ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 41,Issue 1,2015 Table of Contents
2015, 41(1):1-16.
DOI: 10.7519/j.issn.1000-0526.2015.01.001
Abstract:
Using TRMM data from 1998 to 2011, occurrence frequency of radar precipitation feature (RPF) over Tibetan Plateau (TP), eastern China (EC), west subtropical North America (WNA) and east subtropical North America (ENA) in boreal summer (June-August) are comparatively analyzed. A RPF is defined as a three dimensional object consisting of pixels with precipitation near the ground observed by the TRMM precipitation radar. For each region, RPFs are divided into three groups: all RPF, large RPF (area larger than 1000 km2), and small RPF (area less than or equal to 400 km2). Occurrence frequency of RPF number and occurrence frequency of RPF pixel number in each group over each region are analyzed. The results are as follows: (1) The maximum and minimum occurrence frequencies of RPF number are over TP and ENA, respectively. In contrast, the maximum and minimum occurrence frequencies of RPF pixel number are over EC and TP, respectively. (2) Diurnal variations of occurrence frequency of RPF over the four regions mainly present a single peak in afternoon to late afternoon, with the peak of the large RPF appearing later than that of the small RPF. In contrast, diurnal variation of occurrence frequency of RPF pixel number over EC presents double peaks. (3) Diurnal variations of occurrence frequency of RPF pixel number are consistent with those of rainfall based on rain gauge observations in previous literature.
Using TRMM data from 1998 to 2011, occurrence frequency of radar precipitation feature (RPF) over Tibetan Plateau (TP), eastern China (EC), west subtropical North America (WNA) and east subtropical North America (ENA) in boreal summer (June-August) are comparatively analyzed. A RPF is defined as a three dimensional object consisting of pixels with precipitation near the ground observed by the TRMM precipitation radar. For each region, RPFs are divided into three groups: all RPF, large RPF (area larger than 1000 km2), and small RPF (area less than or equal to 400 km2). Occurrence frequency of RPF number and occurrence frequency of RPF pixel number in each group over each region are analyzed. The results are as follows: (1) The maximum and minimum occurrence frequencies of RPF number are over TP and ENA, respectively. In contrast, the maximum and minimum occurrence frequencies of RPF pixel number are over EC and TP, respectively. (2) Diurnal variations of occurrence frequency of RPF over the four regions mainly present a single peak in afternoon to late afternoon, with the peak of the large RPF appearing later than that of the small RPF. In contrast, diurnal variation of occurrence frequency of RPF pixel number over EC presents double peaks. (3) Diurnal variations of occurrence frequency of RPF pixel number are consistent with those of rainfall based on rain gauge observations in previous literature.
2015, 41(1):17-24.
DOI: 10.7519/j.issn.1000-0526.2015.01.002
Abstract:
Based on the 2005-2012 hourly precipitation data from two national meteorological stations on the east and west sides of Diancang Mountain, a part of Hengduan Mountains’ ranges, precipitation characteristics on each side and differences between them have been analyzed in detail. The results show that the climate states of average precipitation, annual precipitation and seasonal evolution on both sides are similar, but there are visible differences of the diurnal variations of precipitation between the east and west sides. The diurnal variation of rainfall amount and rainfall frequency presents a single peak curve on the east side, but significant double peaks are clear on another side. The two sides’ rainfall amount and rainfall frequency show peaks in late night which are mainly caused by long duration rainfall events lasting over 6 hours. The peaks of west side’s rainfall amount and rainfall frequency appear from afternoon to dusk, which are always derived from the contribution of rainfall events lasting less than 6 hours in duration. The accumulated rainfall amount and rainfall frequency reach the maximum in early morning on each side, but the occurrence time on the east side lags behind about 3 hours to the west side. The minimum of the accumulated rainfall amount at dusk on the east side appears, but on the west side it always occurs at noon while the minimum of the accumulated rainfall frequency on each side happens at around noon. The diurnal variation of hourly rain intensity on the west side is bigger than the west side, especially at night. The hourly rain on the west has two intensive periods (21:00 and 03:00 04:00), but it has slow diurnal variation on the east, getting to the maximum from 07:00 to 08:00. The difference of hourly precipitation between two sides is undoubtedly affected by the geography of Diancang Mountain. Due to the topography, the difference of the surface radiation on the east and west sides reaches the maximum at dusk, leading to a peak about rainfall amount and rainfall frequency, and hourly rain intensity on the west side. The inhomogeneity of rainfall distribution in Diancang Mountain area makes it become a typical representative to study the regional differences of climate in Southwest China with complex topography.
