Table of Content

31 December 2013, Volume 29 Issue 6 Previous Issue    Next Issue

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Diagnostic analysis of three heavy rainfall processes during Meiyu period in Hubei province LIU Xi-wen,XU Shuang-zhu, WANG Yan,YANG Hong-long,LI De-qin 2013, 29 (6):  1-7.  Abstract ( 517 )   PDF (2615KB) ( 568 )   Save  Based on the observed meteorological data and the NCEP reanalysis data (2.5°×2.5°), the synoptic background, dynamical conditions, thermodynamic and water vapor conditions of three heavy rainstorms on July 9, 1991, July 21, 1998 and July 8, 2010 during the Meiyu period in Hubei province were analyzed in order to forecast accurately the similar regional rainstorm. The results show that the locations of upper and lower jet streams and the path of water vapor transport are similar for these three rainstorms. The meso-scale system affecting the three processes is the southwest vortex-shear line. The locations of the positive vorticity center at 850 hPa and water vapor flux convergent center are coincident well with the falling area of rainstorm, which indicates that the low-level wind convergence and vertical ascending motion are favorable to the heavy rain. The sum of the absolute values of moist potential vorticity (MPV) barotropic and baroclinic conditions at 700 hPa in the rainstorm area is about 0.5-0.6 PVU during the three rainstorm periods, and the humidity saturation zone of the three rainstorms are extended above 500 hPa. The locations of the southwest vortex-shear line and low-level jet stream are important factors for forecasting the falling area of rainstorm. In addition, the low-level vortex, water vapor flux divergence, high energy tongue of the pseudo-equivalent temperature and atmospheric vertical structure could provide references for forecasting the falling area of rainstorm. Related Articles | Metrics

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Diagnostic analysis of an urban snowstorm process in the middle of Tianshan mountains of Xinjiang WAN Yu,DOU Xin-ying 2013, 29 (6):  8-14.  Abstract ( 596 )   PDF (3129KB) ( 424 )   Save Based on the daily NCEP reanalysis data (1º×1º) in four times and the conventionally observational data, an urban snowstorm process on March of 2011 in the middle of Tianshan mountains of Xinjiang was diagnosed. The diagnostic study includes a mesoscale analysis, calculations of moisture flux and its divergence, horizontal divergence, vertical speed, upper and lower wind fields, helicity and pseudo-equivalent potential temperature. The results indicate that the snowstorm is caused by the eastward movement of the north and south frontal zones after joining up in the central Asia region. The strong southeast wind occurs before snowfall at the urban area of Urumqi. The sharp decompression and warming on the ground provide thermodynamic conditions for the instability energy. There is the southwesterly jet whose wind speed is greater than 30 m·s-1 at 500 hPa, and there exists low-level shear lines at 700 hPa. The vertical distribution of divergence and vertical velocity presents obvious symmetrical structure of lower-level convergence and upper-level divergence. In the period of heavy snowstorm, it shows a couple of vertical helicity with upper negative and lower positive. The low energy tongue of θse extends upward to 200 hPa, while the high energy tongue of θse maintains from 700 hPa to 400 hPa. The deep moist layer reaches to 300 hPa. This kind of configuration of the physical quantity field accelerates the convergence of wet air in low level and their lifting movement upwards, which provides the necessary conditions for generation of snowstorm. The cold air influences the urban area of Urumqi along a western path. Under the cold air condition, the strong snowstorm usually occurs at the central urban areas with higher temperature due to the effect of urban heat island．Meanwhile, the rainfall center is prone to form in the location of frontal zone. Related Articles | Metrics

