ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 43,Issue 9,2017 Table of Contents
2017, 43(9):1029-1040.
DOI: 10.7519/j.issn.1000-0526.2017.09.001
Abstract:
An assessment is presented on the relative forecast impact on the shorttime forecasting for typhoon from six different observation data types: surface, radiosonde, aircraft, satellite, radar reflectivity, and radar radial velocity. In this paper, the landfall Typhoon Fitow, which seriously affected China in 2013, is chosen to investigate the relative impact from different data types on the typhoon track, intensity, and precipitation shorttime forecasting by using Observation System Experiment (OSE) method with the Weather Research and Forecasting model (WRF) and Community Gridpoint Statistical Interpolation (GSI3DVAR) system. The results show that: (1) the contribution of different data types to the simulation results is obviously different. On the whole, the radiosonde, radar reflectivity and aircraft report have a great influence on the simulation of temperature, humidity, and wind of the full troposphere. The root mean square error (RMSE) increases by about 54.8%-62.0%, 9.2%-16.5% and 6.1%-6.4% for the “denied” experiments (NRS, NRF, NAC, respectively) compared to the control experiments. (2) Different sequence of contribution rates can be found in different assessment parameters. The radiosonde and aircraft report have the greatest influence on the simulation of temperature, humidity, and wind of the full troposphere. The sequence of contributions on typhoon intensity simulation is radar radial velocity, radar reflectivity, radiosonde, and aircraft report. Radar reflectivity, radiosonde, and aircraft report have great influence on the precipitation simulation. (3) The timevariations of the contributions to precipitation simulation are different among different data types. The contribution of radar reflectivity data to precipitation decreases with the time of model integration, while the contribution of aircraft report and radiosonde data to precipitation appear after 3 h of model integration. (4) The improvement of precipitation simulation is related to the improvement of typhoon track, intensity and hydrometeors simulation. Therefore, the radar reflectivity, radiosonde and aircraft report, which have high influences on the simulation of the full troposphere, typhoon track, and intensity, also have a great contribution to the precipitation simulation.
An assessment is presented on the relative forecast impact on the shorttime forecasting for typhoon from six different observation data types: surface, radiosonde, aircraft, satellite, radar reflectivity, and radar radial velocity. In this paper, the landfall Typhoon Fitow, which seriously affected China in 2013, is chosen to investigate the relative impact from different data types on the typhoon track, intensity, and precipitation shorttime forecasting by using Observation System Experiment (OSE) method with the Weather Research and Forecasting model (WRF) and Community Gridpoint Statistical Interpolation (GSI3DVAR) system. The results show that: (1) the contribution of different data types to the simulation results is obviously different. On the whole, the radiosonde, radar reflectivity and aircraft report have a great influence on the simulation of temperature, humidity, and wind of the full troposphere. The root mean square error (RMSE) increases by about 54.8%-62.0%, 9.2%-16.5% and 6.1%-6.4% for the “denied” experiments (NRS, NRF, NAC, respectively) compared to the control experiments. (2) Different sequence of contribution rates can be found in different assessment parameters. The radiosonde and aircraft report have the greatest influence on the simulation of temperature, humidity, and wind of the full troposphere. The sequence of contributions on typhoon intensity simulation is radar radial velocity, radar reflectivity, radiosonde, and aircraft report. Radar reflectivity, radiosonde, and aircraft report have great influence on the precipitation simulation. (3) The timevariations of the contributions to precipitation simulation are different among different data types. The contribution of radar reflectivity data to precipitation decreases with the time of model integration, while the contribution of aircraft report and radiosonde data to precipitation appear after 3 h of model integration. (4) The improvement of precipitation simulation is related to the improvement of typhoon track, intensity and hydrometeors simulation. Therefore, the radar reflectivity, radiosonde and aircraft report, which have high influences on the simulation of the full troposphere, typhoon track, and intensity, also have a great contribution to the precipitation simulation.
2017, 43(9):1041-1051.
