Table of Content

01 November 2014, Volume 30 Issue 5 Previous Issue    Next Issue

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Impact of different microphysical processes of WRF model on precipitation phase forecasting in Northeast China CUI Jin ZHOU Xiao-shan YAN Qi ZHANG Ai-zhong LI De-qin SONG Guo-yun CHEN Yu 2014, 30 (5):  1-6.  Abstract ( 632 )   PDF (1599KB) ( 539 )   Save In order to study the impact of different microphysical processes of WRF model on precipitation phase forecasting, 11 precipitation processes with precipitation phase change in the Northeast China from 2006 to 2008 were simulated based on WRF V3.1 and NCEP reanalysis data. Studies were carried out by three microphysical schemes, i.e. a WSM 6 scheme, a Goddard scheme and a New Thompson scheme. According to analysis of precipitation phase and cloud microphysical characteristics, forecast differences existed in the different schemes were obtained. The results show that effects of different microphysical schemes on precipitation falling area and precipitation intensity are not significant, while precipitation phase is sensitive to microphysical schemes, especially for forecasting of falling area of rain and sleet. The Goddard scheme is the best among all schemes according to results of overall forecast. The simulated cloud microphysical features of atmosphere in the bottom layer have singinficant differences among three schemes, which lead directly to the difference of precipitation phase forecast. Related Articles | Metrics

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Analysis of two heavy snow/rain processes influenced by surface cyclone in North China ZHANG Nan,YI Xiao-yuan,ZHU Li-juan,WANG Qing-yuan 2014, 30 (5):  7-14.  Abstract ( 548 )   PDF (4482KB) ( 502 )   Save Based on the GRAPES model data, conventional observation meteorological data, and NCEP reanalysis data, mechanisms of the two heavy snow/rain processes on January 3, 2010 (code 0103), and November 3, 2012 (code 1103) in the North China were analyzed. The results indicate that the rain falling areas and relative locations of the surface cyclone are significantly different in these two processes. Precipitation mainly occurs in the east of cyclone for the “0103” process, while it is in the north for the “1103” process. By test, the GRAPE model could simulate well the rain falling areas for the two processes. In terms of the analysis of numerical simulation results, the reasons for the characteristics of precipitation distribution can be explained as follow: From the thermodynamic features, thermodynamic characteristics of cyclone are different for the two processes. It is warm core structure for the "0103" process, while it is cold core structure for the "1103" process. The cold air is continually invaded into the cyclone in the “1103” process and results in its cold core structure. On the other hand, cold air and warm air converge between cyclone and anticyclone for the “0103” process and form the occlusion around the center of the cyclone, while they convege within the cyclone for the “1103” process and front system leans from south to north. Furthermore, entrainment of water vapor by cyclone occurs at the low level for the “1103” process. From the vertical distribution of the wind field, there is surface easternly wind before two processes occur, and the middle and low level flow transits when processes ends up. Wind direction changes from south to north, while the evolution of wind field is obviously different during the process of precipitation. Related Articles | Metrics

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Characteristics of persistent fog and haze process and its forming reason in Beijing ZHAO Na,YIN Zhi-cong,WU Fang 2014, 30 (5):  15-20.  Abstract ( 641 )   PDF (1049KB) ( 661 )   Save Based on meteorological and pollutional data, a persistent fog and haze process in Beijing on January 9 to 15, 2013 were diagnosed, and the circulation, meteorological elements, physical quantity field and pollution monitoring status were analyzed. The results indicate that the persistent duration of high PM2.5 and SO2 concentrations events exceeds 100 hours, and their concentrations reach a severe pollution level. There are westerly or southwest air flow at upper level, weak warm advection at 850 hPa and inverted trough on surface. They supply favorable background for the persistent fog and haze process. The continuous light fog and haze do not need thicker wet layer and the thickness of wet layer occurring below 925 hPa is sufficient. The thicker wet layer is, the lower visibility is. Maintenance of temperature inversion layer is a main reason for persistent fog and haze. Temperature inversion layer is thin and weak when there is light fog or haze, and its thickness or intensity enlargement is indicative to transition to heavy fog or snow. Weak vorticity advection below 850 hPa is the dynamic condition of persistent light fog or haze. There is a significant dividing line of total temperature advection on 500 hPa, and the height of weaker advection centre is always between 850 hPa and 1000 hPa. The light fog and haze will dissipate when the height of centre reaches 500 hPa. Related Articles | Metrics

