ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 39,Issue 11,2013 Table of Contents
2013, 39(11):1385-1392.
DOI: 10.7519/j.issn.1000-0526.2013.11.001
Abstract:
Cold vortex is identified based on the definition of cold vortex, and 60 cold vortexes are identified in 2005-2011, formed mainly in the northeastern region of China and Mongolia. According to the size, the mesoscale convective system (MCS) is classified into meso α scale convective system (MαCS) and meso β scale convective system (MβCS). Then, MαCS is classified into mesoscale convective complex (MCC) and persistent elongated convective system (PECS), while MβCS into meso β scale convective complex (MβCC) and meso β elongated convective system (MβECS). Based on the FY 2 geostationary satellite infrared images the MCS is identified and its spatial temporal features and its relationship with the 60 cold vortexes are analyzed. The result reveals: (1) 61 MCSs are identified; MCS usually appears in Northeast China and North China; MCC and PECS are generated more decentralized. MβCC mainly concentrates in Northeast China and North China and MβECS mainly in Northeast China. (2) MCS in June is the most and in September the least. Most MCSs are produced in the afternoon and dusk when the convection is prosperous and conducive to production of MCS. MCS gets matured at night and dissipates in the early morning. (3) Most MCSs move from west to east, consistent with the motion of westerlies weather system in middle latitude in China. However due to the impact of cold vortex and other weather systems, there exist different moving paths. The MCS located in the east of cold vortex and near the cold vortex center has the trend of moving easterly and northerly; the MCS in the south of cold vortex and far from the cold vortex center has the trend of moving east southeast. (4) Most MCSs are generated in the developly stage of cold vortex. (5) MCS is mainly produced in the southeast of cold vortex. (6) MβCSs develop faster than MαCSs, and the lasting time is shorter than MαCSs.
Cold vortex is identified based on the definition of cold vortex, and 60 cold vortexes are identified in 2005-2011, formed mainly in the northeastern region of China and Mongolia. According to the size, the mesoscale convective system (MCS) is classified into meso α scale convective system (MαCS) and meso β scale convective system (MβCS). Then, MαCS is classified into mesoscale convective complex (MCC) and persistent elongated convective system (PECS), while MβCS into meso β scale convective complex (MβCC) and meso β elongated convective system (MβECS). Based on the FY 2 geostationary satellite infrared images the MCS is identified and its spatial temporal features and its relationship with the 60 cold vortexes are analyzed. The result reveals: (1) 61 MCSs are identified; MCS usually appears in Northeast China and North China; MCC and PECS are generated more decentralized. MβCC mainly concentrates in Northeast China and North China and MβECS mainly in Northeast China. (2) MCS in June is the most and in September the least. Most MCSs are produced in the afternoon and dusk when the convection is prosperous and conducive to production of MCS. MCS gets matured at night and dissipates in the early morning. (3) Most MCSs move from west to east, consistent with the motion of westerlies weather system in middle latitude in China. However due to the impact of cold vortex and other weather systems, there exist different moving paths. The MCS located in the east of cold vortex and near the cold vortex center has the trend of moving easterly and northerly; the MCS in the south of cold vortex and far from the cold vortex center has the trend of moving east southeast. (4) Most MCSs are generated in the developly stage of cold vortex. (5) MCS is mainly produced in the southeast of cold vortex. (6) MβCSs develop faster than MαCSs, and the lasting time is shorter than MαCSs.
2 Numerical Simulation Analysis on Dynamic Effect of Taishan Mountain Terrain on Local Severe Rainfall
2013, 39(11):1393-1401.
DOI: 10.7519/j.issn.1000-0526.2013.11.002
Abstract:
An extremely heavy rainfall event (435 mm/7 h) that happened in Guolou Town behind the leeward slope of Taishan Mountain on September 2, 2005 is simulated and analyzed by using WRF mesoscale numerical model data and the Jinan SA radar data, and sensitivity tests are carried out to study the influence of the terrain of Taishan Mountain in central Shandong Province on the dynamic process of atmosphere in mid low troposphere. The results show that because of the effect of Taishan Mountain, the northeast airflow becomes circum mountain airflow in the horizontal direction, and is lifted in the vertical direction. The quasi permanent convergence zone of the circum mountain flow and gravity wave disturbance zone are formed near the torrential rain area in the lee side of Taishan Mountain and triggers the severe convection together with the convergence zone of weather system, driving the severe convective system into this area intensify and maintain. If the terrain was changed, the wind field and divergence field in low level could get weakened, affecting the location and the intensity of the extremely severe precipitation, but not having distinct impact on the distribution of the main rain belt.
