ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 37,Issue 12,2011 Table of Contents
2011, 37(12):1473-1480.
DOI: 10.7519/j.issn.1000-0526.2011.12.001
Abstract:
A case on April 18, 2009 in North China with the complex of stratiform clouds and embedded convective clouds is simulated by using WRFARW model. First, we analyze synoptic chart, radar reflectivity image and vertical section of radar reflectivity. Second, by comparison, it shows that the simulation results of precipitation and radar reflectivity are nearly correspondent with observational data. The precipitation mechanism, cloud microphysical characteristics and dynamic characteristics are studied by analyzing elements of cloud. The results indicate that: liquid water content of the stratiform clouds and embedded convective clouds is inhomogeneous. The stratiform clouds and convective clouds connect each other, and mix horizontally. The locations of maxima of rain water, ice crystal and cloud water content are correspondent vertically. Seederfeeder mechanism is obvious. Vertical velocity is accessional in the convective clouds. Downdraft is on the side of the convective clouds at high altitudes. Convergence can be found at low altitudes, while divergence can be found at high altitudes. This configuration is conducive to maintaining the development of cloud.
A case on April 18, 2009 in North China with the complex of stratiform clouds and embedded convective clouds is simulated by using WRFARW model. First, we analyze synoptic chart, radar reflectivity image and vertical section of radar reflectivity. Second, by comparison, it shows that the simulation results of precipitation and radar reflectivity are nearly correspondent with observational data. The precipitation mechanism, cloud microphysical characteristics and dynamic characteristics are studied by analyzing elements of cloud. The results indicate that: liquid water content of the stratiform clouds and embedded convective clouds is inhomogeneous. The stratiform clouds and convective clouds connect each other, and mix horizontally. The locations of maxima of rain water, ice crystal and cloud water content are correspondent vertically. Seederfeeder mechanism is obvious. Vertical velocity is accessional in the convective clouds. Downdraft is on the side of the convective clouds at high altitudes. Convergence can be found at low altitudes, while divergence can be found at high altitudes. This configuration is conducive to maintaining the development of cloud.
2 Study on the Cloud Structure and Precipitation Forming Mechanisms of the Storm near Typhoon Eyewall
2011, 37(12):1481-1488.
DOI: 10.7519/j.issn.1000-0526.2011.12.002
Abstract:
The nonstatic mesoscale model ARPS (Advanced Regional Prediction System) with detailed microphysical processes is used to simulate typhoon Wipha (2007), and the data of numerical simulation are used to analyze the microphysical structures and the precipitation forming mechanisms of the storm near typhoon eyewall. It is found that the ice phase microphysical processes are the main mechanism that initiates and produces the storm rain. Ice crystals can be produced by cloud water homogeneous nucleation, or cloud ices are produced by cloud water nonhomogeneous nucleation at heights 9000-14000 m. The ice grows into snow in 3 main microphysical processes (psfi, praci and piacr, which are defined in body text). The graupel is produced in 4 main microphysical processes (piacr, psacr, praci and pgfr). The graupel grows mainly in 2 main microphysical processes (dgaci and dgacw). The melting graupel and snow produce rain through accretion with cloud water in warm cloud. The production and growth microphysical processes of graupel play important roles in the precipitation forming mechanisms. There is not obvious difference of ice conversion ratios between two precipitation centers at （29.5°N，121.8°E） and （28.3°N，120.4°E）. But the ice grows more quickly into snow and graupel in terms of Bergeron process at （29.5°N，121.8°E） than at （28.3°N，120.4°E）. Then the precipitation particle can grow more quickly at (29.5°N, 121.8°E) than at （28.3°N，120.4°E） due to higher cloud water conversion ratios at low altitudes. There fore the rain conversion ratios are higher at （29.5°N，121.8°E） due to better configuration of clod and warm cloud processes.
The nonstatic mesoscale model ARPS (Advanced Regional Prediction System) with detailed microphysical processes is used to simulate typhoon Wipha (2007), and the data of numerical simulation are used to analyze the microphysical structures and the precipitation forming mechanisms of the storm near typhoon eyewall. It is found that the ice phase microphysical processes are the main mechanism that initiates and produces the storm rain. Ice crystals can be produced by cloud water homogeneous nucleation, or cloud ices are produced by cloud water nonhomogeneous nucleation at heights 9000-14000 m. The ice grows into snow in 3 main microphysical processes (psfi, praci and piacr, which are defined in body text). The graupel is produced in 4 main microphysical processes (piacr, psacr, praci and pgfr). The graupel grows mainly in 2 main microphysical processes (dgaci and dgacw). The melting graupel and snow produce rain through accretion with cloud water in warm cloud. The production and growth microphysical processes of graupel play important roles in the precipitation forming mechanisms. There is not obvious difference of ice conversion ratios between two precipitation centers at （29.5°N，121.8°E） and （28.3°N，120.4°E）. But the ice grows more quickly into snow and graupel in terms of Bergeron process at （29.5°N，121.8°E） than at （28.3°N，120.4°E）. Then the precipitation particle can grow more quickly at (29.5°N, 121.8°E) than at （28.3°N，120.4°E） due to higher cloud water conversion ratios at low altitudes. There fore the rain conversion ratios are higher at （29.5°N，121.8°E） due to better configuration of clod and warm cloud processes.
