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30 June 2016, Volume 32 Issue 3 Previous Issue    Next Issue

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Analysis of physical mechanism and characteristics of strong winds and heavy rainfall from a β mesoscale system in Heilongjiang province WU Ying-xu, ZHOU Yi, LIU Song-tao, ZHANG Li-bao 2016, 32 (3):  1-9.  doi: 10.3969/j.issn.1673-503X.2016.03.001 Abstract ( 261 )   PDF (4253KB) ( 431 )   Save In this paper,the environmental background,formation and evolution processes of a tornado-like storm and local heavy rainfall caused by a β mesoscale system on July 5,2014 in the central region of Heilongjiang province were analyzed based on conventional meteorological data,observations from regional automatic intensive weather stations,cloud images from the T639 model and FY-2 satellite,and data of new generation weather radar,as well as the NECP reanalysis data with 1°×1° resolution.The results show that this process is controlled by a cold vortex at higher altitudes and a low pressure at ground.The weak cold air at middle altitudes invades into strong warm air at low altitudes,and then forms the unstable condition.Low level jet (LLJ) and strong shear at low levels favor the formation of β mesoscale system.The strong vertical wind shears at low levels enhance strong convective conditions and lead to the formation and development of three supercells.The intensity of convective clouds increases rapidly during the primary development stage.Strong winds prevail in the early mature stage,and the supercells exist in the initial of mature convective clouds and develop up to the top of clouds.With the change of β mesoscale to α mesoscale,the clouds become weak and the severe weather generally ends.The formation and extinction of three supercells are clearly found according to the radar detection.The echo from cyclone and vault is also distinct and lasts for a long period of time.The characteristics of storm are shown from the vertical wind profiles and radial vertical velocity.The strong echoes of precipitation move to Langxiang region,and their intense and location vary little,which mainly results in a persisted heavy rainfall in this region. References | Related Articles | Metrics

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Analysis of radar features and environmental background during a severe thunderstorm in early summer 2014 in Guangxi Zhuang Autonomous Region LIANG Wei-liang, QU Mei-fang, LAI Zhen-quan, NONG Meng-song 2016, 32 (3):  10-18.  doi: 10.3969/j.issn.1673-503X.2016.03.002 Abstract ( 269 )   PDF (3683KB) ( 555 )   Save The radar features and environmental background during a regional severe thunderstorm on June 5,2014 in Guangxi Zhuang Autonomous Region were investigated using methods of a synoptic meteorology and a diagnostic analysis with conventional meteorological data,observations from regional automatic weather stations and Doppler radar,as well as the NCEP reanalysis data with resolution of 1.0°×1.0ånd 2.5°×2.5°.The results indicate that the severe thunderstorm is caused by two bow echoes according to the radar detection.The forward-tilting trough at 500 hPa and quasi-stationary front at the surface provide favorable conditions for the formation of the thunderstorms.The intensity of the bow echo in the northern Guangxi Zhuang Autonomous Region is weak and it moves slowly,with a low barycenter and vertical upward structure,which causes repeatedly short-time heavy rainfall and ultimately leads to a large-scale rainstorm.However,the intensity of the bow echo in the southern Guangxi Zhuang Autonomous Region is relatively stronger and it moves faster,with typical characteristics of thunderstorm gale,such as front and rear inflows,inclined structure and mid-altitude radial convergence (MARC).This bow echo causes the regional gale and local short-time heavy rainfall.Mid-level humidity and vertical wind shear are background reasons for the different weather types in the northern and southern Guangxi Zhuang Autonomous Region,respectively.The dry air,controlled by the subtropical high,moves to the north along southwesterly jet,and makes dry air advection over the southern Guangxi Zhuang Autonomous Region.The 500 hPa trough moves rapidly toward the area of the subtropical high,which leads to a greater pressure gradient and generates southwesterly jet between 850 and 500 hPa as well as strong vertical wind shear. References | Related Articles | Metrics