Based on the 2005-2012 hourly precipitation data from two national meteorological stations on the east and west sides of Diancang Mountain, a part of Hengduan Mountains’ ranges, precipitation characteristics on each side and differences between them have been analyzed in detail. The results show that the climate states of average precipitation, annual precipitation and seasonal evolution on both sides are similar, but there are visible differences of the diurnal variations of precipitation between the east and west sides. The diurnal variation of rainfall amount and rainfall frequency presents a single peak curve on the east side, but significant double peaks are clear on another side. The two sides’ rainfall amount and rainfall frequency show peaks in late night which are mainly caused by long duration rainfall events lasting over 6 hours. The peaks of west side’s rainfall amount and rainfall frequency appear from afternoon to dusk, which are always derived from the contribution of rainfall events lasting less than 6 hours in duration. The accumulated rainfall amount and rainfall frequency reach the maximum in early morning on each side, but the occurrence time on the east side lags behind about 3 hours to the west side. The minimum of the accumulated rainfall amount at dusk on the east side appears, but on the west side it always occurs at noon while the minimum of the accumulated rainfall frequency on each side happens at around noon. The diurnal variation of hourly rain intensity on the west side is bigger than the west side, especially at night. The hourly rain on the west has two intensive periods (21:00 and 03:00 04:00), but it has slow diurnal variation on the east, getting to the maximum from 07:00 to 08:00. The difference of hourly precipitation between two sides is undoubtedly affected by the geography of Diancang Mountain. Due to the topography, the difference of the surface radiation on the east and west sides reaches the maximum at dusk, leading to a peak about rainfall amount and rainfall frequency, and hourly rain intensity on the west side. The inhomogeneity of rainfall distribution in Diancang Mountain area makes it become a typical representative to study the regional differences of climate in Southwest China with complex topography.
2015, 41(1):25-33.
DOI: 10.7519/j.issn.1000-0526.2015.01.003
Abstract:
Using conventional and intense automatic observation, CINRAD/SA and wind profiler radar data, the environmental conditions, structures and evolution of two supercell storms are analyzed. The results are as follows: (1) Favorable conditions for the severe convective weather process are large vertical wind shear, high level cold and low level warm, high level dry and low level moist, right height of 0℃ and -20℃ layer and large convective available potential energy (CAPE). The trigger of the severe convective weather is low pressure on surface, convergence line, low level frontal zone. (2) The common characteristics of the two supercell storms are three body scatter, weak echo areas, stronger echo intensity, VIL density value over 4 kg·m-3, and moving rightward 30° with upper wind in the mature stage. (3) The meso cyclone of long life supercell storm Ⅱ lasts more than 2 h, strong updraft causes hails to grow, and storm Ⅱ lasts 6 h. At the same time, high level divergence is longer. Meso cyclone of supercell storm Ⅰ lasts only 18 min, high level divergence and updraft are weak, and their lives are short. These differences are closely bound up with the environmental conditions such as vertical wind shear and vertical vorticity.
Using conventional and intense automatic observation, CINRAD/SA and wind profiler radar data, the environmental conditions, structures and evolution of two supercell storms are analyzed. The results are as follows: (1) Favorable conditions for the severe convective weather process are large vertical wind shear, high level cold and low level warm, high level dry and low level moist, right height of 0℃ and -20℃ layer and large convective available potential energy (CAPE). The trigger of the severe convective weather is low pressure on surface, convergence line, low level frontal zone. (2) The common characteristics of the two supercell storms are three body scatter, weak echo areas, stronger echo intensity, VIL density value over 4 kg·m-3, and moving rightward 30° with upper wind in the mature stage. (3) The meso cyclone of long life supercell storm Ⅱ lasts more than 2 h, strong updraft causes hails to grow, and storm Ⅱ lasts 6 h. At the same time, high level divergence is longer. Meso cyclone of supercell storm Ⅰ lasts only 18 min, high level divergence and updraft are weak, and their lives are short. These differences are closely bound up with the environmental conditions such as vertical wind shear and vertical vorticity.
2015, 41(1):34-44.
