ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 40,Issue 11,2014 Table of Contents
2014, 40(11):1293-1301.
DOI: 10.7519/j.issn.1000-0526.2014.11.001
Abstract:
Based on the 11-15 d forecast data of T213 EPS 500 hPa geopotential height and 850 hPa temperature in China and the adjacent regions in January 2008, an interpretation method of extended range forecast product is designed, and the pentad average and pentad anomaly forecast of extended range (11-15 d) are got after the 11-15 d daily forecast data are processed by ensemble mean, moving average of backward decaying weighting coefficient and pentad average. Meanwhile, the forecast effect of the pentad average and pentad anomaly forecast is verified. The results show that ensemble mean and moving average of backward decaying weighting coefficient both can reduce the prediction error and improve the forecast effect. The pentad mean absolute error of the 11-15 d pentad average forecast of 500 hPa geopotential height and 850 hPa temperature are equal to the level of the 5th d forecast of daily control forecast. The pentad anomaly correlation coefficients of 500 hPa geopotential height and 850 hPa temperature are both close to 0.6. Taken as a whole, the forecast effect of 11-15 d pentad average is good enough to use. The phase accuracy rate of 11-15 d pentad anomaly forecast of 500 hPa geopotential height and 850 hPa temperature are both very good in mainland China except for part of the southeast coastal area and the northeast area. In general, the phase accuracy rate of 850 hPa temperature is better than 500 hPa geopotential height. The 11-15 d pentad anomaly forecast can reflect the persistent large scale anomalous anomaly. The range, distribution and center of anomalous anomaly can all be forecasted well but the overall intensity is weaker than observed field.
Based on the 11-15 d forecast data of T213 EPS 500 hPa geopotential height and 850 hPa temperature in China and the adjacent regions in January 2008, an interpretation method of extended range forecast product is designed, and the pentad average and pentad anomaly forecast of extended range (11-15 d) are got after the 11-15 d daily forecast data are processed by ensemble mean, moving average of backward decaying weighting coefficient and pentad average. Meanwhile, the forecast effect of the pentad average and pentad anomaly forecast is verified. The results show that ensemble mean and moving average of backward decaying weighting coefficient both can reduce the prediction error and improve the forecast effect. The pentad mean absolute error of the 11-15 d pentad average forecast of 500 hPa geopotential height and 850 hPa temperature are equal to the level of the 5th d forecast of daily control forecast. The pentad anomaly correlation coefficients of 500 hPa geopotential height and 850 hPa temperature are both close to 0.6. Taken as a whole, the forecast effect of 11-15 d pentad average is good enough to use. The phase accuracy rate of 11-15 d pentad anomaly forecast of 500 hPa geopotential height and 850 hPa temperature are both very good in mainland China except for part of the southeast coastal area and the northeast area. In general, the phase accuracy rate of 850 hPa temperature is better than 500 hPa geopotential height. The 11-15 d pentad anomaly forecast can reflect the persistent large scale anomalous anomaly. The range, distribution and center of anomalous anomaly can all be forecasted well but the overall intensity is weaker than observed field.
2014, 40(11):1302-1307.
DOI: 10.7519/j.issn.1000-0526.2014.11.002
Abstract:
Based on two processes of the severe sandstorm and the strong wind with dust, this study on spatial distribution characteristics of temperature advection aims at the atmospheric stratification in Inner Mongolia. The results show that during the sandstorm and high wind processes cold advections are stronger than normal, but have different vertical distribution characteristics. The strong cold advections have significant impacts on atmospheric stratification stabilities, vertical temperature profiles and vertical movements. The center of the strong cold advection exists in the higher layer from 700 hPa to 600 hPa, overlapping the weak cold advection in the near surface layer, forming temperature advection differences between higher and lower levels, and increasing vertical temperature lapse rate, which is favorable for the formation of the deep unstable stratification in the sandstorm processes. After the unstable energy is released in the process of the dry convective windstorm formation, the atmosphere stratification tends to become neutral or mixed layer, where the energy exchange is in an equilibrium state. In high wind process, strong cold advection center is located in the lower level of 850 hPa, which is not conducive to the formation of unstable stratification. The mixing layer height is consistent with the sandstorm height, whose location is about 150 hPa higher than the strong cold advection center, when the strong cold advection center (-45×10-3 ℃·s-1) is in the 700-600 hPa level and the thichness of the mixing layer gets to 500 hPa or higher. This sandstorm weather process with such intensity can influence the south of the Yangtze River and the coastal areas of China.