DOI: 10.7519/j.issn.1000-0526.2017.09.002
Abstract:
To improve the radar quantitative precipitation estimation, an optimization rainfall algorithm of Sband dualpolarization radar, named HCALIQ, based on hydrometeor identification is developed by referring to the Colorado State University (CSU)ICE algorithm in this study. The radar estimator R (ZH), R (ZH, ZDR), R (KDP) calculated from the raindrop size distribution data collected in South China are used in this algorithm. Both the data collected from the Sband dualpolarization radar in Zhuhai, Guangdong Province and a network of rain gauges are used to evaluate the performance of the new algorithm. Comparison is also performed between the HCALIQ and CSUICE optimization algorithms and the traditional R (ZH) method. The results show that the HCALIQ optimization algorithm is well correlated with gauges and presents high stability. In addition, the distribution of hourly accumulation bias has light relation with the distance from the radar. The estimation results of the precipitation events show that two kinds of optimization algorithms are obviously superior to the traditional R (ZH) method for convective precipitation; the R (ZH) method is better than the two optimization algorithms for mixed cloud precipitation; the three errors statistics of the HCALIQ optimization algorithm are superior to the CSUICE algorithm. According to the bias statistics of the classification of rainfall intensity, the new HCALIQ optimization algorithm bias decreases by 23% for light rain 71% for heavy rain and 68% for torrential rain respectively in comparison to the traditional R (ZH) method.
To improve the radar quantitative precipitation estimation, an optimization rainfall algorithm of Sband dualpolarization radar, named HCALIQ, based on hydrometeor identification is developed by referring to the Colorado State University (CSU)ICE algorithm in this study. The radar estimator R (ZH), R (ZH, ZDR), R (KDP) calculated from the raindrop size distribution data collected in South China are used in this algorithm. Both the data collected from the Sband dualpolarization radar in Zhuhai, Guangdong Province and a network of rain gauges are used to evaluate the performance of the new algorithm. Comparison is also performed between the HCALIQ and CSUICE optimization algorithms and the traditional R (ZH) method. The results show that the HCALIQ optimization algorithm is well correlated with gauges and presents high stability. In addition, the distribution of hourly accumulation bias has light relation with the distance from the radar. The estimation results of the precipitation events show that two kinds of optimization algorithms are obviously superior to the traditional R (ZH) method for convective precipitation; the R (ZH) method is better than the two optimization algorithms for mixed cloud precipitation; the three errors statistics of the HCALIQ optimization algorithm are superior to the CSUICE algorithm. According to the bias statistics of the classification of rainfall intensity, the new HCALIQ optimization algorithm bias decreases by 23% for light rain 71% for heavy rain and 68% for torrential rain respectively in comparison to the traditional R (ZH) method.
2017, 43(9):1052-1063.
DOI: 10.7519/j.issn.1000-0526.2017.09.003
Abstract:
Using the observation data from November to the next April in 2000-2009, the temperature, relative humidity and pseudoequivalent potential temperature profile characteristics associated with different precipitation types in winter including rain, snow, sleet and freezing rain were analyzed. The results demonstrated that the distinguishing ability for temperature, relative humidity and pseudoequivalent potential temperature profile decreases with altitude from surface to 500 hPa in plain and mountainous areas. In addition, the distinguishing ability for relative humidity in different precipitation types is much weaker than the other two. At the same pressure level, the distinguishing ability of temperature and pseudoequivalent potential temperature is comparative for precipitation type in plain areas, and the distinguishing ability of the latter is better in mountainous areas at some pressure levels. At different pressure levels, the temperature and pseudoequivalent potential temperature are close to normal distribution for different precipitation types in plain areas, and the latter is closer to normal distribution than the former in mountainous areas. Therefore, pseudoequivalent potential temperature is more suitable for the factors to distinguish precipitation types. The multilevel discriminating equation was set up based on pseudoequivalent potential temperature at 6 levels (5 levels in mountainous areas) from surface to 500 hPa. In addition, the independent tests were conducted using the sample of precipitation type in 2010. The results indicated that the discriminating equation could distinguish rain, sleet or snow, freezing rain, but it is poor when distinguishing sleet and snow. The forecast verification based on T639 model data demonstrated that the equation can forecast the change time and region between rain and snow better. It is worth applying to operational prediction of winter precipitation type, and has been used in operations at Anhui Meteorological Observatory since 2011.
Using the observation data from November to the next April in 2000-2009, the temperature, relative humidity and pseudoequivalent potential temperature profile characteristics associated with different precipitation types in winter including rain, snow, sleet and freezing rain were analyzed. The results demonstrated that the distinguishing ability for temperature, relative humidity and pseudoequivalent potential temperature profile decreases with altitude from surface to 500 hPa in plain and mountainous areas. In addition, the distinguishing ability for relative humidity in different precipitation types is much weaker than the other two. At the same pressure level, the distinguishing ability of temperature and pseudoequivalent potential temperature is comparative for precipitation type in plain areas, and the distinguishing ability of the latter is better in mountainous areas at some pressure levels. At different pressure levels, the temperature and pseudoequivalent potential temperature are close to normal distribution for different precipitation types in plain areas, and the latter is closer to normal distribution than the former in mountainous areas. Therefore, pseudoequivalent potential temperature is more suitable for the factors to distinguish precipitation types. The multilevel discriminating equation was set up based on pseudoequivalent potential temperature at 6 levels (5 levels in mountainous areas) from surface to 500 hPa. In addition, the independent tests were conducted using the sample of precipitation type in 2010. The results indicated that the discriminating equation could distinguish rain, sleet or snow, freezing rain, but it is poor when distinguishing sleet and snow. The forecast verification based on T639 model data demonstrated that the equation can forecast the change time and region between rain and snow better. It is worth applying to operational prediction of winter precipitation type, and has been used in operations at Anhui Meteorological Observatory since 2011.