An extremely heavy rainfall event (435 mm/7 h) that happened in Guolou Town behind the leeward slope of Taishan Mountain on September 2, 2005 is simulated and analyzed by using WRF mesoscale numerical model data and the Jinan SA radar data, and sensitivity tests are carried out to study the influence of the terrain of Taishan Mountain in central Shandong Province on the dynamic process of atmosphere in mid low troposphere. The results show that because of the effect of Taishan Mountain, the northeast airflow becomes circum mountain airflow in the horizontal direction, and is lifted in the vertical direction. The quasi permanent convergence zone of the circum mountain flow and gravity wave disturbance zone are formed near the torrential rain area in the lee side of Taishan Mountain and triggers the severe convection together with the convergence zone of weather system, driving the severe convective system into this area intensify and maintain. If the terrain was changed, the wind field and divergence field in low level could get weakened, affecting the location and the intensity of the extremely severe precipitation, but not having distinct impact on the distribution of the main rain belt.
2013, 39(11):1402-1412.
DOI: 10.7519/j.issn.1000-0526.2013.11.003
Abstract:
Based on conventional observation data, satellite cloud imagery, radar detection data and the rainfall data of automatic weather stations etc., comparative analysis on the meteorological conditions for the two severe mountain torrent geological hazards occurred during 27-28 June 2010 and 20-22 May 2012 in northwest Guangxi was done. The results showed that: (1) The torrential rainfall occurs in the northwest of Guangxi with a maximum precipitation >350 mm. The maximum precipitation of mesoscale rain clusters is larger than >100 mm·h-1 in the processes and over 70 mm·h-1 in the hazard areas. The concentrated rainfall period is in 02:00-06:00 BT. The disasters begin in the late night, and occur in the area with maximum precipitation and fragile geological conditions, where different geological conditions correspond to different disasters. The severe weather has characteristics with small range, concentrated rainfall periods, intensity rainfall and triggers serious disasters. (2) The heavy rainfall is caused by circulation background with two ridges and one trough at 500 hPa in Eurasian Region and ridge line of South Asia high throughout Guangxi over at 200 hPa accompanied with active monsoon cloud system. The weather systems with upper trough or vortex and surface dry line or frontal indicate a vortex type storm. (3) The variation of upper air elements is the temperature decreases before the rainfall but rises after it. Unstable energy and stratification, low level convergence, middle and low level vortex, ascending motion of the whole atmosphere layer, high temperature and humidity, and strong convergence of water vapor are characteristics of the physical quantities. (4) Generation and mergence of convective cloud clusters on the satellite cloud images have implications to heavy rainfall. The rainstorm occurs in the developing stage of the clouds, and the TBB value less than 200 K can be used as an indicator to the severe precipitation. Train effect produced by low centroid of radar echoes and the effect of topography are important factors for the heavy rainfall. Strong vertical motion due to low level convergence and upper level divergence is conducive to the development and maintenance of the severe convection.
Based on conventional observation data, satellite cloud imagery, radar detection data and the rainfall data of automatic weather stations etc., comparative analysis on the meteorological conditions for the two severe mountain torrent geological hazards occurred during 27-28 June 2010 and 20-22 May 2012 in northwest Guangxi was done. The results showed that: (1) The torrential rainfall occurs in the northwest of Guangxi with a maximum precipitation >350 mm. The maximum precipitation of mesoscale rain clusters is larger than >100 mm·h-1 in the processes and over 70 mm·h-1 in the hazard areas. The concentrated rainfall period is in 02:00-06:00 BT. The disasters begin in the late night, and occur in the area with maximum precipitation and fragile geological conditions, where different geological conditions correspond to different disasters. The severe weather has characteristics with small range, concentrated rainfall periods, intensity rainfall and triggers serious disasters. (2) The heavy rainfall is caused by circulation background with two ridges and one trough at 500 hPa in Eurasian Region and ridge line of South Asia high throughout Guangxi over at 200 hPa accompanied with active monsoon cloud system. The weather systems with upper trough or vortex and surface dry line or frontal indicate a vortex type storm. (3) The variation of upper air elements is the temperature decreases before the rainfall but rises after it. Unstable energy and stratification, low level convergence, middle and low level vortex, ascending motion of the whole atmosphere layer, high temperature and humidity, and strong convergence of water vapor are characteristics of the physical quantities. (4) Generation and mergence of convective cloud clusters on the satellite cloud images have implications to heavy rainfall. The rainstorm occurs in the developing stage of the clouds, and the TBB value less than 200 K can be used as an indicator to the severe precipitation. Train effect produced by low centroid of radar echoes and the effect of topography are important factors for the heavy rainfall. Strong vertical motion due to low level convergence and upper level divergence is conducive to the development and maintenance of the severe convection.
2013, 39(11):1413-1421.
DOI: 10.7519/j.issn.1000-0526.2013.11.004
Abstract:
This paper has a comprehensive review on researches of the sensitivity of atmosphere to the surface properties and the impact of land atmosphere interaction on the process of mesoscale systems demonstrating the links between surface properties and cumulus convective rainfall. Changes in surface properties influence the heat flux, moisture flux and the convective available potential energy within the planetary boundary layer and the nature of atmosphere is affected through the turbulent vertical transportation. The interaction between the land and atmosphere is very complex and nonlinear. The difference of sensible heat flux and latent heat flux in the atmosphere caused by heterogeneous underlying surface can generate the pressure and temperature gradient and local circulation which can initiate convection and precipitation in suitable conditions. And the heterogeneous distribution of precipitation can in turn aggravate the heterogeneity of the underlying surface. The influence of soil moisture on convection is restricted by various factors including the significant influence of synoptic scale process. The cumulus convection can be triggered by the local circulation which is generated by the inhomogeneous underlying surface.