Based on two processes of the severe sandstorm and the strong wind with dust, this study on spatial distribution characteristics of temperature advection aims at the atmospheric stratification in Inner Mongolia. The results show that during the sandstorm and high wind processes cold advections are stronger than normal, but have different vertical distribution characteristics. The strong cold advections have significant impacts on atmospheric stratification stabilities, vertical temperature profiles and vertical movements. The center of the strong cold advection exists in the higher layer from 700 hPa to 600 hPa, overlapping the weak cold advection in the near surface layer, forming temperature advection differences between higher and lower levels, and increasing vertical temperature lapse rate, which is favorable for the formation of the deep unstable stratification in the sandstorm processes. After the unstable energy is released in the process of the dry convective windstorm formation, the atmosphere stratification tends to become neutral or mixed layer, where the energy exchange is in an equilibrium state. In high wind process, strong cold advection center is located in the lower level of 850 hPa, which is not conducive to the formation of unstable stratification. The mixing layer height is consistent with the sandstorm height, whose location is about 150 hPa higher than the strong cold advection center, when the strong cold advection center (-45×10-3 ℃·s-1) is in the 700-600 hPa level and the thichness of the mixing layer gets to 500 hPa or higher. This sandstorm weather process with such intensity can influence the south of the Yangtze River and the coastal areas of China.
2014, 40(11):1308-1315.
DOI: 10.7519/j.issn.1000-0526.2014.11.003
Abstract:
Using the sounding observation data (SO), raw sounding observation data (RSO), GPS/MET data, microwave radiometer data (MWR), GFS reanalyzed data and the mesoscale area limited model WRF data, the precipitable water vapor (PWV) was estimated. Through the error analysis of different data, it is found that the SO PWV and RSO PWV are the same basically. The correlation coefficient of the GPS/MET PWV, the MWR PWV, the GPS PWV, the WRF PWV and the SO PWV are 0.94, 0.92, 0.93, 0.80， respectively. The correlation coefficients of the GPS/MET PWV, the MWR PWV and the SO PWV reduce to 0.85 and 0.81 seperately when raining, and the error distribution of the GPS/MET PWV is concentrated, while the error distribution of the MWR PWV increases significantly, because the water vapor density error increases abnormally in the part 1-2 km. The PWV is generally low, except for the MWR PWV and the GPS/MET PWV at Yichang. The GPS/MET PWV is averagely 3 mm lower than the SO PWV at Yichang and Enshi, the GFS PWV at Wuhan and Enshi is respectively 1 mm and 7 mm, the WRF PWV at Enshi is averagely 2 mm and 6-8 mm at Wuhan and Yichang. The surface pressure of GFS is lower than the observation at Enshi is the reason for the GFS PWV errors, but the dew point temperature of GFS is higher than SO. The dew point temperature analysis shows that the GFS at Wuhan, the GFS at Yichang, and WRF at three stations are lower below 850 hPa and higher above 850 hPa than SO, except for the GFS at Enshi. The correlation coefficient and the error distribution of the WRF PWV and the SO PWV analysis show that the 12 h forecasting is better than 24 h.
Using the sounding observation data (SO), raw sounding observation data (RSO), GPS/MET data, microwave radiometer data (MWR), GFS reanalyzed data and the mesoscale area limited model WRF data, the precipitable water vapor (PWV) was estimated. Through the error analysis of different data, it is found that the SO PWV and RSO PWV are the same basically. The correlation coefficient of the GPS/MET PWV, the MWR PWV, the GPS PWV, the WRF PWV and the SO PWV are 0.94, 0.92, 0.93, 0.80， respectively. The correlation coefficients of the GPS/MET PWV, the MWR PWV and the SO PWV reduce to 0.85 and 0.81 seperately when raining, and the error distribution of the GPS/MET PWV is concentrated, while the error distribution of the MWR PWV increases significantly, because the water vapor density error increases abnormally in the part 1-2 km. The PWV is generally low, except for the MWR PWV and the GPS/MET PWV at Yichang. The GPS/MET PWV is averagely 3 mm lower than the SO PWV at Yichang and Enshi, the GFS PWV at Wuhan and Enshi is respectively 1 mm and 7 mm, the WRF PWV at Enshi is averagely 2 mm and 6-8 mm at Wuhan and Yichang. The surface pressure of GFS is lower than the observation at Enshi is the reason for the GFS PWV errors, but the dew point temperature of GFS is higher than SO. The dew point temperature analysis shows that the GFS at Wuhan, the GFS at Yichang, and WRF at three stations are lower below 850 hPa and higher above 850 hPa than SO, except for the GFS at Enshi. The correlation coefficient and the error distribution of the WRF PWV and the SO PWV analysis show that the 12 h forecasting is better than 24 h.