2017, 43(9):1064-1072.
DOI: 10.7519/j.issn.1000-0526.2017.09.004
Abstract:
Based on autumn (September to November) rainy days of 81 stations in Guizhou from 1964 to 2013 and National Center for Environmental Prediction/Atmospheric Research Center (NCEP/NCAR) reanalysis data, the spatiotemporal variation of autumn rainy days in Guizhou and its relation with atmospheric circulation were analyzed with Morlet wavelet and synthetic analysis, and other ways. The results show that the autumn rainy days in Guizhou are increased gradually from southeast to northwest between 30.0 d and 52.3 d. Mean autumn rainy days in Guizhou are about 40.5 d. There is the decreasing trend of autumn rainy days in the past 50 years, and its regression coefficient is -1.9 d/10 a. There is an abrupt change around 1987 for the autumn rainy days, which are more than normal in 1964-1987 but less than normal in 1988-2013. Since 1997, the decreasing trend is the most obvious. The autumn rainy days in the past 50 years have obviously quasi 5year and 2-3 year oscillation periods over Guizhou, of which the 5year oscillation is the most obvious, 2-3 year periodic oscillation is the second. At the same time, when the autumn rainy days are more over Guizhou, the South China Sea water vapor flux converges, the cold air activity is more active in the high latitudes, the East Asian trough is strong and the trough and ridge over the low latitudes deepen slightly, Guizhou lies in front of the IndiaBurma trough and, the strong southern airflow is in favor of the intersection of warm and cold airs, thus creating the frequent rainy weather; and vice versa.
Based on autumn (September to November) rainy days of 81 stations in Guizhou from 1964 to 2013 and National Center for Environmental Prediction/Atmospheric Research Center (NCEP/NCAR) reanalysis data, the spatiotemporal variation of autumn rainy days in Guizhou and its relation with atmospheric circulation were analyzed with Morlet wavelet and synthetic analysis, and other ways. The results show that the autumn rainy days in Guizhou are increased gradually from southeast to northwest between 30.0 d and 52.3 d. Mean autumn rainy days in Guizhou are about 40.5 d. There is the decreasing trend of autumn rainy days in the past 50 years, and its regression coefficient is -1.9 d/10 a. There is an abrupt change around 1987 for the autumn rainy days, which are more than normal in 1964-1987 but less than normal in 1988-2013. Since 1997, the decreasing trend is the most obvious. The autumn rainy days in the past 50 years have obviously quasi 5year and 2-3 year oscillation periods over Guizhou, of which the 5year oscillation is the most obvious, 2-3 year periodic oscillation is the second. At the same time, when the autumn rainy days are more over Guizhou, the South China Sea water vapor flux converges, the cold air activity is more active in the high latitudes, the East Asian trough is strong and the trough and ridge over the low latitudes deepen slightly, Guizhou lies in front of the IndiaBurma trough and, the strong southern airflow is in favor of the intersection of warm and cold airs, thus creating the frequent rainy weather; and vice versa.
2017, 43(9):1073-1083.