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Numerical simulation analysis of a haze numerical forecast system in process of different synoptic types WANG Kai-yan,DENG Tao, DENG Xue-jiao,LI Hai-yang,ZHAO Xiao-wei,QI Xiu-xiang 2014, 30 (5):  21-26.  Abstract ( 411 )   PDF (2999KB) ( 504 )   Save Base on observed haze data in 2010 at Nansha weather station, haze processes of different synoptic types were simulated using a haze numerical forecast system. Main control factors, air pollution components, and pollution contribution of various emission sources under different weather systems in the Pearl River Delta region were analyzed. The results show that simulated values from the haze numerical forecast system and observed values are in similar variation trends. In addition to individual extremum, simulation results can better and qualitative reflect the variation of pollutant concentration, so the system is suitable to simulate air pollution status in the Pearl River Delta region. Pollutant concentrations are high when it is controlled by continental denatured high and outer circulation of tropical cyclones, especially concentrations of PM10, PM2.5, EC (Elemental Carbon), OC (Organic Carbon) and CO (Carbon Oxide). Concentrations of EC, OC and CO is very low and other pollutants’ concentrations are close to zero when cold air moves to southward or without significant weather system. Whether haze appears or not, concentrations of EC, OC and CO are higher than that of other pollutants in the Pearl River Delta region, which suggests that carbon pollution is serious in this region. Related Articles | Metrics

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Study on monitoring surface PM2.5 concentration in Jing-Jin-Ji regions using MODIS data CHEN Hui,LI Qing,WANG Zhong-ting,MAO Hui-qin,ZHOU Chun-yan,ZHANG Li-juan,CHAO Xue-lin 2014, 30 (5):  27-37.  Abstract ( 607 )   PDF (5689KB) ( 1300 )   Save Base on meteorological data from a numerical weather prediction model during January to March of 2013, MODIS Deep Blue AOD products were corrected with respect to relative humidity (RH) and vertical heights, and their correlation relationship with ground PM2.5 concentration was analyzed in order to establish a surface fine particulate concentration monitoring model in Jing-Jin-Ji regions. The results indicate that the Aqua MODIS DB algorithm AOD products are more suitable for establishing an AOD-PM2.5 linear correlative model in winter, and the R2 reaches 0.33. Height of planetary boundary layer and RH extracted from the meteorological model are used to substitute for vertical correction factor. Besides, according to the aerosol hygroscopic characteristic from IMPROVE, relative humidity correction is developed to estimate surface PM2.5 concentration in different RH ranges, which could improve precision of AOD-PM2.5 model. Thus, an optimum model of winter remote sensing inversion PM2.5 concentration is established. Finally, the R2 between estimated and observed PM2.5 cocentration reaches 0.51. Based on the above model, monthly average surface PM2.5 concentration is calculated. It suggests that monthly average surface PM2.5 concentration is higher in Janurary, while air quality reaches a severe pollution level in the southern part of Jing-Jin-Ji regions. Related Articles | Metrics