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A numerical simulation test of a sea fog event over the Yellow Sea CHENG Xiang-kun， CHENG Hang，XU Jie，MA Yan-jun 2013, 29 (6):  15-23.  Abstract ( 503 )   PDF (3680KB) ( 516 )   Save  Based on the GOES-9 (Geostationary Operational Environmental Satellite) visible satellite image and the data from the radiosonde station of Jizhou island of South Korea, a sea fog event on March 17 to 18, 2009 under the gale condition over the Yellow Sea was simulated using RAMS (Regional Atmospheric Modeling System) (version 6.1). The results indicate that the generation, development and movement of sea fog could be well simulated. The range of simulated fog area is similar to that presented on the satellite cloud image. The cloud water mixing ratio is the main factor influencing atmospheric horizontal visibility distribution, and its large value area concentrates in layer below 300 m (distance to the ground). There are a few areas having large cloud water mixing ratio values in the fog area, and they are located in the different heights, so it suggests that the sea fog is not even. The sea advection fog often occurs under the large wind speed condition, and it could be well simulated by the RAMS. Related Articles | Metrics

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1. Changchun Meteorological Service, Changchun 130051, China; 2.Nanjing University of Information Science &Technology, Nanjing 210044, China MA Liang-chen,LIU Hai-feng, WANG Ning,LI Hang-yue 2013, 29 (6):  24-30.  Abstract ( 420 )   PDF (2104KB) ( 427 )   Save Based on the meteorological and environmental data, a continuous floating dust pollution event on May 12, 2011 in Changchun was analyzed by methods of a climate statistics, a circulation evolution, a physical diagnosis and a back trajectory analysis. The results show that the annual dust day is in a fluctuant decreasing trend in Changchun. The dust weather mainly occurs during March to May. The sand source is originated from the central Mongolia and mid-eastern of Inner Mongolia, and the dust is transported to northeast China with upper jet stream. There is no local sand source in this process. It is a continuous floating dust process rather than a sandstorm because of obviously upper jet stream, smaller surface wind speed, larger temperature dew point difference, weak wind areas in the eastern Inner Mongolia and northern Liaoning province and stable atmosphere in the whole layer. Related Articles | Metrics

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Analysis of a haze weather process in November of 2011 in Suzhou WU Ke,WANG Ting,ZENG Shan-bai, HE Na 2013, 29 (6):  31-36.  Abstract ( 786 )   PDF (804KB) ( 468 )   Save A serious haze weather process happened in Suzhou from November 11 to 14, 2011. The polluted situations at three stations in Suzhou were analyzed based on the meteorological observation data, sounding data and atmospheric composition monitoring data. The results show that it is controlled by weak air pressure on the ground during haze period with light wind; inversion temperature near the ground exists continually; the horizontal and vertical atmospheric transport is also weak. Thus, a lot of pollutants pile up near the ground and make visibility weakened. Among three stations, the duration of haze is longest in Kunshan station; it sums up to 104 times; the effect of haze is the most serious. The ratio of severe haze accounts for 39 % of the total, and those of the medium and severe haze excess 50 % in Kunshan station. The concentrations of particles at different sizes are high during haze period. The fine particles account for larger proportion among inhable particles, and it suggests that its contribution is obvious. The proportion of fine particles is larger in serious fog weather in the morning on November 14 at Kunshan and Taicang than in haze weather, while the peak value of relative humidity is only 94 %, so this weather process should be called as coexisted fog haze weather or wet haze weather. The concentrations of black carbon (BC) increase obviously during straw burning period and its absolute concentrations are three times higher than that in the normal situation. The comparison between CO/SO2 and PM10/SO2 shows that the pollution from straw burning at Kunshan station is more serious, so it could be speculated that there exists other straw burning points in local suburbs. Related Articles | Metrics

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Development and verification of a method for strong wind forecast during summer half year in Huaibei ZHOU Hou-fu,ZHANG Yong-qin,SUN Jin-he, ZHANG Ping, WANG Su-yao, DENG Shu-mei, 2013, 29 (6):  37-41.  Abstract ( 383 )   PDF (797KB) ( 601 )   Save Based on the forecast field from the T639 numerical model and observational wind data, some indexes such as IW and other convective indexes were computed. A method for strong wind forecast during the summer half year was established in Huaibei, and the forecast results in 2011 were examined. The results show that quantitative and qualitative wind prediction is achieved during the summer half year based on IW index from the T639 numerical model and some other indexes. Combining the various indexes and the simulated value from the T639 model, if three indexes are satisfied among four indexes, the strong wind will appear in Huaibei, otherwise it will not occur. Forecasted wind speed by IW index is relatively close to observational maximum wind speed. The two methods are indicative to strong wind forecast in Huaibei. Most strong wind weather could be forecasted accurately, while the false alarm is significant and the missing forecast is not significant. Related Articles | Metrics

