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30 October 2020, Volume 36 Issue 5 Previous Issue    Next Issue

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Application of joint probability method in severe weather forecast in Beijing Zong-yu FU, Bo YU, Hao JING, Bin JI, Xuan ZHOU, Qing-chang QIN, Jia DU, Sang LI 2020, 36 (5):  1-9.  doi: 10.3969/j.issn.1673-503X.2020.05.001 Abstract ( 271 )   HTML ( 21 )   PDF (2903KB) ( 164 )   Save Based on original ensemble forecast data obtained from the European Center for Medium-range Weather Forecast (ECMWF) and a joint probability method, we produced two ensemble forecast operational products for severe weather occurring frequently in Beijing, including cold wave in winter and severe convection weather in summer.The joint probability forecast product for the cold wave warning was developed based on air temperature at 2 m and mean winds at 10 m, and that for severe convection was produced using the convective available potential energy (CAPE) and vertical wind shear within 0-6 km.We also evaluated the performance of the joint probability forecast products using the observations during cold wave and severe convection events in Beijing in recent years.The results indicated that when the forecast probability reaches 10% and above, the cold wave can probably reach the level of blue warning signals in real-time.The joint probability forecast product for cold wave performs the best in the northwestern region in Beijing, followed by the southeastern region.In areas with the blue warning signals, the cold wave product has a higher capture rate, while in areas with the yellow warning signals it has a high missing rate.The potential prediction of severe convection events using the joint probability method has a high false alarming ratio.Severe convection events can probably occur in real-time only when the forecast probability reaches 90%-100%.Compared with local severe convection events, areas with high forecast probability correspond to the city-scale severe convection events concentrated over the whole city. Figures and Tables | References | Related Articles | Metrics

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Verification of multi-model precipitation forecast in Liaoning province in summer and research on clear or rain forecast method An-qi NIE,De-qin LI,Fang-da TENG,Jing-long LU,Dang WANG 2020, 36 (5):  10-17.  doi: 10.3969/j.issn.1673-503X.2020.05.002 Abstract ( 273 )   HTML ( 7 )   PDF (708KB) ( 119 )   Save Based on precipitation data observed at 291 national meteorological stations from June to September in 2019, we verified the precipitation forecasts from eight numerical models as well as the precipitation grid forecast released from the National Meteorological Center.We also studied the clear or rain forecasts based on the eliminating false alarm ratio (FAR) method.The results showed that the European Center for Medium-range Weather Forecast (ECMWF) model has the best precipitation forecast performance, and the Japan Model has the highest threat score (TS) among all the models.Some mesoscale models show good potential forecast on the local and short-time heavy rainfall events, among which the GRAPES_MESO model and the RMAPS Dongbei-3km model have better performance.The 24- and 3-h occurrence frequency of the heavy rainfall events predicted by the global model is 30% and 60% lower than the real situations, respectively, and that predicted by the mesoscale models is 30% higher and 20% lower than the real conditions, respectively.The false alarm ratio (FAR) for small precipitation events is high, leading to a high false alarm ratio for clear or rain events among the all models.The clear or rain forecast accuracy can be improved significantly using the method of eliminating FAR of small precipitation events.Based on this method, the ECMWF model has the best clear or rain forecast performance among the all models.The optimized eliminating thresholds for 24- and 3-h precipitation forecast are 1.0 mm and 0.8 mm, respectively, and the clear or rain accuracy can be promoted by 15.58% for the 24-h forecast, and by 10%-30% for the 3-h forecast. Figures and Tables | References | Related Articles | Metrics

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Characteristics of daily precipitation concentration in Liaohe River Basin from 1960 to 2018 Xiang-pei LIU,Xiao-hui TONG,Qing-yu JIA,Xiao-na LIU,Jian-ren YANG,Zhi-yang XUE 2020, 36 (5):  18-24.  doi: 10.3969/j.issn.1673-503X.2020.05.003 Abstract ( 198 )   HTML ( 2 )   PDF (2108KB) ( 111 )   Save Using daily precipitation data from 1960 to 2018 over the Liaohe River Basin, the spatiotemporal characteristics of daily precipitation concentration in this region were analyzed after calculating the precipitation concentration index (CI).The results indicated that CI can reflect the degree of precipitation concentration in the Liaohe River Basin, with an annual mean value of 0.67.The precipitation CI is smaller in the eastern and western regions of Liaohe River Basin and higher in the southern and northern regions, exhibiting a saddle pattern.The precipitation concentration is higher in summer, with the seasonal mean CI value at each station being 0.65.The seasonal mean distribution of CI is similar to the annual mean distribution.The smallest seasonal mean CI value of 0.60 occurs in winter, and the CI values decrease from the southeast to the northwest.During the study period, the annual mean CI values exhibit an insignificant decreasing trend, with the largest decreasing rate occurring in the eastern region.The mean variation cycle of CI in each sub-regions is about 3 years.Before 1985, the variation cycle of CI is relative short, about 2 years, while after 1985, it increases to more than 3 years. Figures and Tables | References | Related Articles | Metrics

