ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 37,Issue 8,2011 Table of Contents
2011, 37(8):913-918.
DOI: 10.7519/j.issn.1000-0526.2011.8.001
Abstract:
“Ingredients based forecasting methodology”, which was proposed by Doswell et al. in 1996, is briefly presented. By comparing with traditional “pattern recognition” method, the strength and weakness of the “ingredients based forecasting methodology” are described. With real thunderstorm initiation case, the application of “ingredients based forecasting methodology” is illustrated. It is emphasized that “ingredients based forecasting methodology” and traditional “pattern recognition” forecasting method complement each other. Some misunderstandings on the “ingredients based forecasting methodology” are clarified.
“Ingredients based forecasting methodology”, which was proposed by Doswell et al. in 1996, is briefly presented. By comparing with traditional “pattern recognition” method, the strength and weakness of the “ingredients based forecasting methodology” are described. With real thunderstorm initiation case, the application of “ingredients based forecasting methodology” is illustrated. It is emphasized that “ingredients based forecasting methodology” and traditional “pattern recognition” forecasting method complement each other. Some misunderstandings on the “ingredients based forecasting methodology” are clarified.
2011, 37(8):919-928.
DOI: 10.7519/j.issn.1000-0526.2011.8.002
Abstract:
Based on the sea surface temperature (SST) in Ni〖AKn~D〗o3 region and snow depth from 1979 to 2005, relationships between ENSO and QinghaiTibetan Plateau (QXP) snow depth and their influences on summer rainfall in China were investigated, respectively. In addition, the joint influence of ENSO and QXP snow on summer rainfall in China was also analyzed. The results showed that the summer rainbelt in eastern China often moved southward (northward) only when a strong warm (strong cold) ENSO event and a heavy (light) QXP snow occurred simultaneously during previous winter and spring. Moreover, the monthly Ni〖AKn~D〗o3 SST and QXP snow during previous winter and spring both had a positive correlation with the June rainfall over southward of the Yangtze River, while they both had a negative correlation with August rainfall over southward of the Yangtze River. Furthermore, the monthly Ni〖AKn~D〗o3 SST during previous spring and the QXP snow during previous winter and spring both had a positive correlation with the July rainfall over southward of the Yangtze River. Moreover, the Ni〖AKn~D〗o3 SST and QXP snow during spring had a more important impact on June and July rainfall anomalies over southward of the Yangtze River. It clearly indicated that the impacts of previous ENSO and QXP snow on monthly rainfall anomalies over southward of the Yangtze River are different for each summer month.
Based on the sea surface temperature (SST) in Ni〖AKn~D〗o3 region and snow depth from 1979 to 2005, relationships between ENSO and QinghaiTibetan Plateau (QXP) snow depth and their influences on summer rainfall in China were investigated, respectively. In addition, the joint influence of ENSO and QXP snow on summer rainfall in China was also analyzed. The results showed that the summer rainbelt in eastern China often moved southward (northward) only when a strong warm (strong cold) ENSO event and a heavy (light) QXP snow occurred simultaneously during previous winter and spring. Moreover, the monthly Ni〖AKn~D〗o3 SST and QXP snow during previous winter and spring both had a positive correlation with the June rainfall over southward of the Yangtze River, while they both had a negative correlation with August rainfall over southward of the Yangtze River. Furthermore, the monthly Ni〖AKn~D〗o3 SST during previous spring and the QXP snow during previous winter and spring both had a positive correlation with the July rainfall over southward of the Yangtze River. Moreover, the Ni〖AKn~D〗o3 SST and QXP snow during spring had a more important impact on June and July rainfall anomalies over southward of the Yangtze River. It clearly indicated that the impacts of previous ENSO and QXP snow on monthly rainfall anomalies over southward of the Yangtze River are different for each summer month.
2011, 37(8):929-935.
DOI: 10.7519/j.issn.1000-0526.2011.8.003
Abstract:
Characteristics and causation for tropical cyclone (TC) activities over the Western North Pacific (WNP) and the South China Sea (SCS) in 2010 were analyzed by using the data of TCs, reanalysis data of NCEP/NCAR in this paper. TC activities are characterized by (1) forming the least, and the highest percentages of landing, (2) concentrated and westward genesis, (3) higher proportion of strong TCs and short life cycle TCs, (4) the later for the first TC and last TC, and (5) TC landing fewer in July-August and more than normal in September, 5 of 7 TCs landing on Fujian. The causes were studied and the results were listed as follows. Firstly, the warm mode in the East Indian Ocean in 2010 was one of the key extra forcing factors resulting in the least TC genesis in WNP and SCS in 2010, especially the lag response of extratropical atmosphere to El Nino. Secondly， the atmospheric circulation abnormity was the key reasons. It showed the combined impacts of multifactors including the larger and stronger Northwest Pacific subtropical high extending abnormally west, the abnormally westward monsoon trough and 1arge vertical shear anomalies.
