ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 39,Issue 1,2013 Table of Contents
2013, 39(1):1-10.
DOI: 10.7519/j.issn.1000-0526.2013.01.001
Abstract:
The paper applies BPO (Bayesian Processor of Output) method based on Bayesian theory to the method of rainfall ensemble probability forecast. Using ensemble prediction data and historical observational data, we develop a rainfall probability forecast model, and then revise a set of precipitation predicted value into a set of Bayesian precipitation probability forecast in the form of continuous probability distribution or continuous probability density. Besides, we obtain a group value of Informativeness Score (IS), which can express the prediction ability of each ensemble member. Furthermore, we fuse the probability forecast results of each member into an integration Bayesian precipitation probability forecast on the basis of IS and test the results with Continuous Ranked Probablity Score (CRPS). Experiment results show that the reliability of integration Bayesian precipitation probability forecast is higher than ensemble direct probability forecast.
The paper applies BPO (Bayesian Processor of Output) method based on Bayesian theory to the method of rainfall ensemble probability forecast. Using ensemble prediction data and historical observational data, we develop a rainfall probability forecast model, and then revise a set of precipitation predicted value into a set of Bayesian precipitation probability forecast in the form of continuous probability distribution or continuous probability density. Besides, we obtain a group value of Informativeness Score (IS), which can express the prediction ability of each ensemble member. Furthermore, we fuse the probability forecast results of each member into an integration Bayesian precipitation probability forecast on the basis of IS and test the results with Continuous Ranked Probablity Score (CRPS). Experiment results show that the reliability of integration Bayesian precipitation probability forecast is higher than ensemble direct probability forecast.
2013, 39(1):11-19.
DOI: 10.7519/j.issn.1000-0526.2013.01.002
Abstract:
Based on the conventional observational data, brightness temperature (TBB) data, automatical observational precipitation and NCEP/NCAR reanalysis data, two heavy rainfall processes triggered by low vortex in the western South China during 3-4 July 2009 and 16-17 June 2008 respectively were compared and analyzed. The major conclusions can be drawn as follows: (1) The low vortex was the direct influencing system of these two heavy rainfall processes, the strong southwest jet at low levels was accompanied in the July 2009 process, but not in the June 2008 process. Mesoscale convergence may have a direct triggering effect on these two heavy rainfalls. (2) In the July 2009 process, the intensity of low level convergence was stronger than that in the June 2008 process, so was the intensity of the upward motion and warm advection, and the temperature advection lines were more dense.(3) The net transport of water vapor was more in the July 2009 process than that in the June 2008 process, as a result of the sufficient water vapor transport to the storm area by the southwest low level jet. (4) Both storm processes are closely related to the vertical circulation south of the westerly jet at the high altitude. In the July 2009 process, because of the low level, the upward motion maintains longer than that in the June 2008 process, the intensity of rainfall stronger, and its duration longer.
Based on the conventional observational data, brightness temperature (TBB) data, automatical observational precipitation and NCEP/NCAR reanalysis data, two heavy rainfall processes triggered by low vortex in the western South China during 3-4 July 2009 and 16-17 June 2008 respectively were compared and analyzed. The major conclusions can be drawn as follows: (1) The low vortex was the direct influencing system of these two heavy rainfall processes, the strong southwest jet at low levels was accompanied in the July 2009 process, but not in the June 2008 process. Mesoscale convergence may have a direct triggering effect on these two heavy rainfalls. (2) In the July 2009 process, the intensity of low level convergence was stronger than that in the June 2008 process, so was the intensity of the upward motion and warm advection, and the temperature advection lines were more dense.(3) The net transport of water vapor was more in the July 2009 process than that in the June 2008 process, as a result of the sufficient water vapor transport to the storm area by the southwest low level jet. (4) Both storm processes are closely related to the vertical circulation south of the westerly jet at the high altitude. In the July 2009 process, because of the low level, the upward motion maintains longer than that in the June 2008 process, the intensity of rainfall stronger, and its duration longer.