WEN Yongren〓WEI Na〓ZHANG Xuerong〓MAI Zi
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WEN Yongren〓WEI Na〓ZHANG Xuerong〓MAI Zi
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WEN Yongren〓WEI Na〓ZHANG Xuerong〓MAI Zi
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WEN Yongren〓WEI Na〓ZHANG Xuerong〓MAI Zi
2014, 40(11):1316-1323.
DOI: 10.7519/j.issn.1000-0526.2014.11.004
Abstract:
Based on typhoon best track data from China Meteorological Administration—Shanghai Typhoon Institute and NCEP FNL 1°×1° grid data, causes for rapid dissipation of severe typhoon Fitow after its landfall are investigated by analyzing atmospheric environmental conditions, kinetic energy budgets and its structure change. The results suggest that the rapid decay of Fitow is associated with its interaction with a mid latitude trough and another typhoon Danas (1324). Before Fitow makes landfall, it obtains water vapor transported from a lower layer easterly jet connecting typhoon Fitow and Danas to its east over ocean. Meanwhile, it gets kinetic energy from baroclinic potential energy transferring due to a mid latitude trough approaching. Besides, a small vertical wind shear is also favorable for the development of Fitow. However, the moisture channel is broken after Fiow makes landfall and Danas moves northward. And the cold air invades into the center of typhoon, which causes the kinetic energy to convert into baroclinic potential energy. Meanwhile, the increase of vertical wind shear is also unfavorable for typhoon sustention. Fitow dissipates rapidly after its structure features lost.
Based on typhoon best track data from China Meteorological Administration—Shanghai Typhoon Institute and NCEP FNL 1°×1° grid data, causes for rapid dissipation of severe typhoon Fitow after its landfall are investigated by analyzing atmospheric environmental conditions, kinetic energy budgets and its structure change. The results suggest that the rapid decay of Fitow is associated with its interaction with a mid latitude trough and another typhoon Danas (1324). Before Fitow makes landfall, it obtains water vapor transported from a lower layer easterly jet connecting typhoon Fitow and Danas to its east over ocean. Meanwhile, it gets kinetic energy from baroclinic potential energy transferring due to a mid latitude trough approaching. Besides, a small vertical wind shear is also favorable for the development of Fitow. However, the moisture channel is broken after Fiow makes landfall and Danas moves northward. And the cold air invades into the center of typhoon, which causes the kinetic energy to convert into baroclinic potential energy. Meanwhile, the increase of vertical wind shear is also unfavorable for typhoon sustention. Fitow dissipates rapidly after its structure features lost.
2014, 40(11):1324-1337.
DOI: 10.7519/j.issn.1000-0526.2014.11.005
Abstract:
Using conventional meteorological observations, NCEP reanalysis data (FNL), L band radar data, and applying the multi channel satellite monitoring data from National Satellite Meteorological Centre and qualitatively analyzing the sea fog, this paper discusses the heavy sea fog event during February 22-25, 2010, including the boundary layer (BL) characteristics, formation and disappearance mechanism. The results show that: (1) The fog happens under straight circulation in the Eurasian high latitudes, with stable atmospheric stratification weather conditions. The southwest flow of southern branch trough converges with the southerly flow in the northwest of subtropical high and behind high pressure ridge, and the corresponding low latitude southerly flow provides a favorable moisture condition for the formation of this event. (2) The process of fog is closely related to sea surface temperature, air sea temperature difference, stability of atmosphere, wind and other meteorological or hydrological factors. During the fog process, air sea temperature difference is 0-2℃, inversion and isothermal layers appear from BL to the lower troposphere. There is a 6-8℃ in inversion layer, and vertical temperature increasing by time is greater in the upper level than in the bottom, which causes the inversion layer to strengthen and continue to uplift or reconstruct, and restrains the vertical convection. Air humidity is comparatively large in the near surface layer with a center of 0.6 g·kg-1 in liquid water content around 200 m. And there is 2-4 m·s-1 northeasterly clockwise turning to 6-8 m·s-1 southwesterly below 850 hPa, which provides favorable conditions for the fog. (3) The developed height of turbulence reaches 240 m. The turbulent mixing brings moisture and droplets from upper layer to the surface layer, and contributes to the cooling, which results in the saturation and condensation for the fog event. The warm air in the lower layer is transported to the cold sea surface by the sustained weak and warm advection, which is conducive to the establishment of the inversion. The radiation cooling triggers this fog event.
