Table of Content

30 April 2013, Volume 29 Issue 2 Previous Issue    Next Issue

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Evolution feature of mecoscale convective system (MCS) in a summer low vortex system ZHANG Xi-ying,XU Yue 2013, 29 (2):  1-5.  Abstract ( 614 )   PDF (1467KB) ( 653 )   Save Three mecoscale convective systems (MCS) occurred successively in the west of Heilongjiang province on July 11-13, 2011, which accompanied short-time heavy precipitation, hail, gale, lightning and thunderstorm and so on. Based on the observational data, the circulation feature of MCS and its physical variables were analyzed in order to discuss the evolution of MCS under the low vortex system. The results indicate that the surface convergence line and dry line are key factors in severe convective trigger mechanism. Shear line and convergence line in different altitudes make MCS developing and moving to the areas where there is instability energy. Physical variables such as pseudo-equivalent potential temperature, K index, SI index, water vapor with upper dry and lower wet, temperature advection with upper cold and lower warm flow have important indicative significances for evolution of MCS. Squall line occurs in the front boundary of MCS where cloud cluster has major intensity gradient and short-time severe convection occurs frequently. Related Articles | Metrics

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Formation reason for mesoscale weather system of a short-time rainstorm on May 27, 2008 at Laohekou of Hubei province JIN Qi,SHU Si,WANG Xiao-ling,WANG Yan,WANG Ren-qiao 2013, 29 (2):  6-11.  Abstract ( 571 )   PDF (2390KB) ( 592 )   Save  Based on the NCEP reanalysis data, the mesoscale weather systems of a short-time rainstorm process occurred on May 27, 2008 at Laohekou of Hubei province were analyzed. The results show the movement of mesoscale weather systems of a short time rainstorm such as dry line, cold trough at 500 hPa, convergence zone of rear of cold shear line, wet area at middle and low levels and convergence line of ground wind field and so on are closely related with the occurrence and development of heavy rain. Dry air invades the wet area from north to south and from upper to lower, which is of typical features of rainstorm caused by dry invasion in Hubei province. Dry invasion makes dry-cold air and warm-wet air rising jointly, and it causes the positive vorticity at the convergence area of rear of cold shear line developing upward along the front area of θse, which enhances convective ascending motion in coordination with ground wind field convergence. Cold trough at 500 hPa and dry intrusion result in convective instability, and the convergence of cold-warm advection, dry-wet advection at the rear of cold shear line forms the unstable region at the horizontal direction. The unstable region is disturbed by dew point front, so convective weather is triggered. The sustainability of deep-wet area at middle and low levels and water vapor convergence provide the water vapor source for this process. Related Articles | Metrics

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Application and verification of MOS statistical method for forecasting of short time meteorological elements LI Wen-juan,LI Min-jie 2013, 29 (2):  12-18.  Abstract ( 618 )   PDF (1237KB) ( 821 )   Save  Through the interpretation of MM5 numerical prediction products, the MOS statistical method was applied to forecast short time meteorological elements. A forecast model of precipitation and temperature with 4 hours interval was established in terms of MM5 numerical prediction products, the observational data from automatic weather stations and the radar data. Precipitation was a discontinuous variable, but it could be translated into a continuous variable by establishing a possibility function of precipitation. Thus, quantitative forecasting could be realized. 4140 samples were tested in this paper. The results show that MOS method is better than the MM5 method, especially for the cases when errors with the MM5 method are higher. According to the test of precipitation prediction, TS score is 65 % and the accuracy reaches 91%. The average error is less than 8mm for heavy rain samples (three hours accumulated rainfall > 5 mm), while it is 1 mm or less for weak precipitation samples (three hours accumulated rainfall < 1 mm). The MOS method has the higher accuracy with 98% for the prediction the non-rain day, and it is better than the MM5 prediction. However, the convective precipitation is still hard to forecast. For the temperature model, the error is less than 1.0 ℃ from 20:00 to 08:00, while it is 1.5 ℃ from 11:00 to 17:00.  The error can be controlled about 1.0 ℃ after season corrections. Related Articles | Metrics