DOI: 10.7519/j.issn.1000-0526.2017.09.005
Abstract:
Based on the qualified hourly precipitation data of 123 stations in Sichuan Province and Chongqing City from 1980 to 2012, the multiple spatiotemporal distribution characteristics of the frequency, the intensity and the duration of hourly heavy rainfall (HHR) during main flood season from May to September are investigated. The main conclusions are as follows. The annual variation and diurnal variation of frequency during 1980-2012 are nearly identical at the thresholds above 20 mm, 30 mm and 50 mm per hour. The average annual frequency of HHR is 504, 184 and 28 respectively. According to the dynamic convergence lifting over mountain terrain and the forcing of large mountain gradient in the west of Sichuan and Chongqing Basin, the high frequency areas of HHR at the thresholds above 20 mm per hour distribute in Longshan Mountains in the northwest of the basin and the transition zone between the surrounding area of Ya’an and Leshan and the southwest of basin. The diurnal peak of frequency mainly happens between 20:00 BT and 01:00 BT in the south of basin and between 02:00 BT and 07:00 BT in the central, north and east of the basin. The diurnal variation of different hours shows double active peaks with the first peak after the noon and the second peak between 20:00 BT and the next 07:00 BT. The events of short duration (2-6 h) mostly occur in the day time, yet the events of lasting 2 to 18 hours all happen between the nightfall and the next morning. The intensity, frequency and precipitation amount of the events of HHR at distinct beginning time are characterized by similar daily variation with the single active peak happening between 18:00 BT and 06:00 BT. The accumulating rainfall and the frequency of the HHR events are less during the day time (09:00-20:00 BT) than over night (21:00-08:00 BT), which means the HHR events are remarkable at night time.
Based on the qualified hourly precipitation data of 123 stations in Sichuan Province and Chongqing City from 1980 to 2012, the multiple spatiotemporal distribution characteristics of the frequency, the intensity and the duration of hourly heavy rainfall (HHR) during main flood season from May to September are investigated. The main conclusions are as follows. The annual variation and diurnal variation of frequency during 1980-2012 are nearly identical at the thresholds above 20 mm, 30 mm and 50 mm per hour. The average annual frequency of HHR is 504, 184 and 28 respectively. According to the dynamic convergence lifting over mountain terrain and the forcing of large mountain gradient in the west of Sichuan and Chongqing Basin, the high frequency areas of HHR at the thresholds above 20 mm per hour distribute in Longshan Mountains in the northwest of the basin and the transition zone between the surrounding area of Ya’an and Leshan and the southwest of basin. The diurnal peak of frequency mainly happens between 20:00 BT and 01:00 BT in the south of basin and between 02:00 BT and 07:00 BT in the central, north and east of the basin. The diurnal variation of different hours shows double active peaks with the first peak after the noon and the second peak between 20:00 BT and the next 07:00 BT. The events of short duration (2-6 h) mostly occur in the day time, yet the events of lasting 2 to 18 hours all happen between the nightfall and the next morning. The intensity, frequency and precipitation amount of the events of HHR at distinct beginning time are characterized by similar daily variation with the single active peak happening between 18:00 BT and 06:00 BT. The accumulating rainfall and the frequency of the HHR events are less during the day time (09:00-20:00 BT) than over night (21:00-08:00 BT), which means the HHR events are remarkable at night time.
2017, 43(9):1084-1094.
DOI: 10.7519/j.issn.1000-0526.2017.09.006
Abstract:
The hailstorm process in Nanjing on 28 April 2015 is analyzed by using microwave radiometer, windprofiling radar, laser precipitation particle spectrometer and other automatic observation data. The results show that: (1) The combination of cold air associated with cold vortex over North China stretching towards the south and lowerlevel moisture air was found to be the circulation background of the severe hailstorm in Nanjing. The transportation of upperlevel cold advection and lowerlevel warm advection strengthened the formation of the extreme unstable atmosphere stratification. The lasting of surface mediumscale convergence center and convergence line played the triggering role in the hail weather. (2) In the hail clouds, strong updraft transport of lowlevel air sensible heat and latent heat led to significant increase of ambient temperature above 2 km altitude observed by microwave radiometer. When the hailstorm was in progress, continuous convergence of lowlevel moisture air and the hail fell into the melting area, causing an increase in lowlevel relative humidity and vapor density. Integrated liquid water (ILW) showed doublepeak structure. When the hailstorm process was initiated, ILW increased rapidly and reached maximum, which indicates the beginning of severe convective weather. (3) Comparing windprofile radar products in 3 stations, various vertical wind fields were observed in different regions. The hailstorm process in Luhe was closely related to the deep vertical wind shear at 0-6 km and the upperlevel jet stream, incorporating with the mesoscale cyclone on the ground and middlelevel mesocyclone, which made the hail process very intensive. The east movement of trough in lower troposphere was observed when Nanjing was hailing, while the vertical wind shear at lowerlevel forced continuous hail shooting at Gaochun. The conclusion makes a further understanding of environment condition about vertical structure during this heavy hailstorm event. (4) The microstructure characteristics of the precipitation at Luhe and Gaochun is discussed by using the laser precipitation spectrometers. The different droplet spectra characteristics corresponding with different precipitation types, the raindrop size distribution pattern in two stations basically showed the form of exponential distribution and multipeak structure respectively. Gaochun monitored hail with maximum diameter of 15 mm and Luhe was 5 mm. The raindrop velocity distribution both showed singlepeak type, and the terminal speed of particles during the severe raining period was between 2 and 5 m·s-1. (5) The severe hail supercell storm at Luhe showed typical features of hookshaped echo, suspended high strong echo area and TBSS.
