Table of Content

30 April 2012, Volume 28 Issue 2 Previous Issue    Next Issue

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The objective identification method of northeast cold vortex WANG Cheng-wei,XU Hai-ming,REN Li,CHEN Li 2012, 28 (2):  1-4.  Abstract ( 1063 )   PDF (539KB) ( 1072 )   Save Based on the daily NECP/NCAR reanalysis data from 1991 to 2000, the northeast cold vortex was identified objectively by means of three main physical characteristics of the conceptual model. The results indicated that a given grid-point is identified as the center of cold vortex with a minimum geopotential in 500 hPa, and the zonal wind in two adjacent grid-points of the north of cold vortex is easterly or calm. The relative thickness and thermal front parameter (TFP) are higher in the east of cold vortex than in the center of cold vortex. The following method is employed to determine if the two cold vortexes are the same one in two consecutive days. Firstly, a cold vortex is identified on the first day; secondly, if the cold vortex on the second day is within the range of (-10°, 15°) of longitude and (-7.5°, 7.5°) of latitude from the first front cold vortex; these two cold vortexes are classified as the same one. The climatic characteristics of northeast cold vortex from the above objective method and the subjective methods from literatures are compared, and it finds that the distributional ranges (40°—55°N, 115°—145°E), duration and active periods of the cold vortexes identified by the both methods are essentially consistent. About 72%  of the cold vortex identified by the two methods completely agree. The reasons causing errors are as follows: the standards of subjective and objective methods are different, and it leads to the vain detection if the contours exist, vain and miss detection that the location of central cold vortex and the starting-ending time differ. The above mentioned errors do not influence the climatic characteristics of cold vortex, so it could be considered as the correct identification. Furthermore, there are 19 cases of miss detection from 1991 to 2000, and it is only about 1.4% of all cases. Thus, this objective identification method is reasonable and could be applied for the climatic statistics of the cold vortexes. Related Articles | Metrics

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Climatic characters of northeast cold vortex and its effect on air temperature in Liaoning province from May to September during 1961—2010 JIANG Da-kai,WANG Jiang-shan, YAN Qi,WANG Peng,LU Zhong-yan 2012, 28 (2):  5-9.  Abstract ( 984 )   PDF (703KB) ( 993 )   Save Based on the daily air temperature data in Liaoning province and the NCEP reanalysis data (2.5 ° × 2.5 °) from May to September during 1961—2010, the climatic characters of the northeast cold vortex and its effect on air temperature were analyzed. The results indicated that the variation tendency of the numbers of northeast cold vortex is not significant in recent 50 years. The mean number of annual northeast cold vortex processes is 8.3, and the mean duration of each process is 3.97 d. The northeast cold vortex often appears in May and seldom in September, and the annual mean length influenced by the northeast cold vortex in May, June and July is 7.3 d, 7.5 d and 7.4 d respectively. According to a Morlet wavelet analysis method, there are 13-year, 9-year and 5-year cycles for the numbers of northeast cold vortex processes. The northeast cold vortex could be divided into two types in terms of its structure, namely, deep cold vortex and shallow cold vortex. Air temperature anomalies in Liaoning province are negative when it is influenced by the deep cold vortex process, especially by the deep middle cold vortex process. The longer the duration of deep cold vortex is, the more significant the negative anomaly of air temperature is in Liaoning province. Air temperature anomalies in Liaoning province are positive when it is influenced by the north shallow cold vortex process, while anomalies are weakly negative when influenced by the central and south shallow vortexes. Furthermore, the effects of shallow cold vortex duration on air temperature are not significant. Related Articles | Metrics

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Analysis of a hail weather process in the northern Hubei province on June 6, 2009 ZHANG Ping-ping,LONG Li-min,ZHANG Ning,WANG Xiao-ling,HU Chang-qiong 2012, 28 (2):  10-15.  Abstract ( 812 )   PDF (2959KB) ( 499 )   Save Based on the conventionally observational data and the NCEP/NCAR reanalysis data, a hail weather process on June 6, 2009 in the northern Hubei province was analyzed, and the lifting trigger, water vapor and unstable conditions before this process were diagnosed. The results indicated that the surface meso-scale convergence line is the uplifting conditions of this hail process, which leads to the severe convective weather. A dry layer in the middle and low level effectively inhibits the development of convection in the boundary layer and creates favorable conditions for the accumulation of unstable energy. The formation of surface dry line increases potential atmospheric baroclinicity and promotes the development of the secondary circulation, thus atmospheric instability is increased. The analysis based on Doppler weather radar and lightning location data shows that reflectivity intensity of radar echo, echo top heights and vertical integrated liquid water (VIL) increase rapidly, and it is indicative to hail weather. Moreover, the peak values of lightning frequency during 10 min are important to hail warning if they appear more than 20 times ahead of hail occurrence. Related Articles | Metrics

