ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 34,Issue 2,2008 Table of Contents
2008, 34(2):3-9.
DOI: 10.7519/j.issn.1000-0526.2008.02.001
Abstract:
A severe hailstorm occurred in Shandong Province is simulated with the t hreedimension convection cloud model. The simulated results are compared with the Dopp ler weather radar observations. The wind field, radar echo and microphysics stru cture of the hailstorm are studied. The findings show that location of hail embr yo lies in front of the main updraft, at the turning of updraft to divergence do wndraft, and above the largest ascending velocity in the vertical direction. Ice particles collide with supercooled water to form graupel and hail particles, and the hail particles grow between the ascending and sinking currents. The find ings are valuable in the actual operations of hail suppression.
A severe hailstorm occurred in Shandong Province is simulated with the t hreedimension convection cloud model. The simulated results are compared with the Dopp ler weather radar observations. The wind field, radar echo and microphysics stru cture of the hailstorm are studied. The findings show that location of hail embr yo lies in front of the main updraft, at the turning of updraft to divergence do wndraft, and above the largest ascending velocity in the vertical direction. Ice particles collide with supercooled water to form graupel and hail particles, and the hail particles grow between the ascending and sinking currents. The find ings are valuable in the actual operations of hail suppression.
2008, 34(2):10-17.
DOI: 10.7519/j.issn.1000-0526.2008.02.002
Abstract:
An infrequent big hail event occurring on 29th, Aug. 1969 is analyzed. A trough from Mongolia at 500hPa plays a triggering role. And the upper level c old air accompanying with the trough superposes the low level warm air, which le ads to some instability. The calculation of CAPE and LI indicates that the hails fall in the instable region and Beijing is in the center of this zone with unus ual great CAPE and LI. In addition, the strong wind shear in the low troposphere and the value of CAPE in the layer between -10℃ and -30℃ are both favorable to the big hail event. Finally, the suitable freezing level height and the ratio of cold and warm cloud thickness are also favorable to the hail shooting.
An infrequent big hail event occurring on 29th, Aug. 1969 is analyzed. A trough from Mongolia at 500hPa plays a triggering role. And the upper level c old air accompanying with the trough superposes the low level warm air, which le ads to some instability. The calculation of CAPE and LI indicates that the hails fall in the instable region and Beijing is in the center of this zone with unus ual great CAPE and LI. In addition, the strong wind shear in the low troposphere and the value of CAPE in the layer between -10℃ and -30℃ are both favorable to the big hail event. Finally, the suitable freezing level height and the ratio of cold and warm cloud thickness are also favorable to the hail shooting.
2008, 34(2):18-24.
DOI: 10.7519/j.issn.1000-0526.2008.02.003
Abstract:
Based on meteorological observational data and WRF model products, the severe convective weather process at Baiyun airport on April 1 7, 2007 was analyzed. The results show that the strengthening of southwest monso on and the establishment of the lowlevel jet create the sufficient vapor and u nstable condition in South China. The lifts of cold front and terrain promote the formation and development of convective weather. The precipitation of model out puts and Radar echo have a good instruction to the aviation security.
Based on meteorological observational data and WRF model products, the severe convective weather process at Baiyun airport on April 1 7, 2007 was analyzed. The results show that the strengthening of southwest monso on and the establishment of the lowlevel jet create the sufficient vapor and u nstable condition in South China. The lifts of cold front and terrain promote the formation and development of convective weather. The precipitation of model out puts and Radar echo have a good instruction to the aviation security.
2008, 34(2):25-32.