2013, 39(1):20-27.
DOI: 10.7519/j.issn.1000-0526.2013.01.003
Abstract:
Using ten years of observation data and EC 2.5°×2.5° objective analysis data from 2000 to 2009, persistent rainstorms in northwest Guangxi in main flood period (May to August) were analyzed with the methods of statistics and synoptic climatology. The results showed that persistent rainstorms obviously occurred in the time window which mainly appeared in June and July, especially in early June. The major weather systems causing persistent rainstorm are upper trough, shear line, frontal surface, low level jet, subtropical high and tropical cyclone, etc. According to the weather system configuration, persistent rainstorms can be divided into four weather patterns, including the type of upper trough cooperating with shear line or frontal surface, the type of deep trough on the edge of subtropical high, the type of tropical cyclone, the type of middle level shear line cooperating with low level shear line. It was the type of tropical cyclone that rainfall intensity was the strongest as well as influence range was the most extensive. Based on the conceptual model analysis and ingredients method, four kinds of weather conceptual models and the specific threshold value of decision trees were established. As well as, a 24 h short term forecasting tool with forecast accuracy (TS) of persistent rainstorm in northwest Guangxi more than 10% was established by using the products of EC and T639 model.
Using ten years of observation data and EC 2.5°×2.5° objective analysis data from 2000 to 2009, persistent rainstorms in northwest Guangxi in main flood period (May to August) were analyzed with the methods of statistics and synoptic climatology. The results showed that persistent rainstorms obviously occurred in the time window which mainly appeared in June and July, especially in early June. The major weather systems causing persistent rainstorm are upper trough, shear line, frontal surface, low level jet, subtropical high and tropical cyclone, etc. According to the weather system configuration, persistent rainstorms can be divided into four weather patterns, including the type of upper trough cooperating with shear line or frontal surface, the type of deep trough on the edge of subtropical high, the type of tropical cyclone, the type of middle level shear line cooperating with low level shear line. It was the type of tropical cyclone that rainfall intensity was the strongest as well as influence range was the most extensive. Based on the conceptual model analysis and ingredients method, four kinds of weather conceptual models and the specific threshold value of decision trees were established. As well as, a 24 h short term forecasting tool with forecast accuracy (TS) of persistent rainstorm in northwest Guangxi more than 10% was established by using the products of EC and T639 model.
2013, 39(1):28-38.
DOI: 10.7519/j.issn.1000-0526.2013.01.004
Abstract:
Due to the limitation of data resolution, the understanding of mechanism for precipitation type transition is not deep enough. During the night of March 17, 2012 in Beijing， the precipitation types had gone through three stages of the rain, sleet and snow. By using sounding data, microwave radiometer data and the retrieval results from Doppler radar and mesoscale model, the temperature profiles in 3 precipita tion stages are analyzed and then the mechanism leading to temperature differences is discussed also. The results show that, in snow stage, the depth of ice layer (including snow, ice and supercooled water mixing) becomes thicker and its base is closer to the surface. The main difference of temperature profile for three precipitation stages exists in the lower troposphere, especially around the lifting condensation level. The height of 0℃ level relative to the cloud base is closely related with the precipitation phase. In the rain stage, the 0℃ level is higher than the cloud base; but for the sleet, the 0℃ level goes down below the cloud base when the snow is observed. The cold air causes such difference. However, the way is different. When the rain turns to sleet, the cold air is transported to Beijing by easterly wind. As the result, the boundary layer becomes cooler. However, in sleet to snow stage, the temperature in the lower troposphere reduces further mainly due to the cold air invasion accompanied with a trough passing by. Therefore, the mechanism of precipitation type variety is complicated in Beijing.