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Simulation of atmospheric environmental risks in Xining MA Ming-liang,SHEN Hong-yan,WEI Hong-ye, ZHANG Jia-kun 2013, 29 (6):  42-48.  Abstract ( 458 )   PDF (4037KB) ( 448 )   Save The meteorological elements under special terrain were simulated by the mecoscale numerical model, and the fine diffusion characteristics for an atmospheric environment risk event were simulated by the CALPUFF model. The results show that surface wind direction is parallel to the valley direction. The west-north and east-south wind and north wind prevail in Huangshui river valley and in Beichuan river valley, respectively. Strongly hillside daytime radiative heating and night cooling effect in Qinghai-Tibet plateau lead to inversion layer frequently with high intensity, and the frequency of inversion temperature reaches 36%, while the maximum intensity increases 2.0 ℃ every the 100 m height, which is not favorable to diffuse pollutants in vertical direction. By simulation, temperature in same height hillside is about 1.5 ℃ higher than in the center of valley. CALPUFF plume trajectory model can be applied to the simulation of atmospheric environmental risk events, and the simulation results clearly depict the initial condition and detailed distribution about pollutant transport and diffusion along the valley. Under the complex terrain and weather conditions, some diffusion phenomena will appear such as puff is hindered by the mountain, puff diffusion locus accords to the characteristic and regulation from stream affection and puff diffusion is influenced by circulation of valley wind, which have important significance to estimate the diffusion, influencing range and extent for atmospheric environmental risks in the city. Related Articles | Metrics

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Correlation analysis between Hadley circulation intensity and temperature in the eastern China WANG Yu,HUANG Li-fen, XIE Jian-xing,ZHANG Qing 2013, 29 (6):  49-55.  Abstract ( 424 )   PDF (3417KB) ( 434 )   Save Based on the mean monthly wind field reanalysis data from the NCEP/NCAR and temperature data at 160 weather stations provided by the national climate center from 1951 to 2010, the mass stream function scheme and circulation center value were used to analyze Hadley circulation intensity changes and their relations with temperature in the eastern China. The results show that the mean meridian circulation can well be described by the mass stream function, and circulation center value can represent its intensity vividly. The winter Hadley intensity in the northern hemisphere has a linear increasing trend in the past 60 years, while the summer Hadley intensity in the southern hemisphere has a turning point of inter-decadal change from decreasing trend to increasing trend in the early of 1980s. The inter-decadal change of temperature in the eastern China could be explained well by changes of Hadley circulation intensity. Both relationships are positive, while they are different with the change of seasons in the significant correlation areas. Related Articles | Metrics

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Abnormal precipitation and its circulation characteristics during June to August from 1961 to 2012 in Inner Mongolia YOU Li, CHENG Yu-qin,LI Hui,TA La 2013, 29 (6):  56-62.  Abstract ( 457 )   PDF (1490KB) ( 421 )   Save Based on the monthly precipitation data in 100 weather stations during June to August from 1961 to 2012 in Inner Mongolia, years with abundant and scarce rainfall at a single station and in the study area were classified according to the precipitation anomaly percentage and their characteristics were analyzed. Aiming at the years with abnormally abundant or scarce rainfall, the distribution characteristics of the atmospheric circulation over the northern hemisphere in the corresponding period were discussed. The results show that rainfall is in a decreasing trend in August, while it is periodically abundant (scarce) in June and July and years with scarce rainfall are great than that with abundant rainfall. For the years with abundant rainfall, the circulation distribution in the middle and upper latitude is radial at 100 hPa height field over the Euope-Asia area, and the polar vortex is weak. The circulation situation is two troughs and one ridge in June and Inner Mongolia is located in the front of high ridge, while it is two ridges and one trough in July and August and Inner Mongolia is located in the back of high ridge. The deformation frontogenesis at 500 hPa in Asia is the main circulation causing the abnormally abundant rainfall in June. Meanwhile, the circulation situation in the middle and upper latitude is two ridges and one trough and Inner Mongolia is located in the wide low trough between two ridges in June, while that is high in the east and low in the west and Inner Mongolia is located in the low trough in July and August. It is controlled by cyclonic shear zone or wind convergence zone over Inner Mongolia at 850 hPa contour chart. On the other hand, for years with scarce rainfall, the circulation distribution in the middle and upper latitude is latitudinal, and the polar vortex is strong at 100 hPa and 500 hPa. Inner Mongolia is located in the positive anomaly area of north high pressure in south Asia. Wind field at 850 hPa chart is weak without obvious water vapor transport. Related Articles | Metrics