This paper has a comprehensive review on researches of the sensitivity of atmosphere to the surface properties and the impact of land atmosphere interaction on the process of mesoscale systems demonstrating the links between surface properties and cumulus convective rainfall. Changes in surface properties influence the heat flux, moisture flux and the convective available potential energy within the planetary boundary layer and the nature of atmosphere is affected through the turbulent vertical transportation. The interaction between the land and atmosphere is very complex and nonlinear. The difference of sensible heat flux and latent heat flux in the atmosphere caused by heterogeneous underlying surface can generate the pressure and temperature gradient and local circulation which can initiate convection and precipitation in suitable conditions. And the heterogeneous distribution of precipitation can in turn aggravate the heterogeneity of the underlying surface. The influence of soil moisture on convection is restricted by various factors including the significant influence of synoptic scale process. The cumulus convection can be triggered by the local circulation which is generated by the inhomogeneous underlying surface.
2013, 39(11):1422-1430.
DOI: 10.7519/j.issn.1000-0526.2013.11.005
Abstract:
Using the data obtained by conventional observations, the data collected at a 255 m tower during an atmospheric boundary layer experiment in Tianjin, Doppler radar observations, VDRAS data and mesoscale TJ WRF model data, we analyze the heavy rainfall which occurred on 16 August 2010 in the urban area of Tianjin and highlight the superimposition of urban heat island and sea breeze front and trigger mechanism of local heavy precipitation caused by it. The results show that the local severe precipitation occurs under weak anti circulation conditions after low level trough, and precipitation has obvious characteristics of meso γ scale convection. Urban heat island effect can cause uneven distribution of local thermal, which is very favorable for the formation of the ground mesoscale convergence line. When moving from the shore to the urban, the sea breeze front encounters the ground mesoscale convergence line, being able to stimulate the local unstable energy release and resulting in severe convective weather. Urban heat island can block the movement of the sea breeze front. When the sea breeze front moves near the area with obvious urban heat island effect its rear airflow will be changed into branch flows, climbing. Meanwhile in the meeting place, the convergence and upward motion get strengthened rapidly, providing favorable dynamic and thermodynamic conditions for unstable energy to release and thunderstorm to develop. The mesoscale TJ WRF model can simulate this phenomenon very well.
Using the data obtained by conventional observations, the data collected at a 255 m tower during an atmospheric boundary layer experiment in Tianjin, Doppler radar observations, VDRAS data and mesoscale TJ WRF model data, we analyze the heavy rainfall which occurred on 16 August 2010 in the urban area of Tianjin and highlight the superimposition of urban heat island and sea breeze front and trigger mechanism of local heavy precipitation caused by it. The results show that the local severe precipitation occurs under weak anti circulation conditions after low level trough, and precipitation has obvious characteristics of meso γ scale convection. Urban heat island effect can cause uneven distribution of local thermal, which is very favorable for the formation of the ground mesoscale convergence line. When moving from the shore to the urban, the sea breeze front encounters the ground mesoscale convergence line, being able to stimulate the local unstable energy release and resulting in severe convective weather. Urban heat island can block the movement of the sea breeze front. When the sea breeze front moves near the area with obvious urban heat island effect its rear airflow will be changed into branch flows, climbing. Meanwhile in the meeting place, the convergence and upward motion get strengthened rapidly, providing favorable dynamic and thermodynamic conditions for unstable energy to release and thunderstorm to develop. The mesoscale TJ WRF model can simulate this phenomenon very well.
2013, 39(11):1431-1436.
DOI: 10.7519/j.issn.1000-0526.2013.11.006
Abstract:
To study the role of wind profiler radar (WPR) in the forecasting of typhoon process, this paper statistically analyzed the radar detection data of typhoon Saola when it landed Qinyu Town, Fujian Province during 2-4 August 2012. The results show that there is a significant improvement in data acquisition rate in the high level above 4 km by WPR during the landing process of typhoon Saola and the effective detection height of WPR is 4.8 km. Statistical analysis of SNR (signal to noise ratio) and vertical velocity data show that the typhoon Saola brings intermittent rain before and after the landfall, and the landfall of typhoon eye produces little or no rain. This result is further verified in the hourly precipitation analysis. Statistical analysis of horizontal wind speed data shows that the horizontal wind speed in effective detection height is about 25 m·s-1 before and after the landfall of the typhoon, while the horizontal wind speed of the typhoon eye is about 0 to 3 m·s-1 over the landing period. This statistical result is consistent with the physical process of typhoon Saola landing.