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Comparative analysis of two northward motion tropical cyclones affecting Tianjin SHI De-dao, YI Xiao-yuan, SUN Mi-na, WANG Ya-nan 2016, 32 (3):  19-27.  doi: 10.3969/j.issn.1673-503X.2016.03.003 Abstract ( 270 )   PDF (3043KB) ( 446 )   Save Two northward motion tropical cyclones affecting Tianjin,called Haima (0421) and Damrey (1210),were analyzed using FY-2E TBB (Temperature of Black Body),GMS (Geostationary Meteorological Satellite) TBB and NCEP (National Centers for Environmental Prediction) 1°×1° reanalysis data.The results show that the rainfall triggered by the two tropical cyclones exhibits asymmetric distributions and occurs in the northern and northwestern sides of Haima and northeastern side of Damrey,in connection with the asymmetric distributions of dynamic and thermodynamic conditions.The two tropical cyclones interact with westerly trough to some extents when moving northward.The difference is that Haima interacts with a deep trough and couples with southward jet stream in front of the trough.A higher potential vorticity on the upper troposphere transports downward to lower troposphere to facilitate the development of a surface cyclone.Whereas Damrey strikes a weak trough,only appearing near the bottom of the trough,and the coupling effect is not significant.There is no a clear positive potential vorticity transporting downward to lower levels of the troposphere,so it is not favorable for the development of a surface cyclone.Therefore Haima weakens first and then intensifies again after landing,but Damrey weakens continuously till disappears in the Bohai Sea. References | Related Articles | Metrics

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Evaluation of the prediction by area rainfall forecast model OCF for six big reservoir basins in Zhejiang province ZHU Zhan-yun, CHEN Guang-yu, JIANG Yu-jun, SHEN Ping-yue, XU Luan 2016, 32 (3):  28-33.  doi: 10.3969/j.issn.1673-503X.2016.03.004 Abstract ( 242 )   PDF (1017KB) ( 404 )   Save A fuzzy comprehensive evaluation method and TS (Threat Score) score were used to compare and analyse the forecast skills of OCF (Objective Consensus Forecasting) model based on areal rainfall over six reservoir basins in Zhejiang province during Meiyu period,persistent rainy weather in August,afternoon thundershowers,typhoon precipitation processes in 2014.The results show that during the frontal precipitation processes (i.e.,Meiyu rainfall and August continuous rain processes),OCF model has better forecast skills with higher fuzzy comprehensive and TS scores,and the false alarm ratios are far higher than the miss alarm rates.Prediction skill of OCF model is gradually improved with the lead time from 192 h to 24 h,and the differences predicted among reservoirs are reduced.For the afternoon thundershower cases,OCF model gets a secondary performance in fuzzy comprehensive and TS scores.When these reservoir basins gets higher false alarm rates,they has higher miss alarm rates.The forecast scores of leading time from 192 h to 24 h show an unstable change pattern.There are significant regional differences.For typhoons of Fungwong and Matmo,OCF model exhibits a poor performance both in fuzzy comprehensive and TS scores,and the false alarm rates are higher than those of the miss alarm.The forecast skill shows a distinct improving trend from 192 h to 24 h in the leading time.The differences among reservoirs are obvious. References | Related Articles | Metrics

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Analysis on a persistent haze process in Changzhou CHEN Bo-li, LEI Zheng-cui, WU Jian-qiu, WU Jing-lu, HUANG Wen-yan 2016, 32 (3):  34-40.  doi: 10.3969/j.issn.1673-503X.2016.03.005 Abstract ( 284 )   PDF (1673KB) ( 400 )   Save Using the conventional meteorological observations and the NCEP reanalysis data,a persistent haze process from December 1 to 8,2013 in Changzhou was analyzed comprehensively in this study.The results show that zonal circulation at high levels in the middle-high latitudes is straight during the haze event,and meanwhile the low levels are mostly controlled by the warm and moist southwesterly airflows,with very weak cold-air activities.The reasons for the haze outbreak are mainly due to the transport of upstream contaminants by westerly airflows caused by an "L"-type high pressure locates at Changzhou on November 30,and the existence of a thermal inversion layer is in the early morning of December 1.The continuous uniform pressure field and the frequent thermal inversion layer are the maintaining mechanism of the haze.The strong cold air front leads to the dissipation of the haze on December 9.The haze process is accompanied by decreasing dew point depression,the increasing relative humidity,the southerly and westerly weak winds,and the ineffective upward motion near the surface,which provides a stable atmospheric layer structure and appropriate water vapor for the haze maintenance.The main pollutants during the haze event are particulate matters (PM2.5,and PM10).The gaseous pollutants such as SO2,NO2,and O3 generate particulate matters through the cooperative transformation effect,and lead to the dramatic increase in pollutant concentrations,which is an important internal cause for the haze formation.The backward trajectory analysis illustrates that the transport of pollutants from the upstream region of Jiangsu province also contributes to the haze event. References | Related Articles | Metrics