Using conventional meteorological observations, NCEP reanalysis data (FNL), L band radar data, and applying the multi channel satellite monitoring data from National Satellite Meteorological Centre and qualitatively analyzing the sea fog, this paper discusses the heavy sea fog event during February 22-25, 2010, including the boundary layer (BL) characteristics, formation and disappearance mechanism. The results show that: (1) The fog happens under straight circulation in the Eurasian high latitudes, with stable atmospheric stratification weather conditions. The southwest flow of southern branch trough converges with the southerly flow in the northwest of subtropical high and behind high pressure ridge, and the corresponding low latitude southerly flow provides a favorable moisture condition for the formation of this event. (2) The process of fog is closely related to sea surface temperature, air sea temperature difference, stability of atmosphere, wind and other meteorological or hydrological factors. During the fog process, air sea temperature difference is 0-2℃, inversion and isothermal layers appear from BL to the lower troposphere. There is a 6-8℃ in inversion layer, and vertical temperature increasing by time is greater in the upper level than in the bottom, which causes the inversion layer to strengthen and continue to uplift or reconstruct, and restrains the vertical convection. Air humidity is comparatively large in the near surface layer with a center of 0.6 g·kg-1 in liquid water content around 200 m. And there is 2-4 m·s-1 northeasterly clockwise turning to 6-8 m·s-1 southwesterly below 850 hPa, which provides favorable conditions for the fog. (3) The developed height of turbulence reaches 240 m. The turbulent mixing brings moisture and droplets from upper layer to the surface layer, and contributes to the cooling, which results in the saturation and condensation for the fog event. The warm air in the lower layer is transported to the cold sea surface by the sustained weak and warm advection, which is conducive to the establishment of the inversion. The radiation cooling triggers this fog event.
2014, 40(11):1338-1344.
DOI: 10.7519/j.issn.1000-0526.2014.11.006
Abstract:
In order to study the effect of underlying surface near Bohai Sea on gale, sensitivity experiments of terrain and sea surface with two northeasterly gale cases on 13 and 15 April 2009 were conducted using the WRF (Weather Research and Forecasting) model. The results show that the terrain to the north of Bohai Sea may enhance the wind force over the sea, and gale occurs more easterly and cold air moves more slowly. The dynamic block of the northeastern terrain of Bohai Sea may weaken the wind force over the north Yellow Sea. The bell mouthed terrain to the north of Bohai Sea may enhance the wind force to the northeastern part and weaken the wind force to southwestern part. The sea surface may enhance the wind over the sea to 3-5 m·s-1 in the southern part and 2-3 m·s-1 in the northern part, which causes the “shoreward gale” effect. The stronger the wind, the more obvious the ocean effect. In all, the effect of sea surface is stronger than the effect of terrain.
In order to study the effect of underlying surface near Bohai Sea on gale, sensitivity experiments of terrain and sea surface with two northeasterly gale cases on 13 and 15 April 2009 were conducted using the WRF (Weather Research and Forecasting) model. The results show that the terrain to the north of Bohai Sea may enhance the wind force over the sea, and gale occurs more easterly and cold air moves more slowly. The dynamic block of the northeastern terrain of Bohai Sea may weaken the wind force over the north Yellow Sea. The bell mouthed terrain to the north of Bohai Sea may enhance the wind force to the northeastern part and weaken the wind force to southwestern part. The sea surface may enhance the wind over the sea to 3-5 m·s-1 in the southern part and 2-3 m·s-1 in the northern part, which causes the “shoreward gale” effect. The stronger the wind, the more obvious the ocean effect. In all, the effect of sea surface is stronger than the effect of terrain.
2014, 40(11):1345-1353.
DOI: 10.7519/j.issn.1000-0526.2014.11.007
Abstract:
Based on the dense observation data, NCEP reanalysis and infrared TBB data, the system features and the cause for the rainstorm process on the east side of Ailao Mountain on 15 June 2012 have been diagnostically analyzed. The results show that the shear line at 700 hPa becomes the shear line parallel to Ailao Mountain after it moves to the mountain because of Yunnan Burma ridge and terrain. The surface cold front becomes stationary front after it moves to the east side of Ailao Mountain. At the same time, surface cold air is supplied from north, cold air sinks and warm air increases, so strong ascending motion takes place. The mesoscale convective cloud cluster that forms in the convergent cloud belt near the shear line produces “train effect”, guided by the northwest flow and results in convective rainstorm. The vapor from East China Sea and Bay of Bengal converges at the nearby shear line. Deep moisture convergence layer caused by wind convergence nearby Ailao Mountain is main vapor characteristic in this sudden rainstorms weather. The hourly surface automatic station sea level pressure field and CAPE have significant changes before the occurrence of sudden rainstorm along Ailao Mountain, severe precipitation primarily happens near mesoscale surface warm depression and high value area of CAPE. These results would be indicative to the forecasting and warning of this type short time severe precipitation.