Characteristics and causation for tropical cyclone (TC) activities over the Western North Pacific (WNP) and the South China Sea (SCS) in 2010 were analyzed by using the data of TCs, reanalysis data of NCEP/NCAR in this paper. TC activities are characterized by (1) forming the least, and the highest percentages of landing, (2) concentrated and westward genesis, (3) higher proportion of strong TCs and short life cycle TCs, (4) the later for the first TC and last TC, and (5) TC landing fewer in July-August and more than normal in September, 5 of 7 TCs landing on Fujian. The causes were studied and the results were listed as follows. Firstly, the warm mode in the East Indian Ocean in 2010 was one of the key extra forcing factors resulting in the least TC genesis in WNP and SCS in 2010, especially the lag response of extratropical atmosphere to El Nino. Secondly， the atmospheric circulation abnormity was the key reasons. It showed the combined impacts of multifactors including the larger and stronger Northwest Pacific subtropical high extending abnormally west, the abnormally westward monsoon trough and 1arge vertical shear anomalies.
2011, 37(8):936-942.
DOI: 10.7519/j.issn.1000-0526.2011.8.004
Abstract:
The radar data and GRAPES model data and convective weathers such as thunderstorm wind gusts, hails and tornados simultaneously from surface automatic meteorological stations or human observations from July to October in 2007 and 2008 were collected. Outputs of mesoscale numerical weather prediction (NWP) model of Guangzhou Institute of Tropic and Marine Meteorology of CMA were used to calculate the thunderstorm environment characteristics such as CAPE, winds, temperatures, instabilities etc. NWP variables, radar data together with convective events were incorporated into a statistic development dataset. Based on this dataset and the multiple regression approach, a convective weather potential forcasting method was developed to forecast the probability of a convective cell that could produce convective weathers within 0-1 hour. Scores as POD (probability of detection), FAR (false alarm ratio) and CSI (critical success index) were used to evaluate the performance of the method. The 12 of 31 predictors were chosen into the multiple regression equation. For a threshold value of 0.26, the method for a sample of 5540 cases produces forecast scores as follows: POD=0.73, FAR＝0.61, CSI＝0.338, which are better than results from the early rainy season of Guangdong （April to June） in 2004. This indicates that the convective weather potential forcasting can be a tool to the nowcasting of severe convective weathers in the later flood season of Guangdong.
The radar data and GRAPES model data and convective weathers such as thunderstorm wind gusts, hails and tornados simultaneously from surface automatic meteorological stations or human observations from July to October in 2007 and 2008 were collected. Outputs of mesoscale numerical weather prediction (NWP) model of Guangzhou Institute of Tropic and Marine Meteorology of CMA were used to calculate the thunderstorm environment characteristics such as CAPE, winds, temperatures, instabilities etc. NWP variables, radar data together with convective events were incorporated into a statistic development dataset. Based on this dataset and the multiple regression approach, a convective weather potential forcasting method was developed to forecast the probability of a convective cell that could produce convective weathers within 0-1 hour. Scores as POD (probability of detection), FAR (false alarm ratio) and CSI (critical success index) were used to evaluate the performance of the method. The 12 of 31 predictors were chosen into the multiple regression equation. For a threshold value of 0.26, the method for a sample of 5540 cases produces forecast scores as follows: POD=0.73, FAR＝0.61, CSI＝0.338, which are better than results from the early rainy season of Guangdong （April to June） in 2004. This indicates that the convective weather potential forcasting can be a tool to the nowcasting of severe convective weathers in the later flood season of Guangdong.
2011, 37(8):943-949.
DOI: 10.7519/j.issn.1000-0526.2011.8.005
Abstract:
The diurnal cycle of summer precipitation in Liaoning Province is investigated by using hourly raingauge data from 25 stations during 1961-2008. The results show there are strong regional characteristics of diurnal cycle and differences between coastal station and inland station. In general, the maximum precipitation amount of coastal station occurs at 04-08 BT before noon, while inland station’s diurnal cycle has a form of double peak, one before noon and one afternoon, and the maximum value occurs at 14-20 BT afternoon. The maximum precipitation frequency of coastal station is before noon, while the diurnal cycle of inland station’s frequency also has a form of double peak. The maximum value of precipitation with persistent 6 h or more occurs before noon, which is the reason for coastal station’s peak before noon. On the other hand, the inland station’s afternoon peak is attributed to the short time precipitation which is less than 6 hours and mainly caused by strong convection in the afternoon. The results also show that the diurnal cycle of precipitation can affect TS scores.
The diurnal cycle of summer precipitation in Liaoning Province is investigated by using hourly raingauge data from 25 stations during 1961-2008. The results show there are strong regional characteristics of diurnal cycle and differences between coastal station and inland station. In general, the maximum precipitation amount of coastal station occurs at 04-08 BT before noon, while inland station’s diurnal cycle has a form of double peak, one before noon and one afternoon, and the maximum value occurs at 14-20 BT afternoon. The maximum precipitation frequency of coastal station is before noon, while the diurnal cycle of inland station’s frequency also has a form of double peak. The maximum value of precipitation with persistent 6 h or more occurs before noon, which is the reason for coastal station’s peak before noon. On the other hand, the inland station’s afternoon peak is attributed to the short time precipitation which is less than 6 hours and mainly caused by strong convection in the afternoon. The results also show that the diurnal cycle of precipitation can affect TS scores.