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Application of precipitable water vapor from ground based GPS to three precipitation processes in Dalian region CHENG Hang,CHENG Xiang-kun,ZHU Jing,LI Hong-qiang,LIU Xiao-chu 2014, 30 (5):  38-48.  Abstract ( 644 )   PDF (3703KB) ( 18312 )   Save Based on precipitable water vapor (PWV) data from GPS/MET observation network in Dalian, characteristics of PWV and its relationships with precipitation and precipitation intensity in Wafangdian, Zhuanghe and Changhai regions in 2001 were analyzed. According to the above analysis and physical quantity field as well as weather system, relationships of PWV variation with large-scale water vapor transport convergence and moisture convergence, and application of GPS to a rainstorm process were discussed. The results show that increase of PWV is often restricted by the local weather system. For a clear precipitation process, PWV changes and precipitation have a clear relation from beginning to end of the precipitation process. When water vapor transports from south to north, PWV increases gradually before precipitation begins. When it has large range moisture convergence at surface and upper level, and specific humidity reaches above 10g·kg-1, PWV increases significantly in previous 4-5 hours of rainstorm. Main precipitation period corresponds to the peak value of PWV. Meanwhile, PWV increment has a significant relation with precipitation intensity. Related Articles | Metrics

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Water vapor distribution and transport characteristics in boundary of upper troposphere and lower stratosphere ZHANG Dai-le,BIAN Jian-chun,YANG Jun 2014, 30 (5):  49-56.  Abstract ( 450 )   PDF (2104KB) ( 366 )   Save Based on water vapor, ice water content (IWC), and temperature data from Microwave Limb Sounder (MLS) of Aura satellite, distribution characteristics of water vapor, IWC and total water matter (sum of water vapor and IWC by reconciling the unit of ice water content to the unit of water vapor) contents in the boundary of upper troposphere and lower stratosphere (UTLS) in the Asian Summer Monsoon (ASM) region, North American Monsoon (NAM) region, Warm Pool and Iran Plateau region were analyzed. Water vapor transport and main dehydration mechanisms over the boundary of UTLS were discussed. The results show that the total water matter contents in the ASM region have large value centers between 215 hPa to 83 hPa levels and are larger than that in the NAM region. At 215 hPa level, water vapor contributes more to the total water matter contents, while IWC and water vapor have the same contribution to the total water matter contents between 147 hPa to 83 hPa levels. The confinement effect of ASM anticyclone can restrict water vapor transported by deep convections in the upper troposphere. Probability distributions of water vapor and ice water content at 147 hPa and 100 hPa levels can demonstrate different dehydration mechanisms. Due to the extreme low temperature around warm pool at 100 hPa in winter of the northern hemisphere, the peak probability of water vapor mixing ratio over that region is only 2 ppmv. The “long-tail” distribution of water vapor probability in the ASM region at 147 hPa displays a strong convective influence. IWC mainly concentrates on small values at 147 hPa and 100 hPa, which is probably caused by ice particles sedimentation with ice growth by depleting water vapor. Related Articles | Metrics

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Characteristics of number of high temperature days and heat wave from 1961 to 2010 in Liaoning province ZHAO Zi-qi, LI Li-guang,WANG Hong-bo,ZHAO Xian-li,WAN Zhi-hong,DONG Guo-ping,WU Xiao-ming,FANG Yi-he 2014, 30 (5):  57-61.  Abstract ( 620 )   PDF (1185KB) ( 454 )   Save Using daily maximum temperature data at 52 weather stations in Liaoning province from 1961 to 2010, characteristics of number of high tempetaure days and heat wave as well as their trends were analyzed. The results show that the number of annual mean high temperature day is 7.72 days per year in Liaoning province. For spatial distribution, it is higher in the west than in the east. High temperature days are seldom in the coast regions, and never appear in some regions. High temperatue days occur mainly in Chaoyang with 26.84 days per year. The number of annual high temperature days is in a gradually increasing trend since 1960s. The highest number of temperature days occurs in 2000 according to historical record of meteorologcal observation. Spatial distribution of heat wave is similar to that of high temperature, namely more in the west and less in the east. The significant heat wave occurs in Chaoyang, and its frequency is 2.90 per year. Light heat wave with 3-5 days duration is the main type in Liaoning province, accounting for 86.27 %, and then middle heat wave is 12.58%, while severe heat wave with more than 10 days duration is 1.14% and it only appears in Kazuo, Beipiao and Yangshan stations. Related Articles | Metrics