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Circulation factors in middle and high latitudes and climate anomaly in early of summer in Heilongjiang province ZHANG Jian，LI Yong-sheng 2013, 29 (6):  63-67.  Abstract ( 395 )   PDF (1541KB) ( 390 )   Save  Using the ground temperature and precipitation data, the monthly circulation eigenvalue, the NCEP reanalysis data of height field and so on, the climatic characteristics of air temperature and precipitation in June in Heilongjiang province were analyzed by a conventionally climatic statistic method. The correlations of air temperature and precipitation with geopotential height field at 500 hPa in the northern hemisphere were discussed, and their relationships with circulation factors in the middle and higher latitudes were established. The results show that the abnormal climate in Heilongjiang province in the early summer is related to circulation anomaly in the middle and higher latitudes. The main impacting factors include latitudinal circulation index in Asia, Aleutian low index, polar vortex area index in Asia and Okhotsk blocking high index and so on. On the basis of the above analysis, the background of atmosphere, the indirect action of sea temperature as an outside forcing factor, the background and variation of circulation factors in the middle and higher latitudes are considered, which are the essential premise predicting the climate in the early summer in Heilongjiang province. Related Articles | Metrics

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Temporal and spatial distribution of high temperature weather from 1960 to 2010 in Guangdong province XU Wei，TANG Qiang ，CHEN Huan-huan 2013, 29 (6):  68-74.  Abstract ( 513 )   PDF (1629KB) ( 679 )   Save Using the daily mean temperature, maximum and minimum temperature data at 27 observational stations in Guangdong province from 1961 to 2010, the climate change characteristics of high temperature weather were analyzed by methods of a linear trend, a Morlet wavelet analysis, a Mann-Kendall test, an EOF (empirical orthogonal function) and a REOF (rotated empirical orthogonal function). The results show that the mean high temperature days are in a significant decreasing trend from south to north in Guangdong province. However, it is in an increasing trend in the recent 50 years in the most areas of Guangdong province, especially in the middle area. The long term evolution of high temperature days is in a significantly increasing trend, and the turning occurs in 1990s with small gradient before 1990s and large gradient afterwards. The number of high temperature days increases significantly after 2005 and an abrupt change appears in 1998. It has a cycle of 20-23 years for high temperature days, while the variation of cycle is not significant. The standard anomaly field of high temperature days in Guangdong province can be divided into three regions, i.e. central, north and south regions. Related Articles | Metrics

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Analysis of tropospheric temperature characteristics in Jilin province GAO Feng， WANG Bao-shu ，WANG Yi-ting ，ZHANG Ying ，CHEN Lei 2013, 29 (6):  75-80.  Abstract ( 540 )   PDF (923KB) ( 412 )   Save Using the temperature data from radiosonde station in Changchun, Yanji and Linjiang of Jilin province during 1960 to 2009, the variations of the standard isobaric surface temperature (8 levels) from ground to 100 hPa were analyzed by a linear trend analysis method. The results show that under the global change background, annual tropospheric temperature below 700 hPa is in an increasing trend in Jilin province, while it is in a decreasing trend above 400 hPa. The seasonal change of tropospheric temperature is different. It ascends below 400 hPa in autumn and winter and below 700 hPa in spring and summer. The ascending amplitude of tropospheric temperature is greater in autumn and winter than in spring and summer. The ascending trend of tropospheric temperature differs for different size cities. The ascending amplitude is greater in the large city (Changchun) than in the middle and small cities. The height that warming could reach in the different standard layers is higher in Changchun than in the middle and small cities. Related Articles | Metrics