To study the role of wind profiler radar (WPR) in the forecasting of typhoon process, this paper statistically analyzed the radar detection data of typhoon Saola when it landed Qinyu Town, Fujian Province during 2-4 August 2012. The results show that there is a significant improvement in data acquisition rate in the high level above 4 km by WPR during the landing process of typhoon Saola and the effective detection height of WPR is 4.8 km. Statistical analysis of SNR (signal to noise ratio) and vertical velocity data show that the typhoon Saola brings intermittent rain before and after the landfall, and the landfall of typhoon eye produces little or no rain. This result is further verified in the hourly precipitation analysis. Statistical analysis of horizontal wind speed data shows that the horizontal wind speed in effective detection height is about 25 m·s-1 before and after the landfall of the typhoon, while the horizontal wind speed of the typhoon eye is about 0 to 3 m·s-1 over the landing period. This statistical result is consistent with the physical process of typhoon Saola landing.
2013, 39(11):1437-1444.
DOI: 10.7519/j.issn.1000-0526.2013.11.007
Abstract:
The measurements of solar radiation and meteorology were carried out at Yucheng and Luancheng Stations in North China during 2005-2006. Based on the analysis on the observation data, an energy relation between internal energy of the atmosphere and the surface solar global radiation, the absorption of atmospheric substances, the scattering of substances, the moving energy of atmosphere, the net radiation is developed. The variation of “monthly mean” of surface air temperature at 2 stations is simulated by using the empirical model, the maximum and minimum biases between the calculated and observed surface air temperature are 3.84 and -4.05℃ for “monthly mean”, respectively, and less than 0.36℃ for “annual mean”. The sensitivity calculation shows that the surface air temperature is most sensitive to the variation of net radiation, then to the changes of the scattering of substances, the absorption of atmospheric substances, the moving energy of atmosphere and solar global radiation. The increase of 5% contributed by individual factor, net radiation, the scattering of substances, the absorption of the atmospheric substances, the moving energy of the atmosphere, solar global radiation can cause the changes of surface air temperature by 0.93, -0.40, 0.23, -0.20, -0.12℃, respectively. To study the change of surface air temperature, it is necessary to consider the roles of greenhouse gases (such as CO2, water vapor, and O3). Meanwhile, it is also important to consider the absorption of other substances, the scattering of substances (in gases, liquid and particle phases), the changes of the compositions and characteristics of the Earth’s surface, the changes of surface wind velocity, and solar global radiation, especially the net radiation.
The measurements of solar radiation and meteorology were carried out at Yucheng and Luancheng Stations in North China during 2005-2006. Based on the analysis on the observation data, an energy relation between internal energy of the atmosphere and the surface solar global radiation, the absorption of atmospheric substances, the scattering of substances, the moving energy of atmosphere, the net radiation is developed. The variation of “monthly mean” of surface air temperature at 2 stations is simulated by using the empirical model, the maximum and minimum biases between the calculated and observed surface air temperature are 3.84 and -4.05℃ for “monthly mean”, respectively, and less than 0.36℃ for “annual mean”. The sensitivity calculation shows that the surface air temperature is most sensitive to the variation of net radiation, then to the changes of the scattering of substances, the absorption of atmospheric substances, the moving energy of atmosphere and solar global radiation. The increase of 5% contributed by individual factor, net radiation, the scattering of substances, the absorption of the atmospheric substances, the moving energy of the atmosphere, solar global radiation can cause the changes of surface air temperature by 0.93, -0.40, 0.23, -0.20, -0.12℃, respectively. To study the change of surface air temperature, it is necessary to consider the roles of greenhouse gases (such as CO2, water vapor, and O3). Meanwhile, it is also important to consider the absorption of other substances, the scattering of substances (in gases, liquid and particle phases), the changes of the compositions and characteristics of the Earth’s surface, the changes of surface wind velocity, and solar global radiation, especially the net radiation.
2013, 39(11):1445-1451.
DOI: 10.7519/j.issn.1000-0526.2013.11.008
Abstract:
Because of the influence of Taihang Mountain topography, there is steady wind direction convergence in lower layer in the south central region of Hebei Province, and the local convective weather often occurs near the surface convergence line (SCL). Based on the dense surface observational data from May to September in 2007 and 2008, the relation between evolution characteristics of hourly SCL and local convective rainfall is analyzed. The results show that the SCL gradually expands along the Taihang Mountain after it emerges at dusk in the southwest of Baoding, slowly moving from west towards east with intensity steadily strengthened. In the early morning the next day a cyclonic circulation is almost shaped. The SCLs are classified into 7 types according to the wind fields at the hour with strongest rainfall in each process. Generally, the SCL caused simply by topography cannot generate rainfall, and the intensity is small even if rain falls. That is to say, the SCL caused by topography generally does not produce convective weather, but will result in severe convective weather on the advantageous condition of weather system. By analyzing the daily SCL in the cases of a cold eddy weather system in the last ten days of June 2008, it is indicated that the convective weather first appears, near the convergence line no matter what type of SCL is generated. The time, location and intensity of convective weather can be qualitatively determined according to the evolution of hourly wind and temperature fields under the large scale atmospheric circulation.
