rainfall of these stations over 10 years of temporal scale.
By using the data of Southwest vortex in Sichuan Basin during June to August from 1960 to 1999, the synchro-correlative analysis is done between the frequence of southwest vortex and the rainfall of these stations.Two groups of the data which have passed the significance level test of α=0.05 are analyzed with Mexican Hat wavelet. The results show that more than half of southwest vortex during June to August in the 40 years occurred and died out in Sichuan Basin, southwest vortex that can move onward chiefly takes the eastern route. The relationship between northeast route ones and the rainfall of Taiyuan, Shijiazhuang, between east vortex and the rainfall of Hankou, and between the sum of the moving of southwest vortex and the rainfall of Neijiang are much better. By the results of wavelet analysis, it is showed that there lies much better corresponding relationship in the frequency distribution between the times of northeast or east-moving vortex and the rainfall of these stations over 10 years of temporal scale.
2006, 32(2):28-33.
DOI: 10.7519/j.issn.1000-0526.2006.2.006
Abstract:
The heavy rain in the southeasterly jet in the low-level occurs less in Hubei Province. A mesoscale analysis of this kinds of heavy rain occurred on 4th-5th of June, 2004 in east-central part of Hubei Province is conduced with the satellite pictures, Doppler radar data and surface mesoscale observations. It was found that (1) the heavy rain was produced in the favorable scale background and the special region. (2) The low-level jet plays an important role in the development of the heavy rain. (3) The heavy rain was directly produced by the meso-scale echo mass and complex ; (4) the meso-scale system was one of the most directly affection systems of the heavy rain.
The heavy rain in the southeasterly jet in the low-level occurs less in Hubei Province. A mesoscale analysis of this kinds of heavy rain occurred on 4th-5th of June, 2004 in east-central part of Hubei Province is conduced with the satellite pictures, Doppler radar data and surface mesoscale observations. It was found that (1) the heavy rain was produced in the favorable scale background and the special region. (2) The low-level jet plays an important role in the development of the heavy rain. (3) The heavy rain was directly produced by the meso-scale echo mass and complex ; (4) the meso-scale system was one of the most directly affection systems of the heavy rain.
2006, 32(2):34-39.
DOI: 10.7519/j.issn.1000-0526.2006.02.007
Abstract:
The precipitable water vapor estimated by an area GPS/MET network (GPS/PWV) has brought out the wide application prospects for improvement of detecting and forecasting severe weather and for numerical weather prediction. Some provinces and regions in China are going to build area GPS/MET networks. How to set up reasonably GPS stations within an area becomes a regardful issue. With the instance of the GPS/MET network in Yangtze River Delta area built in 2002, it is analyzed from four aspects, i.e., the moisture transmission passages, the PWV climatic statistic features, the effective radius of retrieving GPS/PWV and the influencing radius of GPS/PWV data assimilation at a station in NMP model of MM5 . Finally, some bases of reasonable distribution of GPS stations within an area GPS/MET network are discussed : more GPS stations should be located along the way of moisture transmission and the severe storm moving, the meridional density of GPS stations should be more than the zonal density; the maximum distance between the two adjacent stations is suggested to be less than 60 km, so that the effective representatives of the PWV data and its influence on the NWP may cover the whole area.
The precipitable water vapor estimated by an area GPS/MET network (GPS/PWV) has brought out the wide application prospects for improvement of detecting and forecasting severe weather and for numerical weather prediction. Some provinces and regions in China are going to build area GPS/MET networks. How to set up reasonably GPS stations within an area becomes a regardful issue. With the instance of the GPS/MET network in Yangtze River Delta area built in 2002, it is analyzed from four aspects, i.e., the moisture transmission passages, the PWV climatic statistic features, the effective radius of retrieving GPS/PWV and the influencing radius of GPS/PWV data assimilation at a station in NMP model of MM5 . Finally, some bases of reasonable distribution of GPS stations within an area GPS/MET network are discussed : more GPS stations should be located along the way of moisture transmission and the severe storm moving, the meridional density of GPS stations should be more than the zonal density; the maximum distance between the two adjacent stations is suggested to be less than 60 km, so that the effective representatives of the PWV data and its influence on the NWP may cover the whole area.
