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31 December 2018, Volume 34 Issue 6 Previous Issue    Next Issue

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Analyses of the structural characteristics of a local heavy rainfall from the mesoscale convective system over the southwestern He'nan province SU Ai-fang, ZHANG Ning, YUAN Xiao-chao, WANG Di 2018, 34 (6):  1-10.  doi: 10.3969/j.issn.1673-503X.2018.06.001 Abstract ( 220 )   PDF (5785KB) ( 238 )   Save In this paper,the FY (Feng Yun) geostationary satellite,Doppler radar products and 4DVAR (Four-Dimensional Variational Data Assimilation),regional automatic station,conventional meteorological and the NCEP reanalyzed data were used to analyze the structure,evolution and formation mechanisms of the MCS (Mesoscale Convective System) on the north side of the Subtropical High and in upper reaches of the Huaihe River on August 16,2011.The MCS formed in the shear line near the edge of the subtropical high.The cold air diffusion to trigger the release of a higher convective instability energy is the main mechanism for the system development.The lifecycle of the convective system consists of four periods:primary stage,merger and development stage of MβCS,maturity and decay stages of round MαCS.The heavy rainfall mainly occurs during the former three stages.On the radar image,the MCS is mainly composed of single and multi-cell storms at the primary stage and shows a β or α mesoscale convective system at the rest stages.The system often appears a linear convective one at the MαCS maturity stage.Convection merger results in an explosive development of the MCS.The positive and negative vorticity layers of the convection system show alternate distribution characteristics.The high-level divergence and vertical upward movement are relatively weak.The width of the low-level convergence is associated with the scale of the system.The intersection of cold and warm air flow and topographic convergence lines play an important role in triggering the convection,and the area current confluence is advantageous to form and develop the round MCS.The mesoscale mountainous topography in the west of He'nan province has an influence on the range and intensity of the heavy rainfall. References | Related Articles | Metrics

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Impacts of different background error samples simulation schemes on numerical forecast-taking typhoon “Soudelor” as an example WANG Ye-hong, ZHAO Yu-chun 2018, 34 (6):  11-23.  doi: 10.3969/j.issn.1673-503X.2018.06.002 Abstract ( 229 )   PDF (2686KB) ( 155 )   Save Based on the methods of WRF (Weather Research and Forecasting Model),WRF-3DVAR (Weather Research and Forecasting-Three-Dimensional Variational Data Assimilation) and the NMC (US National Meteorological Center),we investigated whether or not and how the statistical background error samples under different initialization schemes have non-neglected impacts upon the background error covariance and its related forecasting effects.Experiments with hot-start cycled assimilation and cold-start initialization schemes were carried out.It is seen that the results from single point observation idealized assimilation experiments with background error covariance calculated from statistical background error samples under different initialization schemes are consistent with those from theoretical models.The differences in analyzed incremental fields are obvious and should not be ignored.The experimental results of "Soudelor" typhoon rainfall event in 2015 indicate that the background error covariance calculated from background error samples under different initialization schemes has a certain effect on the assimilation fields,and exerts obvious effects on the forecasts of typhoon track and rainfall,but have little impacts on the typhoon intensity and maximum wind speed near the typhoon center.Numerical experiments with four different initial time indicate that the background error covariance calculated from background error samples under hot-start cycled assimilation schemes shows a much better forecast for "Soudelor" typhoon track and rainfall,and its impacts on typhoon track are mainly shown after 24-h integration of the numerical forecast model. References | Related Articles | Metrics