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Characteristics of air temperature from 1960 to 2008 in Shanxi province ZHANG Hui,GUO Mu-ping,ZHAO Shuang-qiao,JIANG Yuan 2012, 28 (2):  16-21.  Abstract ( 900 )   PDF (899KB) ( 793 )   Save According to the temperature data at 65 weather stations from 1960 to 2008 in Shanxi province, the characteristics of air temperature change were analyzed using the methods of a linear trend analysis, a moving average and a wavelet analysis. The results indicated that the annual average air temperature and seasonal air temperature are in the increasing trends, and their tendency rates are 0.25 ℃/decade, 0.31 ℃ / decade, 0.04 ℃ / decade, 0.19 ℃ / decade and 0.43℃/ decade. There is a 15-year quasi-cycle and a 5-10 years cycle for the annual mean air temperature and autumn air temperate, respectively. The cycles of spring and summer air temperature are mainly 5-10 years, while the cycle of winter air temperature is 15 years. There exist the abrupt changes for the annual mean air temperature, spring and winter air temperature. Their abrupt changes occur in 1993, 1997 and 1988, respectively. Related Articles | Metrics

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Variation of solar radiation and its relationship with meteorological elements from 1961 to 2009 in Datong, Shanxi province MA Qi,DU Ji-wen,YAN Jun-ping,BAI Jing 2012, 28 (2):  22-27.  Abstract ( 973 )   PDF (771KB) ( 1123 )   Save Under the background of global warming, the gross radiation intensity on the ground changes obviously, thus the effects of the natural and human factors on solar radiation have become a hot issue. The characteristics of gross radiation intensity on the ground were analyzed from 1961 to 2009 in Datong using methods of a linear regression analysis, a Mann-Kendall test and a wavelet analysis. The abrupt change year, cycle feature and the future change trends of gross radiation intensity on the ground were revealed, and the relationship between solar radiation and meteorological factors was discussed. The results showed that the annual average gross radiation intensity on the ground is 5617.28 MJ/m2 and it is in a significantly declining trend in the whole period from 1961 to 2009. However, it begins to rise slowly after 2000. The mutation of gross radiation intensity on the ground by M-K test occurs in 1975. There is a 9-year cycle for gross radiation intensity in Datong. Now, it is in the year of high solar radiation. The sunshine duration reduces yearly, and gross radiation intensity on the ground decreases, too. Both are in a significantly positive correlation. Precipitation decreases slowly with the fluctuation, so is gross radiation intensity on the ground. Both are also in a positive correlation. Cloud cover reduces yearly, while the correlation with the ground solar radiation is not significant. The correlation between the climatic elements and the ground solar radiation is not significant. Related Articles | Metrics

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Contrastive verification of three numerical prediction products in the northeast of China in 2010 ZHANG Ning-na,HUANG Ge, WU Man-li,LIANG Han,SHENG Yong,LIU Gui-ying 2012, 28 (2):  28-34.  Abstract ( 975 )   PDF (574KB) ( 1427 )   Save The application results from three numerical weather prediction models in the northeast of China were verified and these include T639 from the national meteorological center of China, the Germany precipitation forecast and the European center for medium-range weather forecasts (ECMWF). The results indicated that for precipitation, the forecast effect of the Germany model is good in the northeast of China, but the missing rates of T639 are lower than that of Germany model. TS score of T639 to 24-120 h rainstorm prediction is also higher than that of Germany model. For temperature, the forecast effect of T639 within 72 h is available in the northeast China, and that of ECMWF within 96 h is good. The accuracy rates of T639 to 24 h temperature prediction are higher than that of ECMWF. The forecast effect of T639 to circulation model within 48 h is better than that of ECMWF, while the forecast effect of ECMWF beyond 72 h is good. Related Articles | Metrics