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Analysis of a convective weather process based on remote sensing data in the Huaihe River basin HUANG Yong, ZHAI Jing,QIU Xue-xing 2013, 29 (2):  19-26.  Abstract ( 584 )   PDF (3350KB) ( 614 )   Save Based on the remote sensing data from the meteorological satellite and new generation weather Doppler radar, a strong convective storm rain case on July 22, 2008 was analyzed in the Huaihe River basin, and the similarities and differences of two remote sensing methods were discussed. The result indicate that the large scale weather background could be observed on the satellite cloud image in spite of its resolution is low compared with that of weather radar. The evolution trend of convective system could be analyzed in terms of the locations of contour line of Tir=Twv. The radar echo intensity has higher temporal and spatial resolutions, so the small scale features of convective system and radical velocity in the different heights could be observed in terms of Doppler weather radar. Two methods could assist each other, so more effective information could be obtained if both are combined. Related Articles | Metrics

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Precipitation verification of multiple models during flood season of 2010 in Shandong province XIAO Ming-jing,SHENG Chun-yan,SHI Chun-ling,SUI Ming,RONG Yan-min 2013, 29 (2):  27-33.  Abstract ( 768 )   PDF (1192KB) ( 1405 )   Save In order to improve the precipitation prediction accuracy of numerical model during flood season in Shandong province and provide scientific references for selection and adjustment of physical parameter schemes of models, the mean absolute error, mean error, TS score of 24 hours and 48 hours precipitation simulated by the MM5, WRF-RUC and T639 models under sunny/rainy weather, general precipitation, grading precipitation conditions were analyzed during flood season (from June to September) of 2010. The results show that the accuracies of precipitation prediciton are similar for three models. TS scores of general precipitation and light rain are the lowest for the MM5 model and the highest for the T639 model. TS score of 24 hours precipitation prediction of middle rain and heavy rain etc. is the highest and that of heavy rain reaches 10.37% for the T639 model, while that of 48 hours precipitation forecast decreases significantly. Weather 24 hours or not 48 hours precipitation forecast, the mean absolute error is the lowest in September for the WRT-RUC model and from June to August for the T639 model, while the monthly mean absolute error is negative for the WRT-RUC model. Diffident precipitation verification schemes and weather processes of diffident types have certain impacts on the verifications results. Related Articles | Metrics

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Relationship between visibility and relative humidity, PM10, PM2.5 in Tianjin SONG Ming,HAN Su-qin,ZHANG Min,YAO Qing,ZHU Bin 2013, 29 (2):  34-41.  Abstract ( 2143 )   PDF (954KB) ( 2310 )   Save Based on the visibility data in 2009 and relative humidity (RH), PM10 and PM2.5 data in Tianjin, their relationships were analyzed. The results indicate that the linear correlation coefficient between RH and visibility is the highest and that between PM2.5 and visibility ranks second. The visibility decreases obviously with the increase of RH. When RH is less than 60%, there exists a significant nonlinear correlation between visibility and PM2.5 concentration and a weak correlation between visibility and PM10 concentration, while the correlation between the visibility and the concentration difference between PM10 and PM2.5 is not significant. When RH is greater than 60%, the nonlinear correlation between visibility and PM10 concentration is more significant than that between the visibility and PM2.5 concentration. The nonlinear correlation efficient between the visibility and RH is higher than their corresponding linear correlation efficient. Finally, a nonlinear fitting formula of visibility in Tianjin is developed using RH, PM10 and PM2.5.  It has been shown through examination against the observation that this formula is able to simulate the visibility in Tianjin with a relatively good accuracy. Related Articles | Metrics

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Characteristics of chemical composition of PM2.5 and its effect on visibility in autumn and winter of 2011 in Tianjin LIU Ai-xia,HAN Su-qin,YAO Qing,ZHANG Min,CAI Zi-ying 2013, 29 (2):  42-47.  Abstract ( 708 )   PDF (844KB) ( 671 )   Save Based on the hourly visibility and relative humidity as well as wind speed data in 2011, particulate sample data from November 16 to December 13, 2011, the relationship between visibility and chemical composition of PM2.5 was analyzed in Tianjin. The results indicate that visibility has a negative correlation with the mass concentration of the particulate, and PM2.5 and relative humidity plays a major role in the poor visibility. Atmospheric visibility also has a significantly negative correlation with the mass concentration of the total carbon (TC). The SO42-, NO3-, OC and EC are the key factors influencing the visibility, especially the SO42-, then the OC and EC, while the effect of the NO3- is relatively small. The simulations of the backward trajectory and analysis of the mixed layer height have shown that the heavy PM2.5 pollution during the observational period is mainly caused by meteorological conditions. Related Articles | Metrics