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Analyses of the mechanisms of the first regional snowstorm associated with an “Elevated Thunderstorm” over Shaanxi province in 2016 YAO Jing, JING Yu, LIU Yong, ZHAO Qiang, WANG Nan 2018, 34 (6):  24-32.  doi: 10.3969/j.issn.1673-503X.2018.06.003 Abstract ( 236 )   PDF (8224KB) ( 134 )   Save Using the surface meteorological station observations,FY-2G hourly satellite TBB (Temperature of Black Body) lightning positioning data,Xi'an CINRAD/CB-type Doppler radar,NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) 1°×1° reanalysis data in every 6 h,and conventional meteorological data,the formation mechanisms of a rare heavy snow process accompanying with an "elevated thunderstorm" occurred on November 22-23,2016 was discussed.The results show that the 500 hPa upper trough,700 hPa low-level shear line and lower troposphere jet are major systems influencing this heavy snow process.The southwest jet at 700 hPa provides sufficient water vapor,and the 850 hPa low-level jet and the inverse trough eastward airflow at the ground provide a deep cold pad.The "elevated thunderstorm" with the heavy snow is a typical "cold sector thunderstorm" which is maintained by the strong inversion layer below 700 hPa and by the wet neutral boundary layer above 700 hPa.The upflow is stronger,so the moist and deep convection is easy to form.The frontal secondary circulation circle is helpful to the development of the slantwise updraft.The vertical wind direction shear is strong.The convective echo intensity ranges from 30-50 dBz,and the echo top height is 10-12 km.The tropopause height exceeds subcooled water layer height with a temperature range of -20~0 ℃,making the thunder to form easily.The thunder and hail normally appear on the left-hand side of the low-level jet entrance region,which is close to the high concentration zone of TBB,water-vapor flux,and θse. References | Related Articles | Metrics

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Comparison analysis of two rare heavy rainfalls in Spring over Heilongjiang province REN Li, ZHANG Gui-hua, ZHAO Ling, LIN Jia-nan 2018, 34 (6):  33-41.  doi: 10.3969/j.issn.1673-503X.2018.06.004 Abstract ( 283 )   PDF (2669KB) ( 244 )   Save Based on the conventional and intensive observation data,FNL (Final Analysis) reanalysis data,as well as the TBB (Temperature of Black Body) observed by the FY-2E satellite,the associated thermodynamics,dynamic and instability mechanisms,warm front frontogenesis and the symmetric instability for the occurrence and evolution of two rare heavy rainfalls at the beginning of May over Heilongjiang province were analyzed.The results suggest that the influencing systems of the two heavy rainfalls are the upper trough that cuts into the cold vortex.The difference of the location at which the new cold cortex is formed leads to a different heavy rainfall area.During the two heavy rain processes,there is a secondary circulation perpendicular to the warm front.The secondary circulation is helpful to strengthen the ascending motion and strengthen the rainfall intensity.During the two heavy rain processes,the characteristics of the atmosphere are thermal stability.The low layer cold zone before the warm front is dry and cold.It acts as a cold wedge.Warm air rising above the cold wedge along the front is the main cause for the persistent rainfall.The difference is that in the cold air below the fronts of the 2016 rainstorm,the range and thickness of the sinking motion are larger.The joint action of the cold wedge and the terrain cause the upward motion mainly happen in the upper and middle layers of the frontal zone.Two rainstorms occur in the warm frontogenesis.Rainfall and frontogenesis accompany with each other.The rainfall intensity reaches the strongest level during the period that the frontogenesis is the strongest.When the frontogenesis starts to weaken,the rainfall intensity also starts to weaken till reaching zero.The moist convective instability of the middle troposphere is conducive to the development and maintenance of rainfall.There is a mesoscale rain belt paralleling with the warm front. References | Related Articles | Metrics

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Assessing CMIP5 climate simulations and objective selection of models over the Yellow River basin ZHOU Wen-chong, HAN Zhen-yu 2018, 34 (6):  42-55.  doi: 10.3969/j.issn.1673-503X.2018.06.005 Abstract ( 197 )   PDF (4435KB) ( 143 )   Save Based on gridded observation dataset,multi-criteria assessment on daily surface air temperature and precipitation (1961-2005) from 18 CMIP5 (Coupled Model Intercomparison Project phase 5) models were conducted over the Yellow River Basin.A suite of statistics is calculated,including climatological mean,interannual variation,seasonal cycle,interannual modes,and probability distribution function,to evaluate their performances.According to the comprehensive rank,the models with poor validation are excluded.Five models,i.e.,MIROC-ESM-CHEM,CSIRO-Mk3-6-0,NorESM1-M,CNRM-CM5,and EC-EARTH are therefore recommended for the regional multi-model climate change projections over the Yellow River basin.The selected subset can also sample the range of uncertainty represented by the full ensemble. References | Related Articles | Metrics