2011, 37(8):950-955.
DOI: 10.7519/j.issn.1000-0526.2011.8.006
Abstract:
Based on the 1958-2009 monthly total precipitation data of 4 stations over Tianjin area, 160 stations over China and the NCEP/NCAR reanalysis data set, the variation characteristics of precipitation over Tianjin area and atmospheric circulation features in the same term of July to August as well as in the previous months from the preceding December through June for the anomalous years are investigated respectively by employing the simple correlation and composite analysis. The results show that the precipitation over Tianjin area is mainly concentrated in the rainy season. There exist interannual and interdecadal variations about the rainfall in rainy season. During the simultaneous term of the more precipitation years，the western Pacific subtropical high lies more northward， the low value systems develop on the northwest side of Tianjin area. Positive vorticity develops in the lower troposphere and the convergence ascending movement is more intense accordingly. The South Asia high and the subtropical upper westerly jet lie more northward. Meanwhile， warm and wet flow coming from southwest is stronger. For the less precipitation years the situations are just opposite. Additionally, there is a significant negative correlation between the precipitation and SAM (Southern Hemisphere Annular Mode) in the preceding June, which provides meaningful references for the shortterm climate prediction of precipitation over Tianjin area.
Based on the 1958-2009 monthly total precipitation data of 4 stations over Tianjin area, 160 stations over China and the NCEP/NCAR reanalysis data set, the variation characteristics of precipitation over Tianjin area and atmospheric circulation features in the same term of July to August as well as in the previous months from the preceding December through June for the anomalous years are investigated respectively by employing the simple correlation and composite analysis. The results show that the precipitation over Tianjin area is mainly concentrated in the rainy season. There exist interannual and interdecadal variations about the rainfall in rainy season. During the simultaneous term of the more precipitation years，the western Pacific subtropical high lies more northward， the low value systems develop on the northwest side of Tianjin area. Positive vorticity develops in the lower troposphere and the convergence ascending movement is more intense accordingly. The South Asia high and the subtropical upper westerly jet lie more northward. Meanwhile， warm and wet flow coming from southwest is stronger. For the less precipitation years the situations are just opposite. Additionally, there is a significant negative correlation between the precipitation and SAM (Southern Hemisphere Annular Mode) in the preceding June, which provides meaningful references for the shortterm climate prediction of precipitation over Tianjin area.
2011, 37(8):956-967.
DOI: 10.7519/j.issn.1000-0526.2011.8.007
Abstract:
With conventional and unconventional meteorological observational data, aiming at the 5 transverse shear regional rainstorm weather processes appearing in the flood season during 2009 in Shanxi area, the authors configured the flow pattern, diagnosed the physical variables, and comprehensively analyzed the satellite, radar, and the GPS/MET data and the predictability, and discovered that within the 5 transverse shear rainstorm processes, the rainstorm process appearing during July 7-8, 2009, was the one that the range was the widest, the precipitation strength was the strongest, and the system configuration was the most complete; in the continuous rainy process, whether rainstorm days or nonstorm days, all have the following features that humidity was high and thick, and this was the biggest difference from the other 4 noncontinuous rainy rainstorm processes; the convective or mixed rainstorm, has characteristics that it would decrease with the increasing height under 500 hPa, and would increase with the increasing height above 500 hPa 12 h ahead of the rainstorm setting in. Moreover the stable rainstorm has characteristics that it would increase with the increasing height. The 500 hPa horse latitude highs were all zonal types in the 5 rainstorm processes, and the 700 hPa horse latitude highs all had the southwest axis of jet stream being combined and the continental small high being accompanied, the rainstorm falling areas were all located at the area between the big value zone of the air column total vapor gradient and its southern (eastern), within 0.5°E (N). The analysis result shows that: the location difference of the small high led to the convergence of the different wind direction and the generation of transverse shear line in different trend, the latitude difference of the jet stream head stretching toward north led to the latitude difference of transverse shear line location, which would directly influence the falling areas of rainstorms; the strength difference of low vortex made the evident difference of precipitation; the more complete the highlow air system configuration is, the stronger will be the predictability of rainstorm falling area and magnitude; during the continuous rainy processes, the vertical speed, moisture flux divergence, and vertical wind shear are the sensitive factors in judging whether rainstorm will approach or not 24 h in advance. The vapor front area trend is almost consistent with the midlow layer shear line; before the rain approaches, the stable rainstorm process has more initial lead time in relation to the formation of the vapor front area than the severe convective rainstorm process, moreover, the stronger the convection is, the later the vapor front area forms.