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Characteristics of snow cover from 1962 to 2008 in Liaoning province YAN Xiao-yu,ZHAO Chun-yu,REN Guo-yu,WANG Ying 2012, 28 (2):  34-39.  Abstract ( 703 )   PDF (1157KB) ( 653 )   Save Based on the daily snow cover depth, temperature and precipitation at 52 weather stations from 1962 to 2008, the characteristics of snow cover variation were analyzed using methods of a statistics and a wavelet analysis. The results indicated that the increasing trend of annual snow cover days is not significant and it only increases 3 d from 1962 to 2008. The increasing trend of annual maximum snow cover depth is also not significant with 0.2 cm/decade, so is that of annual cumulative snow cover depth with 8.9 cm/decade. The number of snow cover days, annual maximum snow cover depth and annual cumulative snow cover depth are all relatively small before 1980s in terms of their inter-decadal variations, while they all increase after 1980s. Related Articles | Metrics

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Characteristics of sea fog along the north coast of the Bohai Sea in China JIN Wei,QU Yan,BIAN Tao,CHEN Jian-jun 2012, 28 (2):  40-43.  Abstract ( 687 )   PDF (698KB) ( 733 )   Save The temporal and spatial distributions of sea fog based on the data at Yingkou and Xiongyue weather stations along the north coast of the Bohai Sea in China were analyzed. The results indicated that the numbers of thick fog days from 1954 to 2007 at two weather stations are in the increasing trends, especially in nighttime, and it passes the significance test with 0.05 levels at Xiongyue weather station. The numbers of light fog days at two weather stations are in the increasing trend from 1954 to 2007, so are the numbers of light fog days in daytime and in nighttime, and they all pass the significance test with 0.01 levels. The monthly thick fog days mainly appear from November to February along the north coast of the Bohai Sea in China. The hourly sea fog concentrates in the morning, especially from 6:00 to 8:00 (BST). Related Articles | Metrics

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Spatial differentiation of land surface temperature and its relationship with land surface parameters in small-medium city based on remote sensing image QI Peng-cheng,LIU Guo-xu 2012, 28 (2):  44-48.  Abstract ( 646 )   PDF (757KB) ( 689 )   Save Based on Landsat 5 thematic mapper (TM) data, the land surface temperature (LST) of urban area in Nanyang were retrieved by using a mono-window algorithm method. The spatial differentiation of LST and its relationship with land surface parameters were analyzed. The results indicated that the high LST patches are mainly concentrated in warehouse area and public service area. The effect of the high LST in these areas on urban environment is negative. The water body by blocking river is the larger low LST patch, and it is positive to adjust the urban thermal environment and blocking river measurement of small-medium city. The spatial autocorrelation of LST has obvious differences in the different directions, and its range is large in east-west and northeast-southwest directions, which is related to the distribution of water body. There is a significant positive correlation between LST and road density index. Accordingly, it suggests that more water bodies and green spaces should be elaborately inserted into the warehouse lands to discretize large-area urban heat island effect for improving the urban environment. Related Articles | Metrics

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Characteristics of soil humidity and its sensitivity to temperature and precipitation in Heilongjiang province WANG Dan1 NAN Rui2 HAN Jun-jie2 GAO Yong-gang2 LI Xiu-fen2 SUN Yan-kun1 2012, 28 (2):  49-53.  Abstract ( 820 )   PDF (1048KB) ( 887 )   Save Temperature and precipitation are mainly impacting factors to soil humidity, and it is important to regional agricultural production, ecological environment improvement and economic sustainable development. Based on temperature and precipitation data at 73 weather stations from 1984 to 2007 in Heilongjiang province, and soil humidity data from 13 soil observational stations, the relationships between soil humidity and temperature, precipitation were analyzed using methods of an EOF and a correlation analysis. The results indicated that soil humidity differs in the different regions of Heilongjiang province from 1984 to 2007. The variation trends of soil humidity are consistent in most agricultural regions except in the middle and west of the Sanjiang plain. Soil is wet before the middle period of 1990s and becomes dry afterwards, while it is seriously dry in 2001. The sensitivity of the soil humidity to climate change differs. Soil humidity is sensitive to temperature in the Songnen plain and to precipitation in the Songnen plain except that in the west and south of the Songnen plain and in the regions of the southern Yichun, the eastern Harbin and the western Sanjiang plain, while it is not sensitive to temperature and precipitation in the regions of Xunke, the northern Yichun, Mudanjing and the eastern Sanjiang plain. Related Articles | Metrics