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Comparison of visibility in Lvshun of Liaoning province and Longkou of Shandong province LIU Cheng,XIE Hai-jun,KE Zong-jian,CHE Da-sheng 2013, 29 (2):  48-53.  Abstract ( 659 )   PDF (639KB) ( 570 )   Save Based on the hourly visibility data from 2002 to 2011 in Lvshun of Liaoning province and Longkou of Shandong province, the daily, monthly and annual visibility characteristics were analyzed by a grade analysis method. The results indicate that the annual mean visibility is higher in Lvshun than in Longkou, and both averages are in decreasing trends in the recent decade, especially in Longkou. The time percentage of annual visibility in the different levels changes significantly in Lvshun, while it is stable in Longkou. The maximum visibilities in both locations appear in October, while the minimum value occurs in July in Lvshun and June in Longkou, respectively. The monthly visibility characters are similar in Lvshun and Longkou, and each has one peak and one valley. Analysis of weather phenomenon and corresponding meteorological elements shows that the regional differences are significant for wind field, temperature and relative humidity field in Lvshun and Longkou when visibility range is from 0 to 1 km. Related Articles | Metrics

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Effect of sifting weather stations on urban island intensity LI Li-guang,WANG Hong-bo,ZHAO Zi-qi1 LIU Xiao-mei,WAN Zhi-hong,SUN Feng-hua,DONG Guo-ping 2013, 29 (2):  54-60.  Abstract ( 570 )   PDF (630KB) ( 559 )   Save The 56 weather stations in Liaoning province were sifting repeatedly according to some rules such as the distance between weather stations and so on. The characteristics of urban heat island (UHI) in four cities (Dalian, Dandong, Jinzhou and Tieling) where the number of weather stations was different with and without sifting weather stations were analyzed using a temperature difference method. The results indicate that for the annual UHI character, the UHI intensity is different in four cities from 1980 to 2011 with and without sifting weather stations, while both trends are similar. Among four cities, the UHI intensity is the highest in Tieling weather sifting weather stations or not, and their average values are 1.53 ℃ and 1.85 ℃; their ranges are 1.17—1.80 ℃ and 1.55—2.15 ℃; their amplitudes of fluctuation are 0.63 ℃ and 0.60 ℃, respectively. The years that the UHI intensity grade changes with and without sifting weather stations account for 25% in Tieling, and it is the highest among four cities. In general, the effect of sifting weather stations on the annual UHI intensity is weak. For the monthly UHI character, the variation is significant in Dalian with and without sifting weather stations from 1980 to 2011, while it is not significant in other three cities, especially in Jinzhou. The variation of monthly UHI intensity grade is obvious in each month, and the maximum appears in October and November in Dandong. The years that the UHI intensity grade changes with and without sifting weather stations account for 90.6%. In general, the effect of sifting stations on the monthly UHI intensity is obvious. Related Articles | Metrics

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Effect of climate change on winter heating period and summer air-condition period from 1961 to 2010 in Tianjin SHI Jun,GUO Jun,SUN Wei-guo 2013, 29 (2):  61-67.  Abstract ( 583 )   PDF (937KB) ( 739 )   Save According to the daily average temperature, maximum temperature, minimum temperature, relative humidity and wind speed from 1961 to 2010 in Tianjin, the changes of cooling degree days (CDD) and heating degree days (HDD), climatic change features during winter heating period and summer air-condition period were analyzed by a statistic method. The relations of the regional climate change with the HDD, CDD and the number of comfortable days were discussed. The results show that the variation trends of the HDD and CDD are contrary. The HDD decreases and the CDD increases significantly, and variation amplitude of the HDD is larger than that of the CDD from 1961 to 2010, especially after 1980s. The extreme weather is significantly correlated with HDD and CDD. The number of low temperature days decrease during winter heating period, while the number of high temperature days increase significantly during summer air-condition period. The number of cold uncomfortable days reduces during winter heating period and that of hot uncomfortable days displays an increasing tendency during summer air-condition period.  These variations have significant correlations with the simultaneous mean temperature. At the same time, the uncomfortable weathers are in a randomly increasing trend. This suggests that the regional climate change has an important effect on winter heating period and summer air-condition period in Tianjin with the climate warming. Related Articles | Metrics