DOI: 10.7519/j.issn.1000-0526.2015.01.004
Abstract:
Two cold air events that happened in Qiongzhou Channel were modeled by mesoscale dynamic model WRF and diagnostic model CALMET, and the research focuses on the near surface wind. Horizontal grid spaces of four nests in WRF model are 27 km, 9 km, 3 km and 1 km respectively. The fourth nest with 1 km grid space of CALMET and the fifth nest in WRF is set as model initial field for down grid space to 200 m, so as to get the final field which is able to fulfill the resolution required. Wind speed and direction of CALMET 200 m, WRF 1 km and WRF 200 m are contrasted with the observed winds at 21 observing stations (including 6 anemometer towers) distributed in the two sides of the Qiongzhou Channel. The main conclusions are as follows: (1) CALMET 200 m speed RMSE is much less than the two other experiments with time going, but there is not any notable difference in wind direction RMSE. In the height of 60-80 m, RMSE can not show any difference in wind direction, either. (2) At 10 m height, CALMET 200 m wind is diagnosed to be the best with the average error varing from 4 m·s-1 to 0 m·s-1. The average errors of the other two experiments are about 2 m·s-1 bigger than CALMET 200 m. The distribution of errors is more concentrated in direction. In 60-80 m height, the three experiments have almost the same results. But the result of WRF 200 m wind speed shows worse than the results of the other two experiments, while not differences in wind direction are found in the three experiments. (3) Smaller wind speed and direction average errors of WRF/CALMET system in non cold air condition show that the system can perform better when the atmospheric stratification is relatively stable.
Two cold air events that happened in Qiongzhou Channel were modeled by mesoscale dynamic model WRF and diagnostic model CALMET, and the research focuses on the near surface wind. Horizontal grid spaces of four nests in WRF model are 27 km, 9 km, 3 km and 1 km respectively. The fourth nest with 1 km grid space of CALMET and the fifth nest in WRF is set as model initial field for down grid space to 200 m, so as to get the final field which is able to fulfill the resolution required. Wind speed and direction of CALMET 200 m, WRF 1 km and WRF 200 m are contrasted with the observed winds at 21 observing stations (including 6 anemometer towers) distributed in the two sides of the Qiongzhou Channel. The main conclusions are as follows: (1) CALMET 200 m speed RMSE is much less than the two other experiments with time going, but there is not any notable difference in wind direction RMSE. In the height of 60-80 m, RMSE can not show any difference in wind direction, either. (2) At 10 m height, CALMET 200 m wind is diagnosed to be the best with the average error varing from 4 m·s-1 to 0 m·s-1. The average errors of the other two experiments are about 2 m·s-1 bigger than CALMET 200 m. The distribution of errors is more concentrated in direction. In 60-80 m height, the three experiments have almost the same results. But the result of WRF 200 m wind speed shows worse than the results of the other two experiments, while not differences in wind direction are found in the three experiments. (3) Smaller wind speed and direction average errors of WRF/CALMET system in non cold air condition show that the system can perform better when the atmospheric stratification is relatively stable.
2015, 41(1):45-51.
DOI: 10.7519/j.issn.1000-0526.2015.01.005
Abstract:
This study aims at assessing the predictability capacity of the Global Forecasting System (GFS) for the atmospheric circulation features and precipitation over East Asia during 11-31 July 2012 by using the GFS data and the extracted components of long wave and ultra long wave via the harmonic filtering. The results show that the GFS model can predict the mid and lower heights over East Asia with reliable lead time of 6 d, and up to 10 d for the higher heights. The predictability for long wave and ultra long wave components is more significant, of which the 5-8 wave band forecast is better than the 3-6 wave one in terms of the forecasting skill for height. However, the forecast result is reversed for the wind filed. In addition, the predictability of the model for the two persistent rainfalls maintains 8 d or so, and moreover it can tell the location of severe rainfall band ahead of 2 d. In general, the GFS model is stronger in forecasting the persistent precipitation process than the observed fields.
This study aims at assessing the predictability capacity of the Global Forecasting System (GFS) for the atmospheric circulation features and precipitation over East Asia during 11-31 July 2012 by using the GFS data and the extracted components of long wave and ultra long wave via the harmonic filtering. The results show that the GFS model can predict the mid and lower heights over East Asia with reliable lead time of 6 d, and up to 10 d for the higher heights. The predictability for long wave and ultra long wave components is more significant, of which the 5-8 wave band forecast is better than the 3-6 wave one in terms of the forecasting skill for height. However, the forecast result is reversed for the wind filed. In addition, the predictability of the model for the two persistent rainfalls maintains 8 d or so, and moreover it can tell the location of severe rainfall band ahead of 2 d. In general, the GFS model is stronger in forecasting the persistent precipitation process than the observed fields.
2015, 41(1):52-58.