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Statistic and diagnosis of storm rainfall areas based on the Northeast Cold Vortex cases XU Hong, CHAO Hua, WANG Wen, CHEN Jun-qing 2016, 32 (3):  41-46.  doi: 10.3969/j.issn.1673-503X.2016.03.006 Abstract ( 244 )   PDF (1811KB) ( 525 )   Save Based on 35 Northeast Cold Vortex cases during 2008-2011 and Micaps observation data,the statistic and diagnosis for storm rainfall areas of Northeast Cold Vortex were carried out.The results indicate that most of storm rainfalls occur in the Ⅱand Ⅲ quadrants.There are three high probability areas with storm rainfall in theⅡquadrant.The three areas include the middle part of Jilin province,the borders of China and Korea and Liaodong Peninsula with the maximum probability of 0.6.There is only one high probability area (the North of Hebei province) in the Ⅲ quadrant with probability of 0.5.Furthermore,based on the NCEP/NCAR reanalysis data and the method of composite analysis with the diagnostic values of dynamic conditions and thermal conditions,the distribution of probability of storm rainfall areas are compared.The above analysis shows that there is an obvious transportation of water vapor belt on synoptic scale at low altitudes when the Northeast Cold Vortex is forming.At the same time,a clear wet tongue is formed when water vapor convergence together and the storm rainfall tends to occur on the tip of the wet tongue.Moisture flux divergence, vector divergence and moisture potential vorticity could be factors for satisfactional forecast of the storm rainfall areas and the areas with high diagnostic value coincide with the high probability areas of storm rainfall,especially in the I,Ⅱ and Ⅲ quadrants of the Northeast Cold Vortex. References | Related Articles | Metrics

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Analysis of precipitation trend in Dalian from 1971 to 2013 WANG Xiu-ping, WANG Shuo, LI Xiao-xiao 2016, 32 (3):  47-52.  doi: 10.3969/j.issn.1673-503X.2016.03.007 Abstract ( 213 )   PDF (562KB) ( 438 )   Save Based on the daily precipitation data from 1971 to 2013 in 7 weather stations in Dalian,the annual and seasonal variations of precipitation amount,precipitation days,precipitation intensity and contribution rate of precipitation under different grades were investigated in terms of a linear trend estimation method.Additionally,the reasons for significant changes in precipitation intensity were also examined.The results indicate that mean annual precipitation in Dalian during 1971-2013 shows a weak increasing trend.Precipitation in spring and summer during the last 43 years increases,whereas precipitation in autumn and winter decreases.Only spring precipitation during the last 43 years increases significantly.The annual and seasonal precipitation days during 1971-2013 show a downward trend and their trend do not pass the significant test.Annual and spring precipitation intensity increase significantly,whereas the variation trends of other seasonal precipitation intensity are not obvious.The significant increase of annual and spring precipitation intensity is due to the increasing contribution rate of annual and spring storm rainfall and storm rainfall days. References | Related Articles | Metrics