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Projection of surface wind by CMIP5 and CMIP3 in China in the 21st century JIANG Ying, XU Xi-yan, LIU Han-wu, WANG Wen-ben, DONG Xu-guang 2018, 34 (6):  56-63.  doi: 10.3969/j.issn.1673-503X.2018.06.006 Abstract ( 313 )   PDF (2410KB) ( 445 )   Save The change of surface wind speed was projected by 23 Climate models from the CMIP5 (Coupled Model Intercomparison Project Phase 5) for IPCC AR5 (Intergovernmental Panel on Climate Change Fifth Assessment Report) adapted by WCRP (Word Climate Research Programme) and 19 Climate models from the CMIP3 (Coupled Model Intercomparison Phase 3) for IPCC AR4 (Intergovernmental Panel on Climate Change Fourth Assessment Report) adapted by WCRP (Word Climate Research Programme).The human emission scenarios used the RCPs (Representative Concentration Pathways) including RCP2.6,RCP4.5 RCP8.5 from CMIP5 and the SRES (Special Report on Emissions Scenarios) including B1,A1B,A2 from CMIP3.The results show that the mean annual wind speeds would decrease slightly in China in the 21st century.The mean wind speeds would reduce more significantly with the increase of human emission concentration.Both CMIP5 and CMIP3 project that the mean annual wind speed in Western China (Northern and Southwestern parts) would decrease in the 21st Century and would increase in the eastern region.Compared with that in the early period of the 21st Century (2006-2015),wind speed would decrease in the south of Northeast China,north of North China and West China,while it would increase in the south of North China,South China and the north of Northeast China in the late 21st Century (2090-2099).With the increase of human emission concentration,the negative (positive) deviation ranges in wind would enlarge and the corresponding center value would be more concentrated in winter (summer). References | Related Articles | Metrics

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A numerical simulation study on the effects of urban expansion on the wind and thermal environment in boundary layer:a case study of Shenyang SHEN Li-du, GONG Qiang, XU Hong, WANG Tao, GU Zheng-qiang, MA Yan-jun 2018, 34 (6):  64-74.  doi: 10.3969/j.issn.1673-503X.2018.06.007 Abstract ( 195 )   PDF (2868KB) ( 184 )   Save Based on the land use data in 1993 and 2005,the effects of urban expansion on the near-surface wind and thermal environment and boundary layer were investigated using the UCM+AH scheme in the WRF model under the conditions of two clear days in August 2005.The results show that UCM+AH scheme is able to properly and accurately simulate the diurnal variations of 2 m temperature and 10 m wind speed,and the accuracy of simulated 2 m temperature is better than that of 10 m wind speed.The scheme overestimates the diurnal range of the simulated 2m temperature and the wind speed systematically by 0.5-1.0 m·s-1.Urban expansion can lead to a general warming in the urban area especially in nighttime.The maximal increasing amplitudes of 7 ℃ and 3 ℃ at nighttime are distributed in the expanded and old urban area,respectively.The increasing amplitude is larger in the upwind direction than in other directions.The warming with a range between 0-1 ℃ at daytime is not obvious in the urban area.In addition,after urban expansion,the wind speed decreases generally with a magnitude smaller than 1.0 m·s-1 in the old urban area and close to 1.0 m·s-1 in the expanded urban area.At the same time,a high-temperature convergent zone in the urban area accelerating the near ground wind speed in the surrounding areas is probably caused by urban expansion.Besides,the urban expansion affects significantly the boundary layer in the afternoon and results in Turbulent Kinematic Energy with an increase of 0.2-0.3 m2·s-2 expanding its range of influence.Moreover,the boundary layer height is risen up by 100-200 m at 14:00 and the local thermal circulation and vertical upward motion are strengthened over the expanded area. References | Related Articles | Metrics