With conventional and unconventional meteorological observational data, aiming at the 5 transverse shear regional rainstorm weather processes appearing in the flood season during 2009 in Shanxi area, the authors configured the flow pattern, diagnosed the physical variables, and comprehensively analyzed the satellite, radar, and the GPS/MET data and the predictability, and discovered that within the 5 transverse shear rainstorm processes, the rainstorm process appearing during July 7-8, 2009, was the one that the range was the widest, the precipitation strength was the strongest, and the system configuration was the most complete; in the continuous rainy process, whether rainstorm days or nonstorm days, all have the following features that humidity was high and thick, and this was the biggest difference from the other 4 noncontinuous rainy rainstorm processes; the convective or mixed rainstorm, has characteristics that it would decrease with the increasing height under 500 hPa, and would increase with the increasing height above 500 hPa 12 h ahead of the rainstorm setting in. Moreover the stable rainstorm has characteristics that it would increase with the increasing height. The 500 hPa horse latitude highs were all zonal types in the 5 rainstorm processes, and the 700 hPa horse latitude highs all had the southwest axis of jet stream being combined and the continental small high being accompanied, the rainstorm falling areas were all located at the area between the big value zone of the air column total vapor gradient and its southern (eastern), within 0.5°E (N). The analysis result shows that: the location difference of the small high led to the convergence of the different wind direction and the generation of transverse shear line in different trend, the latitude difference of the jet stream head stretching toward north led to the latitude difference of transverse shear line location, which would directly influence the falling areas of rainstorms; the strength difference of low vortex made the evident difference of precipitation; the more complete the highlow air system configuration is, the stronger will be the predictability of rainstorm falling area and magnitude; during the continuous rainy processes, the vertical speed, moisture flux divergence, and vertical wind shear are the sensitive factors in judging whether rainstorm will approach or not 24 h in advance. The vapor front area trend is almost consistent with the midlow layer shear line; before the rain approaches, the stable rainstorm process has more initial lead time in relation to the formation of the vapor front area than the severe convective rainstorm process, moreover, the stronger the convection is, the later the vapor front area forms.
2011, 37(8):968-976.
DOI: 10.7519/j.issn.1000-0526.2011.8.008
Abstract:
Using conventional weather charts, rainfall observations and precipitation forecasts made by T213 and T639 (China), MM5 (Hebei), JMA (Japan) and DWD (Germany) numerical models, the TS (threat scores) has been done by interpolating the five models’ precipitation forecasts into the 142 observation stations of Hebei. It is verified by the mutilmodel precipitation forecasts for different synoptic types from July 2009 to June 2010. The results indicate that, TS is closely related with numerical model and area, that the higher score corresponds some precipitation systems, such as shear type, subtropical high type and trough type, and that the accuracy of heavy and torrential rain under the first two type weather systems is higher than other types. The comprehensive evaluation of five models’ precipitation prediction, is that (1) the effects of DWD, T639 and JMA models are better than other models for light and moderate rainfall conditions; and (2) the effects of T639, MM5 and T213 models are better than other models for the heavy and torrential rainfall conditions.
Using conventional weather charts, rainfall observations and precipitation forecasts made by T213 and T639 (China), MM5 (Hebei), JMA (Japan) and DWD (Germany) numerical models, the TS (threat scores) has been done by interpolating the five models’ precipitation forecasts into the 142 observation stations of Hebei. It is verified by the mutilmodel precipitation forecasts for different synoptic types from July 2009 to June 2010. The results indicate that, TS is closely related with numerical model and area, that the higher score corresponds some precipitation systems, such as shear type, subtropical high type and trough type, and that the accuracy of heavy and torrential rain under the first two type weather systems is higher than other types. The comprehensive evaluation of five models’ precipitation prediction, is that (1) the effects of DWD, T639 and JMA models are better than other models for light and moderate rainfall conditions; and (2) the effects of T639, MM5 and T213 models are better than other models for the heavy and torrential rainfall conditions.
2011, 37(8):977-983.
DOI: 10.7519/j.issn.1000-0526.2011.8.009
Abstract:
With the observation data of the automatic weather stations at 5200 m asl, 5600 m asl, 5800 m asl, 6000 m asl and 7028 m asl during May 5-June 4 in 2007， the average diurnal changes of some meteorological e1ements were studied， such as air temperature， humidity， wind direction and speed， and atmospheric pressure, and the distributing differences in various altitude meteorological e1ements were discussed. The causes for the special distribution of each altitude meteorological e1ement on the northern slope of Mountain Qomolangma can be attributed to the distributing differences in substrate characters, the environment of topography, land and water distribution and solar radiation. The observation data and historical corresponding data were contrastively analyzed, and the existing differences between historical data and present data were explored. It can provide some scientific bases for entirely understanding the characters of meteorological e1ements at the Mountain Qomolangma， for exploring the mountain environment， for mountaineering and scientific research of Mountain Qomolangma.