2006, 32(2):40-45.
DOI: 10.7519/j.issn.1000-0526.2006.2.008
Abstract:
The data of TBB has high temporal-special resolution. And it can describe how the heavy convective cloud generates, develops and dissipates, especially TBB can be used to determine the top height of convective cloud. Based on the hourly data of TBB obtained from CMA, the key areas for severe convective weather warning and the key indicator for now-casting of heavy convective system are found. In addition, the displaying system of TBB, which consists of the functions such as animation, statistics and point displaying, is set up.
The data of TBB has high temporal-special resolution. And it can describe how the heavy convective cloud generates, develops and dissipates, especially TBB can be used to determine the top height of convective cloud. Based on the hourly data of TBB obtained from CMA, the key areas for severe convective weather warning and the key indicator for now-casting of heavy convective system are found. In addition, the displaying system of TBB, which consists of the functions such as animation, statistics and point displaying, is set up.
2006, 32(2):46-51.
DOI: 10.7519/j.issn.1000-0526.2006.2.009
Abstract:
The weather Doppler Radar(CINRAD/SA) is of various application and powerful functions. With the observation data of Doppler Radar at Wenzhou,the intensity of radar echo and Doppler velocity about Typhoon Rananim ect.,as well as their variation are analyzed,the features of radar echo and velocity are revealed. The facts are as follow: the smaller the Typhoon eye is, the stronger the typhoon is, the stronger the convection is. There are spiral rain belts and close structure in the strong typhoon. The typhoon heavy rain is connected with convergence upward of cyclone vorticity. The strongest heavy rain distributed in the right head of typhoon track. Because of the impacts of topography, there is very different precipitation even though the vertically integrated liquid water in the same. In the coastal area, it is very important that the typhoon variation is detected by Doppler radar.
The weather Doppler Radar(CINRAD/SA) is of various application and powerful functions. With the observation data of Doppler Radar at Wenzhou,the intensity of radar echo and Doppler velocity about Typhoon Rananim ect.,as well as their variation are analyzed,the features of radar echo and velocity are revealed. The facts are as follow: the smaller the Typhoon eye is, the stronger the typhoon is, the stronger the convection is. There are spiral rain belts and close structure in the strong typhoon. The typhoon heavy rain is connected with convergence upward of cyclone vorticity. The strongest heavy rain distributed in the right head of typhoon track. Because of the impacts of topography, there is very different precipitation even though the vertically integrated liquid water in the same. In the coastal area, it is very important that the typhoon variation is detected by Doppler radar.
10 Analysis of Error Sources of 2m Temperature Prediction in Global Medium-range NWF System T213L31,NMC
2006, 32(2):52-57.
DOI: 10.7519/j.issn.1000-0526.2006.2.010
Abstract:
The global mediumrange NWF system, T213L31, in National Meteorological Center, CMA, is found to exist the problem of systematic low about 2m temperature. In order to solve this problem, the sources of error of the model system are analyzed. Though a series of analysis, such as comparison of the topography height between model and observatory, and the analysis of two kinds of initial value from EC and CMA operational model land surface model, and so on, it shows that the error of 2m temperature is due to the difference of topography height between model and observatory, and incorrect initial soil moisture which is substituted by specifical value.
The global mediumrange NWF system, T213L31, in National Meteorological Center, CMA, is found to exist the problem of systematic low about 2m temperature. In order to solve this problem, the sources of error of the model system are analyzed. Though a series of analysis, such as comparison of the topography height between model and observatory, and the analysis of two kinds of initial value from EC and CMA operational model land surface model, and so on, it shows that the error of 2m temperature is due to the difference of topography height between model and observatory, and incorrect initial soil moisture which is substituted by specifical value.
2006, 32(2):58-63.