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Numerical simulation on “0808” severe rainstorm caused by debris flow disaster based on WRF model in Zhouqu County, China LI An-tai1,2 HE Hong-rang2 ZHANG Yun2 2012, 28 (2):  54-59.  Abstract ( 961 )   PDF (1412KB) ( 686 )   Save Based on the NCEP 1°×1° data with 6 h interval and the meso-scale WRF (V3.2) model, the physical mechanism of severe rainstorm caused by debris flow disaster on August 8, 2010 was diagnosed. The results indicated that the severe rainstorm happened under the common action of short-wave trough at high altitudes, low vortex with shear line, the subtropical high and so on. The triple nested WRF model has simulated this rainstorm event quite well. The prime dynamic conditions of this process include strong convergence in the lower level, non-divergence in the middle level and strong divergence in the upper level as well as strong ascending motion. A lot of instability energy that rainstorm needs is transported by vertical wind shear and high energy tongue of pseudo equivalent potential temperature (θse)isoline which extends upward from the lower level. Convergence of water vapor in the middle and lower levels is favorable to rainstorm occurrence. Related Articles | Metrics

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Correlation analysis between glaze and atmospheric circulation as well as sea surface temperature in Hu’nan province LIAO Yu-fang1 CHEN Xiang-ya1 ZHAO Fu-hua1 KUANG Fang-yi2 2012, 28 (2):  60-65.  Abstract ( 733 )   PDF (457KB) ( 553 )   Save Glaze is one of the major meteorological disasters in winter of Hu’nan province. The correlations between glaze and atmospheric circulation as well as sea surface temperature were analyzed in Hu’nan province. The results indicated that the polar vortex area over Asia and the location of East Asian trough plays an important role to glaze weather in Hu’nan province. It is favorable to the formation of glaze in Hu’nan province when Eurasian zonal circulation index is low. Glaze weather often happens in Hu’nan province when the area index of East Atlantic blocking high over European is low and that of the Ural blocking anticyclone is high. It is not favorable to the development of galze in Hu’nan province if the area of western Pacific subtropical high becomes large and its intensity is strong, and the western normal position leans to west in winter. Glaze in Hu’nan province is most serious in the year that La Nina event ends and at the same time El Nino event begins. On the contrary, it is not serious in the starting year of El Nino event. Related Articles | Metrics

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Comparison on meteorological conditions of growth periods, yield and quality of flue-cured tobacco in different transplanting dates HU Zhong-sheng,YANG Chun-jiang,SHI Xu,ZHAO Qi-bai 2012, 28 (2):  66-70.  Abstract ( 743 )   PDF (568KB) ( 685 )   Save The tobacco planting experiment was conducted using K346 as the material at tobacco base of Mile County of Yunnan province in 2001 in order to improve economic benefit and quality of flue-cured tobacco and enhance the adaptability of flue-cured tobacco to climate change. The agronomic character, economic benefit and chemical composition of flue-cured tobacco, and meteorological conditions in the different transplanting dates were analyzed for obtaining the suitable transplanting date. The results indicated that temperature and precipitation is suitable to growth of flue-cured tobacco transplanted on April 20 and 30 and May 10, so is on May 20 and 30. However, sunshine duration and accumulative temperature (≥10 ℃) is not suitable to growth of flue-cured tobacco transplanted on May 20 and 30. The meteorological conditions are favorable to growth of flue-cured tobacco transplanted on April 20 and May 10, while those are not favorable to that transplanted on May 30. The meteorological conditions from April 20 to May 10 at tobacco bases of Mile County are similar to that of the foreign high quality tobacco region. However, similarity extents of meteorological conditions between tobacco bases in Mile County and in the foreign base with high quality tobacco region are lower on May 20 and 30 than from April 20 to May 10. Appropriate early transplanting could increase leaf area index, plant height, stem circumference and stem length. With deferring the transplanting date, tobacco yield, the proportion of better quality tobacco and economic income increase firstly and then decrease. The optimal transplanting dates are on April 30 and May 10, and the chemical indices of tobacco are perfect and the chemical compositions are reasonable. The tobacco transplanted from April 30 to May 10 has the suitable yield and the high quality at tobacco base of Mile County or at tobacco production region with similar meteorological conditions. Related Articles | Metrics

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Analysis and forecast of short time heavy rain from 2004 to 2009 in Dalian region WU Qi-ping,WANG Shu-xiong,LI-Yan,LIU Xiao-chu,ZHAO Sheng-li 2012, 28 (2):  71-76.  Abstract ( 829 )   PDF (2150KB) ( 630 )   Save Based on the precipitation data and radar echo data from March to October during 2004-2009, 45 heavy rain events were analyzed in order to improve the warning ability to heavy rain. The results indicated that there are 32 short time heavy rain events. Among them, 27 events occur in July and August that accounts for 84.4% of the whole. The mixed precipitation echoes between sever convection and stability along the coast of southwestern, southern and southeastern Dalian are the main reasons causing the short time heavy rain and account for more than 70%. A further study is conducted by using town-level precipitation data from AWS and radar echo data. It finds that the direct cause of short time heavy rain in Dalian is the instantaneously generated mixed meso-β echoes. Thus, the mixed meso-β echoes model is set up. This model could improve early warning ability of short time heavy rain with other methods. References | Related Articles | Metrics

