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29 June 2013, Volume 29 Issue 3 Previous Issue    Next Issue

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Numerical simulation on a convective stratiform mixed cloud process in Northeastern China HUANG Tian-ge,LI Yan-wei,WANG Ji-hong 2013, 29 (3):  1-7.  Abstract ( 355 )   PDF (2962KB) ( 436 )   Save The convective stratiform cloud is one of the main types of precipitation cloud in China, and its dynamic and thermal characteristics are more complicated than that of the single stratiform cloud or convective cloud. Based on the NCEP reanalysis data with 1°×1° spatial resolution, a typical convective stratiform cloud process in the Northeast China was simulated using the WRF model. The results show that this process belongs to a potential instability type  according to an analysis of the stability. The convective available potential energy (CAPE) is not large at the initial phase in the formation of the convective stratiform cloud, and θse decreases with the height increase, which is favorable to the development of the convection. The change of water vapor convergence at the lower levels and divergence  at the upper levels plays a dominant role when the convective cloud embeds the stratiform cloud. The thermal effect creates the conditions for this process and the dynamic factor plays a main role. Related Articles | Metrics

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Numerical simulation on a return-flow snowstorm process in Hebei province SONG Xiao-hui,TIAN Li-qing,TIAN Xiu-xia,MA Hong-qing,ZHANG Gong-wen,DONG Fang-liang 2013, 29 (3):  8-14.  Abstract ( 442 )   PDF (2613KB) ( 471 )   Save Using the WRFV3.2.1 mesoscale numerical model, a return-flow snowstorm process occurred on November 9-12, 2009 in Hebei province was analyzed based on the 1°×1°NCEP-FNL reanalysis data four times a day. The characters of the return-flow snowstorm and its physical mechanism were discussed according to the products from the above model. The results indicate that the surface ground is cold cushion generated by dry and cold air mass. The warm-wet airflow transports from the lower level to upper level along the upper boundary of front surface. The occurrence of snowstorm is related with transportation of high temperature and high humidity energy, and water vapor is mainly from the south. Anticyclone and divergence area is main area near the ground surface, and strength of ascending motion?corresponds to?the activities of?mesoscale convective cloud mass.  The rainfall intensity increases because of the effect of topography of Taihang Mountain Related Articles | Metrics

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Forming reason of a rare rainstorm on July of 2011 in the west of Heilongjiang province HU Hao-li，WANG Cheng-wei 2013, 29 (3):  15-20.  Abstract ( 401 )   PDF (1657KB) ( 257 )   Save Based on the data from the automatic weather stations, the conventional observation data, the data from the satellite cloud imagery and the Doppler radar, a rainstorm process on July 31, 2011 in the west of Heilongjiang province was analyzed synthetically. The results show that the rainstorm falling areas are located in the left side of the upper-level westerly jet exit region and the ultral-low-level jet. The upper divergence and lower convergence, the low-level and ultra-low-level jets provide the dynamic conditions and the water vapor conditions for this process, respectively. The strong dry cold air invades in the middle level of troposphere. The falling area of short-time rainstorm is located in the dry intrusion boundary of the strong cold air in the middle level, and it has a very good corresponding relation with the TBB region of big grads. However, it is near the discontinuity line of wind field on the radar echo velocity chart. Related Articles | Metrics

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Distribution characteristics of atmospheric aerosols in 2009 in Shijiazhuang area under different weather conditions MA Liang-chen,YIN Yan 2013, 29 (3):  21-28.  Abstract ( 397 )   PDF (1316KB) ( 371 )   Save Based on the aerosol data obtained using particle measuring system (PMS)  from four flights in 2009 in Shijiazhuang area, the vertical distributions of number concentrations, mean diameter of atmospheric aerosol particle and its spectral distribution under different weather conditions, its horizontal distribution in a sunny day were analyzed. The results show that the maximum number concentration of aerosol particles with the diameter of 0.1-3.0 μm detected by PCASP probe changes from 102 cm-3 to 104 cm-3, and the average magnitude is from 102-103cm-3. The maximum of the average diameter ranges from 0.225 μm to 0.717 μm and the average is between 0.148-0.167 μm. The number concentration of aerosol particles decreases with the increase of the height under the sunny weather condition, while the diameter changes seldom at the same condition. The aerosol accumulates distinctly on the bottom of inversion temperature layer, and its concentration in the atmospheric boundary layer is significantly higher than in the other levels. The aerosol number concentration of boundary layer is higher in cloudy and fog weather than in rain and sunny weather, and it is the lowest in rain weather. The horizontal distribution of aerosol number concentration is uneven in sunny weather. The aerosol number concentrations decreases significantly inside the cloud, while it is high outside the cloud. The size distributions of aerosol under different weather conditions and different heights of sunny day in Shijiazhuang are consistent and just have a single peak. The fine particles that the diameter is less than 0.3 μm are the main contributor to the number concentration of aerosol, and the spectral width is narrowed with the increase of the height. Related Articles | Metrics