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Construction of temperature series in recent 100 years and its changes over Dongting Lake region PENG Jia-dong,LIAO Yu-fang,LIU Jun-ting,WU Xiang-qin 2014, 30 (5):  62-68.  Abstract ( 552 )   PDF (830KB) ( 581 )   Save Temperature data series for each station in Dongting Lake region during 1910-2010 had been tested for their homogeneity, and the series were adjusted in terms of meteorological historical information by a statistical method. The missing data over the Dongting Lake region before 1951 were then interpolated using data from the surrounding meteorological stations in order to obtain the complete series. The revised temperature series over the Dongting Lake Region during 1910-2010 were built and its changes were analyzed. The results indicate that the annual mean temperature has a significant warming trend during 1910-2010, and it has a largest ascending amplitude in winter and spring, and then in autumn, while it has no significant change in summer. Temperature variation over Dongting Lake Region has several significant warm-cold alternations and it is more frequently in this study area than in whole China region. Annual and seasonal mean temperatures are warming abrupt changes in the recent 100 years, except summer temperature. The wavelet analysis suggests that the annual mean and four seasonal mean temperatures in recent 100 years have experienced two climatic shifts from cold to warm. Related Articles | Metrics

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Characteristics of surface energy balance and CO2 flux in autumn and winter in Shanghai AO Xiang-yu,TAN Jian-guo,LIU Dong-wei,GU Wen,HU Ping 2014, 30 (5):  69-77.  Abstract ( 338 )   PDF (2035KB) ( 333 )   Save Based on eddy covariance observational data from November 11 in 2012 to January 20 in 2013 in Shanghai, diurnal variations of urban surface energy balance and carbon dioxide fluxes under different weather conditions were analyzed. The results show that under sunny and cloudy weather conditions, the maximum energy flux is storage heat, and then is convective transport of sensible heat, while the minimum fraction is latent heat used in evaporation and less than 50 w·m-2. Daily storage heat flux has a peak at 11:00 a.m. which is earlier than that of net radiation flux, while it becomes negative before sunset. Diurnal curve of sensible heat flux is not symmetric around its peak, and its mean diurnal peak occurs in the early afternoon. Also, its value remains significantly positive after sunset. The Bowen ratio remains above 3 from noon to sunset. The effect of wind direction on sensible heat flux is the most significant. Under the dominant northwestly wind direction, daily peak value of sensible heat flux reduces from 175 w·m-2 (under other wind directions) to 120 w·m-2. Haze and cloud show a negative effect on shortwave radiation, and effect of cloud is bigger than that of haze. The existence of cloud results in obvious reduction of upward and net long wave radiation, while it leads to an increase of the atmospheric downward longwave radiation. Carbon dioxide flux keeps positive values throughout the day under sunny weather condition, which means a constant carbon emission. There are two peaks for daily carbon dioxide fluxes, and both occurrence times are corresponding with morning and evening rush hours. Peak value of daily carbon dioxide flux is larger in the evening than in the morning. Related Articles | Metrics

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Comparison on dynamic simulation methods of vegetation surface albedo: a case study in maize field CAI Fu,MING Hui-qing,ZHAO Xian-li,MI Na,LIANG Tao,SONG Guo-yun,CHEN Yu,ZHANG Yu-shu 2014, 30 (5):  78-82.  Abstract ( 458 )   PDF (1431KB) ( 477 )   Save Using radiation data from Jinzhou agricultural ecosystem research station during corn growing season in 2007, simulation precisions of vegetation surface albedo (α) from different dynamic simulation models were compared, including models of a comprehensive (CM), a semi-empirical double layer (SEDLM) and a simplified double layer (SDLM). The results show that the SDLM achieves higher simulation precision in most time of growing season, except during the seedling period. However, simulation errors of the SEDLM are only acceptable when leaf area index reaches the maximum, and α simulated by the SEDLM is useless in most growth periods. By contrast, the CM exhibites stronger simulation ability in most growth periods, except during the late growth. Therefore, the CM is the desirable method to perform dynamic parameterization of α in maize field, which could provide references for improving land surface model. Related Articles | Metrics