DOI: 10.7519/j.issn.1000-0526.2008.02.004
Abstract:
he mesoscale structure and development reasons for a loc al storm in Beijing on 10 July 2004 are investigated by using the mesoscale num erical simulation. The results indicate that the MCS are the mesoscale convergence line and low pressure system in the mid and lowlevel, with the convergence in the low level, divergence in the high level and strong ascending motion during the strong development stage. Before the heavy rain, the surface sensible and la tent heat fluxes resulted in the temperature increase, pressure decrease and the water vapor accumulation, which influenced the wind distribution and played an i mportant role on the formation and development of the local storm.
he mesoscale structure and development reasons for a loc al storm in Beijing on 10 July 2004 are investigated by using the mesoscale num erical simulation. The results indicate that the MCS are the mesoscale convergence line and low pressure system in the mid and lowlevel, with the convergence in the low level, divergence in the high level and strong ascending motion during the strong development stage. Before the heavy rain, the surface sensible and la tent heat fluxes resulted in the temperature increase, pressure decrease and the water vapor accumulation, which influenced the wind distribution and played an i mportant role on the formation and development of the local storm.
2008, 34(2):33-37.
DOI: 10.7519/j.issn.1000-0526.2008.02.005
Abstract:
Using Doppler radar data, the four return flow events were analyzed. T he results are as follows: (1) PPI showed a large range symmetrical flaky reflec tivity with flat top. And 0℃ bright belt occurred in higher beams. (2) On VPPI, “0” line crossed through the radar station and showed a structure like “S”. The wind veered with height from NE to W, until SW with warm advection in lower layer. Acompanying with the cold advection around the top of boundary, efficienc y of precipitation became strong. (3) The wind direction were discontinuous in the vertical direction, NE in the low layer and SW in the middle. The vertical sh ear was observed on VAD.〖JP〗 The start and end time of precipitation was close ly related to the wind direction, including boundary layer NE wind and middle layer SW wind.
Using Doppler radar data, the four return flow events were analyzed. T he results are as follows: (1) PPI showed a large range symmetrical flaky reflec tivity with flat top. And 0℃ bright belt occurred in higher beams. (2) On VPPI, “0” line crossed through the radar station and showed a structure like “S”. The wind veered with height from NE to W, until SW with warm advection in lower layer. Acompanying with the cold advection around the top of boundary, efficienc y of precipitation became strong. (3) The wind direction were discontinuous in the vertical direction, NE in the low layer and SW in the middle. The vertical sh ear was observed on VAD.〖JP〗 The start and end time of precipitation was close ly related to the wind direction, including boundary layer NE wind and middle layer SW wind.
2008, 34(2):38-42.
DOI: 10.7519/j.issn.1000-0526.2008.02.006
Abstract:
A big area hail weather occurred in Heilongjiang province in the early spring of 2005, which has been seldom seen in the history, is studied with rada r and other observation data. The analysis is emphasized on the change in struct ure of the echo during the cloud developing, and also the discussion is laid on the relationship between radar reflectivity factor and radial velocity field. Wi th relative low temperature in the spring the convective cloud did not develop h igh and strong, so the usual standards, with which we judge severe weather, do n ot work well in this case. Though the weak echo and no typical hail echo feature have been observed, the characteristic of radial velocity and mesoscale conve rgence and divergence in spring can be found quite clearly. The analysis a nd study of different characteristics between hail weathers taking place in earl y spring and other seasons, are highly significant for better understanding of t he hail echo characteristics in different season.
A big area hail weather occurred in Heilongjiang province in the early spring of 2005, which has been seldom seen in the history, is studied with rada r and other observation data. The analysis is emphasized on the change in struct ure of the echo during the cloud developing, and also the discussion is laid on the relationship between radar reflectivity factor and radial velocity field. Wi th relative low temperature in the spring the convective cloud did not develop h igh and strong, so the usual standards, with which we judge severe weather, do n ot work well in this case. Though the weak echo and no typical hail echo feature have been observed, the characteristic of radial velocity and mesoscale conve rgence and divergence in spring can be found quite clearly. The analysis a nd study of different characteristics between hail weathers taking place in earl y spring and other seasons, are highly significant for better understanding of t he hail echo characteristics in different season.
2008, 34(2):43-51.