Based on the dense observation data, NCEP reanalysis and infrared TBB data, the system features and the cause for the rainstorm process on the east side of Ailao Mountain on 15 June 2012 have been diagnostically analyzed. The results show that the shear line at 700 hPa becomes the shear line parallel to Ailao Mountain after it moves to the mountain because of Yunnan Burma ridge and terrain. The surface cold front becomes stationary front after it moves to the east side of Ailao Mountain. At the same time, surface cold air is supplied from north, cold air sinks and warm air increases, so strong ascending motion takes place. The mesoscale convective cloud cluster that forms in the convergent cloud belt near the shear line produces “train effect”, guided by the northwest flow and results in convective rainstorm. The vapor from East China Sea and Bay of Bengal converges at the nearby shear line. Deep moisture convergence layer caused by wind convergence nearby Ailao Mountain is main vapor characteristic in this sudden rainstorms weather. The hourly surface automatic station sea level pressure field and CAPE have significant changes before the occurrence of sudden rainstorm along Ailao Mountain, severe precipitation primarily happens near mesoscale surface warm depression and high value area of CAPE. These results would be indicative to the forecasting and warning of this type short time severe precipitation.
2014, 40(11):1354-1362.
DOI: 10.7519/j.issn.1000-0526.2014.11.008
Abstract:
In the premise of supposed disaster standard, the hydrological model is applied to simulating the relations between rainfall and runoff, getting required rainfall for different base water levels that reach disaster standard, and a new method, new ideas for critical area rainfall calculation of small and medium river valleys are discussed. The research takes the Zhanghe Reservoir, Jingmen, Hubei Province as an example, adopts the Xin’anjiang hydrological model, and determines hydrological model parameters through the simulation of historical cases from 1956 to 2012. Based on the simulation result and reservoir flood capacity, the research simulates and calculates the flood critical area rainfall (to reach the critical area rainfall that the flood limit water level needs) under the conditions of different baseline levels, and different rainfall distributions. The results show that it is feasible to use hydrological model to calculate critical area rainfall so that the calculation method of critical area rainfall in small and medium river valleys can be effectively richened.
In the premise of supposed disaster standard, the hydrological model is applied to simulating the relations between rainfall and runoff, getting required rainfall for different base water levels that reach disaster standard, and a new method, new ideas for critical area rainfall calculation of small and medium river valleys are discussed. The research takes the Zhanghe Reservoir, Jingmen, Hubei Province as an example, adopts the Xin’anjiang hydrological model, and determines hydrological model parameters through the simulation of historical cases from 1956 to 2012. Based on the simulation result and reservoir flood capacity, the research simulates and calculates the flood critical area rainfall (to reach the critical area rainfall that the flood limit water level needs) under the conditions of different baseline levels, and different rainfall distributions. The results show that it is feasible to use hydrological model to calculate critical area rainfall so that the calculation method of critical area rainfall in small and medium river valleys can be effectively richened.
9 Sensitivity of CRTM Simulated Microwave Brightness Temperature to Landsurface and Cloud Parameters
2014, 40(11):1363-1371.
DOI: 10.7519/j.issn.1000-0526.2014.11.009
Abstract:
Using rapid radiative transfer model CRTM, the sensitivity of microwave surface emissivity microwave brightness temperature (TB) to landsurface and cloud parameters is analyzed. First, the accurate measured ground and sounding data of Yunnan Simao are used as input of CRTM to simulate 12 microwave channels’ surface emissivity and TB, then the simulated TB is compared with AMSR E satellite TB data, and, moreover, the simulation error and sensitivity to each parameter are analyzed. The results show that soil moisture, surface temperature and vegetation fraction have a great influence on TB simulation, and simulated surface emissivity is affected by soil moisture and vegetation fraction. The influence of precipitation clouds is bigger than non precipitation clouds. Among the 6 kinds of clouds, the rain cloud has the biggest influence. In the clear sky condition, most of the 12 channels’ simulation errors are between 0 to 3 Kelven. Channel 10.65 V is hardly affected by cloud and rain, but it is very sensitive to the landsurface parameters.