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Climatic characters of diurnal temperature range in Altay region BAI Song-zhu,LI Huan,TIAN Zhong-feng 2012, 28 (2):  77-80.  Abstract ( 808 )   PDF (439KB) ( 721 )   Save The variation trend of the diurnal temperature range (DTR) and its impacting factors were analyzed using methods of a liner trend and a statistic correlation analysis based on temperature data at 7 weather stations from 1961 to 2008 in Altay region. The results indicated that the seasonal DTR is in a significant decreasing trend, especially in winter. Variation of autumn DTR is small. The increasing trends of seasonal minimum temperature are the most significant, while those of seasonal maximum temperature are not significant. The monthly mean DTR has significantly positive correlation with sunshine duration, while it has negative correlation with total cloud cover, precipitation and vapor pressure. Annual DTR has significant correlation with precipitation and vapor pressure. Related Articles | Metrics

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Air quality prediction and verification from 2007 to 2008 in Wuhan XU Yang,WANG Kai,JIA Qiao-lian,SUN Jie 2012, 28 (2):  81-84.  Abstract ( 737 )   PDF (402KB) ( 635 )   Save Air quality prediction in Wuhan was investigated and air quality was analyzed. The results indicated that air quality in Wuhan is mostly fine and never exceeds light pollution level. The frequency of the fine air quality is 77.6% from 2007 to 2008. Air quality is better in summer than other seasons. The prediction model established by a stepwise regression method has a certain ability to forecast air quality  and the prediction accuracy of air quality grade reaches 78.1%. According to the statistics of the prediction accuracy, this model is suitable to predict air quality with Ⅱ grades. It suggests that the prediction results should be modified by the observational value of air quality in the day before and combining weather forecast results. Related Articles | Metrics

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Transportation characteristics of PM10 in the typical pollution weather in Xining DOU Xiao-yan, XU Jia,HAN De-hui,ZHAO Xu-dong,CHEN Li,BAI Zhi-peng 2012, 28 (2):  85-90.  Abstract ( 817 )   PDF (2103KB) ( 737 )   Save The daily API (PM10 is the primary pollutant) in the different seasons from March 2006 to February 2010 was analyzed for studying the regional pollution characteristics in Xining. The backward trajectory of air mass in the typical PM10 pollution days that API was more than 200 was simulated based on the trajectory model (HYSPLIT 4.9) in order to discuss the possible PM10 transportation path and the regional pollution source. The result showed that the serious PM10 pollution appears in spring, especially in March and April, which is related to the long-distance transportation of air mass to particulate matter. Sand dust contributes largely to the serious pollution weather in Xining, and its source is located in the desert of the northern and northwestern Xining. The early or deferred API peak value in adjacent cities reflects the transportation process of regional pollution. Related Articles | Metrics

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Dynamical characteristics of aerosol particles from fog to haze weather DING Jue LI Jia-hua LIU Yi ZHANG Bao-liang WANG Qing-tao 2012, 28 (2):  91-96.  Abstract ( 665 )   PDF (920KB) ( 788 )   Save Multi-effective dynamics models of aerosol particles in the fog layer were established and developed to depict the natural phenomenon for conversion from fog to haze weather. Based on the population balance equation (PBE) of discrete system and the Multi-Monte Carlo (MMC) method, the evolution processes of average aerosol particle sizes and particle numbers with the time were simulated numerically for three stages of fog, which involve the formation of fog (dominated by aerosols dynamical effects of coagulation, condensation and nucleation), the development of fog (dominated by aerosols dynamical effects of coagulation, breakage, deposition and nucleation) and the dissipation of fog (dominated by aerosols dynamical effects of breakage, evaporation and deposition). The results indicated that the initial volume of aerosol particle is one. The numbers of particles with 0.0156 of volume-size are increased quickly when the life cycle of fog comes into the dissipation stage. At the time of 1000 s, the numbers of smaller-size particles are 8.12 times higher than those of initial time. The above results reveal the process and physical mechanism of fog conversion into haze weather in nature. Related Articles | Metrics