Because of the influence of Taihang Mountain topography, there is steady wind direction convergence in lower layer in the south central region of Hebei Province, and the local convective weather often occurs near the surface convergence line (SCL). Based on the dense surface observational data from May to September in 2007 and 2008, the relation between evolution characteristics of hourly SCL and local convective rainfall is analyzed. The results show that the SCL gradually expands along the Taihang Mountain after it emerges at dusk in the southwest of Baoding, slowly moving from west towards east with intensity steadily strengthened. In the early morning the next day a cyclonic circulation is almost shaped. The SCLs are classified into 7 types according to the wind fields at the hour with strongest rainfall in each process. Generally, the SCL caused simply by topography cannot generate rainfall, and the intensity is small even if rain falls. That is to say, the SCL caused by topography generally does not produce convective weather, but will result in severe convective weather on the advantageous condition of weather system. By analyzing the daily SCL in the cases of a cold eddy weather system in the last ten days of June 2008, it is indicated that the convective weather first appears, near the convergence line no matter what type of SCL is generated. The time, location and intensity of convective weather can be qualitatively determined according to the evolution of hourly wind and temperature fields under the large scale atmospheric circulation.
2013, 39(11):1452-1460.
DOI: 10.7519/j.issn.1000-0526.2013.11.009
Abstract:
The average frequency, characteristics of circadian distribution, representative weather events of 34 kinds of weather phenomena and the observed weather phenomena at regional representative stations are analyzed by using the observation data from 576 stations during 1961-2010. The results show that rain, dew, freezing, shower, mist and frost have higher annual average frequency, while polar lights, tornado and snowstorm etc. do not occur very often. In recent years, the occurrence of fog is in a slowly decreasing trend but mist increases gradually. Haze has become more since 2000 and the hit area is enlarged more and more. The occurrence of weather events has regional characteristics, but the top 20 types in different areas are similar, only the rank of the frequency is different.
The average frequency, characteristics of circadian distribution, representative weather events of 34 kinds of weather phenomena and the observed weather phenomena at regional representative stations are analyzed by using the observation data from 576 stations during 1961-2010. The results show that rain, dew, freezing, shower, mist and frost have higher annual average frequency, while polar lights, tornado and snowstorm etc. do not occur very often. In recent years, the occurrence of fog is in a slowly decreasing trend but mist increases gradually. Haze has become more since 2000 and the hit area is enlarged more and more. The occurrence of weather events has regional characteristics, but the top 20 types in different areas are similar, only the rank of the frequency is different.
2013, 39(11):1461-1472.
DOI: 10.7519/j.issn.1000-0526.2013.11.010
Abstract:
All the time, because of the limits of observation operator in assimilation system, microwave observation over cloud area from satellite is often made clear hypothesis, which usually brings an overestimated content of atmospheric moisture. To overcome that, this paper designs a scheme to run RTTOV microwave scattering module in WRF 3DVAR for taking the information of atmospheric hydrometeors into assimilating calculation. On this basis, four groups of assimilation contrast tests are carried out for brightness temperature of FY3 A meteorological satellite microwave humidity sounder and reflectivity of Doppler radar. The results show that the introduction of RTTOV microwave scattering module can effectively suppress the overestimate of atmospheric water vapor content. When radar reflectivity factor is assimilated before satellite data, atmospheric hydrometeors content is increased significantly in this region. As a result, the scattering effects is increased too. With the area coverage of radar data assimilation increasing, precipitation forecast effect is improved more and more obviously.
All the time, because of the limits of observation operator in assimilation system, microwave observation over cloud area from satellite is often made clear hypothesis, which usually brings an overestimated content of atmospheric moisture. To overcome that, this paper designs a scheme to run RTTOV microwave scattering module in WRF 3DVAR for taking the information of atmospheric hydrometeors into assimilating calculation. On this basis, four groups of assimilation contrast tests are carried out for brightness temperature of FY3 A meteorological satellite microwave humidity sounder and reflectivity of Doppler radar. The results show that the introduction of RTTOV microwave scattering module can effectively suppress the overestimate of atmospheric water vapor content. When radar reflectivity factor is assimilated before satellite data, atmospheric hydrometeors content is increased significantly in this region. As a result, the scattering effects is increased too. With the area coverage of radar data assimilation increasing, precipitation forecast effect is improved more and more obviously.
2013, 39(11):1473-1480.