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Variation characteristics of annual precipitation from 1960 to 2011 in Dongting Lake area HUANG Ju-mei, ZOU Yong-chang，PENG Jia-dong，CAI Hai-chao，QIN Hong 2013, 29 (6):  81-86.  Abstract ( 433 )   PDF (1502KB) ( 558 )   Save Based on the precipitation data at 24 weather stations from 1960 to 2011 in Donting Lake area, the annual precipitation variation was analyzed by methods of a climatic trend rate, a Mann-Kendall test and a wavelet analysis. Annual SPI (standard precipitation index) was calculated by methods of an EOF (empirical orthogonal function) and a REOF (rotated empirical orthogonal function), and the temporal and spatial distributions of drought and flood were discussed. The results show that the annual precipitation increases from south to north on spatial scale in Dongting Lake area, while its trend is not significant on temporal scale. An abrupt change of annual precipitation appears in 1963. There are 6 years, 9 years, and 16-17 years precipitation oscillation cycles in Dongting Lake area. Drought and flood are frequent and extreme weather events are in increasing trends in the study area. The annual precipitation has good consistency on spatial scale, i.e. general drought or flood. But there are also cases in which it is drought in the south and flood in the north and vice verse. There are the south, northwest and middle areas of abnormal climate regions for annual precipitation in Dongting Lake area. Related Articles | Metrics

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Changes of evaporation and its impact on water resource in Qinghai plateau from 1961 to 2010 SHEN Hong-yan , MA Ming-liang ,WANG Qing-chun, WANG Zhen-yu , LI Jiang-ying 2013, 29 (6):  87-94.  Abstract ( 377 )   PDF (1236KB) ( 543 )   Save Based on the meteorological data from 1961 to 2010 in Qinghai province, the spatial and temporal distributions and the trend of the pan evaporation were analyzed. The major climate factors affecting the pan evaporation were also studied by methods of a partial correlation and a principal component analysis. The results show that the pan evaporation is in a decreasing trend in the recent 50 years in Qinghai plateau, which is caused by thermodynamic, water and dynamic factors together. Among three factors, the dynamic and water factors have greater impact on the pan evaporation than thermodynamic factor. Regional analysis suggests that the major factors influencing pan evaporation are wind speed and relative humidity in the eastern agricultural areas and Qaidam Basin and relative humidity in three rivers source areas respectively, while the main impacting factor is diurnal temperature range in Tangula areas. It is negative correlation between evapotranspiration and surface water resource by analyzing both relationships. Summer evapotranspiration has a significant effect on the mean flow, while the response of mean autumn flow to evapotranspiration is the most sensitive. Related Articles | Metrics

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Impact of regional meteorological conditions on concentration of atmospheric pollutants in Nanjing urban area CHANG Lu-yu, ZHAO Tian-liang,HE Jin-hai,TANG Li-li,YU Hong-xia, SHAN Yun-peng 2013, 29 (6):  95-101.  Abstract ( 610 )   PDF (2803KB) ( 677 )   Save In order to focus on pollutant emission mitigation during the Nanjing Youth Olympic Games in August of 2014, the fine wind field data were obtained by the WRF model using the 6 hours interval NCEP/NCAR reanalysis data in August during 2010 to 2012 as driving field. Combing the observational particles and air pollutants concentration data, the surrounding source regions of main pollutants and its transport pathway that influences the air quality in August in Nanjing area were diagnosed by methods of a correlation analysis and a composite analysis. The results show that the dominant wind in August is southeast from sea to inland during Nanjing Youth Olympic Games, while the source area and transport pathway influencing the concentrations of main pollutants (SO2, NO2, PM10) differ. The southwestern air flow with high SO2 concentration from Hu’nan, Jiangxi and other regions has a great influence on the concentration of SO2 in Nanjing; the southern air flow transport from Anhui and Zhejiang largely contributes the high NO2 concentration in the ambient air in Nanjing; the southwestern pathway connecting the emission sources over Hubei is a key route in the PM10 transport to Nanjing urban area. Related Articles | Metrics