DOI: 10.7519/j.issn.1000-0526.2015.01.006
Abstract:
Thermal convective precipitation (TCP) is a usual weather phenomenon under subtropical high. TCP always occurs suddenly with small temporal and spacial scales, and it is a difficult point in the current weather forecasting operations. In this article, the convective temperature (Tc) is used to forecast TCP. First, the algorithm of Tc in MICAPS 3 is improved, and then the sounding and surface observation data from Nanjing Station in July and August during 2004-2013 are used to discuss the feasibility of forcasting TCP depending on Tc under the control of subtropical high. The results show that, the average probability of TCP occurrence at Nanjing Station is 1/6. The probability of TCP occurrence increases and then decreases with the change of temperature difference between the day high temperature Tmax and Tc. When Tmax-Tc is smaller than -0.5℃, the probability of occurrence is lower than average probability. When Tmax-Tc is 0.5 to 1.5℃, the probability of TCP occurrence is the highest, reaching 40%. The two requirements for TCP occurrence under the control of subtropical high are Tmax > 30℃ and Tmax-Tc > -3.5℃. In addition, statistics of 34 TCP cases show that TCP mainly occurs from 13:00-18:00 BT every day and its duration is 50 min averagely with the mean precipitation being 7.8 mm.
Thermal convective precipitation (TCP) is a usual weather phenomenon under subtropical high. TCP always occurs suddenly with small temporal and spacial scales, and it is a difficult point in the current weather forecasting operations. In this article, the convective temperature (Tc) is used to forecast TCP. First, the algorithm of Tc in MICAPS 3 is improved, and then the sounding and surface observation data from Nanjing Station in July and August during 2004-2013 are used to discuss the feasibility of forcasting TCP depending on Tc under the control of subtropical high. The results show that, the average probability of TCP occurrence at Nanjing Station is 1/6. The probability of TCP occurrence increases and then decreases with the change of temperature difference between the day high temperature Tmax and Tc. When Tmax-Tc is smaller than -0.5℃, the probability of occurrence is lower than average probability. When Tmax-Tc is 0.5 to 1.5℃, the probability of TCP occurrence is the highest, reaching 40%. The two requirements for TCP occurrence under the control of subtropical high are Tmax > 30℃ and Tmax-Tc > -3.5℃. In addition, statistics of 34 TCP cases show that TCP mainly occurs from 13:00-18:00 BT every day and its duration is 50 min averagely with the mean precipitation being 7.8 mm.
2015, 41(1):59-67.
DOI: 10.7519/j.issn.1000-0526.2015.01.007
Abstract:
Analyses and descriptions of the hydrometeorological conditions that contributed to two flood events in the Qiongjiang River Basin from 3 to 5 July 2012 (“7.4”) and from 30 June to 1 July 2013 (“6.30”) are presented. The digital elevation model (DEM) is used to extract the distribution network of Qiongjiang River and its distance to the outlet, and the standard time distance objectively reflects the temporal and spatial distribution of precipitation (especially severe precipitation). Composite reflectivity mosaic from SWAN suggests that the heavy precipitation is caused by multiple extreme rainfall bands in both of the flood events, and the convective systems mainly initiates in the headstreams of the right tributaries moving northeastward slowly down the tributaries and producing flood overlap in Qiongjiang River stem. Since basin wide severe radar echo persists over the Qiongjiang River Basin for about 16 h, serious flood overlap is significant in the “6.30” case, resulting in the flood overflowing in the bank and forming a large area of flood detention basin. When the flood gets to downstream and returns to the river channel, the runway gets narrowed, so the flood peak time at the Taian Hydrological Station is late.
Analyses and descriptions of the hydrometeorological conditions that contributed to two flood events in the Qiongjiang River Basin from 3 to 5 July 2012 (“7.4”) and from 30 June to 1 July 2013 (“6.30”) are presented. The digital elevation model (DEM) is used to extract the distribution network of Qiongjiang River and its distance to the outlet, and the standard time distance objectively reflects the temporal and spatial distribution of precipitation (especially severe precipitation). Composite reflectivity mosaic from SWAN suggests that the heavy precipitation is caused by multiple extreme rainfall bands in both of the flood events, and the convective systems mainly initiates in the headstreams of the right tributaries moving northeastward slowly down the tributaries and producing flood overlap in Qiongjiang River stem. Since basin wide severe radar echo persists over the Qiongjiang River Basin for about 16 h, serious flood overlap is significant in the “6.30” case, resulting in the flood overflowing in the bank and forming a large area of flood detention basin. When the flood gets to downstream and returns to the river channel, the runway gets narrowed, so the flood peak time at the Taian Hydrological Station is late.