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Macro and microphysical characters of precipitable stratiform cloud over Hebei province DENG Yu-peng,DONG Xiao-bo,LV Feng,HU Xiang-feng 2013, 29 (3):  29-34.  Abstract ( 363 )   PDF (2090KB) ( 394 )   Save Based on the observational data from the 17 flights and the corresponding detecting data from the airborne new-generation particle measuring system (PMS) in spring and autumn of 2009 in Hebei province, the microphysical characters of precipitable stratiform cloud were analyzed. The results indicate that the precipitable stratiform cloud is mainly the multi-layer cloud system including nimbostratus (Ns) altostratus (As) and stratiform cloud (Sc) in Hebei province, and it often accompanies with layer-separating phenomena. The mean height of cloud base, the supercooled layer thickness and 0 ℃ layer height are 2002 m, 1106 m and 3811m, respectively. For the microphysical characters, the mean number concentration and mean diameter of cloud droplet are 54.6 cm-3 and 8.64 μm and both are smaller than those in 1990s, while the liquid water content is 0.13 g·m-3 that is larger than that in 1990s. Related Articles | Metrics

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Spatial and temporal distribution of mesoscale convective complex in Northeast China FANG Li-juan,YU Xue-quan,WANG Yuan,WANG Cheng-wei,WANG Yong-bo,CHEN li 2013, 29 (3):  35-41.  Abstract ( 343 )   PDF (2534KB) ( 468 )   Save  A census survey was done using the FY-2C infrared cloud imageries with once every 30 minutes interval from May 1, 2005 to September 30, 2008. The variations of the mesoscale convective complex (MCC) in Northeast China were analyzed based on the amended MCC standards. The results show that there are 22 MCCs during the census survey in Northeast China and 19 of them appear in July or August. The source region of MCCs is of the significantly regional characters, and the generation of MCC is related to the terrains of Daxinganling mountain, while few MCCs are found in Liaoning province and the east of Jilin province. The average life time is 9.3 hours in the Northeast China which is shorter than that in America and the South China, while the scales under -52 ℃ or under -32 ℃ in the Northeast China are all greater than that in the above two regions. The nocturnalism of MCCs is significant in the Northeast China. Among them, 85 % of MCCs generates during afternoon to evening, and its convective frequent period is from 15:00 to 24:00. Related Articles | Metrics

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Comparative analysis of reasons in typical rainy and rainless years during main flood season in Jilin province JI Ling-ling,YANG Xue-yan,ZHANG Ting,JIANG Hong-xia,MA Shu-qing 2013, 29 (3):  42-47.  Abstract ( 499 )   PDF (994KB) ( 585 )   Save The precipitation during main flood season was rankedin a manner that the first and last six orders were defined as rainy years and rainless years respectively. Based on the NECP reanalysis data with resolution of 2.5°× 2.5°, a series of physical quantities such as the average height field, temperature field, the wind field, specific humidity and vorticity during  flood season were analyzed. The structure and location as well as center intensity of synoptic system during flood season of rainy years and rainless years were compared according to synoptic theory and the conventional forecasting experience. The results indicate that compared with rainless years, the location of 568 isoheight at 500 hPa in rainy years is moved to the south about three latitudes, while high subtropical 588 isoheight is moved to the west about seven longitudes and to the north about one latitude. The lower convergence and upper divergence are the main features in a rainy year. The mean water vapor contents at 850 hPa and 700 hPa are higher in a rainy year than in a rainless year. The wind field near the Lake Baikal is a single convergent center in a typical rainy year at 850 hPa, while it is double convergent centers in a typical rainless year. Related Articles | Metrics