Using rapid radiative transfer model CRTM, the sensitivity of microwave surface emissivity microwave brightness temperature (TB) to landsurface and cloud parameters is analyzed. First, the accurate measured ground and sounding data of Yunnan Simao are used as input of CRTM to simulate 12 microwave channels’ surface emissivity and TB, then the simulated TB is compared with AMSR E satellite TB data, and, moreover, the simulation error and sensitivity to each parameter are analyzed. The results show that soil moisture, surface temperature and vegetation fraction have a great influence on TB simulation, and simulated surface emissivity is affected by soil moisture and vegetation fraction. The influence of precipitation clouds is bigger than non precipitation clouds. Among the 6 kinds of clouds, the rain cloud has the biggest influence. In the clear sky condition, most of the 12 channels’ simulation errors are between 0 to 3 Kelven. Channel 10.65 V is hardly affected by cloud and rain, but it is very sensitive to the landsurface parameters.
2014, 40(11):1372-1379.
DOI: 10.7519/j.issn.1000-0526.2014.11.010
Abstract:
The hourly precipitation observation data from 2447 rain gauge records are used to verify and evaluate the satellite precipitation estimation products of Climate Prediction Center Morphing Technique (CMORPH) and Tropical Rainfall Measuring Mission (TRMM) 3B42 during 2007-2010 in China. The results show that the two satellite precipitation data are similar to ground gain gauge data in revealing the spatial patterns of daily mean precipitation amount. The pattern correlation coefficients of 3 h rainfall amount are over 0.5 and 0.4 in most areas, respectively. Bias of two satellite precipitation products are both between the positive and negative 0.25 mm, but there are significant difference between the north and the south. And the mean absolute error, relative error and root mean square error all have a significant seasonal periodic variations. The two satellite precipitation products can reflect the summer rainfall diurnal variation well in most parts of China, but there are also clear distinctions in some areas. The overall vacancy retrieval rate of CMORPH and TRMM 3B42 products are 7.23% and 2.63%, overall missing retrieval rate are 3.25% and 5.5%, respectively.
The hourly precipitation observation data from 2447 rain gauge records are used to verify and evaluate the satellite precipitation estimation products of Climate Prediction Center Morphing Technique (CMORPH) and Tropical Rainfall Measuring Mission (TRMM) 3B42 during 2007-2010 in China. The results show that the two satellite precipitation data are similar to ground gain gauge data in revealing the spatial patterns of daily mean precipitation amount. The pattern correlation coefficients of 3 h rainfall amount are over 0.5 and 0.4 in most areas, respectively. Bias of two satellite precipitation products are both between the positive and negative 0.25 mm, but there are significant difference between the north and the south. And the mean absolute error, relative error and root mean square error all have a significant seasonal periodic variations. The two satellite precipitation products can reflect the summer rainfall diurnal variation well in most parts of China, but there are also clear distinctions in some areas. The overall vacancy retrieval rate of CMORPH and TRMM 3B42 products are 7.23% and 2.63%, overall missing retrieval rate are 3.25% and 5.5%, respectively.
2014, 40(11):1380-1388.
DOI: 10.7519/j.issn.1000-0526.2014.11.011
Abstract:
Based on the CIND3830 CC weather radar data and surface observational data in Puer City, this study reports the statistical characteristics of 27 times of three body scatter Spike (TBSS) in C band weather radar from 2004-2013, the corresponding relation between hails shooting on the ground and TBSS as well as the application of TBSS in hailstorm warning. The results are as follows: (1) The reflectivity range of TBSS echo is 55.0-68.4 dBz, and 70% TBSS appears when reflectivity factor is ≥ 60 dBz. (2) TBSS maintaining time is 10-79 min, and 63% is above 20 min. (3) TBSS usually happens in the height of 4.0-9.5 km, and the minimum/maximum height is 2.6 km/11.4 km. (4) TBSS is 5.6-22.4 km in length, and 1.5-14.6 km in width. The width of TBSS is proportional to the area of echo (at least 60 dBz) along the radially lateral direction, but the length does not have clear correspondence with the reflectivity factor. (5) Hailstorm weather happens in the case of 59% echoes with the occurrence of TBSS. The severe hail appears in 11% of the radar echo. (6) Hailstorm forecasting time by TBSS is 5-100 min in advance, 34.5 min on average when TBSS and hailstorm appear together. (7) When TBSS and hailstorm both happen, the width of TBSS is proportional to the size or density of hailstorm. Furthermore, the reason that TBSS appears but hailstorm does not come down simultaneously is discussed, and the forecasting hailstorm methods, with the accuracy of 89% and 94% respectively, are also found out by using TBSS combining DVIL and 45 dBz strong echo height or TBSS combining echo breadth and 45 dBz strong echo height (Critical Success Index are 0.89 and 0.94).