2015, 41(1):68-75.
DOI: 10.7519/j.issn.1000-0526.2015.01.008
Abstract:
With the development of automation of meteorological data, pyrheliometer which can automatically track solar position to observe sunshine duration has been gradually used in meteorological operations. It is necessary to quantitatively evaluate the difference between pyrheliometer and sunshine recorder observations. This paper discusses the differences between pyrheliometer and sunshine recorder observations over different regions, seasons and time scales. The results are as follows: (1) The sunshine duration observed by pyrheliometer is 0.51 h·d-1 (8.30%) less than that by sunshine recorder. The difference has obvious seasonal and regional variations, which are larger in summer and spring, but the minimum in winter, and also larger in Northwest and Hainan, but the least in Northeast, Huang Huai and Sichuan Basin. (2) Pyrheliometer observation is about 0-0.3 h·h-1 less than sunshine recorder observation at sunrise, and 0-0.3 h·h-1 larger than sunshine recorder observation at sunset while the difference is between ±0.2 h·h-1 in other hours. (3) Affected by observing instruments and weather conditions, the difference between two kinds of sunshine durations are -0.17 h·d-1 (-1.88%) under clear sky conditions, -0.64 h·d-1 (-9.08%) under cloudy conditions, and -0.62 h·d-1 (-26.73%) under overcast conditions. (4) The correlation coefficient between the two kinds of sunshine durations is above 0.88.
With the development of automation of meteorological data, pyrheliometer which can automatically track solar position to observe sunshine duration has been gradually used in meteorological operations. It is necessary to quantitatively evaluate the difference between pyrheliometer and sunshine recorder observations. This paper discusses the differences between pyrheliometer and sunshine recorder observations over different regions, seasons and time scales. The results are as follows: (1) The sunshine duration observed by pyrheliometer is 0.51 h·d-1 (8.30%) less than that by sunshine recorder. The difference has obvious seasonal and regional variations, which are larger in summer and spring, but the minimum in winter, and also larger in Northwest and Hainan, but the least in Northeast, Huang Huai and Sichuan Basin. (2) Pyrheliometer observation is about 0-0.3 h·h-1 less than sunshine recorder observation at sunrise, and 0-0.3 h·h-1 larger than sunshine recorder observation at sunset while the difference is between ±0.2 h·h-1 in other hours. (3) Affected by observing instruments and weather conditions, the difference between two kinds of sunshine durations are -0.17 h·d-1 (-1.88%) under clear sky conditions, -0.64 h·d-1 (-9.08%) under cloudy conditions, and -0.62 h·d-1 (-26.73%) under overcast conditions. (4) The correlation coefficient between the two kinds of sunshine durations is above 0.88.
2015, 41(1):76-83.
DOI: 10.7519/j.issn.1000-0526.2015.01.009
Abstract:
Based on the GIS secondary development techniques VB (Visual Basic) and MO (Map Objects), an applicative method is proposed, that is, the scope, area and precipitation volume of an irregular influence area of cloud seeding catalytic agent during aircraft rain enhancement activity is calculated objectively while considering the two dimensional line source diffusion equation. This method is applied in the technique system on the statistical assessment on aircraft rain enhancement effect conducted by CA FCM method (Cluster Analysis based Floating Control historical regression Method). A real case of aircraft rain enhancement activity in Jilin Province is evaluated and its results are discussed to introduce the specific application.
Based on the GIS secondary development techniques VB (Visual Basic) and MO (Map Objects), an applicative method is proposed, that is, the scope, area and precipitation volume of an irregular influence area of cloud seeding catalytic agent during aircraft rain enhancement activity is calculated objectively while considering the two dimensional line source diffusion equation. This method is applied in the technique system on the statistical assessment on aircraft rain enhancement effect conducted by CA FCM method (Cluster Analysis based Floating Control historical regression Method). A real case of aircraft rain enhancement activity in Jilin Province is evaluated and its results are discussed to introduce the specific application.
2015, 41(1):84-91.