Due to the limitation of data resolution, the understanding of mechanism for precipitation type transition is not deep enough. During the night of March 17, 2012 in Beijing， the precipitation types had gone through three stages of the rain, sleet and snow. By using sounding data, microwave radiometer data and the retrieval results from Doppler radar and mesoscale model, the temperature profiles in 3 precipita tion stages are analyzed and then the mechanism leading to temperature differences is discussed also. The results show that, in snow stage, the depth of ice layer (including snow, ice and supercooled water mixing) becomes thicker and its base is closer to the surface. The main difference of temperature profile for three precipitation stages exists in the lower troposphere, especially around the lifting condensation level. The height of 0℃ level relative to the cloud base is closely related with the precipitation phase. In the rain stage, the 0℃ level is higher than the cloud base; but for the sleet, the 0℃ level goes down below the cloud base when the snow is observed. The cold air causes such difference. However, the way is different. When the rain turns to sleet, the cold air is transported to Beijing by easterly wind. As the result, the boundary layer becomes cooler. However, in sleet to snow stage, the temperature in the lower troposphere reduces further mainly due to the cold air invasion accompanied with a trough passing by. Therefore, the mechanism of precipitation type variety is complicated in Beijing.
2013, 39(1):39-45.
DOI: 10.7519/j.issn.1000-0526.2013.01.005
Abstract:
Based on the NCEP / NCAR wind field, specific humidity, surface pressure and precipitation reanalysis data from 1951 to 2010, a cross equatorial moisture transport intensity index is established to characterize the strength of the Somali jet (SMJ), and the seasonal, interannual, decadal variations and mutations of the SMJ cross equatorial moisture transport intensity are studied, while comparing with the traditional SMJ wind speed intensity index. In addition, the relationship between SMJ and the China early summer precipitation is analyzed. Based on the above analysis, the decadal changes of this relationship are revealed. Main results are as follows. After the 1990s, the SMJ wind speed intensity index is weakening, but the SMJ water vapor transport has no significant variations; compared with the SMJ wind speed strength, the SMJ water vapor transmission intensity is associated with the China early summer rainfall more closely. When the SMJ is weaker, rainfall decreased in the Huanghe Huaihe River Basin and North China in early summer, and vice versa. Besides, this correlation has been strengthened in recent 30 years.
Based on the NCEP / NCAR wind field, specific humidity, surface pressure and precipitation reanalysis data from 1951 to 2010, a cross equatorial moisture transport intensity index is established to characterize the strength of the Somali jet (SMJ), and the seasonal, interannual, decadal variations and mutations of the SMJ cross equatorial moisture transport intensity are studied, while comparing with the traditional SMJ wind speed intensity index. In addition, the relationship between SMJ and the China early summer precipitation is analyzed. Based on the above analysis, the decadal changes of this relationship are revealed. Main results are as follows. After the 1990s, the SMJ wind speed intensity index is weakening, but the SMJ water vapor transport has no significant variations; compared with the SMJ wind speed strength, the SMJ water vapor transmission intensity is associated with the China early summer rainfall more closely. When the SMJ is weaker, rainfall decreased in the Huanghe Huaihe River Basin and North China in early summer, and vice versa. Besides, this correlation has been strengthened in recent 30 years.
2013, 39(1):46-56.
DOI: 10.7519/j.issn.1000-0526.2013.01.006
Abstract:
Using the reanalysis data derived from numerical model and the routine observation data, the mutual influence and interaction between the significant circulation systems in the westerlies, subtropics and tropical area during the summer of 2009 were studied by composite and correlation analysis. The complete form of vertical vorticity tendency equation was used to explore the dynamic mechanism for the northward jump and strength maintenance of the subtropical high. The study reveals that the variance of the subtropical high is closely related to the propagation of the westerly wave, and the jump of the west Pacific subtropical high starts at the strengthening of the middle part of subtropical high (140°-160°E); Severe convection over the Bay of Bengal occurred previous to the northward jump of the subtropical high, which has indicative significance to the forecast of the jump and strengthening of the subtropical high. Nevertheless, the convective activities south to the subtropical high have accompanying relationships with the northward jump of subtropical high; meanwhile, from the perspective of dynamic mechanism, the key factor of northward jump of the subtropical high is the variance of the vorticity over East Asia coastal areas, which is caused mainly by the movement of the trough and ridge in middle high latitudes.