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The climatological calculation of global solar radiation and its temporal and spatial distribution in Inner Mongolia MA Yu-feng，LI Xi-cang，SONG Jin-hua，GAO Chun-xiang，ZHAO Dong， SHEN Yan-bo 2013, 29 (6):  102-109.  Abstract ( 485 )   PDF (1344KB) ( 825 )   Save By analyzing and comparing climatological calculation methods of global solar radiation at home and abroad, an optimal calculation formula was identified and then used in Inner Mongolia. In accordance with monthly global solar radiation and percentage of sunshine at 24 solar radiation observation stations in Inner Mongolia and its surrounding areas, experiential coefficients in the formula were fitted in terms of least square method. An interpolation method of IDW was then used to extend these coefficients to 108 weather stations. Finally, a global solar radiation calculation model was established for Inner Mongolia. The calculating results from this model show that the annual global solar radiation is in a decreasing trend from 1978 to 2010, while it is not significant and the decreasing rates in different regions differ obviously. The highest value of global solar radiation occurs in May, then follows in June and July, and the lowest value is in December. The monthly variation presents a single peak. The spatial distributions of monthly global solar radiation are consistent with that of annual global solar radiation, and both increase gradually from northeast to southwest of Inner Mongolia. The annual global solar radiation ranges from 4633 MJ·m-2 to 6616 MJ·m-2. The grade of solar energy resources in Inner Mongolia is abundance grade or above it. The grades of solar energy resources fall in categories of the best abundance grade and better abundance grade in most areas of Inner Mongolia, so it has great potential for development and utilization of solar energy resources. Related Articles | Metrics

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Remote sensing analysis of ecological recovery in the Liaohe river protection zone WEN Ri-hong， WANG Xiao-ying， LV Guo-hong，XIE Yan-bing， JIANG Peng， LI Si-wen， LIU Xiao-mei 2013, 29 (6):  110-115.  Abstract ( 289 )   PDF (1596KB) ( 484 )   Save  Using remote sensing data from the France SPOT and Japan ALOS satellites with 10 meter-resolution in 2009 and 2011, the land use type characteristics in the Liaohe river protection zone were extracted using visual interpretation in the ArcMap module platform of ArcGIS9.3, and the status of ecological recovery in the Liaohe river zone was analyzed. The results show that the land use types in the protection zone in 2009 are dominated by upland, reed wetland and water area, and their total proportion to the whole protection zone is up to 72.9%, while the land use types in 2011 are mainly dominated by waters, reed wetland and grassland, and their total proportion to the whole protection zone is 62.9%. The land use change characteristics from 2009 to 2011 in the protection zone show that most of cultivated areas in 2009 are converted to waters, reed wetland and grassland areas in 2011. Compared with 2009, the cultivated areas decrease significantly and the vegetation coverage area increases 15.4% in 2011. Related Articles | Metrics