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Analysis of characteristics and impact factors of haze in Changzhou LEI Zheng-cui, QIAN Wei, XIA Wen-mei, SHEN Yan, WU Jing-lu, WU Jian-qiu, HUANG Wen-yan, LIU Yin-feng 2016, 32 (3):  53-60.  doi: 10.3969/j.issn.1673-503X.2016.03.008 Abstract ( 299 )   PDF (1309KB) ( 438 )   Save Based on the meteorological observations and air quality data obtained from environmental monitoring center in Changzhou from 2001 to 2011,the characteristics of haze and its impact factors were analyzed in this study.The results indicate that annual cumulative haze days fluctuate largely.The occurrence frequency of haze is larger from November to January,and smallest in summer.Haze occurs most frequently at 11:00,followed by 14:00,and least at 05:00 in order.The haze formation is usually accompanied with two weather types at upper atmosphere,and three weather types near the surface.Haze dose not occur under strong rainfall conditions,but sometimes occur under weak precipitation conditions.The inversion layer favors greatly the haze formation.Haze in Changzhou usually occurs under conditions with weak easterly winds under 2 grades and with relative humidity between 41.0% and 70.0%.The fog-haze transmission always exists in most of fog events (except rain-fog).There is very close relationship between haze,CO,and PM10 from 2001 to 2011 at Changzhou.According to a haze case,it shows that the straw burnings,pollutants transported by winds,and air descending motions are major reasons for this haze process. References | Related Articles | Metrics

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Characteristics of climate change from 1951 to 2014 in Dandong CHEN Kai-qi, ZHANG Xin-yue, LI Jia-yun, QU Shu-lin, FENG Kai-yue, LENG Wen-nan, ZHANG Wen-yu 2016, 32 (3):  61-70.  doi: 10.3969/j.issn.1673-503X.2016.03.009 Abstract ( 344 )   PDF (1879KB) ( 547 )   Save Based on observations of air temperature and precipitation in Dandong from 1951 to 2014,the evolution and characteristics of mean air temperature,mean maximum and minimum temperature,as well as precipitation amount and days,were analyzed in this study.The results show that the annual mean air temperature in Dandong from 1951 to 2014 increases obviously,by about 1.5℃,which is larger than the increasing rate averaged in China.Seasonal mean air temperature also increases in Dandong,with the largest increasing rate in winter.The increase of annual mean minimum temperature is greater than that of the annual mean maximum temperature,resulting in an asymmetric growth.The mean daily temperature difference decreases in all seasons,especially in winter.Both precipitation amount and days decrease in all seasons,particularly in summer,except in spring,resulting in a decrease of the annual mean precipitation. References | Related Articles | Metrics

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Pan evaporation characteristics and its influencing factor over Tarim irrigation area from 1961 to 2010 NIU Jian-long, GE Guang-hua, WANG Jia-qiang, PENG Jie, WANG Yu-dong, HAO Lu 2016, 32 (3):  71-76.  doi: 10.3969/j.issn.1673-503X.2016.03.010 Abstract ( 342 )   PDF (618KB) ( 285 )   Save Using the meteorological data including daily pan evaporation,mean air temperature,minimum and maximum air temperature,relative humidity,sunshine duration and mean wind speed from 1961 to 2010,the characteristics and impact factors of pan evaporation were analyzed based on the methods of a climate inclination rate,an anomalies and correlation in Alar of Tarim irrigation area.The results show that annual fluctuation of pan evaporation is very obvious,with a "high-low-high-low" inter-decadal variability feature.The amplitude of pan evaporation decreases by 62.4 mm per decade (P<0.01),and has totally reduced about 312.0 mm in Alar of Tarim irrigation area in the past 50 years.The pan evaporation is the largest in summer,and then in spring,autumn,and winter in order from 1961 to 2010 in Alar of Tarim irrigation area.The decrease in pan evaporation is relatively larger in winter and summer (P<0.01),relatively smaller in spring (P<0.05),and very little in autumn (P>0.05).The cumulative decrease amplitudes are 81.5 mm,182.5 mm,28.5 mm,and 198.0 mm in spring,summer,autumn,and winter,respectively.The decrease in the annual cumulative pan evaporation depends strongly on the decreasing mean wind speed and increasing mean relative humidity,but less so on air temperature,precipitation,and sunshine duration.However,the decrease trend of seasonal cumulative pan evaporation is determined by the increasing (decreasing) air temperature,declining sunshine duration,increasing (decreasing) precipitation,decreasing mean wind speed,and increasing mean relative humidity together,although in spring and autumn it is little influenced by air temperature and sunshine duration. References | Related Articles | Metrics