Using the reanalysis data derived from numerical model and the routine observation data, the mutual influence and interaction between the significant circulation systems in the westerlies, subtropics and tropical area during the summer of 2009 were studied by composite and correlation analysis. The complete form of vertical vorticity tendency equation was used to explore the dynamic mechanism for the northward jump and strength maintenance of the subtropical high. The study reveals that the variance of the subtropical high is closely related to the propagation of the westerly wave, and the jump of the west Pacific subtropical high starts at the strengthening of the middle part of subtropical high (140°-160°E); Severe convection over the Bay of Bengal occurred previous to the northward jump of the subtropical high, which has indicative significance to the forecast of the jump and strengthening of the subtropical high. Nevertheless, the convective activities south to the subtropical high have accompanying relationships with the northward jump of subtropical high; meanwhile, from the perspective of dynamic mechanism, the key factor of northward jump of the subtropical high is the variance of the vorticity over East Asia coastal areas, which is caused mainly by the movement of the trough and ridge in middle high latitudes.
2013, 39(1):57-66.
DOI: 10.7519/j.issn.1000-0526.2013.01.007
Abstract:
By numerical experiments， the EC cloud fraction schemes (ECFS), the WRF cloud fraction schemes (WCFS), the GRAPES cloud fraction scheme (GCFS) and the simple cloud fraction scheme (SCFS) are compared. The results show that： (1) The cloud coverage is well simulated by all schemes, but the results by ECFS and SCFS are more accurate； (2) The total cloudiness simulation is more than observations in SCFS, that in GCFS and WCFS is less than observations, and that in ECFS is closer to observations； (3) The surface temperature is general agreement between simulations and observations in East China, but the temperature has much error in West China. By contrast, the simulation in ECFS is closer to observations； （4） Based on a comprehensive analysis, ECFS produces a better simulation. Thus ECFS can be used as a reference of a new cloud fraction scheme which would be introduced into GRAPES model.
By numerical experiments， the EC cloud fraction schemes (ECFS), the WRF cloud fraction schemes (WCFS), the GRAPES cloud fraction scheme (GCFS) and the simple cloud fraction scheme (SCFS) are compared. The results show that： (1) The cloud coverage is well simulated by all schemes, but the results by ECFS and SCFS are more accurate； (2) The total cloudiness simulation is more than observations in SCFS, that in GCFS and WCFS is less than observations, and that in ECFS is closer to observations； (3) The surface temperature is general agreement between simulations and observations in East China, but the temperature has much error in West China. By contrast, the simulation in ECFS is closer to observations； （4） Based on a comprehensive analysis, ECFS produces a better simulation. Thus ECFS can be used as a reference of a new cloud fraction scheme which would be introduced into GRAPES model.
2013, 39(1):67-73.
DOI: 10.7519/j.issn.1000-0526.2013.01.008
Abstract:
The characteristics of water vapor conditions of stratiform cloud and its potential for rainfall enhancement in the autumn 2002 in Henan Province have been investigated by means of data from meteorological observation, from upper air soundings at 3 h intervals, and from Ground Based Dual Wavelength Microwave Radiometer (GBDWMR) system and meteorological satellite and combined with the results of MM5V3. It is shown from the analysis of those data that the main positions of potential are located at the 700－300 hPa level at 07:00, 13:00, 16:00 BT moment. As the result of model simulation, it is beneficial for the formation of rain in which the content of supercooled liquid water is abundant while the number concentration of ice crystal is little.
The characteristics of water vapor conditions of stratiform cloud and its potential for rainfall enhancement in the autumn 2002 in Henan Province have been investigated by means of data from meteorological observation, from upper air soundings at 3 h intervals, and from Ground Based Dual Wavelength Microwave Radiometer (GBDWMR) system and meteorological satellite and combined with the results of MM5V3. It is shown from the analysis of those data that the main positions of potential are located at the 700－300 hPa level at 07:00, 13:00, 16:00 BT moment. As the result of model simulation, it is beneficial for the formation of rain in which the content of supercooled liquid water is abundant while the number concentration of ice crystal is little.