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Climatic characteristics of fog and its forming reason in Chongqing HAN Yu,LIU De,WANG Huan,JIANG Yu-hua, XIA Bai-cheng 2013, 29 (6):  116-122.  Abstract ( 602 )   PDF (1605KB) ( 594 )   Save Based on the visibility and relative humidity data at 36 weather stations from 1980 to 2011 in Chongqing, the climatic characteristics of fog were analyzed. Typical heavy fog events were selected, and the circulation situation of radiation fog and rainy fog, vertical structure of temperature, humidity and wind were discussed using the NCEP reanalysis data with the resolution of 1°×1°and the L band radar data. The results indicate that the number of fog events is larger in the west than in the east of Chongqing, and the fog weather usually appears from October to February of next year. Annual mean number of fog days is in a significant decreasing trend in the early of this century, and an abrupt change occurs in 2002. There is high pressure ridge at 500 hPa in areas of Central Asia and Qinghai-Tibet plateau when radiation fog takes place, and Chongqing is located in the pressure equalization field inside the high atmosphere pressure and cold front reaches the South China. However, there is low pressure trough at 500 hPa in Qinghai-Tibet plateau when rainy fog takes place, and the center of surface cold high pressure is located in the north of China, which makes the weak cold air penetrating through Daba Mountain into Chongqing from the northeast. The vertical structures of temperature, humidity and wind speed for fogs of two types differ each other. Inversion temperature of radiation fog near the ground layer is obviously stronger than that of rainy fog. The vertical structure of humidity for radiation fog is dry in the upper layer and wet in the lower layer, while that of rainy fog is deep wet layer. At the same time, wind speed near the ground is slow, while the wind speed in each layer is faster during rainy fog than during radiation fog. Related Articles | Metrics

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Analysis of meteorological condition on regional air pollution in the coastal counties and cities of Quanzhou ZHAO Hui-fang， SHEN Wen-wu，YANG Jian-dong，CHEN Li-zhen， ZHAO Ying-long 2013, 29 (6):  123-127.  Abstract ( 590 )   PDF (406KB) ( 398 )   Save Based on the weather situation and the local meteorological elements and so on, the meteorological conditions leading to the regional air pollution in Quanzhou were analyzed. Wet and dry pollution characteristics in the coastal zone of Quanzhou were discussed in terms of dry and wet conditions, relative humidity and the non-rainy days and so on. The results indicate that regional air pollution is generated in the coast of Quanzhou under those main weather systems, such as the ground high pressure (the bottom, rear or ridge of high pressure), the ground inverted trough, low vortex front, warm zones before the front and so on. For the ground meteorological elements, temperature increases and air pressure decreases; the direction and speed of the daily sea and breeze transforms each other; it has fog and haze at night or in the morning. When the relative humidity reaches 70%-80%, it is easily lead to the regional air pollution. Related Articles | Metrics

Scientific Notes

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The distribution of oxygen anion concentration, forecasting model in Ningbo and its application in tourism meteorology GU Xiao-li， BAO Yue-jian， QIAN Yan-zhen， WU Fang-ping 2013, 29 (6):  128-133.  Abstract ( 566 )   PDF (1209KB) ( 461 )   Save Based on the oxygen anion concentration data from 2010 to 2011 in Ningbo, its distribution and the relationship with meteorological elements were analyzed. A forecasting model of oxygen anion concentration was established by a stepwise regression analysis method. The results show that the oxygen anion concentration is lower near the urban center and higher at suburb in Ningbo; it is higher at nighttime and in early morning and lower at daytime; it is higher in summer and lower in winter. Therefore it suggests that people should go touring in the early morning or evening at suburb. It is better to avoid fog or haze weather with serious air pollution. The oxygen anion concentration is in a negative correlation with air temperature and PM10, and in a positive correlation with relative humidity, thunderstorm and lightning, so it is better to take a trip on a clear day after thunder shower. The model could quantitatively predict the oxygen anion concentration in Ningbo, which is important to tourism meteorology service. Related Articles | Metrics

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Spatial distribution of human comfort and its impact factors in 2011 in Shenzhen ZHANG Li-jie， ZHANG Li， LI Lei， LI Mei 2013, 29 (6):  134-139.  Abstract ( 389 )   PDF (1884KB) ( 504 )   Save According to the temperature, wind speed, relative humidity data from several regional automatic meteorological stations in Shenzhen, the human comfort index and the days on different comfort levels were calculated by a human comfort index scheme, and the influences of urban landform, road network density and population density on human comfort were analyzed. The results show that the people feel more comfortable in the coastal area than in the inland of Shenzhen. The annual comfortable days are about 7-9 months in Shenzhen. The hot days are about 2-3 months in summer, while that of cold days are about 30 days in most areas in winter. According to the variation of daily human comfort index, the effect of geographical location and underlying surface on the index is significant in summer than in winter. Besides the above elements, topography, sea land distribution and urban planning could also impact the human comfort. The summer heat-hot days are in a logarithmic relation with elevation, road cover area and population density by a correlation analysis method. However, it is not comfortable in the eastern Shenzhen where hot days frequent because of low population density and small road cover areas, which is relate to the weak annual mean wind speed in this region. Related Articles | Metrics