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Temporal-spatial distributions of hail disaster from 1952 to 2012 in Weifang of Shandong province GAO Xiao-mei, WANG Ling-jun, WANG Shi-jie, HAN Xiao, WANG Wen-bo, QIU Gang, MA Shou-qiang 2016, 32 (3):  77-82.  doi: 10.3969/j.issn.1673-503X.2016.03.011 Abstract ( 639 )   PDF (781KB) ( 400 )   Save Temporal and spatial distributions of hail disaster were analyzed using hail and meteorological disaster data from nine stations in Weifang from 1952 to 2012.The results show that the hail disaster is serious in Weifang during this period of time.The frequency of occurrence for large hails is higher,and in most cases,the hail disaster lasts for more than 20 minutes.The hail occurrence exhibits strong local characteristics,and topography plays a crucial role in determining the spatial distribution of hail days,with a high value in the mountain and a low one in the plain.Most hail storms occur in June.The maxima appears in the middle ten-day of June.The monthly variation of hail days in Weifang shows a ruled pattern,which increases first and then decreases later.Normally hail occurs at 14-16 p.m.There is a significant inter-decadal variation in the number of hail days,existing about 16 and 2 years of periodic variations.The climatic abrupt change in the number of hail days appears in 1970.After 1970,especially after 1974,the hail occurrence frequency is found to increase.The number of hail days shows a pronounced negative correlation with the corresponding cold-air activity index. References | Related Articles | Metrics

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Comparison and analysis of cloud-ground lightning characteristics in Anhui province and its southern mountains WANG Kai, ZHU Hao, JU Xiao-yu, QIU Yang-yang, CHENG Xiang-yang 2016, 32 (3):  83-88.  doi: 10.3969/j.issn.1673-503X.2016.03.012 Abstract ( 198 )   PDF (946KB) ( 369 )   Save Using the data of ADTD (Active Divectory Topology Diagrammer)lightning location system in Anhui province from 2011 to 2013,lightning occurrence frequency,lightning current intensity,lightning temporal and spatial distribution characteristics in the southern mountains Anhui province were analyzed,and compared with those in Anhui province.The results show that lightning frequency in the southern mountains accounts for 28.2% of total value in Anhui province.The average lightning density in the southern mountains is 3.21 times·km-2·a-1,while the corresponding value in Anhui province is 2.51 times·km-2·a-1.The main type of lightning in Anhui province and its southern mountains is negative.The peak period of lightning appears from June to September.The lightning frequency during this period is 90.8% of the whole value of a year.The lightning in the southern mountain mainly occurs from afternoon to evening.The crucial time-period is 14:00-17:00,and this is similar to that in Anhui province.Lightning current intensity in Anhui province mainly concentrates in 10-50 kA.The percentage of positive cloud-ground lightning increases at the region with a higher lightning current intensity.The average intensity of positive cloud-ground lightning in the southern mountains is 45 kA,and the negative one is 36 kA,which are both slightly lower than those in Anhui province. References | Related Articles | Metrics

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Analysis of meteorological factors effecting on yield of Camellia oleifera and construction of yield forecasting model in Hu'nan province PENG Jia-dong, JIANG Yuan-hua, LIAO Yu-fang, CHEN Long-sheng 2016, 32 (3):  89-94.  doi: 10.3969/j.issn.1673-503X.2016.03.013 Abstract ( 322 )   PDF (517KB) ( 545 )   Save Based on the collection and processing of yield data from multiple Camellia oleifera sample plots in different counties of Hu'nan province during 2006-2013 and temperature,sunshine and precipitation data from the nearby meteorological observation stations during the same period,the quality control of Camellia oleifera yield data was made in order to remove the influences of Camellia oleifera's age,species,and soil on the yield data.Then statistical method was used to analyze impacts of meteorological factors in different phonological phases on Camellia oleifera's yield and to construct Camellia oleifera's yield forecasting model by taking meteorological factors as independent variables.The results show that the key meteorological factors affecting Camellia oleifera's yield are average temperature during flowering,rain days during peaking period of fruit enlargement,sunshine hours during lipid transformation and peak period of accumulation,and average temperature during flower bud maturing.A yield forecasting model constructed by use of the above factors has a relative high accuracy and can be applied in the operation. References | Related Articles | Metrics