2013, 39(1):74-79.
DOI: 10.7519/j.issn.1000-0526.2013.01.009
Abstract:
The sea surface temperature (SST) was retrieved by nonlinear algorithm for Visible and Infra Red Radiometer (VIRR) onboard the Chinese Fengyun 3A (FY 3A) polar orbiting meteorological satellite. In this paper, the matchup dataset was created by the SST measurements from global ship observation and FY 3A/VIRR data in 2010, and the coefficients for the nonlinear SST (NLSST) equation applicable to FY 3A/VIRR data were derived by using multiple linear regression, which could be used to retrieve accurate SST products for FY 3A/VIRR data. An independent matchup dataset was used to assess the accuracy of NLSST algorithm by linear model using a robust least absolute deviation method, and the result showed that the biases were 0.05℃ and -0.05℃ for daytime and nighttime, respectively. The absolute deviation was less than 0.5℃ and the standard deviation was less than 0.65℃. The VIRR SST was calculated by the SST algorithm presented in this paper to contrast with official MODIS SST products, showing that there was a good correlation between VIRR SST and MODIS SST. All these have indicated that the SST algorithm realized in this paper could provide reliable VIRR SST products to ocean and climate variability studies.
The sea surface temperature (SST) was retrieved by nonlinear algorithm for Visible and Infra Red Radiometer (VIRR) onboard the Chinese Fengyun 3A (FY 3A) polar orbiting meteorological satellite. In this paper, the matchup dataset was created by the SST measurements from global ship observation and FY 3A/VIRR data in 2010, and the coefficients for the nonlinear SST (NLSST) equation applicable to FY 3A/VIRR data were derived by using multiple linear regression, which could be used to retrieve accurate SST products for FY 3A/VIRR data. An independent matchup dataset was used to assess the accuracy of NLSST algorithm by linear model using a robust least absolute deviation method, and the result showed that the biases were 0.05℃ and -0.05℃ for daytime and nighttime, respectively. The absolute deviation was less than 0.5℃ and the standard deviation was less than 0.65℃. The VIRR SST was calculated by the SST algorithm presented in this paper to contrast with official MODIS SST products, showing that there was a good correlation between VIRR SST and MODIS SST. All these have indicated that the SST algorithm realized in this paper could provide reliable VIRR SST products to ocean and climate variability studies.
2013, 39(1):80-87.
DOI: 10.7519/j.issn.1000-0526.2013.01.010
Abstract:
The satellite’s 3.7 μm channel is widely used in the retrieval of cloud droplet effective radius. In order to know the effects of cloud droplets’ vertical inhomogeneity on the reflectance of this channel, based on the SBDART radiative transfer scheme, the 3.7 μm reflectance is calculated separately for two particle profiles, the droplet effective radius in the vertical stratified homogeneous distribution and the droplet effective radius in the vertical continuous changing distribution. For the first type, if it is the thin cloud (optical thickness less than 10), there will exist obvious errors when the effective radius of vertical inhomogeneous cloud is retrieved as the vertical homogeneous cloud, and the error decreases with the increase of the optical thickness. If the cloud is thick enough (optical thickness greater than 10), the error will be less than 10%. In this case, we can regard that the changes of cloud droplets’ vertical structure do not influence the reflectance of 3.7 μm channel. For the second type, the results show that when the optical thickness is large, the 3.7 μm reflectance only can be affected by the cloud parameters near the cloud top’s “shallow” part (effective radiation layer， whose optical thickness is about 3-10). There exists negative correlation between the optical thickness of effective radiation layer and the droplet effective radius near cloud top, the solar zenith angle and satellite zenith angle, but there has no obvious relation between the optical thickness and the relative azimuth angle.