With the observation data of the automatic weather stations at 5200 m asl, 5600 m asl, 5800 m asl, 6000 m asl and 7028 m asl during May 5-June 4 in 2007， the average diurnal changes of some meteorological e1ements were studied， such as air temperature， humidity， wind direction and speed， and atmospheric pressure, and the distributing differences in various altitude meteorological e1ements were discussed. The causes for the special distribution of each altitude meteorological e1ement on the northern slope of Mountain Qomolangma can be attributed to the distributing differences in substrate characters, the environment of topography, land and water distribution and solar radiation. The observation data and historical corresponding data were contrastively analyzed, and the existing differences between historical data and present data were explored. It can provide some scientific bases for entirely understanding the characters of meteorological e1ements at the Mountain Qomolangma， for exploring the mountain environment， for mountaineering and scientific research of Mountain Qomolangma.
2011, 37(8):984-990.
DOI: 10.7519/j.issn.1000-0526.2011.8.010
Abstract:
The features of water vapor transfer in rainy season (May to September) are studied based on the NCEP/NCAR reanalysis data that are used to compute the vertically integrated water vapor flux and water vapor flux divergence from 1979 to 2006. The results have shown that the main features of the water vapor transfer over the Tibetan Plateau are one monsoon, two water vapor transfer channels and three important water vapor sources. The India summer monsoon which dominates the start time of plateau’s rainy season and the motion rainfall bands, plays a decisive role in the Tibetan Plateau’s rainy season water vapor transfer. The weather stations near the longitude that northern water vapor flux reached 30 kg·m-1·s-1 would gradually come into the rainy season. The three centers of water vapor transfer divergence field in the southern border of the Tibetan Plateau are just corresponding to the plateau’s water transfer channel, and its formation is related to the terrain of Tibetan Plateau. Rainfall anomalies in Tibetan rainy season can be mainly divided into three raining patterns, they are Whole Region Pattern, EastWest Pattern and NorthSouth Pattern. These patterns are related to different water vapor transfer anomalies. For example, when it is in the whole Region Pattern the anomaly of the Somali crossequatorial flow zone is stronger.
The features of water vapor transfer in rainy season (May to September) are studied based on the NCEP/NCAR reanalysis data that are used to compute the vertically integrated water vapor flux and water vapor flux divergence from 1979 to 2006. The results have shown that the main features of the water vapor transfer over the Tibetan Plateau are one monsoon, two water vapor transfer channels and three important water vapor sources. The India summer monsoon which dominates the start time of plateau’s rainy season and the motion rainfall bands, plays a decisive role in the Tibetan Plateau’s rainy season water vapor transfer. The weather stations near the longitude that northern water vapor flux reached 30 kg·m-1·s-1 would gradually come into the rainy season. The three centers of water vapor transfer divergence field in the southern border of the Tibetan Plateau are just corresponding to the plateau’s water transfer channel, and its formation is related to the terrain of Tibetan Plateau. Rainfall anomalies in Tibetan rainy season can be mainly divided into three raining patterns, they are Whole Region Pattern, EastWest Pattern and NorthSouth Pattern. These patterns are related to different water vapor transfer anomalies. For example, when it is in the whole Region Pattern the anomaly of the Somali crossequatorial flow zone is stronger.
2011, 37(8):991-998.
DOI: 10.7519/j.issn.1000-0526.2011.8.011
Abstract:
Based on T639 (0.28125°×0.28125°) global grid data, the snowstorm process during 9-11 November 2009 in North China was simulated by WRF model. The results indicate that precipitation belt distribution in this process can be simulated well by WRF model. Diagnoses of the output data show that the vapor transported by the 700 hPa southwest jet flow made a humidity province in North China and prepared sufficient moist conditions for the snowstorm; the convergence of low level air flows and the divergence of upper air flows result in the strengthening of ascending motion and the genesis and maintenance of the center of low level positive vorticity, therefore the water vapor condensation in the vertical direction is the genesis mechanism of the snowstorm. Based on the CloudSat satellite data downloaded, the shape of ice water content distribution simulated in middle latitudes (39.9°N,117.3°E-33.7°N,115.5°E) is similar to ice water content of CloudSat, but in lower latitudes （30.6°N,114.6°E-24.2°N,112.7°E） the model simulated nothing.
Based on T639 (0.28125°×0.28125°) global grid data, the snowstorm process during 9-11 November 2009 in North China was simulated by WRF model. The results indicate that precipitation belt distribution in this process can be simulated well by WRF model. Diagnoses of the output data show that the vapor transported by the 700 hPa southwest jet flow made a humidity province in North China and prepared sufficient moist conditions for the snowstorm; the convergence of low level air flows and the divergence of upper air flows result in the strengthening of ascending motion and the genesis and maintenance of the center of low level positive vorticity, therefore the water vapor condensation in the vertical direction is the genesis mechanism of the snowstorm. Based on the CloudSat satellite data downloaded, the shape of ice water content distribution simulated in middle latitudes (39.9°N,117.3°E-33.7°N,115.5°E) is similar to ice water content of CloudSat, but in lower latitudes （30.6°N,114.6°E-24.2°N,112.7°E） the model simulated nothing.