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Analysis of multi-scale characteristics of a short-time rainstorm process in Liaoning province in 2014 LI Shuang, DING Zhi-ying, ZHAO Huan, XING Rui, KANG Xiao-yu, HAN Yan-feng 2018, 34 (6):  75-83.  doi: 10.3969/j.issn.1673-503X.2018.06.008 Abstract ( 222 )   PDF (3155KB) ( 205 )   Save The circulation situation,mesoscale characteristics and cloud physics mechanism of precipitation during a short-time rainstorm process in Liaoning province from 20 to 21 July 2014 were studied based on NCEP (National Centers for Environmental Prediction) reanalysis data and high-resolution data output from mesoscale numerical WRF (Weather Research Forcast) model.The results show that the occurrence of the short-time rainstorm is firstly due to the fact that it is in front of the trough at 500 hPa and the shear line at 850 hPa and in the convergence zone of the left-hand side of the low-level jet.At the same time,the pumping action of upper-level jet strengthens ascending movement and a remote tropical cyclone transfers indirectly water vapor to Liaoning area along the west edge of the Pacific Subtropical High.Then,the β-scale cyclone on the ground triggers the precipitation at the storm center.In addition,the intrusion of the cold air has an important effect on the precipitation intensity.The maximum precipitation is collectively caused by the low-level convergence of the southward cold outflows from the sinking movement and southerly warm and humid inflows,and the middle-level convergence of northward and southward inflows.Besides,the γ-scale secondary circulation strengthens the ascending motion.Moreover,the cloud physical mechanisms of precipitation are different between the different periods.More specifically,when the heaviest precipitation occurs,the rainwater content increases rapidly with the growth of graupel particles,and cold cloud precipitation with the melting graupel particles plays a leading role in this rain.The efficiency of cold cloud precipitation is obviously higher than that of warm cloud,which causes easily the short-time heavy rainfall. References | Related Articles | Metrics

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Comparison analysis of circulation anomalies in midsummer between drought and flood years in Dalian WANG Xiu-ping, CHEN Xi-zhuang, CHENG Hang, JIN Wei 2018, 34 (6):  84-90.  doi: 10.3969/j.issn.1673-503X.2018.06.009 Abstract ( 204 )   PDF (3259KB) ( 293 )   Save Based on the observed monthly precipitation data at 6 stations in Dalian from 1964 to 2016,the NCEP/NCAR monthly mean reanalysis data during 1948-2016 and the circulation feature data of the western Pacific subtropical high (WPSH) given by the National Climate Center,the characteristics of the atmospheric circulation anomalies of the extremely drought/flood occurrences from July to August were studied using the methods of composite analysis and correlation analysis.Meanwhile,the causes of midsummer drought and waterlogging were revealed by considering atmospheric circulation anomalies.The results show that in midsummer waterlogging (drought) years in Dalian area,the northeast China westerly jet at 200 hPa is stronger (weaker) and the Yangtze River Valley westerly jet is weaker (stronger).At the same time,the location of the Western Pacific Subtropical high ridge line is more-northward (more-southward) and that of the East Asia trough is more-westward (more-eastward) at 500 hPa as well as the south wind anomalies at 850hPa is stronger (weaker).In addition,the anomalous ascending (descending) motions occur in the meridional circulation of vertical speed along the longitude of Dalian,which results in midsummer precipitation anomalously increasing (decreasing) over Dalian area. References | Related Articles | Metrics

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The experimental analysis on the response of the annual average runoff to climate change in Liaohe river basin SUN Feng-hua, LI Li-guang, YUAN Jian, LIU Ming-yan, XIE Yan-bing, HU Wei 2018, 34 (6):  91-95.  doi: 10.3969/j.issn.1673-503X.2018.06.010 Abstract ( 163 )   PDF (672KB) ( 112 )   Save Based on the historical meteorological and hydrological observation data over the past several decades,the parameters of the model established by Holland et al(1978).were calibrated.Meanwhile,an annual time-scale climate-runoff simulation model for the Liaohe River basin was built.Based on the new model,the simulation,sensitivity and prediction tests were carried out.The results indicate that under the condition of increase of annual precipitation by 10%,the annual runoff will increase by 14% and 31.5% in accordance with temperature increasing and decreasing by 1 ℃,respectively.However,under the condition of the increase of 1 ℃ in annual mean temperature,the annual runoff will increase by 14% and decrease by 30% corresponding to annual precipitation increasing and decreasing by 10%,respectively,which indicates that the response of runoff to the variation of precipitation is relatively more sensitive.On the basis of the estimated data for climate change scenarios released by the national climate center,the simulated predication results during 2001-2030 show that under the scenario of B1,temperature rises moderately and precipitation increases significantly as well as runoff increases evidently.In addition,under the scenario of A1B,temperature rises obviously and precipitation increases moderately while runoff increases with a small amplitude.Besides,under the scenario of A2,the increasing amplitude of temperature is smallest and precipitation increase moderately as well as the increase of runoff is in a medium level. References | Related Articles | Metrics