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Circulation situation of low temperature and cold damage for corn during growth period from 1980 to 2009 in Heilongjiang province ZHANG Xue-mei,CHEN Li,ZHU Hai-xia,LAN Bo-wen,WANG Ji 2013, 29 (3):  48-51.  Abstract ( 416 )   PDF (1600KB) ( 434 )   Save Based on the mean monthly air temperature in 24 weather stations during May to September from 1980 to 2009 in Heilongjiang province, maize varieties data, the observational data during corn growth period and the monthly NCAR/NCEP reanalysis data at 500 hPa, the characters of low temperature and cold damage and the mean monthly anomaly synthetic field of different circulation situations at 500 hPa were analyzed. The results indicate that cold damage often happens in August and September during corn growth period, followed in June, July and May. The frequency of cold damage is the highest in the north, then in the east, the middle and the west, while it is the lowest in the south of Heilongjiang province. When cold damage appears in the south, it also happens in the north, the middle and the west as well as in most of the east. The mean monthly 500 hPa anomaly fields in the region of cold damage are mostly negative values in the month of cold damage. The cold damage regions are divided into three subregions, i.e. serious subregion, common subregion and weak subregion. The 500 hPa anomaly values in cold damage region are the highest in the serious subregion, then in the common subregion, and it is the lowest in the weak subregion. Related Articles | Metrics

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Temporal and spatial distributions of heavy rainstorm from 1962 to 2011 in Hunan province LI Qiao-yuan,TANG Ming-hui 2013, 29 (3):  52-57.  Abstract ( 434 )   PDF (912KB) ( 502 )   Save Base on the daily precipitation data in 97 weather stations from 1962 to 2011 in Hu’nan province, the temporal and spatial characters of the heavy rainstorm were analyzed by methods of a time series analysis and a cluster analysis. The results indicate that the heavy rainstorm day is in an increasing trend with 0.73 day per decade from 1962 to 2011, and the peak value appears in 1990s. The heavy rainstorm day mainly appears in summer, especially in June and July, while it never happens in winter. For the spatial distribution, the two high frequencies regions of heavy rainstorm occur in the northwest and northeast of Hu’nan province. The heavy rainstorm could be divided into three types, i.e. a single-season type, a double-season type and a three-season type, and they are correspondingly located in the southwest, the middle, the northwest and southeast of Hu’nan province respectively. Related Articles | Metrics

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Characters of precipitation, droughts and floods from 1953 to 2010 in southwest mountain area of Zhejiang province WU Hao-min,YANG Xian-min,JIANG Yan-min 2013, 29 (3):  58-62.  Abstract ( 371 )   PDF (699KB) ( 705 )   Save Based on the monthly precipitation data from 1953 to 2010 in the southwest mountain area of Zhejiang province, the precipitation characteristics were analyzed on the different time scales. The annual, seasonal and monthly drought and flood distributions and its evolution trend were studied using methods of a precipitation anomaly percentage and a Morlet wavelet transform. The results show that the rainfall and rain day are in the decreasing trends in the southwest mountain area of Zhejiang province over the past 58 years, especially for rain day, and its decreasing rate is 3.39 days per decade. Rainfall increases in August and decreases in May significantly, while rain day decreases in May and December significantly. The drought and flood has different cycles on different scales according to a Morlet wavelet transform method, and the intensity of each cycle differs. Among all cycles, features of two cycles i.e. a 4-8 years cycle and a 16-20 years cycle are significant. It is estimated that the trend of drought and flood will develop to flood after 2010 in the southwest mountain area of Zhejiang province. It is light drought and light flood on inter-annual scale in the study area. Drought and flood mainly appears from August to December on seasonal and monthly scales. The probability of drought is higher than that of flood, while the intensity of flood is greater than that of drought. Related Articles | Metrics

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Climatic characters of evaporation from 1971 to 2010 in Heilongjiang province ZHU Hong-rui,LIU He-nan,ZHANG Hong-ling,YIN Chang-jiao 2013, 29 (3):  63-68.  Abstract ( 444 )   PDF (1059KB) ( 455 )   Save Based on the observational data in 63 weather stations from 1971 to 2010 in Heilongjiang province, the spatial and temporal characters of pan evaporation and actual evaporation were analyzed using methods of a climate trend coefficient and a climatic tendency. The results show that pan evaporation is in a decreasing trend in Heilongjiang province and its climatic trend is -62.7 mm per decade in the recent 40 years, especially in spring and summer. For the spatial distribution, pan evaporation is also in a decreasing trend in the whole province, while its trend in the local region is not synchronized with the whole one. Among the meteorological factors, wind speed and diurnal temperature range (DTR) are the key elements effecting pan evaporation. The annual actual evaporation accounts for 30% of pan evaporation and is in a slightly increasing trend, while its trend is not significant. The actual evaporation is significantly correlated with precipitation, sunshine duration and DTR, especially with diurnal temperature range. Related Articles | Metrics