DOI: 10.7519/j.issn.1000-0526.2006.2.011
Abstract:
Based on the products of JMH,MM5,NMC,MOS and forecaster's subjective forecast, precipitation and temperature prediction in Shaoxing City are verified in terms of natural weather season,grade and main synoptic system.The results show that the TS score of JMA and NMC is better from light rain to middle rain,but the TS score of all products is not satisfactory for heavy rain prediction.When the rain is caused by cold front,cyclone or typhoon,the rainfall forecast skill is higher than warm front or subtropical high.As for temperature prediction, MM5 is lower systematically and MOS responds score varies with season.
Based on the products of JMH,MM5,NMC,MOS and forecaster's subjective forecast, precipitation and temperature prediction in Shaoxing City are verified in terms of natural weather season,grade and main synoptic system.The results show that the TS score of JMA and NMC is better from light rain to middle rain,but the TS score of all products is not satisfactory for heavy rain prediction.When the rain is caused by cold front,cyclone or typhoon,the rainfall forecast skill is higher than warm front or subtropical high.As for temperature prediction, MM5 is lower systematically and MOS responds score varies with season.
2006, 32(2):64-69.
DOI: 10.7519/j.issn.1000-0526.2006.2.012
Abstract:
Based on the monthly ground temperature data from 40 stations in Qinghai- Tibetan Plateau for the period of 1970-2002,the temporal-spatial distribution of annual ground temperature in Qinghai-Tibetan Plateau are investigated with the methods empirical orthogonal function, second order polynomial function and wavelet analysis. The results show that the first characteristic vector of the ground temperature over the plateau reveals the overall consistency. The second and third vectors reveal the fact that weather system and the sea level elevation affect on the distribution of ground temperature. The ground temperature abnormal area can be divided into four sub-regions, i.e., north-east, south, center and west. With the second order polynomial function, it shows that the ground temperature, in general, in the east-north sub-region, is decreasing, increasing in the south region and there is a high-low-high change feature in the center and west sub-regions. There are the periodic oscillations of 3-year and quasi-7-year of ground temperature over the plateau.
Based on the monthly ground temperature data from 40 stations in Qinghai- Tibetan Plateau for the period of 1970-2002,the temporal-spatial distribution of annual ground temperature in Qinghai-Tibetan Plateau are investigated with the methods empirical orthogonal function, second order polynomial function and wavelet analysis. The results show that the first characteristic vector of the ground temperature over the plateau reveals the overall consistency. The second and third vectors reveal the fact that weather system and the sea level elevation affect on the distribution of ground temperature. The ground temperature abnormal area can be divided into four sub-regions, i.e., north-east, south, center and west. With the second order polynomial function, it shows that the ground temperature, in general, in the east-north sub-region, is decreasing, increasing in the south region and there is a high-low-high change feature in the center and west sub-regions. There are the periodic oscillations of 3-year and quasi-7-year of ground temperature over the plateau.
2006, 32(2):70-74.
DOI: 10.7519/j.issn.1000-0526.2006.2.013
Abstract:
Three kinds of drought indexes are introduced and assessed, these indexes are all able to be used for abnormal dryness calculating and drought monitoring. But to the actual, the anomalous precipitation index reflect more lighter, and the dryness degree index reflects too sensitive, Z index can be more accurate to reflect the drought disaster. So a drought intensity index and a drought area index are developed based on the Z index, and these two indexes are used to analyze the dryness year by year from 1952 to 2004 in Zhejiang Province. It indicates that there is a increases of drought frequency since 1990′s in Zhejiang Province, the drought is heavier also, and drought in autumn occurred more frequently especially. 2003 is the second severe drought year after 1967 since 1950′s.
Three kinds of drought indexes are introduced and assessed, these indexes are all able to be used for abnormal dryness calculating and drought monitoring. But to the actual, the anomalous precipitation index reflect more lighter, and the dryness degree index reflects too sensitive, Z index can be more accurate to reflect the drought disaster. So a drought intensity index and a drought area index are developed based on the Z index, and these two indexes are used to analyze the dryness year by year from 1952 to 2004 in Zhejiang Province. It indicates that there is a increases of drought frequency since 1990′s in Zhejiang Province, the drought is heavier also, and drought in autumn occurred more frequently especially. 2003 is the second severe drought year after 1967 since 1950′s.