DOI: 10.7519/j.issn.1000-0526.2008.02.007
Abstract:
Based on the explanation and application of T213L31 numerical forecast model pro ducts, an operational MOS prediction system and a set of realtime statistical prediction equations are established for stations of Hubei province. The system firstly adopted Kalman Filter and AnalogueKalman Filter, and the equations sel ected several linear predictors that are relative to the model outputs, such as precipitation, surface air temperature and wind fields. This MOS system can for ecast above meteorological elements quantitatively in the form of fixed point (e very county), fixed time (every six hours). The experiments show that the MOS sy stem has good stability and excellent forecast scores in the testing period in J uneAugust from 2005 to 2006.
Based on the explanation and application of T213L31 numerical forecast model pro ducts, an operational MOS prediction system and a set of realtime statistical prediction equations are established for stations of Hubei province. The system firstly adopted Kalman Filter and AnalogueKalman Filter, and the equations sel ected several linear predictors that are relative to the model outputs, such as precipitation, surface air temperature and wind fields. This MOS system can for ecast above meteorological elements quantitatively in the form of fixed point (e very county), fixed time (every six hours). The experiments show that the MOS sy stem has good stability and excellent forecast scores in the testing period in J uneAugust from 2005 to 2006.
2008, 34(2):52-60.
DOI: 10.7519/j.issn.1000-0526.2008.02.008
Abstract:
By use of Guangzhou temperature and NCEP reanalysis data from 1951-200 5, the change of Guangzhou temperature and its probable cause is studied. Eviden ce suggests that Guangzhou temperature shows an obvious increase since the middl e of 1980s, with the most prominent trend in winter minimal temperature. The num ber of low temperature day (≤5℃) in winter decreases obviously and that of hig h temperature day (≥35℃) in summer increases prominently. Results also show th at the increase in Guangzhou temperature has a direct relationship with the heig ht of 500hPa fields and the weakening of winter and summer monsoon. And the r ole of urbanization process can’t be neglected in the increase of Guangzhou tem perature, especially in winter minimal temperature.
By use of Guangzhou temperature and NCEP reanalysis data from 1951-200 5, the change of Guangzhou temperature and its probable cause is studied. Eviden ce suggests that Guangzhou temperature shows an obvious increase since the middl e of 1980s, with the most prominent trend in winter minimal temperature. The num ber of low temperature day (≤5℃) in winter decreases obviously and that of hig h temperature day (≥35℃) in summer increases prominently. Results also show th at the increase in Guangzhou temperature has a direct relationship with the heig ht of 500hPa fields and the weakening of winter and summer monsoon. And the r ole of urbanization process can’t be neglected in the increase of Guangzhou tem perature, especially in winter minimal temperature.
2008, 34(2):61-68.
DOI: 10.7519/j.issn.1000-0526.2008.02.009
Abstract:
Using American National Centre of Environmental Prediction reanalysis data and monthly precipitation data at 64 observational stations of Shanxi Prov ince, the summer rainfall anomalies in1960-2003, that is the second rainfall patt ern of rich/seldom in the north and seldom/rich in the south, and temperature an omalies variation were analyzed with EOF, wavelet analysis and composite analysi s methods. The temperature linear trend indicated that warmer in the north and c ooler in the south was well accordance to the seldom rainfall in the north and r ich in the south from 1960 to 2003. The distinctive years of the second rainfall pattern were selected and the corresponding spatial and temporal distributions were made. The analysis was performed for the general circulation anomalies fea tures with 500hPa potential height field, zonal winds, 850hPa wind vector anomal ous fields, 700hPa water vapor field and water vapor transportation field. The r esults showed that the second rainfall pattern was closely related to weak East Asian summer monsoon and rich in the north or in the south were different appear ances of weak monsoon. When the rich/poor rainfall in the north and poor/rich ra infall in the south pattern happened, the subtropical high was stronger/weaker a nd presented belt/block pattern, and there was westerly/easterly anomalies in no rth/south, which meant that the northern front region was located more north. A nd the water vapor transport from the southwest to the northeast was stronger/we aker too. When rainfall was rich in the north and seldom in the south, there was a wave train appearing big circle route at mid and high latitudes, while at high latitude the latitudinal wave train appeared -+- anomalous circulation patte rn and along the coast of East Asian continent -+- anomalous circulation pattern too. Analysis of sea surface temperature showed that the second rainfall patter n has strong connection with Pacific SSTA at middle and high latitudes.