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Evolution feature of agroclimatological resources from 1961 to 2010 in Jiangsu province ZHU Min,YUAN Jian-hui 2013, 29 (3):  69-77.  Abstract ( 363 )   PDF (3230KB) ( 782 )   Save Based on the observational data at 59 weather stations in Jiangsu province from 1961 to 2010, the temporal and spatial evolution features of agroclimatological resources were analyzed using methods of a trend analysis and a Mann-Kendall test. The results show that the total amount of agroclimatological resources such as heat, water and sunshine changes significantly. For example, the annual average temperature is in an increasing trend with a rate of 0.29 ℃ per decade, so is the annual accumulated temperature (≥0 ℃ and ≥10 ℃) and their rates are 101.1 ℃ and 83.4 ℃ per decade, respectively; frost-free season prolongs slightly; rainfall is in a slightly increasing trend with 9.1 mm per decade; annual sunshine duration decreases significantly with a rate of -65.4 hours per decade. The abrupt changes of agroclimatological resources mainly appear in 1990s. The variation of agroclimatological resources will affect agricultural general layout and development planning of Jiangsu province, so the corresponding planning should be established in order to ensure sustainable development of agriculture in the future. Related Articles | Metrics

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Time series characters of air temperature based on a wavelet method and a Mann-Kendall analysis in Shangqiu LI Guo-dong,TIAN Hai-feng,PENG Jian-feng,LIU Ya-ru,YIN Xue 2013, 29 (3):  78-84.  Abstract ( 345 )   PDF (1654KB) ( 708 )   Save  Based on the daily air temperature data in Shangqiu weather station from 1955 to 2011, the annual, seasonal and inter-annual variations of air temperature and their trends, the abrupt changes were analyzed using methods of a Morlet wavelet analysis, a Mann-Kendall analysis, a regression analysis and a variation coefficient. The results indicate that the annual mean air temperature is in an increasing trend by a regression analysis and a 5-year slipping mean analysis, and its rate is 0.17 ℃ per decade. The trends of air temperature in four seasons differ significantly. Air temperature in summer is in a decreasing trend with a rate of -0.08 ℃ per decade, while that in the other three seasons is in an increasing trend, especially in winter with a rate of 0.35 ℃ per decade. An abrupt change of mean annual air temperature appeared in 1992 according to the Mann-Kendall analysis, while that for winter is in 1986. There is not the abrupt change for summer air temperature. According to the Morlet analysis, there is a 17-year cycle for the mean annual air temperature from 1950s to 1980s and then it disappears afterwards, while there is a 32-year cycle from 1980s to 1990s. There are a 5-year cycle and a 2-year cycle from 1955 to 2011 in the study area. It suggests that low temperature could appear in the future according to the cycle signals. The inter-annual variation coefficient of the mean air temperature is 0.04 and it is stable, and its variation rate is weak. The analysis of temperature variation characteristic and trend prediction has an important guiding significance for agricultural planting activities of Shangqiu. Related Articles | Metrics

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Comparison on two prediction methods of minutely global solar radiation JIANG Ying,SHEN Yan-bo,DANG Jun 2013, 29 (3):  85-91.  Abstract ( 462 )   PDF (650KB) ( 415 )   Save Using the minutely global solar radiation data from September 1, 2010 to August 31, 2011 at the Turpan solar energy station of center for wind and solar energy resources of China Meteorological Administration (CMA), two prediction methods of minutely global solar radiation were compared, namely, a statistical extrapolation (TRD) method and a dynamic neural network (NNN) method. The results show that for the annual average, the prediction effect is better by the TRD than by the NNN. The prediction accuracy rates of the two methods is related with weather situation, and it is higher in a sunny day than in a rainy day, while it is lower in a cloud day and a sand-storm day. The impact factors of radiation observation such as cloud, aerosol and dust and so on could be accurately expressed by the TRD method at the beginning time of prediction, which could be continued to the first or second step of rolling forecasts. The prediction effect is better by the NNN than by the TRD for the non-linear variation of global solar radiation under complex weather such as rainy day and cloud day. The predication accuracy of global solar radiation is higher by the TRD than by the NNN for three hours after sunrise and before sunset. The prediction effect is slightly better by the NNN than by the TRD for a sudden variation of global solar radiation. Related Articles | Metrics