2011, 37(8):999-1005.
DOI: 10.7519/j.issn.1000-0526.2011.8.012
Abstract:
Satellite based evapotranspiration according to the energy balance principle has clear physical meaning, and is widely used in the field of remote sensing for drought monitoring. Based on the China Energy and Water Balance Monitoring System (CEWBMS) and long timeseries (11 years) dataset of geostationary satellite, the percentage of relative evapotranspiration anomaly (PRETA) is obtained by using FY2/VISSR remote sensing data and investigated for largearea drought monitoring. Compared with polarorbiting satellite based drought indices, the FY2 based PRETA drought index has obvious advantages in the scope and frequency of monitoring. Due to the introduction of anomaly to relative evapotranspiration, the drought intensity classification is no longer dependent on seasonal and regional variations. Continuous quantitative evaluations of drought conditions in Southwest China from autumn 2009 to spring 2010 are carried out and statistics of the arid area are collected. Results show that spatial and temporal changes of drought status derived from PRETA are highly correlated with the actual drought situations. Trends of the areaaveraged PRETA and the precipitation anomaly percentage timeseries are highly consistent. Meanwhile, PRETA has a reasonable correlation with 10 cm relative soil moisture measurements. On the whole, the drought monitoring application in this study provided a practical way for realtime, largearea, high spatial resolution, quantitative and dynamic monitoring of drought.
Satellite based evapotranspiration according to the energy balance principle has clear physical meaning, and is widely used in the field of remote sensing for drought monitoring. Based on the China Energy and Water Balance Monitoring System (CEWBMS) and long timeseries (11 years) dataset of geostationary satellite, the percentage of relative evapotranspiration anomaly (PRETA) is obtained by using FY2/VISSR remote sensing data and investigated for largearea drought monitoring. Compared with polarorbiting satellite based drought indices, the FY2 based PRETA drought index has obvious advantages in the scope and frequency of monitoring. Due to the introduction of anomaly to relative evapotranspiration, the drought intensity classification is no longer dependent on seasonal and regional variations. Continuous quantitative evaluations of drought conditions in Southwest China from autumn 2009 to spring 2010 are carried out and statistics of the arid area are collected. Results show that spatial and temporal changes of drought status derived from PRETA are highly correlated with the actual drought situations. Trends of the areaaveraged PRETA and the precipitation anomaly percentage timeseries are highly consistent. Meanwhile, PRETA has a reasonable correlation with 10 cm relative soil moisture measurements. On the whole, the drought monitoring application in this study provided a practical way for realtime, largearea, high spatial resolution, quantitative and dynamic monitoring of drought.
2011, 37(8):1006-1017.
DOI: 10.7519/j.issn.1000-0526.2011.8.013
Abstract:
The paper has described the principals of the stacked spectral plots （SSP）in the control and dwell display window of boundary wind profiler (BWP). Some typical SSP patterns including precipitation, nonprecipitation, snow, radial velocity ambiguity, ground clutter as well as outliers have been provided in the paper for application references. It has also been found that the raw data of BWP for producing wind measurement products can be obtained not only from the SSP onlined, but also it can offer lots of potential meteorological information in a realtime. All of those said above can be used to carry out a roundclock weather monitoring over the observation station, understand the wind shear with height in advance, determine rainfall commence time and estimate the wind direction and speed, online estimate the bottom height of rainfall clouds and the range of 0° layer, verify the data quality in other nonrealtime products, support site selection for both stationary and mobile BWP, diagnose BWP system issues, assess the software and hardware of BWP, etc. It has been pointed out for the first time that developing the potential abilities of BWP sounding in the rainfall weather systems with a high temporal resolution and making it working well in both precipitation and nonprecipitation conditions are significantly meaningful with respect to BWP to be deployed to the weather observation stations nationwide in the near future to enhance the integrated capabilities in weather surveillance and detailed weather forecast. The comments and suggestions are also presented in order to improve the performance for the current commercial BWP to meet online analysis demand.
The paper has described the principals of the stacked spectral plots （SSP）in the control and dwell display window of boundary wind profiler (BWP). Some typical SSP patterns including precipitation, nonprecipitation, snow, radial velocity ambiguity, ground clutter as well as outliers have been provided in the paper for application references. It has also been found that the raw data of BWP for producing wind measurement products can be obtained not only from the SSP onlined, but also it can offer lots of potential meteorological information in a realtime. All of those said above can be used to carry out a roundclock weather monitoring over the observation station, understand the wind shear with height in advance, determine rainfall commence time and estimate the wind direction and speed, online estimate the bottom height of rainfall clouds and the range of 0° layer, verify the data quality in other nonrealtime products, support site selection for both stationary and mobile BWP, diagnose BWP system issues, assess the software and hardware of BWP, etc. It has been pointed out for the first time that developing the potential abilities of BWP sounding in the rainfall weather systems with a high temporal resolution and making it working well in both precipitation and nonprecipitation conditions are significantly meaningful with respect to BWP to be deployed to the weather observation stations nationwide in the near future to enhance the integrated capabilities in weather surveillance and detailed weather forecast. The comments and suggestions are also presented in order to improve the performance for the current commercial BWP to meet online analysis demand.