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Spatial distribution of winter wheat root in soil under field condition in North China plain LIAO Rong-wei,LIU Jing-miao,BAI Yue-ming,AN Shun-qing,LIANG Hong,LU Jian-li,LE Zhang-yan,CAO Yu-jing 2014, 30 (5):  83-89.  Abstract ( 716 )   PDF (658KB) ( 1982 )   Save Development of wheat root system in soil under field condition is an indispensable parameter, which could quantify accurately the reaction between vegetation and climate and provide references for scientific management of wheat production and development of water saving agriculture. Using a large root monitoring system at Gucheng ecological environment and agriculturual observation station, roots of wheat species “NO.22Jimai” were observated, including root length, root length density, root dry-weight density and root diameter. Vertical distributions of roots were analyzed. The results indicate that the root length and root dry-weight decrease with increase of soil depth. There are four different treatments in this experiment, i.e. severe drought, light/middle drought, suitable moisture and heavy moisture. Correlation coefficients of root lengths between four treatments and a control experiment are 0.91, 0.29, 0.90 and 0.86 respectively. Root growth can be affected by soil moisture conditions. It is conducive to increase the amount of wheat root in upper layers and root biomass under sufficient soil water condition, while the inverse is true under water stress. Light drought is favorable to extend wheat roots in middle/lower layer soil. Root length density and root dry-weight density have a significant positive linear correlation in various soil depths. Root diameter decreases with increase of soil depth. Related Articles | Metrics

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Effect of soil moisture on growth and yield of winter wheat LI Yu-chun,YUAN Shu-jie,GUO Xiao-mei,LIU Jing-miao,LIANG Hong,BAI Yue-ming,AN Shun-qing 2014, 30 (5):  90-97.  Abstract ( 593 )   PDF (1241KB) ( 513 )   Save Based on soil moisture at different growth stages, root length density, plant height, leaf area and yield data from field experiments at Gucheng agro-meteorological field experimental station of Chinese Academy of Meteorological Sciences during 2011 to 2013 for winter wheat, effects of different soil moisture on growth and yield were analyzed. The results indicate that soil relative humidity greater than 50% in 0-50 cm soil layer is favorable for winter wheat during 2011-2012 at Gucheng station. Root system of winter wheat is not dense and yield of winter wheat are not high when soil moisture in 0-80 cm soil layer is less than 50% during 2012 to 2013, even soil moisture in 80-120 cm soil layer is between 55%-88%. Root system is the densest when soil moisture in 0-80 cm soil layer reaches 55% to 70%, which results in better growth of winter wheat and a good yield. Root system of winter wheat is in the worst condition when relative humidity in 0-120 cm soil layer is less than 55% while it is in the best condition when relative humidity in  0-120 cm soil layer is greater than 80%. Thus, yield of the former is the lowest, but the yield of latter is not highest. The yield under a condition that the soil moisture in 0-80 cm soil layer ranges 55% to 70% is better instead. Related Articles | Metrics