2011, 37(12):1489-1497.
DOI: 10.7519/j.issn.1000-0526.2011.12.003
Abstract:
Using observed data of fifteen Beijing automatic weather stations during June 1 2008 to May 31 2009, the forecasting performances of Beijing rapid update cycle of assimilation forecast system (BJRUC) to the air temperature, relative humidity, 1 h rainfall and the wind speed were analyzed in detail. The results showed that the meteorological elements of BJRUC system had a very good consistency with the corresponding observed data. The forecast accuracy rate of ±1℃ error to the 2 m temperature was from 0.2 to 0.5, and even higher if with ±2℃. The performance to the 2 m temperature did not change obviously with the forecast range, which was closely related to seasonal and diurnal variations. The forecast accuracy was better in spring and autumn than in summer and winter, and was better in nighttime than daytime. In general, the temperature forecasted by BJRUC system was often higher in daytime and summer. The relative humidity of BJRUC system was lower than observation, and usually, it was lower in daytime of summer and higher in nighttime of winter. The BJRUC system has a good performance of raining or shine to 1 h rainfall. Relatively, the accuracy rate to the rain was lower during afternoon to the evening, which may be related to the convective weather. The BJRUC system has a different performance to different meteorological stations. Relatively, the forecasting performance was better on the plain area than the station of high altitude. For example, among fifteen stations, the accuracy rate of Beijing was the highest, and which of Yanqing Station is the lowest. To the different station, the performances of various meteorological elements were different. For instance, there had a most obvious difference to the temperature, which was maybe caused by the elevation underestimation of BJRUC system.
Using observed data of fifteen Beijing automatic weather stations during June 1 2008 to May 31 2009, the forecasting performances of Beijing rapid update cycle of assimilation forecast system (BJRUC) to the air temperature, relative humidity, 1 h rainfall and the wind speed were analyzed in detail. The results showed that the meteorological elements of BJRUC system had a very good consistency with the corresponding observed data. The forecast accuracy rate of ±1℃ error to the 2 m temperature was from 0.2 to 0.5, and even higher if with ±2℃. The performance to the 2 m temperature did not change obviously with the forecast range, which was closely related to seasonal and diurnal variations. The forecast accuracy was better in spring and autumn than in summer and winter, and was better in nighttime than daytime. In general, the temperature forecasted by BJRUC system was often higher in daytime and summer. The relative humidity of BJRUC system was lower than observation, and usually, it was lower in daytime of summer and higher in nighttime of winter. The BJRUC system has a good performance of raining or shine to 1 h rainfall. Relatively, the accuracy rate to the rain was lower during afternoon to the evening, which may be related to the convective weather. The BJRUC system has a different performance to different meteorological stations. Relatively, the forecasting performance was better on the plain area than the station of high altitude. For example, among fifteen stations, the accuracy rate of Beijing was the highest, and which of Yanqing Station is the lowest. To the different station, the performances of various meteorological elements were different. For instance, there had a most obvious difference to the temperature, which was maybe caused by the elevation underestimation of BJRUC system.
2011, 37(12):1498-1503.
DOI: 10.7519/j.issn.1000-0526.2011.12.004
Abstract:
Based on the MODE method in the MET packet of WRF, the forecasting abilities of the numerical precipitation products of the BJRUC model were objectively verified. Using hourly rainfall observations of automatic weather stations in the flood season from 2008 to 2009, heavy rainfall examples and its main precipitation period were selected, in which the accumulated precipitation of more than two stations is larger than 50 mm in three hours, then according to their circulation patterns and influence systems, these cases are divided into three types, the west coming trough, the lowpressure vortex, and the shear line. The emphasis of verification is put on the main periods in the heavy rainfall and the QPE products of the radar are regarded as live data. The results show that the misses of precipitation from BJRUC model are much more than false alarm, the forecast rainfall intensity is weaker than observation and the BJRUC model is not good at forecasting precipitation by the west coming trough. This work is aimed at providing references for application and improvement of the BJRUC model.
Based on the MODE method in the MET packet of WRF, the forecasting abilities of the numerical precipitation products of the BJRUC model were objectively verified. Using hourly rainfall observations of automatic weather stations in the flood season from 2008 to 2009, heavy rainfall examples and its main precipitation period were selected, in which the accumulated precipitation of more than two stations is larger than 50 mm in three hours, then according to their circulation patterns and influence systems, these cases are divided into three types, the west coming trough, the lowpressure vortex, and the shear line. The emphasis of verification is put on the main periods in the heavy rainfall and the QPE products of the radar are regarded as live data. The results show that the misses of precipitation from BJRUC model are much more than false alarm, the forecast rainfall intensity is weaker than observation and the BJRUC model is not good at forecasting precipitation by the west coming trough. This work is aimed at providing references for application and improvement of the BJRUC model.