Based on the CIND3830 CC weather radar data and surface observational data in Puer City, this study reports the statistical characteristics of 27 times of three body scatter Spike (TBSS) in C band weather radar from 2004-2013, the corresponding relation between hails shooting on the ground and TBSS as well as the application of TBSS in hailstorm warning. The results are as follows: (1) The reflectivity range of TBSS echo is 55.0-68.4 dBz, and 70% TBSS appears when reflectivity factor is ≥ 60 dBz. (2) TBSS maintaining time is 10-79 min, and 63% is above 20 min. (3) TBSS usually happens in the height of 4.0-9.5 km, and the minimum/maximum height is 2.6 km/11.4 km. (4) TBSS is 5.6-22.4 km in length, and 1.5-14.6 km in width. The width of TBSS is proportional to the area of echo (at least 60 dBz) along the radially lateral direction, but the length does not have clear correspondence with the reflectivity factor. (5) Hailstorm weather happens in the case of 59% echoes with the occurrence of TBSS. The severe hail appears in 11% of the radar echo. (6) Hailstorm forecasting time by TBSS is 5-100 min in advance, 34.5 min on average when TBSS and hailstorm appear together. (7) When TBSS and hailstorm both happen, the width of TBSS is proportional to the size or density of hailstorm. Furthermore, the reason that TBSS appears but hailstorm does not come down simultaneously is discussed, and the forecasting hailstorm methods, with the accuracy of 89% and 94% respectively, are also found out by using TBSS combining DVIL and 45 dBz strong echo height or TBSS combining echo breadth and 45 dBz strong echo height (Critical Success Index are 0.89 and 0.94).
2014, 40(11):1389-1397.
DOI: 10.7519/j.issn.1000-0526.2014.11.012
Abstract:
Based on automatic identification and tracking MCSs (mesoscale convective systems), long axis of MCSs was used to design dynamic templet and score function in order to complete the algorithm for automatically identifying linear MCSs. The performance of the algorithm is evaluated by applying in several different types of convection cases. The results demonstrate that the algorithm can automatically identify linear MCSs and behave well, even the convective system change rapidly as a result of splitting or merging. The algorithm can track linear MCSs system normally well, but when splitting or merging occurs it can not do so well.
Based on automatic identification and tracking MCSs (mesoscale convective systems), long axis of MCSs was used to design dynamic templet and score function in order to complete the algorithm for automatically identifying linear MCSs. The performance of the algorithm is evaluated by applying in several different types of convection cases. The results demonstrate that the algorithm can automatically identify linear MCSs and behave well, even the convective system change rapidly as a result of splitting or merging. The algorithm can track linear MCSs system normally well, but when splitting or merging occurs it can not do so well.
2014, 40(11):1398-1407.
DOI: 10.7519/j.issn.1000-0526.2014.11.013
Abstract:
Under the situation of growing water shortage, determining the optimum irrigation period and the best irrigation quantity of winter wheat is an important issue that needs immediate solution in Baoding, Hebei Province. In order to determine the optimal irrigation quantity and irrigation time, this paper using WOFOST model to simulate the winter wheat in Baoding Area. In this paper the Baoding Station is selected as a representative station. During the different rainfall year types in 2003/2004, 2005/2006 and 2008/2009, the different irrigation plans and quantities are simulated, including irrigating once, twice and three times, to reveal the correlation between the yield under water stress and irrigation time. The simulation results show that optimal irrigation time in the whole winter wheat growth process is the period of booting stage and heading to filling stage. During these periods, irrigation can achieve the most obvious effect, and have the highest contribution to wheat yield. Besides, the best plan of irrigating twice and three times to meet the winter wheat growth is given out, which might help obtain greater economic benefits at the same time.