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Effects of temperature and humidity due to adding small plastic shed within sunlight greenhouse CHEN Xiao-juan,WEI Rui-jiang,XUE Hua,HUA Guo-jun,WANG Xin,LE Zhang-yan 2014, 30 (5):  98-105.  Abstract ( 587 )   PDF (1031KB) ( 360 )   Save Using the measured temperature and humidity data inside and outside small plastic shed within a sunlight greenhouse at Qinghe county of Hebei province from January to February in 2013 and the corresponding data from a nearby weather station, temperature and humidity characteristics and their effects in small plastic shed under different weather conditions were analyzed by a mathematical statistics method. The results indicate that the maximum daily temperature in the small plastic shed could reach above 30.0 ℃ and 25.0 ℃ in a clear day and a partly cloudy to cloudy day respectively which are about 1.3-6.6 ℃ and 1.0-4.5 ℃ higher than those of outside shed. The daily minimum temperature in the small plastic shed is 4.0-11.0 ℃ and 6.0-14.0 ℃ corresponding to the above two weather conditions, and they are about 0.0-1.5 ℃ higher than those of outside shed. The minimum daily relative humidity inside the small plastic shed is about 50% and about 2%-11% higher than that outside the small plastic shed, while the maximum relative humidity inside the small plastic shed is either equal to or slightly higher than that of outside the small plastic shed. Inside the small plastic shed, daily variation ranges of temperature and relative humidity on the height of 0.0 m are less than those on the height of 0.5 m. In persistent sunless days, temperature inside the small plastic shed changes from 5.0 ℃ to 15.0 ℃ and relative humidity reaches above 85% in a whole day. Change ranges of temperature and relative humidity inside the small plastic shed are not significant and both values are similar or higher than those outside the small plastic shed. In general, adding small plastic shed within the sunlight greenhouse has evident effects on increasing inner temperature and keeping moisture in sunny or slight cloud to cloudy days, but no distinct effect on maintaining its inner temperature in sunless days. Large temperature and relative humidity differences between inside and outside the small plastic shed could be observed in daytime, especially at noon, but small or no difference in nighttime. In the actual production, thermal burn at noon in sunny days, the frostbite and diseases caused by low temperature and high?relative humidty in sunless days inside the small plastic shed should be prevented. Related Articles | Metrics

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Meteorological index of freeze injury for species “shouguang wudai” tomato in greenhouse and its temporal change characteristics in the middle of Hebei province SUN Dong-lei,WEI Rui-jiang,WANG Xin,CUI He-yi,YANG Li-na 2014, 30 (5):  106-112.  Abstract ( 367 )   PDF (660KB) ( 341 )   Save Based on the observed meteorological data within a greenhouse, tomato growth investigation data and meteorological data from weather stations in the middle of Hebei province, increasing temperature effect of greenhouse planting a species "Shouguang wudai" tomato was analyzed, and regression models about daily minimum temperature forecast index inside and outside greenhouse for freeze injury were established in different weather conditions. At the same time, the minimum temperature index for tomato freeze injury of different levels was ascertained, and time distribution and multi-time-scale features of freeze injury were discussed by methods of a regression analysis, a wavelet analysis and a climatic abrupt change analysis. The results show that the daily minimum temperature inside the greenhouse changes with that outside the greenhouse in clear, cloudy and overcast days, and both relationships can be fitted in terms of a quadratic curve. Corresponding correlation coefficients in three weather conditions are 0.896, 0.895 and 0.414, respectively. Temperature forecast index for severe freeze injury is Td (daily minimum temperature outside the greenhouse) ≤-15.0 ℃, Td≤-17.5 ℃ and Td ≤-16.5 ℃ in three weather conditions respectively; the corresponding values for moderate and mild freeze injury are -15 ℃＜Td ≤ -13.0 ℃, -17.5 ℃＜Td ≤ -14.5 ℃, 16.5 ℃＜Td ≤-14.0 ℃ and -13.0 ℃＜Td ≤-8.5 ℃, -14.0 ℃＜Td ≤ -9.5 ℃, -14.5 ℃＜Td ≤ -9.0 ℃ respectively. Annual mean freeze injury day is 42.0 days. It is 3.6 days for severe freeze injury and mainly occurs from early December to late February. It is in a decreasing trend for tomato freeze injury from the middle of 1970s to 2000s, and there is an abrupt change in 1986. There are 7 years and 15 years periods for the number of days of severe freeze injury, 5 years, 10 years and 20 years periods for that of moderate one, and 10 years and 18 years periods for that of mild one in the middle of Hebei province. Freeze injury can be divided into three types according to temperature outside the greenhouse, i.e. a clear-cold type, a spare sunlight type and a mixing type. The number of days for three types is 12.0 days, 22.0 days and 36.0 days from November of 2012 to February of 2013, and they account for 17.1%, 31.4% and 51.4% to the total freeze injury days. Related Articles | Metrics