DOI: 10.7519/j.issn.1000-0526.2015.01.010
Abstract:
How to use the echo changes of new generation of weather radar before and after the operation in assess ment the result of artificial precipitation enhancement is very important for improving the scientificity of weather modification. In this paper, the method of tracking the seeding coverage based on both maximum correlation coefficients (TREC) and a new generation of weather radar three dimensional CAPPI grid data is realized by considering multiple effective duration and the seeding coverage in artificial precipitation enhancement by antiaircraft guns and aircraft. Meanwhile, the echo parameters such as maximum reflectivity, VIL, etc., are calculated. Besides, the paper also analyzes the rationality of echo tracking method by using two precipitation processes and continuously tracking the related areas. One artificial precipitation enhancement operation by antiaircraft guns in Beijing and one artificial precipitation enhancement simulated by aircraft are chosen to track the seeding coverage. The result indicates that using the algorithm TREC, we can track the echoes reasonablely in both vertical and horizontal positions in space, and also can track well the echo change in seeding coverage during artificial precipitation enhancement operations by single or several antiaircraft guns and aircraft. So, the work provides a meaningful scientific reference for the assessment of artificial precipitation enhancement.
How to use the echo changes of new generation of weather radar before and after the operation in assess ment the result of artificial precipitation enhancement is very important for improving the scientificity of weather modification. In this paper, the method of tracking the seeding coverage based on both maximum correlation coefficients (TREC) and a new generation of weather radar three dimensional CAPPI grid data is realized by considering multiple effective duration and the seeding coverage in artificial precipitation enhancement by antiaircraft guns and aircraft. Meanwhile, the echo parameters such as maximum reflectivity, VIL, etc., are calculated. Besides, the paper also analyzes the rationality of echo tracking method by using two precipitation processes and continuously tracking the related areas. One artificial precipitation enhancement operation by antiaircraft guns in Beijing and one artificial precipitation enhancement simulated by aircraft are chosen to track the seeding coverage. The result indicates that using the algorithm TREC, we can track the echoes reasonablely in both vertical and horizontal positions in space, and also can track well the echo change in seeding coverage during artificial precipitation enhancement operations by single or several antiaircraft guns and aircraft. So, the work provides a meaningful scientific reference for the assessment of artificial precipitation enhancement.
11 Study on Adaptability of Meteorological High Performance Computing Application Services Environment
2015, 41(1):92-97.
DOI: 10.7519/j.issn.1000-0526.2015.01.011
Abstract:
With the continuous development of meteorological numerical models, the demand for high performance computing services sees a drastic increase. In order to provide a stable and efficient application platform, we carry out tasks for establishing and implementing meteorological high performance computing application service environment. This article conducts thorough analysis of application requirements and explains the design, planning and initial implementation of service environment building programs, including unified planning of system and application process, component based software framework and a rich set of tools, and provide strong technical support for the development of meteorological numerical model operations and research work.
With the continuous development of meteorological numerical models, the demand for high performance computing services sees a drastic increase. In order to provide a stable and efficient application platform, we carry out tasks for establishing and implementing meteorological high performance computing application service environment. This article conducts thorough analysis of application requirements and explains the design, planning and initial implementation of service environment building programs, including unified planning of system and application process, component based software framework and a rich set of tools, and provide strong technical support for the development of meteorological numerical model operations and research work.
XIONG Yajun
,
LIAO Xiaonong
,
LI Ziming
,
ZHANG Xiaoling
,
SUN Zhaobin
,
ZHAO Xiujuan
,
ZHAO Pusheng
,
MA Xiaohui
,
PU Weiwei
2015, 41(1):98-104.
DOI: 10.7519/j.issn.1000-0526.2015.01.012
Abstract:
Based on meteorological data and PM2.5 concentration data of 2013， the statistical analysis shows that temperature, pressure, relative humidity, dew point temperature, surface wind, U wind， V wind and PM2.5 hourly concentration are the 7 key factors affecting the haze grade of Beijing Area. The attribute vectors of KNN training sample set are the above 7 factors and the label vector is haze grade. The classifier can be established combining KNN Data Mining Algorithm and its best value is parameter K=3. The classification accuracy of the 13 meteorological stations is 88.2%. The forecasting model based on KNN Algorithm has good accuracy. When it predicts no haze, the accuracy rate is 91.8% and missing forecast chance is very small. When mild, moderate or severe haze is predicted, the probability of empty forecast is only 4.7%, 1.4% and 2.6%, respectively. There was one frog haze weather process from 29 August to 2 September 2014 in Beijing Area. Its prediction results show the forecast accuracy of Nanjiao, Miyun and Yanqing is 74%, 64% and 84% respectively, but the accuracy of the haze grade remains to be further improved.