The hailstorm process in Nanjing on 28 April 2015 is analyzed by using microwave radiometer, windprofiling radar, laser precipitation particle spectrometer and other automatic observation data. The results show that: (1) The combination of cold air associated with cold vortex over North China stretching towards the south and lowerlevel moisture air was found to be the circulation background of the severe hailstorm in Nanjing. The transportation of upperlevel cold advection and lowerlevel warm advection strengthened the formation of the extreme unstable atmosphere stratification. The lasting of surface mediumscale convergence center and convergence line played the triggering role in the hail weather. (2) In the hail clouds, strong updraft transport of lowlevel air sensible heat and latent heat led to significant increase of ambient temperature above 2 km altitude observed by microwave radiometer. When the hailstorm was in progress, continuous convergence of lowlevel moisture air and the hail fell into the melting area, causing an increase in lowlevel relative humidity and vapor density. Integrated liquid water (ILW) showed doublepeak structure. When the hailstorm process was initiated, ILW increased rapidly and reached maximum, which indicates the beginning of severe convective weather. (3) Comparing windprofile radar products in 3 stations, various vertical wind fields were observed in different regions. The hailstorm process in Luhe was closely related to the deep vertical wind shear at 0-6 km and the upperlevel jet stream, incorporating with the mesoscale cyclone on the ground and middlelevel mesocyclone, which made the hail process very intensive. The east movement of trough in lower troposphere was observed when Nanjing was hailing, while the vertical wind shear at lowerlevel forced continuous hail shooting at Gaochun. The conclusion makes a further understanding of environment condition about vertical structure during this heavy hailstorm event. (4) The microstructure characteristics of the precipitation at Luhe and Gaochun is discussed by using the laser precipitation spectrometers. The different droplet spectra characteristics corresponding with different precipitation types, the raindrop size distribution pattern in two stations basically showed the form of exponential distribution and multipeak structure respectively. Gaochun monitored hail with maximum diameter of 15 mm and Luhe was 5 mm. The raindrop velocity distribution both showed singlepeak type, and the terminal speed of particles during the severe raining period was between 2 and 5 m·s-1. (5) The severe hail supercell storm at Luhe showed typical features of hookshaped echo, suspended high strong echo area and TBSS.
2017, 43(9):1095-1109.
DOI: 10.7519/j.issn.1000-0526.2017.09.007
Abstract:
The extreme weather forecast products of ECMWF ensemble prediction system (EPS) are analyzed and verified. The products include extreme forecast index (EFI) and “shift of tail” index (SOT) of 08-08 BT mean temperature, maximum temperature, minimum temperature and total precipitation. The results indicate that the forecast skill of temperature EFI is similar to SOT for extreme temperature, but the precipitation SOT is better than EFI for extreme precipitation. Using the last 3 years’ dataset, the thresholds and corresponding measures are estimated for different lead times and extreme events over different percentiles of extreme temperature and precipitation, under the criteria of TS maximization. For the extreme low (high) temperature over 1% (99%) percentile, the thresholds of mean temperature EFI and SOT are about -0.85 (0.75) and 0.38 (0.00), respectively. The thresholds of maximum and minimum temperature EFI and SOT are nearly to that of mean temperature. For the extreme precipitation over 95% and 99% percentiles, the thresholds of EFI are about 0.45 and 0.7, and that of SOT are about -0.6 and 0.4. The longer the lead times, the smaller the thresholds and the lower the forecast skills. And the more extreme the events, the larger the thresholds. Under the criteria of TS maximization, the forecast biases are nearly 1, so these thresholds could be applied in the operation. The thresholds and forecast skill of temperature EFI and SOT show significant seasonal variation, with higher skill and thresholds in the summer half year and lower in the winter half year. The temporal variation of precipitation EFI and SOT is not significant. There are spatial variations of these thresholds and forecast skills and they are different for different indexes.