2011, 37(12):1504-1510.
DOI: 10.7519/j.issn.1000-0526.2011.12.005
Abstract:
The renewal of Lband upperair meteorological sounding system increases the atmospheric sounding precision, and the Lband “seconds level” data offer the basis platform of “seconds level” meteorological element data reanalysis for the Lband vetical high resolution profile. In order to discuss the application feasibility of Lband sounding vertical high resolution data, considering the acquisition conditions of other observation system “high time density” synchronous observation data, this paper selects the JICA (Japan International Cooperation Agency) PBL (planetary boundary layer) flux tower gradient observation to compare with, and also constructs the correlation model of Lband sounding data and flux tower surface layer meteorological information. The result shows that the Lband sounding vertical highresolution profile reanalysis surface data can preferably describe pressure, temperature, and humidity of the surface layer; the pressure, temperature, and humidity models have the feasibilities of calculating PBL surface layer pressure, temperature, and humidity. It provides the scientific proof and technical basis for the development and application of Lband detection “seconds level” data.On the basis of constructing Lband high resolution vertical profile reanalysis platform, it will help to develop national Lband sounding application in numerical model and promote the new technical development of radiosonde vertical high resolution information in numerical model assimilation system.
The renewal of Lband upperair meteorological sounding system increases the atmospheric sounding precision, and the Lband “seconds level” data offer the basis platform of “seconds level” meteorological element data reanalysis for the Lband vetical high resolution profile. In order to discuss the application feasibility of Lband sounding vertical high resolution data, considering the acquisition conditions of other observation system “high time density” synchronous observation data, this paper selects the JICA (Japan International Cooperation Agency) PBL (planetary boundary layer) flux tower gradient observation to compare with, and also constructs the correlation model of Lband sounding data and flux tower surface layer meteorological information. The result shows that the Lband sounding vertical highresolution profile reanalysis surface data can preferably describe pressure, temperature, and humidity of the surface layer; the pressure, temperature, and humidity models have the feasibilities of calculating PBL surface layer pressure, temperature, and humidity. It provides the scientific proof and technical basis for the development and application of Lband detection “seconds level” data.On the basis of constructing Lband high resolution vertical profile reanalysis platform, it will help to develop national Lband sounding application in numerical model and promote the new technical development of radiosonde vertical high resolution information in numerical model assimilation system.
2011, 37(12):1511-1518.
DOI: 10.7519/j.issn.1000-0526.2011.12.006
Abstract:
In this paper, GPS occultation refractive index data are assimilated by threedimensional variation assimilation system of WRF model which is used to explore the improvement of its initial value through the numerical simulation of 4-6 July 2007 Meiyu. GPS occultation data adjustments to the initial data are mainly at lowlevel moisture field; For the temperature and height fields, adjustments are gradually increasing from bottom to top. The horizontal and vertical incremental analysis is able to explore the effects of assimilation on improving the forecast， as well as learn more about the spatial structure of the system as a way to explore the dynamic mechanism of its occurrence and development. Assimilated results show that adding GPS occultation data to precipitation forecasting is the most obvious because of the initial lowlevel moisture field adjustment. The negative divergence and positive vorticity increments are well corresponding to precipitation zones. And it enhances the dynamic conditions of precipitation.
In this paper, GPS occultation refractive index data are assimilated by threedimensional variation assimilation system of WRF model which is used to explore the improvement of its initial value through the numerical simulation of 4-6 July 2007 Meiyu. GPS occultation data adjustments to the initial data are mainly at lowlevel moisture field; For the temperature and height fields, adjustments are gradually increasing from bottom to top. The horizontal and vertical incremental analysis is able to explore the effects of assimilation on improving the forecast， as well as learn more about the spatial structure of the system as a way to explore the dynamic mechanism of its occurrence and development. Assimilated results show that adding GPS occultation data to precipitation forecasting is the most obvious because of the initial lowlevel moisture field adjustment. The negative divergence and positive vorticity increments are well corresponding to precipitation zones. And it enhances the dynamic conditions of precipitation.
2011, 37(12):1519-1525.
DOI: 10.7519/j.issn.1000-0526.2011.12.007
Abstract:
Based on the routine observation data and the Doppler weather radar data, the largescale hail in the northwest of Guangxi is analyzed. The results show that: (1) The systems csusing hail are upperairvortex and lowlevel shear line. Although the CAPE was moderate before the hail, it has necessary conditions for the severe convection potential occurrence such as the stratification of upper dry and lower wet, strong environmental wind shear and the strong clockwise curvature at low levels. (2) The lowlevel reflectivity on the right front of the supercell shows a typical hook echo and it is a typical feature of supercells. Along the inflow direction and through the strongest echo, the reflectivity shows typical BWER (Boundary Weak Echo Region), overhang echo and echo wall. The strongest echo is within a vertical narrow region along the echo wall and can be more than 65 dBz. The corresponding radial velocity in the lower atmosphere has a moderate mesoscale vortex street and its rotation speed can be 22 m·s-1. Meanwhile the VIL exceeds 70 kg·m-2 and its density exceeds 5 g·m-3. (3) The positive vorticity at upper levels, high CAPE value, convergence line on the ground stranding in the Youjiang Valley and the special terrain are the main causes for many convection cells moving along similar paths.