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Study on the trend of precipitation cycle in Lishui city from 1901 to 2015 WU Hao-min, WANG Qi, JIANG Yan-min, ZHANG Xin, LUO Xu-hui 2018, 34 (6):  96-101.  doi: 10.3969/j.issn.1673-503X.2018.06.011 Abstract ( 214 )   PDF (1142KB) ( 202 )   Save Based on the Climatic Research Unit (CRU) reanalysis dataset,a trend analysis method and the Mann-Kendall trend test method were used to analyze the variation trend and sharply change feature of precipitation in Lishui.The characteristics of precipitation cycle were studied based on the Morlet wavelet transform method and a Multi-Taper method (MTM),and significant period signals were reconstructed in order to further explore its variation trend.The results show that annual precipitation from 1901 to 2015 increases slightly by 8.41 mm/10 a,and there is a mutation in annual precipitation between 1962 and 1963.The Morlet wavelet analysis results indicate that a 20-a decadal precipitation cycle and two inter-annual precipitation cycles of 4.0-8.0 a and 2.0-4.0 a are significant in Lishui during the whole study period,especially the cycle of 2.0-4.0 a with a significance level of P<0.01.The precipitation cycle with the strongest oscillation in Lishui is 2.5 a,followed by 2.1 a and 4.1 a,according to the MTM analysis. References | Related Articles | Metrics

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Characteristics analysis of heavy precipitation in China from 1961 to 2013 ZHENG Shi, WANG Guan, LIN Zhong-guan, GUAN Jian-hua, HUANG Xing-you 2018, 34 (6):  102-107.  doi: 10.3969/j.issn.1673-503X.2018.06.012 Abstract ( 223 )   PDF (1426KB) ( 408 )   Save Heavy precipitation was defined separately according to the intensity and frequency of extremely heavy precipitation based on the precipitation data obtained from 726 meteorological stations in China from 1961 to 2013.The spatial and temporal variations of heavy precipitation over China in the recent 50a were analyzed using the methods of Rotated Empirical Orthogonal Function (REOF),wavelet analysis,and the Mann-Kendall trend test.An indicator for heavy precipitation was defined by the intensity of extremely heavy precipitation.Based on this indicator,four regions with high load values are distinguished,most regions concentrate in the middle of eastern China and the other in the southern and southwestern China.Heavy precipitation events in different regions increase significantly (p < 0.05),all with an abrupt change in the early 1980s.The strongest energy fluctuation over the four regions occurs in the periods of 1995-2005,1997-2010,1996-2010,and 1961-2013,respectively.The other indicator for heavy precipitation defined by the frequency of extremely heavy precipitation shows that the heavy precipitation events increase significantly in some regions of the middle and eastern China in the second EOF mode (P<0.1). References | Related Articles | Metrics