The satellite’s 3.7 μm channel is widely used in the retrieval of cloud droplet effective radius. In order to know the effects of cloud droplets’ vertical inhomogeneity on the reflectance of this channel, based on the SBDART radiative transfer scheme, the 3.7 μm reflectance is calculated separately for two particle profiles, the droplet effective radius in the vertical stratified homogeneous distribution and the droplet effective radius in the vertical continuous changing distribution. For the first type, if it is the thin cloud (optical thickness less than 10), there will exist obvious errors when the effective radius of vertical inhomogeneous cloud is retrieved as the vertical homogeneous cloud, and the error decreases with the increase of the optical thickness. If the cloud is thick enough (optical thickness greater than 10), the error will be less than 10%. In this case, we can regard that the changes of cloud droplets’ vertical structure do not influence the reflectance of 3.7 μm channel. For the second type, the results show that when the optical thickness is large, the 3.7 μm reflectance only can be affected by the cloud parameters near the cloud top’s “shallow” part (effective radiation layer， whose optical thickness is about 3-10). There exists negative correlation between the optical thickness of effective radiation layer and the droplet effective radius near cloud top, the solar zenith angle and satellite zenith angle, but there has no obvious relation between the optical thickness and the relative azimuth angle.
2013, 39(1):88-93.
DOI: 10.7519/j.issn.1000-0526.2013.01.011
Abstract:
On the basis of the physiological characteristics of single cropping rice and existing research results, the suitability models in different regions about temperature, precipitation and sunshine are constructed. In order to express the synergetic effect of meteorological factors and yields, a climatic suitability model of single cropping rice is established. According to suitability of single cropping rice in different periods, suitability indicator models on different time scales are set up by two methods. Based on the relationship between climate suitability index and single cropping rice yield, climatic suitability indicators on different time scales are set up. The results indicated that the climatic suitability index constructed by the normalization method is much better than that by the absolute value method. The discrimination of climatic suitability indicators is suitable for measuring the level of single cropping rice yield. Climatic suitability indicators have high evaluation accuracy, thus it can meet the needs of operational services and can be used in evaluating the suitable level of climatic condition on rice growth and yield.
On the basis of the physiological characteristics of single cropping rice and existing research results, the suitability models in different regions about temperature, precipitation and sunshine are constructed. In order to express the synergetic effect of meteorological factors and yields, a climatic suitability model of single cropping rice is established. According to suitability of single cropping rice in different periods, suitability indicator models on different time scales are set up by two methods. Based on the relationship between climate suitability index and single cropping rice yield, climatic suitability indicators on different time scales are set up. The results indicated that the climatic suitability index constructed by the normalization method is much better than that by the absolute value method. The discrimination of climatic suitability indicators is suitable for measuring the level of single cropping rice yield. Climatic suitability indicators have high evaluation accuracy, thus it can meet the needs of operational services and can be used in evaluating the suitable level of climatic condition on rice growth and yield.
2013, 39(1):94-100.
DOI: 10.7519/j.issn.1000-0526.2013.01.012
Abstract:
Climate and energy has an increasingly close relationship and degree day is the simplest and the most reliable index to measure energy demand. Spatial and temporal distribution characteristics of heating and cooling degree days, based on Mann Kendall test, by selecting a set of daily average temperature data in Shandong Province, have been analyzed in this paper. Also, urban heat island effect has been discussed by means of the trend of degree days in Jinan. Results show as follows: （1) Spatial distribution of heating degree days is mainly affected by latitude and topography, average value fluctuating in a range of 2279-2945 ℃·d, while distribution of cooling degree days tends to be related to topography and land sea distribution, average value varying between 1 and 155℃·d. （2) Heating degree days appear to be significant decreasing trends varying between 44.6 and 162.3 ℃·d·（10 a）-1, while cooling degree days at 18 stations present significant increasing trends, ranging between 4.5 and 17.3℃·d·（10 a）-1, no remarkable positive trends observed at the other stations. （3) Heating degree days in the suburb of Jinan are always higher than those in the urban during the period from 1965 to 2010, on the contrary, cooling degree days in the urban are higher in most years of the period. The difference value of heating degree days and cooling degree days between in the urban and in the suburb indicates the highest level in the late 1970s and in the early 1980s and the lowest level in recent years.