Based on the routine observation data and the Doppler weather radar data, the largescale hail in the northwest of Guangxi is analyzed. The results show that: (1) The systems csusing hail are upperairvortex and lowlevel shear line. Although the CAPE was moderate before the hail, it has necessary conditions for the severe convection potential occurrence such as the stratification of upper dry and lower wet, strong environmental wind shear and the strong clockwise curvature at low levels. (2) The lowlevel reflectivity on the right front of the supercell shows a typical hook echo and it is a typical feature of supercells. Along the inflow direction and through the strongest echo, the reflectivity shows typical BWER (Boundary Weak Echo Region), overhang echo and echo wall. The strongest echo is within a vertical narrow region along the echo wall and can be more than 65 dBz. The corresponding radial velocity in the lower atmosphere has a moderate mesoscale vortex street and its rotation speed can be 22 m·s-1. Meanwhile the VIL exceeds 70 kg·m-2 and its density exceeds 5 g·m-3. (3) The positive vorticity at upper levels, high CAPE value, convergence line on the ground stranding in the Youjiang Valley and the special terrain are the main causes for many convection cells moving along similar paths.
2011, 37(12):1526-1533.
DOI: 10.7519/j.issn.1000-0526.2011.12.008
Abstract:
This paper presents a diagnosis of an intense developing extratropical cyclone that occurred in conjunction with a 500 hPa trough merger over the Bohai and Yellow Sea in March 2007. To analyze the dynamics of the cyclone development, the NCEP analysis data and the ZwackOkossi （ZO） vorticity tendency equation are employed. Results show that there are three phases during the cyclone development. Firstly the cyclone appeared at the lower troposphere with significant frontogenesis and baroclinity. Secondly the approaching of the 500 hPa trough increased the vorticity advection above the cyclone, and the difference between the upper and lower levels accelerated the cyclone’s development after the cyclone entered the Yellow Sea. Finally, the 500 hPa trough merger increased the cyclonic vorticity in the midlevel troposphere which in turn enhanced the ascent movement at the mid and lowerlevels, and increased the latent heat release. Thus its central pressure reached the lowest.
This paper presents a diagnosis of an intense developing extratropical cyclone that occurred in conjunction with a 500 hPa trough merger over the Bohai and Yellow Sea in March 2007. To analyze the dynamics of the cyclone development, the NCEP analysis data and the ZwackOkossi （ZO） vorticity tendency equation are employed. Results show that there are three phases during the cyclone development. Firstly the cyclone appeared at the lower troposphere with significant frontogenesis and baroclinity. Secondly the approaching of the 500 hPa trough increased the vorticity advection above the cyclone, and the difference between the upper and lower levels accelerated the cyclone’s development after the cyclone entered the Yellow Sea. Finally, the 500 hPa trough merger increased the cyclonic vorticity in the midlevel troposphere which in turn enhanced the ascent movement at the mid and lowerlevels, and increased the latent heat release. Thus its central pressure reached the lowest.
2011, 37(12):1534-1543.
DOI: 10.7519/j.issn.1000-0526.2011.12.009
Abstract:
Based on the dry intrusion theory and potential vorticity theorem, by using the water vapor image and NCEP/NCAR 1°×1° reanalysis data, the synoptic and dynamic characteristics of a strong storm surge over the Bohai Sea from 3 to 5 March 2007 are analyzed. The feature and influence of dry intrusion on the Yellow River cyclone are also revealed. The result shows that the storm surge occurred during the adjustment of Eurasia mid and high latitude circulation, the east moving and development of unstable low rough and the rebuilding of EastAsia major trough. Northerly gale induced by strongly developed the Yellow River cyclone forced the surge to sharply bloom. Dry intrusion has features of high PV value. The shape and strength changes of high PV area, with dark zone on water vapor image, have a meaningful prediction to different stages of cyclones. When drycold air currents meet with warmer wet air flow along a inverted “Ω” lapping belt from north to south, the isentropic surface becomes steeper and the stability of atmosphere decreases. Although the downward progress of dry intrusion from high level will lead to warming effect, the cooling effect from the strong cold advection can give birth to decreasing of atmospheric stability. Therefore the high level vortex, corresponding to surface cyclone, has lower temperature than the adjacent areas. As a result, the midlow level cyclonic vorticity is increased, the upward vertical movement is reinforced, and then the surface cyclone is strongly developed.