The extreme weather forecast products of ECMWF ensemble prediction system (EPS) are analyzed and verified. The products include extreme forecast index (EFI) and “shift of tail” index (SOT) of 08-08 BT mean temperature, maximum temperature, minimum temperature and total precipitation. The results indicate that the forecast skill of temperature EFI is similar to SOT for extreme temperature, but the precipitation SOT is better than EFI for extreme precipitation. Using the last 3 years’ dataset, the thresholds and corresponding measures are estimated for different lead times and extreme events over different percentiles of extreme temperature and precipitation, under the criteria of TS maximization. For the extreme low (high) temperature over 1% (99%) percentile, the thresholds of mean temperature EFI and SOT are about -0.85 (0.75) and 0.38 (0.00), respectively. The thresholds of maximum and minimum temperature EFI and SOT are nearly to that of mean temperature. For the extreme precipitation over 95% and 99% percentiles, the thresholds of EFI are about 0.45 and 0.7, and that of SOT are about -0.6 and 0.4. The longer the lead times, the smaller the thresholds and the lower the forecast skills. And the more extreme the events, the larger the thresholds. Under the criteria of TS maximization, the forecast biases are nearly 1, so these thresholds could be applied in the operation. The thresholds and forecast skill of temperature EFI and SOT show significant seasonal variation, with higher skill and thresholds in the summer half year and lower in the winter half year. The temporal variation of precipitation EFI and SOT is not significant. There are spatial variations of these thresholds and forecast skills and they are different for different indexes.
2017, 43(9):1110-1116.
DOI: 10.7519/j.issn.1000-0526.2017.09.008
Abstract:
This paper establishes a multimode integrated dynamicstatistical objective forecast model (SVM multimodel integration forecast) based on the European Centres for MediumRange Weather Forecasts (ECMWF) and the National Centers for Environmental Prediction Center (NCEP) ensemble forecast data and support vector machine regression method, then carries out a forecast test for heavy rain process that occurred in the Huaihe River Basin and its south of China during the period from May to September in 2012, and finally the forecast results are compared with the control forecast and ensemble average forecast of ECMWF. The results show that in the mediumterm forecasting timescale (4-7 days), the SVM multimodel integrated forecast method is the best for forecasting heavy rain compared with the control forecast of the ECMWF and the ensemble average forecast during the period from May to September in 2012. Especially for the accuracy of rainstorm forecasting, it is more effective, and the advantage is that its forecast of the distribution and intensity of heavy rain is closer to the observation.
This paper establishes a multimode integrated dynamicstatistical objective forecast model (SVM multimodel integration forecast) based on the European Centres for MediumRange Weather Forecasts (ECMWF) and the National Centers for Environmental Prediction Center (NCEP) ensemble forecast data and support vector machine regression method, then carries out a forecast test for heavy rain process that occurred in the Huaihe River Basin and its south of China during the period from May to September in 2012, and finally the forecast results are compared with the control forecast and ensemble average forecast of ECMWF. The results show that in the mediumterm forecasting timescale (4-7 days), the SVM multimodel integrated forecast method is the best for forecasting heavy rain compared with the control forecast of the ECMWF and the ensemble average forecast during the period from May to September in 2012. Especially for the accuracy of rainstorm forecasting, it is more effective, and the advantage is that its forecast of the distribution and intensity of heavy rain is closer to the observation.
2017, 43(9):1117-1129.
DOI: 10.7519/j.issn.1000-0526.2017.09.009
Abstract:
Rainfallinduced landslide disasters, which involve hydrological processes and geotechnical processes, are a complex prediction problem. In this study, a coupled hydrologicalgeotechnical model called CRESLIDE (Coupled Routing and Excess Storage and SLopeInfiltrationDistributed Equilibrium) was applied for landslides forecasting in the Yuehe River Basin. The hourly gridded precipitation data as the input of the CRESLIDE model were calculated using the inversedistance weighted interpolation method from reported values by encryption rainfall stations of China Meteorological Administration (CMA). By utilizing GIS, DEM and RS technology, the characteristic information of the test basin was extracted. The CREST distributed hydrological model was applied for simulating hydrological processes and computing the key intermediate variables as forcings of the SLIDE model to forecast rainfallinduced landslide events. We chose the Yuehe River Basin, located in the south of Shaanxi Province, as the test region for landslide forecasting. The results show that the CRESLIDE model has a generally good reliability to accurately predict occurrence of landslides (location and timing). Receiver Operating Characteristic (ROC) analysis indicated that the CRESLIDE model perform well with a high specificity (87.8%) and a reasonably good sensitivity (52.9%). Coupled hydrologicalgeotechnical framework like the CRESLIDE model is based on physical processes and has a more realistic representation of hydrological processes, so this type of model is very useful for landslide prediction and early warning. This study provides valuable information and insight for similar studies in this field.