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Characteristics of warm-dry heavy rain events from 2008 to 2011 in Hubei province SHEN Wei LI Wu-jie DENG Hong LONG Li-min NIU Ben DONG Liang-peng CHEN Xuan 2014, 30 (5):  113-119.  Abstract ( 421 )   PDF (4222KB) ( 373 )   Save Base on the 0.5°×0.5° NCEP- GFS reanalysis data, seven warm-dry heavy rain events from 2008 to 2011 in Hubei province were analyzed. The results indicate that positive vorticity advection doesn’t occur in large areas during a warm-dry heavy rain process, but moves with wind as a positive vorticity advection core, which leads to rapid variation of vorticity advection in different tropospheric layers over the heavy rain areas. This is easy to make the upward motion strengthened suddenly. Warm advection expandes from mid-upper troposphere to the whole troposphere; strong warm advection center appears in boundary layer where the heavy rains just occur; thermal forcing action leads to strong convergence in lower troposphere; locations of upper-lower strong warm advection center of 950 hPa and heavy rain area are similar; the above four conditions are indicative to prediction of warm-dry heavy rain. Invasion of dry air in the middle troposphere and warm-moist air in the lower troposphere is a main impacting factor for increase of convective instability in the heavy rain areas, and both are related to the westward development of subtropical high. Related Articles | Metrics

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Spatial and temporal chacracteristics of ice-freezing disasters and its relationship with meorological conditions from 1961 to 2010 in Zhejiang province GU Ting-ting,LUO Yue-zhen,LIANG Zhuo-ran,PAN Ya-ying 2014, 30 (5):  120-124.  Abstract ( 535 )   PDF (905KB) ( 596 )   Save Using daily ice freezing data and corresponding temperature, wind speed as well as relative humidity data at 68 weather stations in Zhejiang province from 1961 to 2010, spatial and temporal distribution characteristics of ice freezing disasters were analyzed using methods of a linear trend analysis, a wavelet analysis and a correlation analysis. Meteorological conditions causing ice freezing disaster were studied. The results show that for temporal variations, annual average number of ice freezing day is in a significantly decreasing trend from 1961 to 2010, and an abrupt change point is observed in the late 1980s. Ice freezing disaster mainly occurs from December and February, especially in January. For spatial distributions, the number of ice freezing day is also in a decreasing trend from northwest to southeast, and it is a tonguelike distribution in the middle and northern regions of Zhejiang province. Ice freezing disaster occurs more frequent in Tianmu Mountains and hilly region of northern Zhejiang province than in Jinhua and Quzhou Basin although these areas are in the same latitudes. The number of ice freezing day is closely related to the minimum air temperature. It is easy to cause ice freezing disaster when the minimum air temperature is about -2℃, daily mean wind speed is equal or less than 4 m·s-1, and daily mean relative humidity is about 80%. Related Articles | Metrics

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Climatic characterisitcs of cold wave in Heilongjiang province from 1961 to 2012 WANG Ying,CHEN Li,LI Yong-sheng,LI Shuai 2014, 30 (5):  125-130.  Abstract ( 614 )   PDF (2352KB) ( 366 )   Save Based on daily average temperature and the minimum temperature at 62 weather stations in Heilongjiang province from 1961 to 2012, cold wave at a single weather station was defined, and climatic characteristics of cold wave were analyzed. The results indicate that frequency of cold wave decreases significantly in recent 52 years, and it is in a good agreement with topography distribution. Frequency of cold wave is higher in the mountainous region than in the plain region. Cold wave appears mainly in November and December, seldom in September. Frequency of cold wave is higher in winter than in spring and autumn. Frequency of cold wave is in a decreasing trend in spring, autumn and winter in recent 52 years, except in autumn in Daxing’anling region. Related Articles | Metrics