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Comparison of wind direction forecast methods based MOS ZENG Xiao-qing，ZHAO Sheng-rong，DUAN Yun-xia 2013, 29 (6):  140-144.  Abstract ( 502 )   PDF (833KB) ( 730 )   Save A numerical forecast product explanation technology by the model output statistics (MOS) method was a good measure of element forecast. Wind direction was general explained by a scalar method, while it is not perfect. A vector method of wind direction forecast was set up by the MOS method. Wind direction models of u wind and v wind in the different stations for different time validity were established by methods of a correlation analysis and a regression analysis. The composite wind direction of u wind and v wind was predicted by the models. Three schemes were compared, including the vector method, scalar method and model output method. Wind direction in the 20 weather stations and at the four times was predicted based on daily observational fields of many physical elements from T639 model. The data from May 15 to September 15 during 2008-2012 were used to build the model, and those on June 1 to 30, 2012 were used to test the sample. The results show that the accuracy rates of wind direction for 12 hours, 24 hours, 36 hours and 48 hours is higher from the vector method than from the scalar method, and they are increased by 85.0%, 26.3%, 11.30% and 19.9% respectively. The accuracy rates for these hours forecasts are increased by 35.3%, 20.2%, 43.6% and 21.0% compared with the results from model output. In general, the vector method is the best among three methods. It is difficult to forecast for a certain station because unreasonable estimation for the model or frequent wind direction change. Related Articles | Metrics

Bulletins

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Application of K index on rain or shine weather forecast in Heilongjiang province ZHAO Ling， LI Shu -ling，WANG An -na ，FENG Qi ， LV Shuang 2013, 29 (6):  145-149.  Abstract ( 360 )   PDF (1617KB) ( 597 )   Save Although the relative humidity and wind field in lower atmosphere were very effective to forecast rain or shine weather, there were still some missing or false-alarm forecasts. In order to improve the accuracy rates of rain or shine weather forecast in Heilongjiang province, the forming reasons of weather cases with and without rain were analyzed. The results indicate that the temporal and spatial distributions of K index are indicative to rain or shine weather forecast, and could help to forecast the complex weather condition in which relative humidity in low level is small or wind convergence is poor, which are easy to lead to a missing or false-alarm forecast. Precipitation often appears in the high value center area or high energy tongue area of K index and in the strong K index gradient area or energy front, while it is seldom in the low value center area of K index. The threshold values with or without rain in the high and low values area of K index vary in different seasons. Related Articles | Metrics

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Ambient air quality change and its relationship with meteorological conditions in Xi’an HU Lin, CAO Hong-li, ZHANG Wen-jing, WANG Qi, MU Jun 2013, 29 (6):  150-153.  Abstract ( 617 )   PDF (677KB) ( 660 )   Save Based on the data of atmospheric pollutants and the corresponding meteorological observation data from 2002 to 2011 in Xi’an, the temporal and spatial distributions of air pollution and its relationship with meteorological conditions were analyzed. The typical upper-level circulation situation in the day when air quality is superior grade or above light pollution grade, forming reasons and transport path of pollutants were discussed. The results indicate that the primary pollutant is PM10 in Xi’an, and its maximum concentration appears in winter during heating period. Rainfall is the significant wet scavenging effect for pollutants, and air quality status has obvious continuity owing to the continuity of weather system. Presence of inversion temperature and decrease of the maximum mixed layer height make atmospheric stratification stable and wind speed small, hinder the convective movement of air, which lead to the weak diffusion of pollutants along the vertical direction. Thus, it is not favorable to the diffusion of pollutants, and it easily makes the ambient air quality descended. Related Articles | Metrics