2006, 32(2):75-80.
DOI: 10.7519/j.issn.1000-0526.2006.2.014
Abstract:
Based on the single-Doppler weather radar observations and 255m meteorological tower data, the thunderstrom occured from 20:00 to 21:40, June 22, 2004 in Tianjin area is analyzed. It is proved that thunderstrom can be caused by convective system with bow echo, and strong wind can bring on outflow boundary, and further proved the top and the middle of the bow echo can generate severe strom. In addition, the airflow structure of thunderstrom is discussed also.
Based on the single-Doppler weather radar observations and 255m meteorological tower data, the thunderstrom occured from 20:00 to 21:40, June 22, 2004 in Tianjin area is analyzed. It is proved that thunderstrom can be caused by convective system with bow echo, and strong wind can bring on outflow boundary, and further proved the top and the middle of the bow echo can generate severe strom. In addition, the airflow structure of thunderstrom is discussed also.
2006, 32(2):81-86.
DOI: 10.7519/j.issn.1000-0526.2006.2.015
Abstract:
Based on T213,NCEP/NCAR reanalyzed and conventional observation data, the general circulation and the physical field of the heavy precipitation on August 19 are analyzed at first. The result shows that this event is a typical southwest flow type caused by West Pacific subtropical high extending westward. The moisture mainly moved from the Bay of Bengal and the South China Sea. The moisture transport in low-and medium-level is very strong and the convergence occurs in Ningxia and east of Gansu Province. Second, with the three-way nested high resolution mesoscale NWP model MM5 to simulate this event by two methods, the four-dimensional data assimilation model is proved to be of quite good quality in circulation and precipitation forecasts.
Based on T213,NCEP/NCAR reanalyzed and conventional observation data, the general circulation and the physical field of the heavy precipitation on August 19 are analyzed at first. The result shows that this event is a typical southwest flow type caused by West Pacific subtropical high extending westward. The moisture mainly moved from the Bay of Bengal and the South China Sea. The moisture transport in low-and medium-level is very strong and the convergence occurs in Ningxia and east of Gansu Province. Second, with the three-way nested high resolution mesoscale NWP model MM5 to simulate this event by two methods, the four-dimensional data assimilation model is proved to be of quite good quality in circulation and precipitation forecasts.
2006, 32(2):87-91.
DOI: 10.7519/j.issn.1000-0526.2006.2.016
Abstract:
A freezing event in Hunan Province in February 2005 is analyzed. It is a light freezing, but it caused heavy hazard. The main reasons of the phenomena are as follows. The height of the bottom of the inversion layer is relatively low, the temperature at the top of the layer is relatively high and the wet weather remains long time. This situation led the air between 1000hPa and 925hPa to supercooled layer, which corresponds to the strong freezing region, while the cold air on the ground is a little weak. for the reasons, the surface freezing is not obvious.
A freezing event in Hunan Province in February 2005 is analyzed. It is a light freezing, but it caused heavy hazard. The main reasons of the phenomena are as follows. The height of the bottom of the inversion layer is relatively low, the temperature at the top of the layer is relatively high and the wet weather remains long time. This situation led the air between 1000hPa and 925hPa to supercooled layer, which corresponds to the strong freezing region, while the cold air on the ground is a little weak. for the reasons, the surface freezing is not obvious.
2006, 32(2):92-97.
DOI: 10.7519/j.issn.1000-0526.2006.2.017
Abstract:
A heavy rainfall occurred in Beijing on June 25,2005 is quite different from the weather forecast. With the data from satellite,radar,observations,wind profiler and automatic weather station, a study is made. The event is not a typical heavy rainfall, but it has clear mesoscale characteristics. The results show that low-level weak cold air from the north, low-level southwesterly jet stream and mesoscale convergence line in the south are the main factors.