DOI: 10.7519/j.issn.1000-0526.2013.11.011
Abstract:
Based on the conventional observational data, satellite remote sensing data, main pollutants monitoring data and NCEP/NCAR reanalysis data, together with the airflow backward trajectory simulation method, comparative analysis is conducted on the atmospheric conditions, planetary boundary layer features, air pollutant sources and transport paths of the two serious air pollution events which respectively took place on 10 and 13 June 2011. The results show that the concentrations of PM2.5 display a more significant peak valley variation during the two air pollution events, which result from crop residue burning. The event seen on 13 June has a longer duration and a stronger intensity than the event on 10 June. The weather situation and the physical quantity field of the event on 10 June are favourable for the rainfall, which plays a role in flushing the pollutants. However, the weather conditions on 13 June are conducive to accumulation of pollutants. Both of the boundary inversion layers are not obvious. Air mass backward trajectory simulation show that two air pollution events are caused by the transport of regional pollution due to crop residue burning in the central and north parts of Jiangsu Province. Moreover, the pollution sources for the event on 13 June probably include the south part of Jiangsu Province and part of Anhui Province additional as well.
Based on the conventional observational data, satellite remote sensing data, main pollutants monitoring data and NCEP/NCAR reanalysis data, together with the airflow backward trajectory simulation method, comparative analysis is conducted on the atmospheric conditions, planetary boundary layer features, air pollutant sources and transport paths of the two serious air pollution events which respectively took place on 10 and 13 June 2011. The results show that the concentrations of PM2.5 display a more significant peak valley variation during the two air pollution events, which result from crop residue burning. The event seen on 13 June has a longer duration and a stronger intensity than the event on 10 June. The weather situation and the physical quantity field of the event on 10 June are favourable for the rainfall, which plays a role in flushing the pollutants. However, the weather conditions on 13 June are conducive to accumulation of pollutants. Both of the boundary inversion layers are not obvious. Air mass backward trajectory simulation show that two air pollution events are caused by the transport of regional pollution due to crop residue burning in the central and north parts of Jiangsu Province. Moreover, the pollution sources for the event on 13 June probably include the south part of Jiangsu Province and part of Anhui Province additional as well.
2013, 39(11):1481-1489.
DOI: 10.7519/j.issn.1000-0526.2013.11.012
Abstract:
In order to analyze the influence of soil moisture on the simulation of precipitation in the WRFV3.3.1 mode, we use the soil moisture output from the China Land Soil Moisture Data Assimilaton System (CLSMDAS) to replace the soil moisture in the WRF initial field, on the basis of comparative analysis of four land surface process schemes, the heavy precipitation which occurred in Jiangxi Province on 19 June 2010 was simulated to study the influence of improved soil moisture on the model simulation of precipitation. The results show that the Noah scheme gives more reasonable results than SLAB, RUC and PX schemes. By comparative test we find that the simulation from the CLSMDAS output soil moisture generally agree with the observations, being able to simulate the intensity and range of heavy precipitation in 24 h as well as the response of the surface energy. The statistical verification test also shows that the TS score is higher, the miss rate, the false alarm and the bias are lower than the results from NCEP initial soil moisture. All these tell us that the accurate soil moisture can improve the forecasting capability of model simulation.
In order to analyze the influence of soil moisture on the simulation of precipitation in the WRFV3.3.1 mode, we use the soil moisture output from the China Land Soil Moisture Data Assimilaton System (CLSMDAS) to replace the soil moisture in the WRF initial field, on the basis of comparative analysis of four land surface process schemes, the heavy precipitation which occurred in Jiangxi Province on 19 June 2010 was simulated to study the influence of improved soil moisture on the model simulation of precipitation. The results show that the Noah scheme gives more reasonable results than SLAB, RUC and PX schemes. By comparative test we find that the simulation from the CLSMDAS output soil moisture generally agree with the observations, being able to simulate the intensity and range of heavy precipitation in 24 h as well as the response of the surface energy. The statistical verification test also shows that the TS score is higher, the miss rate, the false alarm and the bias are lower than the results from NCEP initial soil moisture. All these tell us that the accurate soil moisture can improve the forecasting capability of model simulation.
2013, 39(11):1490-1499.
DOI: 10.7519/j.issn.1000-0526.2013.11.013
Abstract:
On March 11, 2011, the Fukushima Daiichi Nuclear Power Plant was severely damaged by the massive 9.0 earthquakes and tsunami that struck off the northeast coast of the Island of Honshu. The damage to the nuclear facility has resulted in substantial environmental releases of radioactive materials into atmosphere. As a consequence, on March 26, the radioactive material I 131 from Fukushima Daiichi nuclear accident (FDNA) was monitored in China’s Heilongjiang air sampling for the first time. The monitoring of FDNA in China lasted for nearly a month, till April 22, the radioactive substances monitored in China mainland, which are I 131, Cs 137 and Cs 134, were close to basic values. Based on these monitoring data and HYSPLIT’s forward and backward trajectory modeling, this paper estimates the impacts of Fukushima Daiichi accident on China’s radioactivity levels. During the monitoring period, the maximum concentration of I 131 which is located in Jilin Province, is 8.01 mBq·m 3 and occurs in April 7. This value is closely related to the prevailing eastern winds during this period. Meanwhile, relatively high I 131 concentration is monitored in North China, the Northeast and Northwest of China. For Cs 137 and Cs 134, the maximum values both are found in the Xinjiang Region, being 1.55 and 1.42 mBq·m-3, respectively around April 4 and 9. At the same time, the trend of national averaged concentration shows two peaks around. Northwest and North China are found to have higher concentration of Cs 137 and Cs 134. Additionally, the ratios of Cs 137/I 131 and Cs 134/Cs 137 are analyzed and compared with the measurement results by other countries. The Cs 137/I 131 activity ratios (0.04-0.9) are observed to increase with time as expected from radioactive decay, and Cs 134/Cs 137 activity ratio is measured near the line 1.0.