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Climatic features of glaze and its synoptic patterns in Jilin province WANG Bao-shu,MIN Shi-chun,CHEN Lei 2013, 29 (2):  68-74.  Abstract ( 969 )   PDF (2310KB) ( 694 )   Save Based on the conventionally observed data at 11 weather stations from 1980 to 2007 in Jilin province, the spatial and temporal distributions of 100 glaze cases were analyzed by a statistical analysis method. The results indicate that the glaze weather often appears in the south of Jilin province, especially in hill area and the windward slope of Changbai Mountain and seldom in the north of Jilin province. The glaze weather mainly appears in the early winter and early spring, and the frequency of glaze is reducing. The structure of vertical temperature stratification under glaze weather in Jilin province differs from that in other provinces in  southern China where the melt layer and inversion layer for glaze weather occurred in Jilin province do not exist. By analysis of the ground situation, glaze weather was divided into four main patterns, i.e. the rear of low pressure, the front of high pressure, the south of low pressure and low pressure center. A deep backward-tilting trough at upper level moves over Jilin province, and temperature trough is behind the height trough. Temperature increases firstly and then decreases near ground layer. The relative humidity reaches about 70% at 850 hPa and 80% near the ground, respectively. Strong glaze weather often occurs in the southeastern region of Jilin province and its ground and upper situations are similar to the situations of general glazes, while its relative humidity is 10% more than that of the general glaze both at 850 hPa and near the ground. Related Articles | Metrics

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Doppler weather radar echo characteristics in a short-term heavy rain on July 14, 2011 in Shenyang LI Da-wei,LIANG Hong,JIA Dong-chan,XIA Chuan-dong,ZHAO Liu-yang,MENG Peng 2013, 29 (2):  75-80.  Abstract ( 621 )   PDF (2829KB) ( 658 )   Save Based on the Doppler radar data from Shenyang and Yingkou and surface and upper meteorological data from automatic weather stations, a supercell storm process on July 14, 2011 in Shenyang was analyzed in order to forecast accurately the short-time heavy rain caused by a supercell storm. The results show that the formation of ground convergence line and shear line are about  2 hours ahead of  that of precipitation, and both locations are consistent with the storm location. The heavy convective storm is of feature of supercell storm, and it appears bow echo. An inflow gap with a “V” shape appears on the speed chart, so is a mesocyclone in the corresponding speed field. The maximum basic reflectivity rate in Yinkou reaches 61 dBz, and there are weak echo area and echo overhang on the vertical profile of reflectivity factor. The severe convective weather disaster warning about short-term rain and thunderstorms can be  issued when the mescocyclone is found in the radar echo and the cyclone could maintain about 1 hour or it appears the bow echo, and radar base reflectivity intensity in Shenyang is more than 45dBz. Related Articles | Metrics

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Climatic characteristics of gale days in Shijiazhuang region YAN Fang,YUE Yan-xia,Zhang Bing-xiang,LIAO Ying-hui 2013, 29 (2):  81-88.  Abstract ( 663 )   PDF (1653KB) ( 668 )   Save Based on the surface gale data at 17 weather stations in Shijiazhuang region from 1972 to 2009, temporal and spatial distribution characteristics of gale days in the study area and 5 representative stations were analyzed by methods of a linear regression, a Morlet wavelet analysis and a Mann-Kendall mutation test. The results show that the spatial distribution of annual mean gale days is a “low-high-low” shape. The climatic characters of gale days are consistent in five representative stations with higher frequency in spring and lower frequency in autumn. The daily variation of gale frequency is significant. The gale frequency is higher in daytime than in nighttime.  The highest frequency occurs between 10:00 and 16:00 accounting for about 45.8%. The high frequent gale days appear in 1970s in Shijiazhuang region, so is in five representative stations. However, the number of gale days in these regions is in decreasing trends in the recent 38 years. There is a significant difference in average of gale days in the different regions during the same decade. The cycle characteristics of the annual gale days were significant in Shijiazhuang region and 5 representative stations, and the long and short cycles both appear during the few gale days. The annual gale day reduces mutationally in Shijiazhuang region and 4 representative stations. Related Articles | Metrics

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Temporal and spatial characters of winter wind chill temperature from 1960 to 2009 in Liaoning province XI Tao,ZHANG Peng,LI Lan,SUN Li,WANG Yan-li 2013, 29 (2):  89-95.  Abstract ( 527 )   PDF (1090KB) ( 1050 )   Save Based on the meteorological data at 52 weather stations in Liaoning province from 1960 to 2009, the number of winter wind chill temperature days for the different levels was calculated using a winter wind chill temperature formula and its optimal classification standard for Liaoning province. Based on the winter wind chill temperature days, the study area was divided by a rotated experience orthogonal function (REOF) method, and its spatial distribution and trend were analyzed. The results show that it could be divided into four levels based on winter wind chill temperature in Liaoning province, and each level has different sub-regions. The study area could be divided into four regions for cold to slight wind chill level, while it is three regions for the other three levels, i.e. mild, moderate and severe levels. There is less number of winter wind chill temperature days in five cities around Liaodong peninsula, while there is more in the north and northeast of Liaoning province. The variation trends of winter wind chill temperature days for four levels are similar. The number of annual mean winter wind chill temperature days is higher during 1960-1985, while it is less during 1986-2009. There is an abrupt change in 1986 for winter wind chill temperature days. Related Articles | Metrics