2011, 37(8):1018-1025.
DOI: 10.7519/j.issn.1000-0526.2011.8.014
Abstract:
The maximum wind velocity of automatic weather station (AWS) in Caofeidian Industrial Zone from 2007 to 2008 and the maximum wind velocity of meteorological stations at Tanghai, Laoting and Luannan from 1972 to 2008 were resolved into u and v components, and the regression models of u and v components were established respectively. Using the maximum wind speed data in Tanghai, Laoting and Luannan from 1972 to 2006, the data series of maximum wind speed in Caofeidian Industrial Zone during 1972-2006 were rebuilt. The observing and rebuilding data in Caofeidian were compared with its observing data in Tanghai, and the results show that the correlation coefficient of the maximum wind speed between Tanghai and Caofeidian is quite steady and there are some differences in wind direction between the two stations. When the wind speed is slower, the difference of wind direction between the two stations is larger. When the wind speed is larger, the difference of wind direction is smaller. The observed data of Caofeidian and Tanghai show that the times of same bearing are 28.3 percent in spring, 31.5 percent in summer, 24.7 percent in autumn, and 33.1 percent in winter. The rebuilding data of Caofeidian and the observed data in Tanghai show that the times of same bearing are 46 percent in spring, 29.4 percent in summer, 42.7 percent in autumn, and 54 percent in winter. In order to investigate the reality of the rebuilding data， we take 120 cases of high wind in different months as examples and analyze the relationship between rebuilding data and weather system. In the 120 cases, 114 cases meet obvious weather systems and 5 cases do not. The probability distribution of rebuilding maximum wind speed is obvious. Through hypothesis test, the daily maximum wind speed in Caofeidian follows a Gamma distribution. The series of maximum wind speed in Caofeidian can be used for the analysis and evaluation of wind disasters.
The maximum wind velocity of automatic weather station (AWS) in Caofeidian Industrial Zone from 2007 to 2008 and the maximum wind velocity of meteorological stations at Tanghai, Laoting and Luannan from 1972 to 2008 were resolved into u and v components, and the regression models of u and v components were established respectively. Using the maximum wind speed data in Tanghai, Laoting and Luannan from 1972 to 2006, the data series of maximum wind speed in Caofeidian Industrial Zone during 1972-2006 were rebuilt. The observing and rebuilding data in Caofeidian were compared with its observing data in Tanghai, and the results show that the correlation coefficient of the maximum wind speed between Tanghai and Caofeidian is quite steady and there are some differences in wind direction between the two stations. When the wind speed is slower, the difference of wind direction between the two stations is larger. When the wind speed is larger, the difference of wind direction is smaller. The observed data of Caofeidian and Tanghai show that the times of same bearing are 28.3 percent in spring, 31.5 percent in summer, 24.7 percent in autumn, and 33.1 percent in winter. The rebuilding data of Caofeidian and the observed data in Tanghai show that the times of same bearing are 46 percent in spring, 29.4 percent in summer, 42.7 percent in autumn, and 54 percent in winter. In order to investigate the reality of the rebuilding data， we take 120 cases of high wind in different months as examples and analyze the relationship between rebuilding data and weather system. In the 120 cases, 114 cases meet obvious weather systems and 5 cases do not. The probability distribution of rebuilding maximum wind speed is obvious. Through hypothesis test, the daily maximum wind speed in Caofeidian follows a Gamma distribution. The series of maximum wind speed in Caofeidian can be used for the analysis and evaluation of wind disasters.
2011, 37(8):1026-1030.
DOI: 10.7519/j.issn.1000-0526.2011.8.015
Abstract:
In order to improve the ability to use the products of T639, a synoptic verification on its mediumrange forecasting in Spring 2011 is made in comparison with the NWP of ECMWF and Japan models. The results show that the three models have good performances on the aspect of predicting the largescale circulation evolution and adjustment in Asian middle and high latitude areas. As a whole, the ECMWF model is better in forecasting most weather systems compared with the T639 and Japan models. Taking the sandstorm process during the period of April 28-30, 2011 as a case, it is found that the Japan model is more effective than the other two models in mediumrange forecasting of strong surface wind, causing this sand and dust weather process.
In order to improve the ability to use the products of T639, a synoptic verification on its mediumrange forecasting in Spring 2011 is made in comparison with the NWP of ECMWF and Japan models. The results show that the three models have good performances on the aspect of predicting the largescale circulation evolution and adjustment in Asian middle and high latitude areas. As a whole, the ECMWF model is better in forecasting most weather systems compared with the T639 and Japan models. Taking the sandstorm process during the period of April 28-30, 2011 as a case, it is found that the Japan model is more effective than the other two models in mediumrange forecasting of strong surface wind, causing this sand and dust weather process.
2011, 37(8):1031-1037.