Based on the dry intrusion theory and potential vorticity theorem, by using the water vapor image and NCEP/NCAR 1°×1° reanalysis data, the synoptic and dynamic characteristics of a strong storm surge over the Bohai Sea from 3 to 5 March 2007 are analyzed. The feature and influence of dry intrusion on the Yellow River cyclone are also revealed. The result shows that the storm surge occurred during the adjustment of Eurasia mid and high latitude circulation, the east moving and development of unstable low rough and the rebuilding of EastAsia major trough. Northerly gale induced by strongly developed the Yellow River cyclone forced the surge to sharply bloom. Dry intrusion has features of high PV value. The shape and strength changes of high PV area, with dark zone on water vapor image, have a meaningful prediction to different stages of cyclones. When drycold air currents meet with warmer wet air flow along a inverted “Ω” lapping belt from north to south, the isentropic surface becomes steeper and the stability of atmosphere decreases. Although the downward progress of dry intrusion from high level will lead to warming effect, the cooling effect from the strong cold advection can give birth to decreasing of atmospheric stability. Therefore the high level vortex, corresponding to surface cyclone, has lower temperature than the adjacent areas. As a result, the midlow level cyclonic vorticity is increased, the upward vertical movement is reinforced, and then the surface cyclone is strongly developed.
2011, 37(12):1544-1552.
DOI: 10.7519/j.issn.1000-0526.2011.12.010
Abstract:
Based on the daily maximum surface air temperature data of 35 stations during 1961-2008 in the Three Gorges area, the climatic characteristics of high temperature are analyzed. Using the empirical mode decomposition, we have discussed the mean annual high temperature days as well as the vacillation mode structure characteristics of the mean daily highest temperature during annual high temperature days in the Three Gorges area in recent 48 years, and we constructed a new prediction model by using function extension of mean value generated by generating function model as well as BP nerve net. The prediction model made the projection of the mean annual high temperature days and the mean daily highest temperature. The results show that the mean annual high temperature days were 24.07 and the mean daily highest temperature during annual high temperature days was 36.69℃ in the past 48 years. Meanwhile, the mean annual high temperature days were negative anomaly in the 1980s and 1990s, but positive anomaly in the other periods of time, oscillating with a cycle of about 3-5 and 16 years. The mean annual high temperature days were more in the northern part, but less in the southeast part of the Three Gorges area. The mean daily highest temperature during annual high temperature days was lower in southeast part, but higher in northeast part of the Three Gorges area. By comparing the prediction value of the model with real value, it showed that the model not only could fit the history in the Three Gorges area, but also could predict the trend of the future 5-10 years in the Three Gorges area. However, the model should improve the prediction ability of the extreme climate events occurring occasionally.
Based on the daily maximum surface air temperature data of 35 stations during 1961-2008 in the Three Gorges area, the climatic characteristics of high temperature are analyzed. Using the empirical mode decomposition, we have discussed the mean annual high temperature days as well as the vacillation mode structure characteristics of the mean daily highest temperature during annual high temperature days in the Three Gorges area in recent 48 years, and we constructed a new prediction model by using function extension of mean value generated by generating function model as well as BP nerve net. The prediction model made the projection of the mean annual high temperature days and the mean daily highest temperature. The results show that the mean annual high temperature days were 24.07 and the mean daily highest temperature during annual high temperature days was 36.69℃ in the past 48 years. Meanwhile, the mean annual high temperature days were negative anomaly in the 1980s and 1990s, but positive anomaly in the other periods of time, oscillating with a cycle of about 3-5 and 16 years. The mean annual high temperature days were more in the northern part, but less in the southeast part of the Three Gorges area. The mean daily highest temperature during annual high temperature days was lower in southeast part, but higher in northeast part of the Three Gorges area. By comparing the prediction value of the model with real value, it showed that the model not only could fit the history in the Three Gorges area, but also could predict the trend of the future 5-10 years in the Three Gorges area. However, the model should improve the prediction ability of the extreme climate events occurring occasionally.
2011, 37(12):1553-1559.
DOI: 10.7519/j.issn.1000-0526.2011.12.011
Abstract:
The occurrence of summer high temperature is the comprehensive reflection of joint actions of several factors， in which atmospheric circulation background plays an important role in hightemperature events. According to the study of airsea interaction, there are maybe some feedback relations between SST change and atmospheric circulation, which determine the certain predictability of land temperature using SST. Based on this principle, with the 30year (1978—2007) West Pacific SST, and the numbers of high temperature days of different time, the strong signal sea area related to average high temperature days of different regions of Jiangsu is explored by using regional average method, field correlation analysis and optimization correlation processing technology. Setting West Pacific SST as the longterm forecast factor, the longterm forecast models of summer monthly high temperature days in different areas of Jiangsu are established. These models all pass through the significance level of α=0.01, and the effects of fitting are good. Experiments of practical forecast are carried out with good effects, and can be put into meteorological operations. The study has important guiding significance for service on the longterm forecast of high temperature and high temperature disasters in Jiangsu Province.