Climate and energy has an increasingly close relationship and degree day is the simplest and the most reliable index to measure energy demand. Spatial and temporal distribution characteristics of heating and cooling degree days, based on Mann Kendall test, by selecting a set of daily average temperature data in Shandong Province, have been analyzed in this paper. Also, urban heat island effect has been discussed by means of the trend of degree days in Jinan. Results show as follows: （1) Spatial distribution of heating degree days is mainly affected by latitude and topography, average value fluctuating in a range of 2279-2945 ℃·d, while distribution of cooling degree days tends to be related to topography and land sea distribution, average value varying between 1 and 155℃·d. （2) Heating degree days appear to be significant decreasing trends varying between 44.6 and 162.3 ℃·d·（10 a）-1, while cooling degree days at 18 stations present significant increasing trends, ranging between 4.5 and 17.3℃·d·（10 a）-1, no remarkable positive trends observed at the other stations. （3) Heating degree days in the suburb of Jinan are always higher than those in the urban during the period from 1965 to 2010, on the contrary, cooling degree days in the urban are higher in most years of the period. The difference value of heating degree days and cooling degree days between in the urban and in the suburb indicates the highest level in the late 1970s and in the early 1980s and the lowest level in recent years.
2013, 39(1):101-111.
DOI: 10.7519/j.issn.1000-0526.2013.01.013
Abstract:
A raingauge based local classified average bias adjusted algorithm for radar quantitative precipitation estimate is presented. Based on the elaborate distribution of precipitation with a resolution of 0.01°×0.01° from the proposed algorithm, the meteorological conditions are examined for three flood peak events of Shijiao Catchment (707 km2) in Qijiang, Chongqing Municipality occurring on 28 May 2008， 5 August 2009 and 23 June 2010, respectively. A method of extrapolating lossless runoff series (given all precipitation transforming into runoff) is developed by combining the elaborate distribution of precipitation and the distribution of distance from catchment outlet calculated from DEM (digital elevation model). The results show that: the local classified average bias adjusted algorithm is a better way in the intense rainfall estimate than the local average bias adjusted algorithm. The lossless runoff forecast gives support to alert forecasters to the potential for flash flood.
A raingauge based local classified average bias adjusted algorithm for radar quantitative precipitation estimate is presented. Based on the elaborate distribution of precipitation with a resolution of 0.01°×0.01° from the proposed algorithm, the meteorological conditions are examined for three flood peak events of Shijiao Catchment (707 km2) in Qijiang, Chongqing Municipality occurring on 28 May 2008， 5 August 2009 and 23 June 2010, respectively. A method of extrapolating lossless runoff series (given all precipitation transforming into runoff) is developed by combining the elaborate distribution of precipitation and the distribution of distance from catchment outlet calculated from DEM (digital elevation model). The results show that: the local classified average bias adjusted algorithm is a better way in the intense rainfall estimate than the local average bias adjusted algorithm. The lossless runoff forecast gives support to alert forecasters to the potential for flash flood.
2013, 39(1):112-117.
DOI: 10.7519/j.issn.1000-0526.2013.01.014
Abstract:
Based on acquiring rainflood curve of Zhanghe River Basin and analyzing cases of historical rainstorm flood disaster risk， the disaster critical area rainfall and flood risk water levels of the river basin are obtained: The Gumbel I extreme distribution is used to calculate the area rainfall of different return period, and D8 and Manning’s formulas are also used to calculate the submerged area and depth of areal precipitation from different recurrence interval by GIS rainstorm flood inundation model. According to disaster risk theory， the rainstorm flood disaster risk regionalization of Zhanghe River Basin is done. Meantime， a plot of rainstorm flood disaster risk zoning of Zhongxiang City in Hubei Province is performed， and compared with the actual disaster situation, the flood disaster areas and high risk areas are correspondent. The results show that the method can express flood disasters intuitively, and also reflect the flood disaster risk of the basin and the study areas. It has a clear physical significance.