DOI: 10.7519/j.issn.1000-0526.2011.8.016
Abstract:
The following are the main characteristics of the general circulation of atmosphere in May 2011. There are two centers of the Northern Hemisphere polar vortex and four waves around the earth in middlehigh latitudes. More troughs occur in middlehigh latitudes in the Asian area, and lead to several streams of cold air which influence China. The East Asia major trough is stronger than usual at same time period. The subtropical high and the southern branch trough are near climatological normals. The monthly mean temperature averaged over China is 17.7℃ which is 0.3℃ higher than climatological normals, and the monthly mean precipitation averaged over China is 81.4 mm which is 12.1% less than climatological normals (92.6 mm). There are two cold airs, seven precipitations and one strong sanddust process in May 2011 respectively. Rain storm and flooding occur in Sichuan, Hunan, Guangdong, Guangxi, etc. Meanwhile, the drought continues developing at the middle and lower reaches of the Changjiang River. Strong wind and hail disasters hit Xinjiang, Gansu, Ningxia, Hebei, Shandong, Hunan, Guizhou, Guangdong, etc.
The following are the main characteristics of the general circulation of atmosphere in May 2011. There are two centers of the Northern Hemisphere polar vortex and four waves around the earth in middlehigh latitudes. More troughs occur in middlehigh latitudes in the Asian area, and lead to several streams of cold air which influence China. The East Asia major trough is stronger than usual at same time period. The subtropical high and the southern branch trough are near climatological normals. The monthly mean temperature averaged over China is 17.7℃ which is 0.3℃ higher than climatological normals, and the monthly mean precipitation averaged over China is 81.4 mm which is 12.1% less than climatological normals (92.6 mm). There are two cold airs, seven precipitations and one strong sanddust process in May 2011 respectively. Rain storm and flooding occur in Sichuan, Hunan, Guangdong, Guangxi, etc. Meanwhile, the drought continues developing at the middle and lower reaches of the Changjiang River. Strong wind and hail disasters hit Xinjiang, Gansu, Ningxia, Hebei, Shandong, Hunan, Guizhou, Guangdong, etc.
2011, 37(8):1038-1041.
DOI: 10.7519/j.issn.1000-0526.2011.8.017
Abstract:
The wet bulb temperature is an important meteorological parameter in heating, ventilation, power plant cooling towers and other many engineering designs. As automatic weather stations (AWS) are widely used in the meteorological station, the direct observation data of wetbulb temperature gradually stop, which gives difficulty in the engineering design parameters of wetbulb temperature in the weather analysis and the application. For the calculation of the wetbulb temperature at AWS, we employed the groundbased meteorological observation humidity formula and the basic idea of Newton’s iterative method, and obtained a simplified general iterative formula. An empirical formula of wetbulb temperature is used to calculate its initial value, and an EXECL spreadsheet is used to complete the iterative calculation of wetbulb temperature. The results show that, this calculation method of wetbulb temperature has high accuracy, less computation, as well as the calculation process simple and controllable. Therefore, it can be widely used in the wetbulb temperature calculation at AWS.
The wet bulb temperature is an important meteorological parameter in heating, ventilation, power plant cooling towers and other many engineering designs. As automatic weather stations (AWS) are widely used in the meteorological station, the direct observation data of wetbulb temperature gradually stop, which gives difficulty in the engineering design parameters of wetbulb temperature in the weather analysis and the application. For the calculation of the wetbulb temperature at AWS, we employed the groundbased meteorological observation humidity formula and the basic idea of Newton’s iterative method, and obtained a simplified general iterative formula. An empirical formula of wetbulb temperature is used to calculate its initial value, and an EXECL spreadsheet is used to complete the iterative calculation of wetbulb temperature. The results show that, this calculation method of wetbulb temperature has high accuracy, less computation, as well as the calculation process simple and controllable. Therefore, it can be widely used in the wetbulb temperature calculation at AWS.
2011, 37(8):1042-1044.
DOI: 10.7519/j.issn.1000-0526.2011.8.018
Abstract:
In recent years, the microwave power sensor taking planar potential barrier diode as core component that coordinates with small power meter makes the high speed, high precision and successive power measurements and thus comes into realization. It is widely used to measure high frequency equipment such as the weather radar signal power. The paper analyzes the characteristics and circuit principle of microwave power sensor, introduces the connecting and setting methods with power meter and discusses the method to judge the fault of new generation weather radar by using microwave power sensor in the two typical maintenances of CINRAD/SA as examples.
In recent years, the microwave power sensor taking planar potential barrier diode as core component that coordinates with small power meter makes the high speed, high precision and successive power measurements and thus comes into realization. It is widely used to measure high frequency equipment such as the weather radar signal power. The paper analyzes the characteristics and circuit principle of microwave power sensor, introduces the connecting and setting methods with power meter and discusses the method to judge the fault of new generation weather radar by using microwave power sensor in the two typical maintenances of CINRAD/SA as examples.
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ISSN:1000-0526 CN:11-2282/P