The occurrence of summer high temperature is the comprehensive reflection of joint actions of several factors， in which atmospheric circulation background plays an important role in hightemperature events. According to the study of airsea interaction, there are maybe some feedback relations between SST change and atmospheric circulation, which determine the certain predictability of land temperature using SST. Based on this principle, with the 30year (1978—2007) West Pacific SST, and the numbers of high temperature days of different time, the strong signal sea area related to average high temperature days of different regions of Jiangsu is explored by using regional average method, field correlation analysis and optimization correlation processing technology. Setting West Pacific SST as the longterm forecast factor, the longterm forecast models of summer monthly high temperature days in different areas of Jiangsu are established. These models all pass through the significance level of α=0.01, and the effects of fitting are good. Experiments of practical forecast are carried out with good effects, and can be put into meteorological operations. The study has important guiding significance for service on the longterm forecast of high temperature and high temperature disasters in Jiangsu Province.
2011, 37(12):1560-1566.
DOI: 10.7519/j.issn.1000-0526.2011.12.012
Abstract:
In order to effectively integrate the prediction results of various forecasting methods, the monthly mean temperatures of the three climatic zones in Shaanxi from July 1999 to June 2010 are employed in the experiments. Based on the historical precision derived from products of the National Climate Centre and three kinds of prediction methods, the two schemes involving six objectiveintegrated dynamic forecasting models are established. The results show that: (1) The yearly average score is higher than each member in the range of the whole ensemble forecasting models. Average score of six ensemble forecasting models is 4.6 higher than other four members, and is 5.1 higher than operational publishing products provided by Shaanxi Climate Center. The yearly anomaly sign consistency rate of each ensemble forecasting model is higher than every value resulting from at least three prediction methods among all. The average value of six ensemble forecasting models with the anomaly sign consistency rate is 4.7% higher than other four members, and is 5.1% higher than operational publishing products predicted by Shaanxi Climate Center. (2) Yulin received the best forecasting result among three climatic zones. Average score of six ensemble forecasting models is 5.7 higher than other four members, and is 5.7 higher than operational publishing products provided by Shaanxi Climate Center. The average value of ensemble forecasting models with the anomaly sign consistency rate is 6.9% higher than four members, and is 7.3% higher than operational publishing products predicted by Shaanxi Climate Center. (3) The second scheme of ensemble forecasting models is better than the first one. Especially, the average score of Z23 is 5.1 higher than other four members, and is 5.7 higher than operational publishing products. The average value of ensemble forecasting models with the anomaly sign consistency rate is 6.0% higher than four members, and is 7.6% higher than operational publishing products score. Thus, it is recommended to be used in climate prediction.
In order to effectively integrate the prediction results of various forecasting methods, the monthly mean temperatures of the three climatic zones in Shaanxi from July 1999 to June 2010 are employed in the experiments. Based on the historical precision derived from products of the National Climate Centre and three kinds of prediction methods, the two schemes involving six objectiveintegrated dynamic forecasting models are established. The results show that: (1) The yearly average score is higher than each member in the range of the whole ensemble forecasting models. Average score of six ensemble forecasting models is 4.6 higher than other four members, and is 5.1 higher than operational publishing products provided by Shaanxi Climate Center. The yearly anomaly sign consistency rate of each ensemble forecasting model is higher than every value resulting from at least three prediction methods among all. The average value of six ensemble forecasting models with the anomaly sign consistency rate is 4.7% higher than other four members, and is 5.1% higher than operational publishing products predicted by Shaanxi Climate Center. (2) Yulin received the best forecasting result among three climatic zones. Average score of six ensemble forecasting models is 5.7 higher than other four members, and is 5.7 higher than operational publishing products provided by Shaanxi Climate Center. The average value of ensemble forecasting models with the anomaly sign consistency rate is 6.9% higher than four members, and is 7.3% higher than operational publishing products predicted by Shaanxi Climate Center. (3) The second scheme of ensemble forecasting models is better than the first one. Especially, the average score of Z23 is 5.1 higher than other four members, and is 5.7 higher than operational publishing products. The average value of ensemble forecasting models with the anomaly sign consistency rate is 6.0% higher than four members, and is 7.6% higher than operational publishing products score. Thus, it is recommended to be used in climate prediction.
2011, 37(12):1566-1571.
DOI: 10.7519/j.issn.1000-0526.2011.12.013
Abstract:
With the analysis on the aerosol scattering coefficient in urban site of Tianjin in September 2006 to February 2007, it is found that there are two peaks for the average diurnal variations of the scattering coefficient of aerosols which can be seen at 06:00 BT and 22:00 BT, with values of 508.5 and 431.4 Mm-1. The scattering coefficient is usually higher in winter than that in autumn. The average scattering coefficients are 588.8 Mm-1 in fog days, 403.7 Mm-1 in haze days, and 172.5 Mm-1 in fine days. Therefore, the average scattering coefficient is the highest in fog days, while the lowest in fine days. The aerosol scattering coefficient varies obviously in gale weather and dust weather. Before wind speed increases the scattering coefficient is higher, and it decreases in gale weather and dust weather. Diurnal change of the PM2.5 mass concentrations accords with the daily change of the scattering coefficient. A good correlation between scattering coefficient and PM2.5 mass concentration can be found with a high coefficient of 0.78.