A heavy rainfall occurred in Beijing on June 25,2005 is quite different from the weather forecast. With the data from satellite,radar,observations,wind profiler and automatic weather station, a study is made. The event is not a typical heavy rainfall, but it has clear mesoscale characteristics. The results show that low-level weak cold air from the north, low-level southwesterly jet stream and mesoscale convergence line in the south are the main factors.
2006, 32(2):98-103.
DOI: 10.7519/j.issn.1000-0526.2006.2.018
Abstract:
A heavy rain at the rear of typhoon Rananim is analyzed, based on the observations mesoscale automatic weather stations data in a mesoscale network, regular meteorological, 1°×1° NCEP reanalysis dataset and CINRAD Doppler radar data. The results reveal that after typhoon landing, the intensively ascending motion of middle-upper level and intensive and continuous moisture transport in lower levels caused the heavy rain in northern Wenzhou and southern Taizhou. The analysis radar echo shows that the spiral cloud bands of typhoon is the direct reason which caused the heavy rain at the rear part of typhoon.
A heavy rain at the rear of typhoon Rananim is analyzed, based on the observations mesoscale automatic weather stations data in a mesoscale network, regular meteorological, 1°×1° NCEP reanalysis dataset and CINRAD Doppler radar data. The results reveal that after typhoon landing, the intensively ascending motion of middle-upper level and intensive and continuous moisture transport in lower levels caused the heavy rain in northern Wenzhou and southern Taizhou. The analysis radar echo shows that the spiral cloud bands of typhoon is the direct reason which caused the heavy rain at the rear part of typhoon.
2006, 32(2):104-110.
DOI: 10.7519/j.issn.1000-0526.2006.2.019
Abstract:
In order to run a numerical models, the Linux-OS installation, the compiling and parallel environment setup process, and other correlative software are emphatically introduced with less about their principles. All the software can be got from the internet, so it is very suitable for basic meteorological stations to set up their parallel computer systems to solve the contradiction between computer sources and development of practical operation. The systems are the bases to do the finer forecasting, and can also be applied to sciences research.
In order to run a numerical models, the Linux-OS installation, the compiling and parallel environment setup process, and other correlative software are emphatically introduced with less about their principles. All the software can be got from the internet, so it is very suitable for basic meteorological stations to set up their parallel computer systems to solve the contradiction between computer sources and development of practical operation. The systems are the bases to do the finer forecasting, and can also be applied to sciences research.
2006, 32(2):111-115.
DOI: 10.7519/j.issn.1000-0526.2006.2.020
Abstract:
GrADS is used to analyze meso-scale automatic weather station data. The method of data conversion and batch mode drawing is introduced. The graphic analysis and application of meso-scale automatic weather station data is achieved. Several technique problems are discussed.
GrADS is used to analyze meso-scale automatic weather station data. The method of data conversion and batch mode drawing is introduced. The graphic analysis and application of meso-scale automatic weather station data is achieved. Several technique problems are discussed.
2006, 32(2):116-120.
DOI: 10.7519/j.issn.1000-0526.2006.2.021
Abstract:
Based on the micro-climatic observation data by the automatic weather stations installed in 6 kinds of farmland local conditions. The relationship between the soil temperature of vegetables field, air temperature in the fruit tree garden, water temperature of fishpond and the observations at weather station are analyzed. The prediction models of soil temperature of vegetables field, air temperature of fruit tree garden, water temperature of fishpond as the function of the air temperature of weather station are developed using the stepwise progression method. And then with Visual Basic 6.0, an agricultural weather forecast system is set up on windows platform.
Based on the micro-climatic observation data by the automatic weather stations installed in 6 kinds of farmland local conditions. The relationship between the soil temperature of vegetables field, air temperature in the fruit tree garden, water temperature of fishpond and the observations at weather station are analyzed. The prediction models of soil temperature of vegetables field, air temperature of fruit tree garden, water temperature of fishpond as the function of the air temperature of weather station are developed using the stepwise progression method. And then with Visual Basic 6.0, an agricultural weather forecast system is set up on windows platform.
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ISSN:1000-0526 CN:11-2282/P