Based on meteorological data and PM2.5 concentration data of 2013， the statistical analysis shows that temperature, pressure, relative humidity, dew point temperature, surface wind, U wind， V wind and PM2.5 hourly concentration are the 7 key factors affecting the haze grade of Beijing Area. The attribute vectors of KNN training sample set are the above 7 factors and the label vector is haze grade. The classifier can be established combining KNN Data Mining Algorithm and its best value is parameter K=3. The classification accuracy of the 13 meteorological stations is 88.2%. The forecasting model based on KNN Algorithm has good accuracy. When it predicts no haze, the accuracy rate is 91.8% and missing forecast chance is very small. When mild, moderate or severe haze is predicted, the probability of empty forecast is only 4.7%, 1.4% and 2.6%, respectively. There was one frog haze weather process from 29 August to 2 September 2014 in Beijing Area. Its prediction results show the forecast accuracy of Nanjiao, Miyun and Yanqing is 74%, 64% and 84% respectively, but the accuracy of the haze grade remains to be further improved.
2015, 41(1):105-112.
DOI: 10.7519/j.issn.1000-0526.2015.01.013
Abstract:
Based on daily precipitation data from June to August during 1961-2013 from 77 weather stations, using the methods of precipitation concentration period, precipitation concentration degree and statistical regression, this paper studies the distribution and variation of the main flood season precipitation and the comparison between 2013 and 1998, and analyses influence of abnormal precipitation on crop yield. The results show that rain days in 2013 are more than other years in Heilongjiang. A wide range of continuous heavy rain is more intensive and earlier. The precipitation is abnormally more, getting to the extreme value in the past 53 years. There aren’t obvious spatial change characteristics in longitude or latitude. The areas with most precipitation are in Songnen Plain while the less rainfall areas are along the river basin. The temporal variation is in the style of less more less. The concentrated period of the severe rainfall is the first dekad of July, when the most precipitation is collected during the whole flood season. There are differences in temporal spatial distributions of precipitation in main flood season between 2013 and 1998.The amount and duration of precipitation in 2013 exceed the previous peaks in 1998, especially in Heilong River Valley. However the rainfall has some local features and sudden ones in 1998. By using FY 3A/MERSI satellite data and WOFOST crop model, this paper consistently monitors flooded crop planting area, and simulates crop yield in flooded regions, and on the basis of this, this paper evaluates the crop production losses. The sum of losses is 3.97×109 kg.
Based on daily precipitation data from June to August during 1961-2013 from 77 weather stations, using the methods of precipitation concentration period, precipitation concentration degree and statistical regression, this paper studies the distribution and variation of the main flood season precipitation and the comparison between 2013 and 1998, and analyses influence of abnormal precipitation on crop yield. The results show that rain days in 2013 are more than other years in Heilongjiang. A wide range of continuous heavy rain is more intensive and earlier. The precipitation is abnormally more, getting to the extreme value in the past 53 years. There aren’t obvious spatial change characteristics in longitude or latitude. The areas with most precipitation are in Songnen Plain while the less rainfall areas are along the river basin. The temporal variation is in the style of less more less. The concentrated period of the severe rainfall is the first dekad of July, when the most precipitation is collected during the whole flood season. There are differences in temporal spatial distributions of precipitation in main flood season between 2013 and 1998.The amount and duration of precipitation in 2013 exceed the previous peaks in 1998, especially in Heilong River Valley. However the rainfall has some local features and sudden ones in 1998. By using FY 3A/MERSI satellite data and WOFOST crop model, this paper consistently monitors flooded crop planting area, and simulates crop yield in flooded regions, and on the basis of this, this paper evaluates the crop production losses. The sum of losses is 3.97×109 kg.
2015, 41(1):113-120.
DOI: 10.7519/j.issn.1000-0526.2015.01.014
Abstract:
Doppler weather radar VAD wind profile (VWP) products are widely used in operational forecast, and the corresponding relations between the wind profile structure characteristics and the thunderstorm, and severe convection have been achieved. Not knowing much about the VAD algorithm of wind profile products which are got by retrieving the radial velocity of Doppler radar, there are still some errors in using VWP and velocity azimuth display (VAD) products. In this paper, based on the basic principle of single Doppler radar wind field retrieval, VWP and VAD products applications in heavy rain forecasting and severe convection nowcasting are reviewed, and operational application errors of VWP and VAD products are emphatically discussed.