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Climate change characteristics from 1960 to 2009 in Shiyang river basin ZHAO Fu-nian,WANG Ying,ZHANG Long 2014, 30 (5):  131-140.  Abstract ( 526 )   PDF (2147KB) ( 420 )   Save Based on daily temperature, precipitation and evaporation data at five meteorological observation stations in Shiyang river basin, temporal and spatial characteristics of interdecadal variability of three elements were analyzed by methods of a liner tendency rate, a Mann-Kendall test and a Kriging interpolation. The results indicate that the minimum increasing rate of air temperature is 0.25 ℃ per decade from 1960 to 2009 in Shiyang river basin, and it is higher than that in the whole China and the globe. Increasing rate of air temperature is higher in the eastern area than in the western area in the study area. Air temperature is in a decreasing trend in 1960s in Shiyang river basin, while it is in an increasing trend during 1970s to 2000s in most areas of this basin. Besides, temperature increase has a mutation phenomenon in Shiyang river basin. Interdecadal precipitation and its average are higher in the western area than in the eastern area. However, increasing rate of precipitation in Shiyang river basin rarely reaches significant level, and precipitation change is caused by its interannual oscillation. Evaporation in most areas of Shiyang river basin increases first and then decreases in the past fifty years. Evaporation has an abrupt change phenomenon in Shiyang river basin, except at Minqin. Drought could become severe in this region because of continuous increase temperature and evaporation as well as both cooperation relations. Related Articles | Metrics

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Development of a model for evaluation of disaster loss due to heavy rainstorm in Jilin province XI Zhu-xiang,JI Ling-ling,ZHANG Shuo 2014, 30 (5):  141-145.  Abstract ( 437 )   PDF (474KB) ( 295 )   Save Based on daily precipitation data, rainstorm disaster data, annual GDP data and population data from 1961 to 2012 in Jilin province, a heavy rainstorm process index and a disaster loss index were established by a grey correlative degree analysis method. The influence factors of loss caused by the heavy rainstorm process were discussed using a correlation analysis method. A loss evaluation model of heavy rainstorm was established by a multivariate regression method, and its fitting and evaluate test were carried out. The results show that losses caused by the heavy rainstorm process in Jilin province have significant correlations with rainfall during the previous 7 days of the heavy rain and the heavy rainstorm process index. The above two factors are used to establish a loss evaluation model of heavy rain, and it has better effect of fitting and evaluation test. Thus, this model can be applied in operational business. The evaluation factors could be obtained before a heavy rain occurs, so disaster loss could be predicted in advance, which is important for operational business. Related Articles | Metrics

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Objective definition of monitoring index for extreme precipitation processes in Hu’nan province LIAO Yu-fang1 ZHANG Jian-ming2 LIU Bing1,3 LI Ying4 TANG Ai-jun5 DUAN Li-jie1 2014, 30 (5):  146-152.  Abstract ( 349 )   PDF (658KB) ( 345 )   Save Based on daily precipitation data at 97 ground weather stations from 1981 to 2010 in Hu’nan province, mutations of short-time precipitation sequence and process precipitation sequence were analyzed by methods of a second-order derivative analysis and a Cusp catastrophe model analysis. The results indicate that the maximum hourly accumulated short-time precipitation has two mutation points and both occur in the point of 12.0 hours and 6.1 hours respectively, while process precipitation has also two mutation points and both occur in the point of 10.0 days and 4.4 days. Percentage of duration of the maximum precipitation to the total process precipitation has two mutation points and both appear in the point of 10.0 days and 4.6 days. Two mutation points of maximum precipitation occur in the point of 10.0 days and 4.9 days. Thus, we establish a series of monitoring index of extreme precipitation process in Hu’nan province, including 1-6 hours and 12 hours maximum continuous precipitation, 1-5 days and 10 days maximum continuous precipitation, accumulated precipitation process and precipitation duration. The indexes have been verified by correlation coefficients of monitoring indexes of extreme precipitation processes with afftected and suffering rate of crop flooding disaster, and reduction rate of crop yield per unit. Related Articles | Metrics