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Variation of characteristics of an extreme snowfall index over Sanjiangyuan region from 1961 to 2017 WANG Yu-juan, LIU Xiao-yan, BAI Ai-juan, QI Dong-lin, XIAO Hong-bin, OU Jian-fang 2018, 34 (6):  108-115.  doi: 10.3969/j.issn.1673-503X.2018.06.013 Abstract ( 195 )   PDF (2211KB) ( 210 )   Save Based on daily precipitation data at 14 meteorological stations in the Sanjiangyuan region during winter period (from October to April) from 1961 to 2017,the spatiotemporal characteristics of precipitation and an extreme snowfall index defined by a percentile threshold method were analyzed,using some statistical methods such as the linear tendency analysis,the Mane-Kendal trend test,and the Morlet wavelet analysis.The results show that there is a significant increase in precipitation over the Sanjiangyuan region during winter period.The extreme snowfall threshold varies between 2.6 and 7.8 mm with an occurrence frequency ranging from 1.6 to 3.8 d.It also exhibits an increasing distribution from the northwestern region to the southeastern region,with the high-value center located in the Qingshui River and low-value center in Xinghai.The extreme snowfall increases significantly by 2.2 mm/10 a with a distinct abrupt change in 1993 and has an obvious quasi-periodic cycle of 12 a.The extreme snowfall mostly occurs in April and October,and the regions with a higher occurrence frequency of snow disaster are located in the middle and southern areas (centers located in Qingshui River and Zaduo) with a higher occurrence probability of moderate snow disasteron References | Related Articles | Metrics

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Influence mechanism of meteorological conditions on a heavy pollution event in Shenyang and the Songliao Plain during January 2017 YANG Yuan-qin, WANG Ji-zhi, ZHANG Xiao-ye, CHE Hui-zheng, ZHONG Jun-ting 2018, 34 (6):  116-124.  doi: 10.3969/j.issn.1673-503X.2018.06.014 Abstract ( 214 )   PDF (2067KB) ( 247 )   Save Based on the surface observational data,sounding data,monitoring data from automatic weather stations (AWS) and atmospheric constituent stations,an indicator that was established using parameters linking air-quality to meteorological condition (PLAM) was used to diagnose and predict the contribution of polluted meteorological conditions to aerosol pollution.An extremely heavy polluted event rarely occurred in Shenyang and the Songliao Plain in January 2017.The vertical structure of atmosphere as well as its effect on the increase in aerosol concentration, was studied in this polluted event,in order to investigate the influence mechanism of meteorological conditions on the formation of heavy air pollution in Shenyang.An index of the height of pollution mixing layer (H_PML) is defined in this study,which has significant meaning for the analysis and diagnoses of air pollution.The decrease in H_PML value favors the accumulation and increase in PM2.5 concentration and vice versa.Based on the PLAM indicator and through the analysis of the atmospheric isentropic process,it is revealed that the atmospheric stratification can suppress the vertical dispersion and the H_PML value continues to decrease due to the feedback effect.The two-way belt of pollutant transport exists in the surrounding regions of Shenyang according to the indicator PLAM→Shenyang,resulting in an obvious overlying effect on the air pollution in Shenyang,which is the crucial reason of this persistent and heavy pollution event. References | Related Articles | Metrics

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Characteristics of haze day in the urban and suburban areas of Liaoning province LI Li-guang, DING Kang-kang, WANG Hong-bo, ZHAO Zi-qi, ZHAO Xian-li, CHEN Gang, DONG Guo-ping 2018, 34 (6):  125-132.  doi: 10.3969/j.issn.1673-503X.2018.06.015 Abstract ( 170 )   PDF (2732KB) ( 148 )   Save A total of 61 meteorological stations were selected according to their positions,distances among the urban and suburban stations,data record duration and continuity.These stations were then grouped into four types,i.e.,the urban stations,the suburban stations,the outer suburban stations,and the rural stations.Based on meteorological data such as visibility,relative humidity measured at 02:00,08:00,14:00 and 20:00 as well as daily weather phenomena in Liaoning province from 1960 to 2013, the characteristics of haze day in urban and suburban regions were statistically analyzed.The results indicate that monthly variations in haze days in urban,suburban and outer suburban,and all over regions in Liaoning province all exhibit a "W"-shape pattern.The largest monthly mean number (7.6 d) of haze days occurs in the suburban area,and those in the urban and suburban (6.8 d) regions are obviously larger than those in the outer suburban area (4.9 d) and rural areas (2.3 d).Among the four areas,the haze day numbers in suburban regions are the largest,followed by the urban,outer suburban,and rural areas.In the suburban regions,the number of haze day is 31.7 d in winter,14.6 d in spring,22.1 d in summer,22.9 d in autumn.The annual mean haze day numbers in four type regions and in the whole Liaoning province all decrease during 1980 to 2013,especially in the urban region with a decreasing trend of -9.9 d/10 a but only -0.1 d/10 a in the suburban regions.The inter-decadal mean haze day number in Liaoning province slightly decreases and that in the urban area decreases significantly; it fluctuates and decreases in suburb area and outer suburb area.The monthly,seasonal,annual,and inter-decadal haze day numbers have various spatial distributions,with a multi-center distribution,which means the maximum and minimum center of haze days depend on different time scales.The largest haze day number center and the second one both occur at the urban and suburban stations such as the Shenyang,Sujiatun and Liaoyang County stations,while the lowest haze day number centers mostly occur at the outer suburban stations.The analysis results suggest that haze pollution is heavier in suburban areas.The annual haze day numbers observed at typical stations in urban,suburban,and outer suburban regions vary significantly,which is closely related to the local economic development and environmental conditions. References | Related Articles | Metrics