Doppler weather radar VAD wind profile (VWP) products are widely used in operational forecast, and the corresponding relations between the wind profile structure characteristics and the thunderstorm, and severe convection have been achieved. Not knowing much about the VAD algorithm of wind profile products which are got by retrieving the radial velocity of Doppler radar, there are still some errors in using VWP and velocity azimuth display (VAD) products. In this paper, based on the basic principle of single Doppler radar wind field retrieval, VWP and VAD products applications in heavy rain forecasting and severe convection nowcasting are reviewed, and operational application errors of VWP and VAD products are emphatically discussed.
2015, 41(1):121-125.
DOI: 10.7519/j.issn.1000-0526.2015.01.015
Abstract:
In summer 2014, the surface air temperature averaged over China was 21.1℃, which is 0.2℃ above normal. The mean precipitation over China was 320.1 mm, which was less than normal by 1.6%, and its spatial distribution shows the significant feature of less in the north but more in the south. The average rainfall over the Huanghe River and Huaihe River region was minimum in historic records tied for the same period in 1999. Further analysis on the summer rainfall anomaly shows that the summer precipitation anomaly in China is because the East Asian summer monsoon was weaker and the Northwest Pacific subtropical high was stronger and further southward than normal. Warm Indian Ocean SST and the El Nino condition jointly resulted in continued stronger and southward Northwest Pacific subtropical high. The two parts were important external forcing conditions for abnormal rainfall.
In summer 2014, the surface air temperature averaged over China was 21.1℃, which is 0.2℃ above normal. The mean precipitation over China was 320.1 mm, which was less than normal by 1.6%, and its spatial distribution shows the significant feature of less in the north but more in the south. The average rainfall over the Huanghe River and Huaihe River region was minimum in historic records tied for the same period in 1999. Further analysis on the summer rainfall anomaly shows that the summer precipitation anomaly in China is because the East Asian summer monsoon was weaker and the Northwest Pacific subtropical high was stronger and further southward than normal. Warm Indian Ocean SST and the El Nino condition jointly resulted in continued stronger and southward Northwest Pacific subtropical high. The two parts were important external forcing conditions for abnormal rainfall.
2015, 41(1):126-132.
DOI: 10.7519/j.issn.1000-0526.2015.01.016
Abstract:
The main characteristics of the general atmospheric circulation in October 2014 are as follows: There was one polar vortex center in Northern Hemisphere. In the middle high latitudes, the circulation presented a five wave pattern. The southern trough was to the north and the subtropical high was almost same as its climatological mean. Meanwhile, monthly mean precipitation amount was 29.5 mm, which is 17.7% less than its climatological mean (35.8 mm). Monthly mean temperature was 11.2℃, which is 0.9℃ higher than its climatological mean (10.3℃). 51 stations observed extreme temperature drop events in one day in the south of Gansu, the east of Northeast and the Beijing Tianjin Hebei Region and 17 stations had events of extremely continuous drop in temperature in the east of Northeast. There were three severe rainfall processes, of which Hainan, Sichuan Basin, Guizhou to the middle and lower reaches of Changjiang River had heavy to torrential rains and some local areas had rainstorm to downpours from 27 to 31 October. Cold air was weak in October and only two cold air processes influenced China. Wide range of fog and haze weather appeared in central and eastern China 4 times. Moderate meteorological droughts were found in Jiangxi, the south and east of Hunan, the most part of Guangdong, the south and west of Fujian and the east of Guangxi.
The main characteristics of the general atmospheric circulation in October 2014 are as follows: There was one polar vortex center in Northern Hemisphere. In the middle high latitudes, the circulation presented a five wave pattern. The southern trough was to the north and the subtropical high was almost same as its climatological mean. Meanwhile, monthly mean precipitation amount was 29.5 mm, which is 17.7% less than its climatological mean (35.8 mm). Monthly mean temperature was 11.2℃, which is 0.9℃ higher than its climatological mean (10.3℃). 51 stations observed extreme temperature drop events in one day in the south of Gansu, the east of Northeast and the Beijing Tianjin Hebei Region and 17 stations had events of extremely continuous drop in temperature in the east of Northeast. There were three severe rainfall processes, of which Hainan, Sichuan Basin, Guizhou to the middle and lower reaches of Changjiang River had heavy to torrential rains and some local areas had rainstorm to downpours from 27 to 31 October. Cold air was weak in October and only two cold air processes influenced China. Wide range of fog and haze weather appeared in central and eastern China 4 times. Moderate meteorological droughts were found in Jiangxi, the south and east of Hunan, the most part of Guangdong, the south and west of Fujian and the east of Guangxi.
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ISSN:1000-0526 CN:11-2282/P