Rainfallinduced landslide disasters, which involve hydrological processes and geotechnical processes, are a complex prediction problem. In this study, a coupled hydrologicalgeotechnical model called CRESLIDE (Coupled Routing and Excess Storage and SLopeInfiltrationDistributed Equilibrium) was applied for landslides forecasting in the Yuehe River Basin. The hourly gridded precipitation data as the input of the CRESLIDE model were calculated using the inversedistance weighted interpolation method from reported values by encryption rainfall stations of China Meteorological Administration (CMA). By utilizing GIS, DEM and RS technology, the characteristic information of the test basin was extracted. The CREST distributed hydrological model was applied for simulating hydrological processes and computing the key intermediate variables as forcings of the SLIDE model to forecast rainfallinduced landslide events. We chose the Yuehe River Basin, located in the south of Shaanxi Province, as the test region for landslide forecasting. The results show that the CRESLIDE model has a generally good reliability to accurately predict occurrence of landslides (location and timing). Receiver Operating Characteristic (ROC) analysis indicated that the CRESLIDE model perform well with a high specificity (87.8%) and a reasonably good sensitivity (52.9%). Coupled hydrologicalgeotechnical framework like the CRESLIDE model is based on physical processes and has a more realistic representation of hydrological processes, so this type of model is very useful for landslide prediction and early warning. This study provides valuable information and insight for similar studies in this field.
DANG Bing
,
FANG Xiaoyi
,
Lü Hongliang
,
CHENG Chen
,
DU Wupeng
,
LIU Yonghong
,
ZHANG Shuo
,
YANG Fan
2017, 43(9):1130-1137.
DOI: 10.7519/j.issn.1000-0526.2017.09.010
Abstract:
Based on the data of meteorological observation, NCEP and satellite remote sensing, the wind field characteristics and heat island distribution of Nanjing Jiangbei New Region were analyzed by using the methods of statistical analysis, numerical simulation and surface temperature retrieval. The ventilated corridor system of core area would be built with combinations of the land use status and new construction plan. The results indicate that the dominant wind direction is easterly, mountainvalley wind and landriver wind existing in local field. The wind speed is mainly concentrated in the period of 2-4 m·s-1, presenting downward trend in the recent 10 years. The wind speed in town and industrial park is small, for town and industrial park are stronger heat islands region. The fast wind speeds and freshair area are in the cool island area like Yangtze River, Laoshan and woodlands, where winds help air exchange with town. Combined with the local climate condition, topographic feature and landuse planning, we suggest the ventilated corridor system including 1 main ventilation corridor (northeastsouthwest), 3 minor ventilation corridors (northeastsouthwest) and 8 local ventilation corridors (southeastnorthwest, eastwest) could be built. In addition, the control index and construction strategy to the design length, width and layout of ventilated corridor were proposed.
Based on the data of meteorological observation, NCEP and satellite remote sensing, the wind field characteristics and heat island distribution of Nanjing Jiangbei New Region were analyzed by using the methods of statistical analysis, numerical simulation and surface temperature retrieval. The ventilated corridor system of core area would be built with combinations of the land use status and new construction plan. The results indicate that the dominant wind direction is easterly, mountainvalley wind and landriver wind existing in local field. The wind speed is mainly concentrated in the period of 2-4 m·s-1, presenting downward trend in the recent 10 years. The wind speed in town and industrial park is small, for town and industrial park are stronger heat islands region. The fast wind speeds and freshair area are in the cool island area like Yangtze River, Laoshan and woodlands, where winds help air exchange with town. Combined with the local climate condition, topographic feature and landuse planning, we suggest the ventilated corridor system including 1 main ventilation corridor (northeastsouthwest), 3 minor ventilation corridors (northeastsouthwest) and 8 local ventilation corridors (southeastnorthwest, eastwest) could be built. In addition, the control index and construction strategy to the design length, width and layout of ventilated corridor were proposed.
2017, 43(9):1138-1151.
DOI: 10.7519/j.issn.1000-0526.2017.09.011
Abstract:
In this paper, 6 h surface pressure observation and T639 analysis field in the summer (from June to August) 2013 in five different regions are analyzed firstly by wavelet and spectrum methods. Then, a progressive OMB (observationminusbackground) quality control method is put forward, and the surface pressure observations in China and the neighboring regions are studied. The research results indicate that in the regions with different elevations between surface observation sites and numerical model surface, the cycle and amplitude characteristics can be described accurately after the background data are corrected by the barometric height method. By using the barometric height formula and weighted average method, we correct surface pressure from model height to observation sites, making a good foundation for the quality control of surface pressure observation. Progressive OMB quality control method makes the observation increment very close to normal distribution. The progressive OMB quality control method is better than the OMB quality control method, because it can effectively identify outlier data and guarantee the quality of remained data.