Using American National Centre of Environmental Prediction reanalysis data and monthly precipitation data at 64 observational stations of Shanxi Prov ince, the summer rainfall anomalies in1960-2003, that is the second rainfall patt ern of rich/seldom in the north and seldom/rich in the south, and temperature an omalies variation were analyzed with EOF, wavelet analysis and composite analysi s methods. The temperature linear trend indicated that warmer in the north and c ooler in the south was well accordance to the seldom rainfall in the north and r ich in the south from 1960 to 2003. The distinctive years of the second rainfall pattern were selected and the corresponding spatial and temporal distributions were made. The analysis was performed for the general circulation anomalies fea tures with 500hPa potential height field, zonal winds, 850hPa wind vector anomal ous fields, 700hPa water vapor field and water vapor transportation field. The r esults showed that the second rainfall pattern was closely related to weak East Asian summer monsoon and rich in the north or in the south were different appear ances of weak monsoon. When the rich/poor rainfall in the north and poor/rich ra infall in the south pattern happened, the subtropical high was stronger/weaker a nd presented belt/block pattern, and there was westerly/easterly anomalies in no rth/south, which meant that the northern front region was located more north. A nd the water vapor transport from the southwest to the northeast was stronger/we aker too. When rainfall was rich in the north and seldom in the south, there was a wave train appearing big circle route at mid and high latitudes, while at high latitude the latitudinal wave train appeared -+- anomalous circulation patte rn and along the coast of East Asian continent -+- anomalous circulation pattern too. Analysis of sea surface temperature showed that the second rainfall patter n has strong connection with Pacific SSTA at middle and high latitudes.
2008, 34(2):69-76.
DOI: 10.7519/j.issn.1000-0526.2008.02.010
Abstract:
Based on the daily maximum temperature data in 1961—2006 from 33 sta tions in Chongqing, spatial distribution feature and longterm change tendency of annul extreme high temperature frequency and intensity and annul extreme maxi mum temperature are analyzed. The result shows that in recent 46 years the trend of annual extreme high temperature frequency is decreasing in the western part of Chongqing and increasing in the eastern part，but the increase/decrease tre nd is not significant. In the recent 46 years the annual extreme high temperatur e intensity and annual extreme maximum temperature strengthen gradually. Increas ing tendency of annual extreme high temperature frequency in response to regiona l warming of Chongqing is most remarkable. Increasing tendency of annual extreme maximum temperature in respon se to regional warming of Chongqing is stronger than annual extreme high tempera ture intensity.
Based on the daily maximum temperature data in 1961—2006 from 33 sta tions in Chongqing, spatial distribution feature and longterm change tendency of annul extreme high temperature frequency and intensity and annul extreme maxi mum temperature are analyzed. The result shows that in recent 46 years the trend of annual extreme high temperature frequency is decreasing in the western part of Chongqing and increasing in the eastern part，but the increase/decrease tre nd is not significant. In the recent 46 years the annual extreme high temperatur e intensity and annual extreme maximum temperature strengthen gradually. Increas ing tendency of annual extreme high temperature frequency in response to regiona l warming of Chongqing is most remarkable. Increasing tendency of annual extreme maximum temperature in respon se to regional warming of Chongqing is stronger than annual extreme high tempera ture intensity.
2008, 34(2):77-82.
DOI: 10.7519/j.issn.1000-0526.2008.02.011
Abstract:
Seven mainly meteorological disasters might threaten 2008 Beijing Olym pic Game, which are lightning, hailstone, gale, high temperature, rainstorm, fog and haze. A suit of index system is set up to analyze the ability of risk contr ol and risk tolerance of the meteorological disaster in Beijing Olympic Game. Th e grade value of index system is given by experts, and the weight coefficients a re calculated by using the analytical hierarchy process. The results show that it is most frangible when Beijing encounters high temperature disaster and rains torm disaster. If lightning disaster and fog disaster occur, Beijing is medium f rangible. When hailstorm disaster and haze disaster happen in Beijing, it is rel atively frangible. Beijing is least frangible if haze disaster takes place. The analysis of vulnerability zoning shows that city region, Haidian district and Ch aoyang district are the most frangible area. Fengtai district, Fangshan county, Shijingshan district, Changping district, Shunyi county and Daxing county belong to the moderate frangible area. The other sites belong to low frangible area.