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Aircraft observation of atmospheric ice nuclei concentration in Liaoning and Shenyang regions ZHOU De-ping, SU Hang, GENG Shu-jiang, WANG Yang-feng, HONG Ye, LIU Ning-wei 2018, 34 (6):  133-139.  doi: 10.3969/j.issn.1673-503X.2018.06.016 Abstract ( 197 )   PDF (858KB) ( 349 )   Save For better understanding the distribution and variation characteristics of atmospheric ice nuclei (IN) concentration at different altitudes,an aircraft observational experiment was carried out over Shenyang and its surrounding areas from April to September in 2011 and 2012.The analysis results show that the values of IN number concentration in the near-surface layer at Shenyang range from 101 to 102 L-1 in the range of air temperature between -15 and -20 ℃,and the background concentration of IN at different altitudes (1.5- 4.5 km) in clouds are less than 2.0 L-1 and 10.0 L-1,respectively.The spatial distribution and temporal variation of atmospheric IN in the near-surface layer and in clouds over Liaoning and Shenyang areas have large variability,with 1-2 order of magnitude in the difference between the maximum and minimum concentrations.The IN number concentration decreases gradually with increasing height below 4.5 km.The vertical distribution of the number concentration of natural IN that has not been affected by artificial catalysis follows a power function well,while the IN number concentration increases by an order of magnitude at least observed in clouds at 3.1 km after distributing silver iodide as the artificial catalyst.The IN number concentration detection corresponds to a water-surface supersaturation of -1.0% to 5.0%,and the ice formation process includes the deposition and condensation-freezing nucleation mechanisms. References | Related Articles | Metrics

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Advanced in research on rainfed crop yield gaps MI Na, CAI Fu, ZHANG Yu-shu, ZHAO Yi-jun, ZHANG Shu-jie, JI Rui-peng, WANG Yang, WANG He-ran, SUI Ming 2018, 34 (6):  140-147.  doi: 10.3969/j.issn.1673-503X.2018.06.017 Abstract ( 170 )   PDF (540KB) ( 214 )   Save This paper reviewed the latest 10 years',especially the latest 5 years',advances in research on rainfed crop yield gaps from the respects of the size of yield gap between average and rainfed potential yields,yield gap explaining factors and possible methods regarding reducing the gap.The definitions and measurements of water-limited yield potential,average yield,and yield gap were also summarized.In addition,yield potentials and yield gaps at the cropping system level released from the latest research were also introduced in this paper.According to the different methods used to measure yield potential,the yield gaps can be grouped to model-based yield gap,experiment-based yield gap,and farmer-based yield gap.The cropping system yield potential was defined as the output from the combination of crops that gives the highest energy yield per unit of land and time,and the copping system yield gap as the difference between actual energy yield of an existing cropping system and the cropping system yield potential.Yield gap explaining factors were grouped into five main categories,comprising the climate factors,the edaphic factors,the crop and farm management factors,the farm characteristics and the socio-economic factors.There are three broad areas for closing yield gap in rainfed grain crops in the future and they are breeding,genetics and physiology,tactical managements including decisions of cultivar,sowing date,planting population,fertilizer rates,weed,and pest control methods etc.,strategic management revolving around soil improvement (such as amelioration of acidity,soil compaction and low SOC).There is still substantial room (from about 0.5 to over 5 t ha-1) to increase the average yield of crops in rainfed systems in both developed and developing regions.In the future,a subsequent study of crop yield gap should focus on the multi-model ensembles of yield gap analysis,climate-pattern based yield gap analysis,and yield gaps at the cropping system level. References | Related Articles | Metrics