Under the situation of growing water shortage, determining the optimum irrigation period and the best irrigation quantity of winter wheat is an important issue that needs immediate solution in Baoding, Hebei Province. In order to determine the optimal irrigation quantity and irrigation time, this paper using WOFOST model to simulate the winter wheat in Baoding Area. In this paper the Baoding Station is selected as a representative station. During the different rainfall year types in 2003/2004, 2005/2006 and 2008/2009, the different irrigation plans and quantities are simulated, including irrigating once, twice and three times, to reveal the correlation between the yield under water stress and irrigation time. The simulation results show that optimal irrigation time in the whole winter wheat growth process is the period of booting stage and heading to filling stage. During these periods, irrigation can achieve the most obvious effect, and have the highest contribution to wheat yield. Besides, the best plan of irrigating twice and three times to meet the winter wheat growth is given out, which might help obtain greater economic benefits at the same time.
2014, 40(11):1408-1413.
DOI: 10.7519/j.issn.1000-0526.2014.11.014
Abstract:
Thunderstorm gale is one of the main threats to aviation flight. It is a far more difficult challenge to forecast the thunderstorm gale accurately. The WINDEX empirical equation proposed by McCann is applied to the Capital Airport. Using 54511 sounding data from 2006 to 2010, the WI values are calculated and compared to strong gusts triggered by thunderstorm at the Capital Airport. Finally the forecast process of strong gusts is established.
Thunderstorm gale is one of the main threats to aviation flight. It is a far more difficult challenge to forecast the thunderstorm gale accurately. The WINDEX empirical equation proposed by McCann is applied to the Capital Airport. Using 54511 sounding data from 2006 to 2010, the WI values are calculated and compared to strong gusts triggered by thunderstorm at the Capital Airport. Finally the forecast process of strong gusts is established.
2014, 40(11):1414-1421.
DOI: 10.7519/j.issn.1000-0526.2014.11.015
Abstract:
The performances of medium range forecasts are verified and compared for the T639, ECMWF and JP models from June to August 2014. The result shows that the three models have good performance on predicting the variation and adjustment of the atmospheric circulation and 850 hPa temperature over Asian middle and high latitude areas. In contract, ECMWF model has better performance than T639 or JP models. Both ECMWF and T639 models have good performance on predicting western Pacific subtropical high while they still have some bias at some time. T639 model is the best at the prediction of the track and intensity of typhoon Rammasun among all three models, and the forecasting intensity of ECMWF model is weaker than that of the observation.
The performances of medium range forecasts are verified and compared for the T639, ECMWF and JP models from June to August 2014. The result shows that the three models have good performance on predicting the variation and adjustment of the atmospheric circulation and 850 hPa temperature over Asian middle and high latitude areas. In contract, ECMWF model has better performance than T639 or JP models. Both ECMWF and T639 models have good performance on predicting western Pacific subtropical high while they still have some bias at some time. T639 model is the best at the prediction of the track and intensity of typhoon Rammasun among all three models, and the forecasting intensity of ECMWF model is weaker than that of the observation.
2014, 40(11):1422-1428.
DOI: 10.7519/j.issn.1000-0526.2014.11.016
Abstract:
The main characteristics of the general circulation in August 2014 are listed as follows: There are two polar vortex centers in the Northern Hemisphere. In the middle high latitudes, the circulation presents a four wave pattern. The subtropical high lies southwards and is stronger than its climatological mean. Meanwhile, monthly mean precipitation amount is 104.4 mm, which is 0.9% less than its climatological mean (105.3 mm). Monthly mean temperature over China is 20.6℃, which is a little lower than its climatological mean (20.8℃). There are 8 severe rainfall events with extreme daily precipitation records observed at some stations in China. No typhoon forms over the northwestern Pacific Ocean and the South China Sea in August, which happens firstly since 1949. The only active typhoon is No.1314 Genevieve, which comes from the eastern Pacific. Some low temperature and sunlight lack events happen in the middle and lower reaches of Yangtze River region.
The main characteristics of the general circulation in August 2014 are listed as follows: There are two polar vortex centers in the Northern Hemisphere. In the middle high latitudes, the circulation presents a four wave pattern. The subtropical high lies southwards and is stronger than its climatological mean. Meanwhile, monthly mean precipitation amount is 104.4 mm, which is 0.9% less than its climatological mean (105.3 mm). Monthly mean temperature over China is 20.6℃, which is a little lower than its climatological mean (20.8℃). There are 8 severe rainfall events with extreme daily precipitation records observed at some stations in China. No typhoon forms over the northwestern Pacific Ocean and the South China Sea in August, which happens firstly since 1949. The only active typhoon is No.1314 Genevieve, which comes from the eastern Pacific. Some low temperature and sunlight lack events happen in the middle and lower reaches of Yangtze River region.
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ISSN:1000-0526 CN:11-2282/P