Seven mainly meteorological disasters might threaten 2008 Beijing Olym pic Game, which are lightning, hailstone, gale, high temperature, rainstorm, fog and haze. A suit of index system is set up to analyze the ability of risk contr ol and risk tolerance of the meteorological disaster in Beijing Olympic Game. Th e grade value of index system is given by experts, and the weight coefficients a re calculated by using the analytical hierarchy process. The results show that it is most frangible when Beijing encounters high temperature disaster and rains torm disaster. If lightning disaster and fog disaster occur, Beijing is medium f rangible. When hailstorm disaster and haze disaster happen in Beijing, it is rel atively frangible. Beijing is least frangible if haze disaster takes place. The analysis of vulnerability zoning shows that city region, Haidian district and Ch aoyang district are the most frangible area. Fengtai district, Fangshan county, Shijingshan district, Changping district, Shunyi county and Daxing county belong to the moderate frangible area. The other sites belong to low frangible area.
2008, 34(2):83-91.
DOI: 10.7519/j.issn.1000-0526.2008.02.012
Abstract:
The NCEP/NCAR analysis data is widely used not only in climate change simu lation and prediction research but also in cloud detection of remote sensing are a as initial data. An systematic intercomparison and analysis by Cressman interpolation is made between the NCEP Global Final Ana lysis (FNL) dataset and 753 station observed land surface temperature and 1.5 m above air temperature data over China in 2005 in terms of time, season and geo g raphical position. Through this comparison, some differences existed between the NCEP and the observed data can be identified.Comparison with the observed data , land surface temperature of the NCEP data is lower than the observed data in g eneral, while 1.5mabove air temperature is overestimated in the north of China and is generally underestimated in the south. In terms of season and geographic al position variation, the reliability of the NCEP dataset is better in summer t han in winter and is better in the southeast than in the northeast and northwest . From the point of diurnal variation (from 2:00 to 20:00 in local time) in land and air temperatures there is a tendency that the positive value areas (NCEP an alysis>observations) shrink and the negativevalue areas expand. The normalized RMSE shows that the practicability of air temperature NCEP reanalysis for Chi na is better than the land temperature NCEP reanalysis.
The NCEP/NCAR analysis data is widely used not only in climate change simu lation and prediction research but also in cloud detection of remote sensing are a as initial data. An systematic intercomparison and analysis by Cressman interpolation is made between the NCEP Global Final Ana lysis (FNL) dataset and 753 station observed land surface temperature and 1.5 m above air temperature data over China in 2005 in terms of time, season and geo g raphical position. Through this comparison, some differences existed between the NCEP and the observed data can be identified.Comparison with the observed data , land surface temperature of the NCEP data is lower than the observed data in g eneral, while 1.5mabove air temperature is overestimated in the north of China and is generally underestimated in the south. In terms of season and geographic al position variation, the reliability of the NCEP dataset is better in summer t han in winter and is better in the southeast than in the northeast and northwest . From the point of diurnal variation (from 2:00 to 20:00 in local time) in land and air temperatures there is a tendency that the positive value areas (NCEP an alysis>observations) shrink and the negativevalue areas expand. The normalized RMSE shows that the practicability of air temperature NCEP reanalysis for Chi na is better than the land temperature NCEP reanalysis.
2008, 34(2):92-100.
DOI: 10.7519/j.issn.1000-0526.2008.02.013
Abstract:
Spatial grid metrological data is an essential environmental factor for various geomodel and climatemodel, and the interpolation software is a tool to make the data spacedependent. As a specially designed interpolation package for meteorological data, ANUSPLIN has advantages of its solid theory of thin pl ate spline function, high interpolation accuracy by the incorporation of paramet ric linear submodel, in addition to the independent spline variables. Furtherm ore,it is more suitable for time series of meteorological data by process ing one more surface layer one time. So many contents of ANUSPLIN, such as the interpo lation theory, main data flows, parameters setting, model selection, statistic a nalyses and inputoutput formats are introduced through an example. It is expe cted that this paper is helpful for the researchers to use the ANUSPLIN more easi ly.