Based on acquiring rainflood curve of Zhanghe River Basin and analyzing cases of historical rainstorm flood disaster risk， the disaster critical area rainfall and flood risk water levels of the river basin are obtained: The Gumbel I extreme distribution is used to calculate the area rainfall of different return period, and D8 and Manning’s formulas are also used to calculate the submerged area and depth of areal precipitation from different recurrence interval by GIS rainstorm flood inundation model. According to disaster risk theory， the rainstorm flood disaster risk regionalization of Zhanghe River Basin is done. Meantime， a plot of rainstorm flood disaster risk zoning of Zhongxiang City in Hubei Province is performed， and compared with the actual disaster situation, the flood disaster areas and high risk areas are correspondent. The results show that the method can express flood disasters intuitively, and also reflect the flood disaster risk of the basin and the study areas. It has a clear physical significance.
2013, 39(1):118-122.
DOI: 10.7519/j.issn.1000-0526.2013.01.015
Abstract:
The average precipitations were more than normal in northern China in summer 2012. The causes of precipitation anomalies were analyzed. Results showed that more warm and humid water vapor was transported continuously to northern China due to the stronger East Asian summer monsoon and the northward West Pacific subtropical high ridge. While shortwave troughs were in activities in the mid high latitudes over the Eurasia in summer 2012, they brought about more cold airs, and the latter converged with the warm and humid airs from the South China Sea and the East China Sea in northern China, which contributed to the more precipitation above normal in northern China. In addition, early La Ni〖AKn~D〗a event and the PDO cold phase were the external forcing conditions to the precipitation anomalies in northern China.
The average precipitations were more than normal in northern China in summer 2012. The causes of precipitation anomalies were analyzed. Results showed that more warm and humid water vapor was transported continuously to northern China due to the stronger East Asian summer monsoon and the northward West Pacific subtropical high ridge. While shortwave troughs were in activities in the mid high latitudes over the Eurasia in summer 2012, they brought about more cold airs, and the latter converged with the warm and humid airs from the South China Sea and the East China Sea in northern China, which contributed to the more precipitation above normal in northern China. In addition, early La Ni〖AKn~D〗a event and the PDO cold phase were the external forcing conditions to the precipitation anomalies in northern China.
2013, 39(1):123-128.
DOI: 10.7519/j.issn.1000-0526.2013.01.016
Abstract:
The following are the main characteristics of the general atmospheric circulation in October 2012. There was one weak polar vortex center in the Northern Hemisphere. The circulation presents a four wave pattern in middle high latitudes. The meridional circulation is more obviously, the south branch trough and the West Pacific subtropical high are stronger than normal years’. The monthly mean precipitation is 29.1 mm, and is 18.9% less than normal. The monthly mean temperature is 10.3℃, and is equivalent to normal. There were four cold air processes affecting China. Typhoon Son Tinh made landfall in South China and brought a heavy rainfall process. The rainy weather in Southwest China and the autumn drought in South China are continued, but improved in both the mid and late October. Parts of the middle and east of China suffered from fog disasters. The individual parts of China suffered from low temperature freezing damage, local flooding and hail disasters.
The following are the main characteristics of the general atmospheric circulation in October 2012. There was one weak polar vortex center in the Northern Hemisphere. The circulation presents a four wave pattern in middle high latitudes. The meridional circulation is more obviously, the south branch trough and the West Pacific subtropical high are stronger than normal years’. The monthly mean precipitation is 29.1 mm, and is 18.9% less than normal. The monthly mean temperature is 10.3℃, and is equivalent to normal. There were four cold air processes affecting China. Typhoon Son Tinh made landfall in South China and brought a heavy rainfall process. The rainy weather in Southwest China and the autumn drought in South China are continued, but improved in both the mid and late October. Parts of the middle and east of China suffered from fog disasters. The individual parts of China suffered from low temperature freezing damage, local flooding and hail disasters.
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ISSN:1000-0526 CN:11-2282/P