In this paper, 6 h surface pressure observation and T639 analysis field in the summer (from June to August) 2013 in five different regions are analyzed firstly by wavelet and spectrum methods. Then, a progressive OMB (observationminusbackground) quality control method is put forward, and the surface pressure observations in China and the neighboring regions are studied. The research results indicate that in the regions with different elevations between surface observation sites and numerical model surface, the cycle and amplitude characteristics can be described accurately after the background data are corrected by the barometric height method. By using the barometric height formula and weighted average method, we correct surface pressure from model height to observation sites, making a good foundation for the quality control of surface pressure observation. Progressive OMB quality control method makes the observation increment very close to normal distribution. The progressive OMB quality control method is better than the OMB quality control method, because it can effectively identify outlier data and guarantee the quality of remained data.
2017, 43(9):1152-1159.
DOI: 10.7519/j.issn.1000-0526.2017.09.012
Abstract:
Based on 77 rainfall processes in Shijiazhuang from 2006 to 2008, this paper analyzes how quantitative precipitation estimation (QPE) is influenced by the altitude and horizontal distance from radar stations. Meanwhile, the optimum height of reflectivity factor for radar QPE and the values of distance and height corrections are suggested. The effect of QPE using the empirical formula and the optimization method are contrasted with and without distance and height corrections in four situations, and a QPE optimum scheme is designed according to the comparison results. No correction but only optimization method is adopted when the reflectivity is less than 30 dBz. Otherwise, distance and height corrections are performed firstly, and then optimization method is used in QPE. The results show that the proposed scheme has a good effect on heavy precipitation exceeding 10 mm·h-1 at single station, and on the process rainfall as well as on the estimation of regional precipitation.
Based on 77 rainfall processes in Shijiazhuang from 2006 to 2008, this paper analyzes how quantitative precipitation estimation (QPE) is influenced by the altitude and horizontal distance from radar stations. Meanwhile, the optimum height of reflectivity factor for radar QPE and the values of distance and height corrections are suggested. The effect of QPE using the empirical formula and the optimization method are contrasted with and without distance and height corrections in four situations, and a QPE optimum scheme is designed according to the comparison results. No correction but only optimization method is adopted when the reflectivity is less than 30 dBz. Otherwise, distance and height corrections are performed firstly, and then optimization method is used in QPE. The results show that the proposed scheme has a good effect on heavy precipitation exceeding 10 mm·h-1 at single station, and on the process rainfall as well as on the estimation of regional precipitation.
2017, 43(9):1160-1164.
DOI: 10.7519/j.issn.1000-0526.2017.09.013
Abstract:
The main characteristics of the general atmospheric circulation are as follows. There was one polar vortex center in the Northern Hemisphere, stronger than usual. The circulation in Eurasian middlehigh latitudes showed a multiwave pattern. The strength of Western Pacific subtropical high was a little weaker than in normal years. The monthly mean temperature in June was 20.3℃, 0.3℃ higher than the normal value, while the monthly mean precipitation amount was 112.3 mm which is 13% more than normal. The plum rains or Meiyu started earlier in the year of 2017. Typhoon Merbok landed in Guangdong Province in this month, which is the first landing typhoon in China this year. There were 6 heavy precipitation processes in the South of China, and in some places severe rainstorm and floods occurred. Meanwhile, Northeast China and North China rained less with high temperature during this month, causing drought to last for a long time. In addition, strong wind and hail disasters hit 19 provinces.
The main characteristics of the general atmospheric circulation are as follows. There was one polar vortex center in the Northern Hemisphere, stronger than usual. The circulation in Eurasian middlehigh latitudes showed a multiwave pattern. The strength of Western Pacific subtropical high was a little weaker than in normal years. The monthly mean temperature in June was 20.3℃, 0.3℃ higher than the normal value, while the monthly mean precipitation amount was 112.3 mm which is 13% more than normal. The plum rains or Meiyu started earlier in the year of 2017. Typhoon Merbok landed in Guangdong Province in this month, which is the first landing typhoon in China this year. There were 6 heavy precipitation processes in the South of China, and in some places severe rainstorm and floods occurred. Meanwhile, Northeast China and North China rained less with high temperature during this month, causing drought to last for a long time. In addition, strong wind and hail disasters hit 19 provinces.
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ISSN:1000-0526 CN:11-2282/P