On March 11, 2011, the Fukushima Daiichi Nuclear Power Plant was severely damaged by the massive 9.0 earthquakes and tsunami that struck off the northeast coast of the Island of Honshu. The damage to the nuclear facility has resulted in substantial environmental releases of radioactive materials into atmosphere. As a consequence, on March 26, the radioactive material I 131 from Fukushima Daiichi nuclear accident (FDNA) was monitored in China’s Heilongjiang air sampling for the first time. The monitoring of FDNA in China lasted for nearly a month, till April 22, the radioactive substances monitored in China mainland, which are I 131, Cs 137 and Cs 134, were close to basic values. Based on these monitoring data and HYSPLIT’s forward and backward trajectory modeling, this paper estimates the impacts of Fukushima Daiichi accident on China’s radioactivity levels. During the monitoring period, the maximum concentration of I 131 which is located in Jilin Province, is 8.01 mBq·m 3 and occurs in April 7. This value is closely related to the prevailing eastern winds during this period. Meanwhile, relatively high I 131 concentration is monitored in North China, the Northeast and Northwest of China. For Cs 137 and Cs 134, the maximum values both are found in the Xinjiang Region, being 1.55 and 1.42 mBq·m-3, respectively around April 4 and 9. At the same time, the trend of national averaged concentration shows two peaks around. Northwest and North China are found to have higher concentration of Cs 137 and Cs 134. Additionally, the ratios of Cs 137/I 131 and Cs 134/Cs 137 are analyzed and compared with the measurement results by other countries. The Cs 137/I 131 activity ratios (0.04-0.9) are observed to increase with time as expected from radioactive decay, and Cs 134/Cs 137 activity ratio is measured near the line 1.0.
2013, 39(11):1500-1506.
DOI: 10.7519/j.issn.1000-0526.2013.11.014
Abstract:
The wind profiler radar data has high temporal and spatial resolution, but is more used in the forecasts and analysis about the strong convective weather. This paper uses the horizontal wind speed and direction data of LAP 3000 boundary layer wind profile radar from January 2009 to June 2010 over Pudong International Airport in the study and analysis of the wind field stucture of the low level atmosphere. The original data with vertical interpolating (the vertical resolution is 50 m in the altitude range from 150 m to 3250 m, and the time interval is about 15 min), are analyzed statistically. The results show that the maximum values of wind speed appear mainly in the following height: 1000 m, 600 m, 500 m, 450 m, 550 m and 250 m, and the maximum value of wind vector difference between two adjacent layers is between 250 m and 300 m. According to the vertical shear intensity standards of horizontal wind recommented by International Civil Aviation Organiztaion (ICAO), the wind vector difference between different adjacent layers is counted up and divided into mild, medium, strong and severe grades. The results show that the seasonal distribution of different grade wind shear is pronounced. These conclusions are beneficial to the study on detailed forecasting, and warning of the lower wind shear at airport and even inland airport area based on AMDAR data, microwave radiometer, electric radiosonde and so on.
The wind profiler radar data has high temporal and spatial resolution, but is more used in the forecasts and analysis about the strong convective weather. This paper uses the horizontal wind speed and direction data of LAP 3000 boundary layer wind profile radar from January 2009 to June 2010 over Pudong International Airport in the study and analysis of the wind field stucture of the low level atmosphere. The original data with vertical interpolating (the vertical resolution is 50 m in the altitude range from 150 m to 3250 m, and the time interval is about 15 min), are analyzed statistically. The results show that the maximum values of wind speed appear mainly in the following height: 1000 m, 600 m, 500 m, 450 m, 550 m and 250 m, and the maximum value of wind vector difference between two adjacent layers is between 250 m and 300 m. According to the vertical shear intensity standards of horizontal wind recommented by International Civil Aviation Organiztaion (ICAO), the wind vector difference between different adjacent layers is counted up and divided into mild, medium, strong and severe grades. The results show that the seasonal distribution of different grade wind shear is pronounced. These conclusions are beneficial to the study on detailed forecasting, and warning of the lower wind shear at airport and even inland airport area based on AMDAR data, microwave radiometer, electric radiosonde and so on.
15 Research on Apple Wintering Frost Damage Risk Distribution Based on County Level in Shaanxi Province
2013, 39(11):1507-1513.