With the analysis on the aerosol scattering coefficient in urban site of Tianjin in September 2006 to February 2007, it is found that there are two peaks for the average diurnal variations of the scattering coefficient of aerosols which can be seen at 06:00 BT and 22:00 BT, with values of 508.5 and 431.4 Mm-1. The scattering coefficient is usually higher in winter than that in autumn. The average scattering coefficients are 588.8 Mm-1 in fog days, 403.7 Mm-1 in haze days, and 172.5 Mm-1 in fine days. Therefore, the average scattering coefficient is the highest in fog days, while the lowest in fine days. The aerosol scattering coefficient varies obviously in gale weather and dust weather. Before wind speed increases the scattering coefficient is higher, and it decreases in gale weather and dust weather. Diurnal change of the PM2.5 mass concentrations accords with the daily change of the scattering coefficient. A good correlation between scattering coefficient and PM2.5 mass concentration can be found with a high coefficient of 0.78.
2011, 37(12):1572-1577.
DOI: 10.7519/j.issn.1000-0526.2011.12.014
Abstract:
In terms of the daily fixed time surface meteorological data over recent 50 years, the standard layer daily sounding data at 07:00 BT and 19:00 BT from 2002 to 2006, the daily concentration data of main pollutants and sources from 2001 to 2006, the social and economic data from 1961 to 2006, the city development situations in 2002, and the Hohhot City planning maps from 1996 to 2010, the influence of urban development on atmospheric environment in Hohhot City was analyzed with the regional boundary layer numerical simulation method. The results have shown that: (1) The temperature in Hohhot City is higher after development than before, the temperature difference between urban center and surrounding areas increases and the heat island effect enhances. (2) The current convergence area increases and the capacity of convergence enhances in winter after development, as a result, the urban atmospheric pollution aggravates in winter. (3) The change of thermal and dynamic parameters of the underlying surface resulting from city expansion leads to air current fields to change remarkably, and then the capacity of convergence of pollutants strengthens. In short, although the green lands are increased after development, the higher and closer buildings and the change of underlying surface’s characters make the capacity of diffusion of atmospheric environments weaken and atmospheric pollutions become heavier.
In terms of the daily fixed time surface meteorological data over recent 50 years, the standard layer daily sounding data at 07:00 BT and 19:00 BT from 2002 to 2006, the daily concentration data of main pollutants and sources from 2001 to 2006, the social and economic data from 1961 to 2006, the city development situations in 2002, and the Hohhot City planning maps from 1996 to 2010, the influence of urban development on atmospheric environment in Hohhot City was analyzed with the regional boundary layer numerical simulation method. The results have shown that: (1) The temperature in Hohhot City is higher after development than before, the temperature difference between urban center and surrounding areas increases and the heat island effect enhances. (2) The current convergence area increases and the capacity of convergence enhances in winter after development, as a result, the urban atmospheric pollution aggravates in winter. (3) The change of thermal and dynamic parameters of the underlying surface resulting from city expansion leads to air current fields to change remarkably, and then the capacity of convergence of pollutants strengthens. In short, although the green lands are increased after development, the higher and closer buildings and the change of underlying surface’s characters make the capacity of diffusion of atmospheric environments weaken and atmospheric pollutions become heavier.
2011, 37(12):1578-1583.
DOI: 10.7519/j.issn.1000-0526.2011.12.015
Abstract:
To improve fine temperature forcasting, based on the result amending of MM5 by grey dynamic model, and using the temperature interpolation methods with altitude and distance weight, the high and low temperatures in 72 hours at 717 automatic weather stations with 4 meteorological elements in Hubei Province, are forecasted on the basis of the MOS technique and the mesoscale model and tested by observations. The results show that the test score in this method to the stations without historical data is better than that by the mesoscale model and is approximate to that by the MOS technique,〖JP2〗 thus this method can be used in actual operations. The test also indicates that the forecasting difficulty in northwestern Hubei is the most compared with other areas and is the least in the Jianghan Plain. In this method, the forecasting errors of the lowest temperatue in autumn and spring are more than those in other seasons, and the prediction errors are the smallest in summer. Meanwhile, the trends of low temperature are similar in five areas of Hubei. However, the change trends of maximum temperature forecasting are inconsistent in these areas.
To improve fine temperature forcasting, based on the result amending of MM5 by grey dynamic model, and using the temperature interpolation methods with altitude and distance weight, the high and low temperatures in 72 hours at 717 automatic weather stations with 4 meteorological elements in Hubei Province, are forecasted on the basis of the MOS technique and the mesoscale model and tested by observations. The results show that the test score in this method to the stations without historical data is better than that by the mesoscale model and is approximate to that by the MOS technique,〖JP2〗 thus this method can be used in actual operations. The test also indicates that the forecasting difficulty in northwestern Hubei is the most compared with other areas and is the least in the Jianghan Plain. In this method, the forecasting errors of the lowest temperatue in autumn and spring are more than those in other seasons, and the prediction errors are the smallest in summer. Meanwhile, the trends of low temperature are similar in five areas of Hubei. However, the change trends of maximum temperature forecasting are inconsistent in these areas.