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Climate warming and its effect on soybean from 1980 to 2008 in Heilongjiang province YANG Xiao-qiang,ZHANG Li-qun,LI Shuai,JIANG Li-Xia 2013, 29 (2):  96-100.  Abstract ( 577 )   PDF (571KB) ( 541 )   Save Based on the observational data at the agricultural field and the daily meteorological data at 10 weather stations from 1980 to 2008 in Heilongjiang province, the temporal and spatial characteristics of main climatic elements and the impact of climate warming on soybean were analyzed by methods of a climatic variability, a Mann-Kendall test and a statistical regression. The results show that the warming trend is significant in the study area from 1980 to 2008. Annual mean air temperature increases; frost-free season extends and has the difference between different regions; heat resource increases significantly, especially in the south of Heilongjiang province. Hundred-grain weight of soybean increases with the increase of air temperature in September, while it decreases with the increase of annual mean air temperature. It suggests that the effect of warming in autumn on soybean yield is positive, while that of annual mean air temperature is negative. The effects of climatic warming on soybean yield are both advantages and disadvantages. Thus, it should be greatly considered for adjustment of planting pattern of soybean. Related Articles | Metrics

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Progress of urban heat island effect BAI Yang,WANG Xiao-yun,JIANG Hai-mei,LIU Shou-dong 2013, 29 (2):  101-106.  Abstract ( 751 )   PDF (494KB) ( 1414 )   Save With the rapidly development of city scale and the rapid expansion of urban population, the urban heat island effect caused by dramatic changes of the structure of urban underlying surface and the increasing of urban anthropogenic heat have gradually become an important?impact factor on?urban living environment and?human health. Urban heat island effect has become a hot topic of urban climate and regional climate. In?order?to study?the?urban heat island effect, progresses at home and abroad were summarized, including the concept and formation mechanism of urban heat island, the three methods used to study the urban heat island effect i.e. the observation method of ground meteorological elements, remote sensing monitoring method, and simulation method of boundary layer numerical model. These summaries indicate that there are some shortages in this area. For example, the research in this area is not perfect and deep enough. Most studies are based on the large scale, and there is certain limitation for each method. Thus, the high-resolution satellite remote sensing images for multi-scale, multi-platform monitoring systems should be combined, and the effect of aerosol particles on radiative forcing should be taken into account for studying the urban heat island. Related Articles | Metrics

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Effects of deicing salt of different concentrations on antioxidant enzymes activities in various organs of grass carp (ctenopharyngodon idellus) GAO Qun,LI Fa-yun,FAN Zhi-ping,CHENG Zhi-hui,HU Shui,ZHANG Ying 2013, 29 (2):  107-112.  Abstract ( 425 )   PDF (662KB) ( 585 )   Save Using deicing salt was one of the primary measures to remove the snow and ice in cold regions in winter, and its negative effect on ecosystem and environment has been gradually attracted attention. In order to detect the toxicity of deicing salt to aquatic organisms, the effects of deicing salt on superoxide dismutase (SOD) and catalase (CAT) activity in gills and muscle tissues of Ctenopharyngodon idellu (C.idellu) were investigated, with experimental methods of a pyrogallol autoxidation and a UV absorption spectrum. The exposure experiments of deicing salt on the C. idellus were carried out under five concentration treatments (4.10 g·L-1, 5.13 g·L-1, 6.41 g·L-1, 8.01 g·L-1 and 10.01 g·L-1), and the control treatment was set without deicing salt (0 g·L-1). The results show that the 96 h LC50 value of deicing salt for C. idellus is 14.19 g·L-1 and the safe concentration is 4.03 g·L-1. According to the 96 h LC50 value, the SOD activity in gills and muscle tissues of C. idellus is inhibited significantly under the concentrations of 5.13, 6.41, 8.01 g·L-1 and 10.01 g·L-1 (P<0.05 or P<0.01) compared with the control treatment. The CAT activity in gills and muscle tissues of C. idellus is inhibited significantly (P<0.05 or P<0.01) after 7 days comparing with the control treatment, and the CAT activity in gills of C. idellus is higher than that in the muscle tissues. Related Articles | Metrics