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A refined forecast method of township minimum and maximum temperature QIU Xue-xing,WANG Dong-yong,ZHU Hong-fang 2013, 29 (3):  92-96.  Abstract ( 382 )   PDF (496KB) ( 993 )   Save The differences of minimum and maximum air temperature between weather stations located in county and township of Anhui province were analyzed from October of 2008 to September of 2009. The results show that both differences are significant and it changes with the seasons. According to the forecast product of forecaster and the methods of the revised Barnes and the first-order Kalman filter, it forecasts the minimum and maximum air temperature in township. It suggests that the prediction accuracy rates are high using this method. The accuracy rates of the minimum temperature in the first 3 days are close to that in county and both differences are only in 1%, while the differences increase with the increasing of valid forecast time. For the maximum temperature, the accuracy rates that the forecast error is within 2 ℃ are still within 3 % compared with the forecast product in county. This method is better than the MOS method based on output products of the WRF model. The effects of the first-order Kalman filter after and before the revise show that the Kalman filter has a positive effect for township temperature in the first four days, while it has no effect or a negative effect from the fifth to seventh day. The forecast accuracy rates of the maximum temperature from the fourth to seventh days could be significantly improved after the turning synoptic processes are discriminated. Related Articles | Metrics

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A Lossless compression scheme for precipitation grid data LUO Jian,JIANG Yong-qiang,DAI Cai-ti 2013, 29 (3):  97-101.  Abstract ( 357 )   PDF (859KB) ( 374 )   Save  Grid data is one of the important forms for the storage and exchange of the meteorological data. An efficient compression scheme is very important for the data compression, and a compression scheme must be lossless for the meteorological data. Precipitation is a special element because of its spatial and temporal discontinuity, so the lossless compression scheme used for those continuous elements is not suitable to the precipitation data. The fundamental features of the precipitation grid data were analyzed. Basing on the run length encoding (RLE) and Shuffle encoding as well as entropy encoding, a new lossless compression scheme was presented for precipitation grid data. The results show that the compression efficiency of the new scheme is high and it can greatly save storage space and the transmission time. The compressed data are completely lossless within available precision, so this scheme can be used for other meteorological elements with spatial and temporal discontinuity and has great practical application in meteorology. Related Articles | Metrics

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The effect of deicing salt on growth and physiological features of Chlorella vulgaris HU Shui,LI Fa-yun,FAN Zhi-ping,CHENG Zhi-hui,GAO Qun,ZHANG Ying 2013, 29 (3):  102-106.  Abstract ( 334 )   PDF (581KB) ( 339 )   Save Deicing salt was applied for clearing ice and snow on road in winter and entered into river with the surface runoff, so it affected the growth of aquatic organism and broke the equilibrium of aquatic ecosystem. In order to study the toxic effect of deicing salt on aquatic organisms, the effects of deicing salt on the growth, the content change of photosynthesis pigments, protein and polysaccharides of Chlorella vulgaris were analyzed. The results show that there is no significant effect for the growth of Chlorella vulgaris when the deicing salt concentration is 2 g·L-1. However, there is a  significant inhibitory effect on the cell growth of Chlorella vulgaris when it is 4 g·L-1, and the inhibitive effect of deicing salt significantly increases (P<0.01) with the increase of the concentrations. There is the significant stimulative effect on biosynthesis of chlorophyll (a) in a cell of Chlorella vulgaris when it is less than 4 g·L-1, while the chlorophyll (a) contents decrease with further increase of deicing salt concentrations. Compared with the control, protein and polysaccharides contents decrease (P<0.01) significantly when it is more than 4 g·L-1. It suggests that the growth and reproduction of Chlorella vulgaris will be inhibited and the cell will be destroyed when deicing salt concentration is more than 4 g·L-1, and finally it will break the balance of aquatic ecosystem. Related Articles | Metrics

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Control unit zoning based on water eco-functional regionalization for the Liaohe river basin in Liaoning province WANG Jian,HAN Jing-Nan,WANG Lei,LI Fa-yun,HU Cheng,TANG Da-yuan 2013, 29 (3):  107-111.  Abstract ( 366 )   PDF (1337KB) ( 475 )   Save The control unit zoning is a necessary process to implement the water quality management based on the control units, by which the complex issues in the water environmental management of river basin can be distributed to the different control units. According to the control unit zoning theory, principles and methods as well as the water eco-functional regionalization results, the control units for the Liaohe river basin in Liaoning province were zoned and adjusted with the GIS technology. The results indicate that the control units of the river basin are classified into three levels, and the number of the first level, the second level and the third level control units are 5, 56 and 245, respectively based on the indices of physical geography, water ecological environment and social economy. The above results can provide the  technical support for establishing management system of the water environmental quality based on the control units. Related Articles | Metrics