DOI: 10.7519/j.issn.1000-0526.2013.11.015
Abstract:
In order to effectively use local climate resources, reasonably plan and develop Shaanxi apple industry, and optimize apple planting layout in county level to get healthful and sustainable product, the research was carried out and described in this paper. Transplanting probability was conducted according to the relationship between wintering temperature in 3 apple planting counties and its regional automatic weather stations. By using winter temperature data during 1971 to 2011 from the weather stations of the 3 apple plant counties, this paper calculated the probability of damage to apple plant by frost at different weather stations as well as their regional automatic weather stations. According to the result of analyzing more than 30 historical apple wintering disaster cases, damage loss coefficient was got encoding 0.3, 0.5, 0.7 as mild, moderate, severe level, separately. Besides, by using the fundamental theories and model of climate hazard risk, the apple wintering frost damage risk index of the representative apple plant counties’ weather stations was successfully obtained. The result is visualized by drawing the apple wintering frost damage down scaling risk maps in using GIS system.
In order to effectively use local climate resources, reasonably plan and develop Shaanxi apple industry, and optimize apple planting layout in county level to get healthful and sustainable product, the research was carried out and described in this paper. Transplanting probability was conducted according to the relationship between wintering temperature in 3 apple planting counties and its regional automatic weather stations. By using winter temperature data during 1971 to 2011 from the weather stations of the 3 apple plant counties, this paper calculated the probability of damage to apple plant by frost at different weather stations as well as their regional automatic weather stations. According to the result of analyzing more than 30 historical apple wintering disaster cases, damage loss coefficient was got encoding 0.3, 0.5, 0.7 as mild, moderate, severe level, separately. Besides, by using the fundamental theories and model of climate hazard risk, the apple wintering frost damage risk index of the representative apple plant counties’ weather stations was successfully obtained. The result is visualized by drawing the apple wintering frost damage down scaling risk maps in using GIS system.
2013, 39(11):1514-1520.
DOI: 10.7519/j.issn.1000-0526.2013.11.016
Abstract:
The performances of medium range forecasts from the models of T639, ECMWF and Japan during June-August 2013 are verified and compared. The results show that ECMWF have best performance in predicting western Pacific subtropical high (WPSH). The three models all have good performances in predicting the anomaly high temperature in central and eastern part of China. As far as duration, range and turning time of high temperature weather are concerned, ECMWF plays better than the other two models. In addition, ECMWF has better performance in the prediction of the track and the landing time of typhoon Suli than T639 and JP, however the forecasting intensity of ECMWF is worse than that of the observation.
The performances of medium range forecasts from the models of T639, ECMWF and Japan during June-August 2013 are verified and compared. The results show that ECMWF have best performance in predicting western Pacific subtropical high (WPSH). The three models all have good performances in predicting the anomaly high temperature in central and eastern part of China. As far as duration, range and turning time of high temperature weather are concerned, ECMWF plays better than the other two models. In addition, ECMWF has better performance in the prediction of the track and the landing time of typhoon Suli than T639 and JP, however the forecasting intensity of ECMWF is worse than that of the observation.
2013, 39(11):1521-1528.
DOI: 10.7519/j.issn.1000-0526.2013.11.017
Abstract:
The main characteristics of the general atmospheric circulation in August 2013 are as follows: The polar vortex took the form of one single pole surrounding the North Pole and the geopotential height to the east of Lake Baikal had distinct minus anomaly. The upper troughs and northeast cold vortex in North China were active. The Northwest Pacific subtropical high was stronger than normal. The monthly mean precipitation amount was 101.0 mm， which is 4.1% more than normal. The monthly mean temperature was 22.0℃, being 1.2℃ higher than normal and it is the warmest August (same as 2006) since 1961. There were 7 large range heavy rainfall processes over China in this month. Heavy rainfall frequently appeared in Northeast China and due to the 5 local severe precipitation events, flood disasters attacked Songhua River, Nenjiang River and Heilongjiang River. Six tropical cyclones appeared over the South China Sea and Northwest Pacific and three of them landed China. Abnormal high temperature weather occurred in the west of Huanghuai area and the major part to the south of Huaihe River with the maximum temperature of many places reaching 38-40℃ and even higher than 40℃ in some local areas.
The main characteristics of the general atmospheric circulation in August 2013 are as follows: The polar vortex took the form of one single pole surrounding the North Pole and the geopotential height to the east of Lake Baikal had distinct minus anomaly. The upper troughs and northeast cold vortex in North China were active. The Northwest Pacific subtropical high was stronger than normal. The monthly mean precipitation amount was 101.0 mm， which is 4.1% more than normal. The monthly mean temperature was 22.0℃, being 1.2℃ higher than normal and it is the warmest August (same as 2006) since 1961. There were 7 large range heavy rainfall processes over China in this month. Heavy rainfall frequently appeared in Northeast China and due to the 5 local severe precipitation events, flood disasters attacked Songhua River, Nenjiang River and Heilongjiang River. Six tropical cyclones appeared over the South China Sea and Northwest Pacific and three of them landed China. Abnormal high temperature weather occurred in the west of Huanghuai area and the major part to the south of Huaihe River with the maximum temperature of many places reaching 38-40℃ and even higher than 40℃ in some local areas.
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ISSN:1000-0526 CN:11-2282/P