Spatial grid metrological data is an essential environmental factor for various geomodel and climatemodel, and the interpolation software is a tool to make the data spacedependent. As a specially designed interpolation package for meteorological data, ANUSPLIN has advantages of its solid theory of thin pl ate spline function, high interpolation accuracy by the incorporation of paramet ric linear submodel, in addition to the independent spline variables. Furtherm ore,it is more suitable for time series of meteorological data by process ing one more surface layer one time. So many contents of ANUSPLIN, such as the interpo lation theory, main data flows, parameters setting, model selection, statistic a nalyses and inputoutput formats are introduced through an example. It is expe cted that this paper is helpful for the researchers to use the ANUSPLIN more easi ly.
2008, 34(2):101-106.
DOI: 10.7519/j.issn.1000-0526.2008.02.014
Abstract:
Based on the realtime meteorological observation and the Mesoscale Numerical M odel (MM5V3), and supported by on the GIS application System, in pivot serving a rea of the Yellow River Basin (from Tuoketuo County to Wanjiazhai Reservoir),th e realtime rainfall of Yellow River Basin and the reservoir was monitored and t he warning index was automatically calculated. The arearainfall forecast of the Yellow River Basin (from Tuoketuo county to Wanjiazhai Reservoir) was output . The system was used in the oprational application, and provided the service f or Tianqiao hydropower station, Wanjiazhai Reservoir,the enterprises and some de partments of the government through the information issuing platform.
Based on the realtime meteorological observation and the Mesoscale Numerical M odel (MM5V3), and supported by on the GIS application System, in pivot serving a rea of the Yellow River Basin (from Tuoketuo County to Wanjiazhai Reservoir),th e realtime rainfall of Yellow River Basin and the reservoir was monitored and t he warning index was automatically calculated. The arearainfall forecast of the Yellow River Basin (from Tuoketuo county to Wanjiazhai Reservoir) was output . The system was used in the oprational application, and provided the service f or Tianqiao hydropower station, Wanjiazhai Reservoir,the enterprises and some de partments of the government through the information issuing platform.
2008, 34(2):107-114.
DOI: 10.7519/j.issn.1000-0526.2008.02.015
Abstract:
In order to understand the efficiency of the products from a mediumange foreca sting model, the synoptic verification and some compa risons of T213 Model with the ECMWF and JAPAN model are investigated from Septem ber to Novembe r 2007. The results show that all the three models have a good performance in f orecasting the largescale circulation in the high and middle latitudes, and th e y all show significant indication to forecast the transition and the weather dis aster. On the whole, ECMWF got the minimum errors in forecasting the weather sys tem a nd weather factors, while T213 got the maximum errors. Taking typhoon No. 0713 as a case, it was found that ECMWF got the most correct results for its location and moving speed, and that T213 got slow moving speed before l anding but the most correct location after landing, and that JAPAN model complet ely failed in forecasting the location and the strength of the typhoon.
In order to understand the efficiency of the products from a mediumange foreca sting model, the synoptic verification and some compa risons of T213 Model with the ECMWF and JAPAN model are investigated from Septem ber to Novembe r 2007. The results show that all the three models have a good performance in f orecasting the largescale circulation in the high and middle latitudes, and th e y all show significant indication to forecast the transition and the weather dis aster. On the whole, ECMWF got the minimum errors in forecasting the weather sys tem a nd weather factors, while T213 got the maximum errors. Taking typhoon No. 0713 as a case, it was found that ECMWF got the most correct results for its location and moving speed, and that T213 got slow moving speed before l anding but the most correct location after landing, and that JAPAN model complet ely failed in forecasting the location and the strength of the typhoon.
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ISSN:1000-0526 CN:11-2282/P