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Homogeneity test and correction of temperature series in Chongqing ZHAO Mei-yan, YU Jun, JIANG Zhen, SHAN Wei-wei 2018, 34 (6):  148-155.  doi: 10.3969/j.issn.1673-503X.2018.06.018 Abstract ( 215 )   PDF (763KB) ( 302 )   Save With the historical information of each station,using the software package of RHtest V5 and MASH V3.03,the homogeneity of the surface air temperature data from 1951 to 2015 in Chongqing was tested.Results indicate that the inhomogeneity of temperature series can be detected by both two methods.Location change of meteorological station is the main factor causing the inhomogeneity of temperature series.Also,some changes of the environment around the station,the replace of the observation equipment and the operational running of automatic station exert impacts on continuity of temperature data.The corrected amount and direction using RHtest method agree with that using MASH method.Moreover,the climatic trends of corrected air temperature using the two methods are similar.The number of break points detected by MASH method is more than that by RHtest method because of their different rules for judging inhomogeneity.Researchers at the National Meteorological Information Center had tested the homogeneity of surface air temperature data for Chongqing using RHtest method and the results are similar to this study.Finally,the climatic trend analysis using the temperature series before and after correction shows that the homogeneity of the corrected temperature is better than that before correction. References | Related Articles | Metrics

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Variation characteristics of soil heat flux in Panjin reed wetland LV Guo-hong, WANG Xiao-ying, JIA Qing-yu, WEN Ri-hong, XIE Yan-bing 2018, 34 (6):  156-160.  doi: 10.3969/j.issn.1673-503X.2018.06.019 Abstract ( 158 )   PDF (826KB) ( 117 )   Save Taking reed wetland in Panjin as study testbed,the dynamic variation of soil heat flux at different soil depths and the effect of soil temperature on soil heat flux were analyzed.The results show that diurnal and annual variations of soil heat flux present an "S" curve pattern for different soil depths.The amplitude of diurnal variation of soil heat flux obviously decreased along with the soil depth.Daily-averaged soil heat fluxes show high values at 5 cm depth,followed by that at 10 cm depth and 15 cm depth.For soil heat flux in four seasons,the maximum value of daily-averaged soil heat flux is in spring,followed by that in summer and autumn,with the lowest value in winter.The diurnal variations of soil heat flux show the same characteristic under different weather types.The amount of soil heat flux under different weather types in order from largest to smallest is sunny days > cloudy days > rainy days.Soil temperature at 15 cm depth affects the soil heat flux of different depths significantly.The correlation coefficient between soil temperature at 15 cm depth and soil heat flux of different depths become larger along with the depth of the soil layer. References | Related Articles | Metrics

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Research on the construction of Ecological and Agrometeorological Field Experimental Base in Northeast China JIA Qing-yu, WANG Xiao-ying, XIE Yan-bing, WEN Ri-hong 2018, 34 (6):  161-168.  doi: 10.3969/j.issn.1673-503X.2018.06.020 Abstract ( 173 )   PDF (946KB) ( 141 )   Save Ecological and agrometeorological field experimental observation are of vital importance for the research of ecology and meteorology to obtain basic data.Construction of ecological and agrometeorological field stations,continuous monitoring air,water,soil,climate,and biological conditions,obtaining the results of the comprehensive impact of weather and climate factors on the ecosystem is important for us to improve scientific cognition of interdisciplinary science,such as agrometeorology,ecology,environmental science and other disciplines.This paper discusses construction background of the Ecological and Agrometeorological Field Experimental Base in Northeast China,main ecological and agrometeorological problems of this region,regional representative of site selection,researching target,function and orientation,observation items and equipment,shortage,planning and so on.The construction of Ecological and Agrometeorological Field Experimental Base in Northeast China can improve the monitoring and early warning capability and provide meteorological support for ecological protection. References | Related Articles | Metrics