2011, 37(12):1584-1588.
DOI: 10.7519/j.issn.1000-0526.2011.12.016
Abstract:
Using daily precipitation and air temperature data of Lhasa to analyze the nightrain rate in rainy season (May-September) during years 1955-2007, the results could be summarized as follows: The variations of nightrain rate was comparatively stable in whole rainy season, without obvious interdecadal changes during the past 50 years. The nightrain rate was significantly associated with daily precipitation, and the nightrain rate increased with the enhancement of precipitation when rainfall was below 25 mm, it was the minimum 75.2% when daily rainfall was below 1 mm, and it was the maximum 93.4% when daily rainfall was 25 mm. There is a significantly negative correlation between night rain rate and daily temperature. In the meantime, the nightrain is related with the terrain. The high nightrain rate has its advantageous aspect, but also it will bring some negative influences.
Using daily precipitation and air temperature data of Lhasa to analyze the nightrain rate in rainy season (May-September) during years 1955-2007, the results could be summarized as follows: The variations of nightrain rate was comparatively stable in whole rainy season, without obvious interdecadal changes during the past 50 years. The nightrain rate was significantly associated with daily precipitation, and the nightrain rate increased with the enhancement of precipitation when rainfall was below 25 mm, it was the minimum 75.2% when daily rainfall was below 1 mm, and it was the maximum 93.4% when daily rainfall was 25 mm. There is a significantly negative correlation between night rain rate and daily temperature. In the meantime, the nightrain is related with the terrain. The high nightrain rate has its advantageous aspect, but also it will bring some negative influences.
2011, 37(12):1589-1594.
DOI: 10.7519/j.issn.1000-0526.2011.12.017
Abstract:
The following are the main characteristics of the general circulation of atmosphere in September 2011. The polar center over the Northern Hemisphere is a singlevortex pattern and deviated to the Western Hemisphere. The circulation presents a fivewave pattern in middlehigh latitudes and the trough areas are over the northeast part of North Pacific, the east part of North America, the north part of North Atlantic, the east part of Europe and the northeast part of Asia, respectively. A negative anomaly with more than 160 gpm difference is found over the northeast part of North Pacific on the 500 hPa geopotential height field. The intensity of the subtropical high over the Northwest Pacific is weaker than the corresponding period of normal years. The location of west ridge spot is further east and north than normal years. The monthly mean temperature (16.4℃) is 0.4℃ higher than the same period of normal years and the mean precipitation (65.0 mm) is nearly the same as the value (65.3 mm) of normal years. In this month, there were 3 obvious cold air processes and 7 precipitation processes, 7 tropical cyclones generated, in which typhoon Nesat landed in China and resulted in heavy damages.
The following are the main characteristics of the general circulation of atmosphere in September 2011. The polar center over the Northern Hemisphere is a singlevortex pattern and deviated to the Western Hemisphere. The circulation presents a fivewave pattern in middlehigh latitudes and the trough areas are over the northeast part of North Pacific, the east part of North America, the north part of North Atlantic, the east part of Europe and the northeast part of Asia, respectively. A negative anomaly with more than 160 gpm difference is found over the northeast part of North Pacific on the 500 hPa geopotential height field. The intensity of the subtropical high over the Northwest Pacific is weaker than the corresponding period of normal years. The location of west ridge spot is further east and north than normal years. The monthly mean temperature (16.4℃) is 0.4℃ higher than the same period of normal years and the mean precipitation (65.0 mm) is nearly the same as the value (65.3 mm) of normal years. In this month, there were 3 obvious cold air processes and 7 precipitation processes, 7 tropical cyclones generated, in which typhoon Nesat landed in China and resulted in heavy damages.
2011, 37(12):1595-1600.
DOI: 10.7519/j.issn.1000-0526.2011.12.018
Abstract:
Taking lightning density, incidence of lightning disaster, lightning disaster economic loss rate and the rate of lightning disaster damage as the lightning vulnerability assessment indices, we employed the analytic geometry of linear equation to standardize data and the AHP anlysis method to modify the index data, and finally utilized the cluster analysis to the total value of the vulnerability for a more rational and scientific classification, with Fujian Province as an example for the new model. The results show that the composite evaluation of model calculations is much better mathematically than other methods, and this method can detailedly and completely represent the relation between indices of lightning disaster vulnerability zoning and the combined effects of indices on lightning disaster vulnerability.
Taking lightning density, incidence of lightning disaster, lightning disaster economic loss rate and the rate of lightning disaster damage as the lightning vulnerability assessment indices, we employed the analytic geometry of linear equation to standardize data and the AHP anlysis method to modify the index data, and finally utilized the cluster analysis to the total value of the vulnerability for a more rational and scientific classification, with Fujian Province as an example for the new model. The results show that the composite evaluation of model calculations is much better mathematically than other methods, and this method can detailedly and completely represent the relation between indices of lightning disaster vulnerability zoning and the combined effects of indices on lightning disaster vulnerability.
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ISSN:1000-0526 CN:11-2282/P