Reviews

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Effects of biochar application on soil physical properties:a review ZHAO Jian-kun, LI Jiang-zhou, DU Zhang-liu, WANG Yi-ding, ZHANG Qing-zhong 2016, 32 (3):  95-101.  doi: 10.3969/j.issn.1673-503X.2016.03.014 Abstract ( 257 )   PDF (457KB) ( 472 )   Save The biochar characteristics,e.g.,specific density,surface structures and pore structures may potentially affect soil physical properties.This paper summarized the current research advances about the effect of biochar amendment on soil physical properties with respect to soil aggregation,structure,hydraulic and thermal properties.In general,biochar application reduces the soil bulk density and improves soil pore structure.However,the effects of biochar on soil aggregation and soil hydraulic characteristics show some uncertainty.Biochar application can modify soil temperature variation and reduce soil thermal conductivity and surface albedo,but the relevant mechanisms remain unclear.Additionally,the potential mechanisms that may reveal the changes in soil physical properties induced by biochar addition in terms of biochar types,pyrolysis conditions and soil texture are analyzed in this study and perspectives in future studies are also presented. References | Related Articles | Metrics

Scientific Notes

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Risk division and assessment of low-temperature,rain/snow and freezing disasters on highway in Zhejiang province GU Ting-ting, PAN Ya-ying, LUO Yue-zhen 2016, 32 (3):  102-106.  doi: 10.3969/j.issn.1673-503X.2016.03.015 Abstract ( 294 )   PDF (1531KB) ( 521 )   Save Highway was taken as the division object in this paper.Based on the conventional observation data from 68 weather stations in Zhejiang province and combined with the geographic information,social and economic,and traffic accident data,the risk assessment index sets were established on the basis of the analysis of disaster-causing factors,risk exposure index and characteristics of traffic accidents on highway from 2004 to 2013.The risk division and assessment of low-temperature,rain/snow and freezing disasters on highway in Zhejiang province were performed using methods of ArcGIS spatial analysis technique,weighted comprehensive evaluation and hierarchy analysis.The results show that it is divided into five categories of risk,i.e.,higher,sub-high,medium,inferior and lower risks on highway in Zhejiang province.The higher risk road length accounts for 13.49% of the total value.The higher risk sections are mainly located in Hang-Jingxin highway Jiande,Hang-Rui highway from Hangzhou to Lin'an,Hu-Yu highway Huzhou,Shen-Jiahu highway Huzhou,Lian-Hang highway from Deqing to Yuhang,Chang-Shen highway Hangzhou city and from Huzhou to Yuhang,Hang-Jinqu highway Quzhou,Zhu-Yong highway from Dongyang to Pan'an,and Tai-Jin highway Jinyun ones.This study provides a scientific reference for the highway management department to prevent and mitigate disasters. References | Related Articles | Metrics

Bulletins

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Comparative study on calculation methods of dew-point temperature XU Xin-yin, YU Jun-qi, LI Hong-lian, YANG Liu 2016, 32 (3):  107-111.  doi: 10.3969/j.issn.1673-503X.2016.03.016 Abstract ( 782 )   PDF (665KB) ( 4898 )   Save This article introduced three methods for calculating dew-point temperature.The three methods include calculating dew-point temperature directly through the formula with dry-bulb temperature and relative humidity,calculating dew-point temperature indirectly through the formula with dry-bulb temperature,relative humidity,and environmental vapor pressure,and calculating dew-point temperature through the formula with dry bulb temperature,wet bulb temperature,and atmospheric pressure.This study analyzed the deviations between estimated dew-point temperature and observed dew-point temperature in Changchun,Xi'an,Wuhan,and Guangzhou.The results show that the direct and indirect calculating methods both have their merits.The error of the direct calculating method for estimating the dew-point temperature is within 0.5℃ when dry bulb temperature is between 0.0℃and 30.0℃ and relative humidity is between 40% and 100%.The direct calculating method is suitable for areas with higher temperature and relative humidity.Comparatively,the indirect calculating method for estimating the dew point temperature has a higher accuracy and the error is within 0.2℃,so this method can be applied in the future. References | Related Articles | Metrics