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Characteristics of daily precipitation probability distribution in Jinzhou area Zhou WEN,Ri-hong WEN,Zi-yi QU,Fang-lei LOU,Shu-ting CHANG,Hong-ting SHI,Xiao-ying WANG 2020, 36 (5):  25-32.  doi: 10.3969/j.issn.1673-503X.2020.05.004 Abstract ( 302 )   HTML ( 5 )   PDF (1981KB) ( 84 )   Save Based on observation data of daily precipitation in Jinzhou area, we analyzed the probability distribution of daily precipitation in this region, and determined the shape parameter and scale parameter of the Gamma function distribution using the maximum likelihood estimation method.We used the Gamma distribution to simulate the probability distribution of daily precipitation.The results showed that the occurrence frequency of daily precipitation has a trend that increases first and then decreases, and exhibits a symmetrical distribution.Precipitation probability has some oscillation, with the precipitation frequency on some specific days much higher than that on the adjacent days at times.The highest precipitation frequency occurs on July 21, and the lowest value is zero on several days when ignoring small precipitation.Low precipitation probability during all seasons is one of the reasons responsible for the drought in the Yixian area.Beizhen area has the lowest precipitation frequency and the highest precipitation amount during summer, which means that heavy and extremely heavy precipitation events are likely to occur in Beizhen.The precipitation probability is higher than 50% during the Qingming Festival and higher than 80% during the national college entrance examination, which is consistent with the public knowledge on the precipitation on these special days.Daily precipitation probability can provide a new way for public meteorological services.Extreme precipitation events are prone to occur in Linghai and Beizhen.Small rainfall events have the highest occurrence probability in Jinzhou, heavy precipitation and above have a low probability, and extremely heavy precipitation hardly occurs at stations in Jinzhou area.It has some meaningful guidance for the precipitation level forecast, especially for the heavy precipitation or extremely heavy precipitation and the level above. Figures and Tables | References | Related Articles | Metrics

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Characteristics of spatio-temporal variation of abrupt alternation of drought and flood in Liaoning province during precipitation concentration period from 1961 to 2017 Qian LI,Yi LIN,Lin-lin YU,Da-jun WANG,Rong LIN,Yi-tong LIN,Chun-yu ZHAO 2020, 36 (5):  33-39.  doi: 10.3969/j.issn.1673-503X.2020.05.005 Abstract ( 295 )   HTML ( 2 )   PDF (1604KB) ( 97 )   Save Based on the monthly precipitation data from 61 national weather stations during 1961-2017 in Liaoning province, the characteristics of spatio-temporal variation of abrupt alternation of drought and flood during precipitation concentration period were analyzed using the linear tendency, trend analysis, stage analysis, sliding t-test curve, and ArcGIS spatial interpolation methods, in which the stage from May to August was selected as the research time to establish a sequence of drought-flood abrupt alternation index (DFAI).The results show that the DFAI of precipitation in Liaoning province during the precipitation period from 1961 to 2017 decreases at a rate of -0.7 per decade, with thirteen years appearing drought-to-flood, and nineteen years appearing flood-to-drought.The intensity of DFAI shows a slight upward trend at a rate of 0.1 per decade.In recent 57 years, the drought-to-flood mostly occurs in 1960s, and flood-to-drought mostly occurs in 1970s and after 2000s.The first abrupt point appears in 1989.After 1989, the intensity of DFAI shows an increasing trend.Another abrupt point appears in 1994, with a decreasing trend.In a typical drought-to-flood year (2013), the high-value area of DFAI is distributed in the central and western regions.In the typical flood-to-drought year (2014), the high-value areas of the absolute value of DFAI are distributed in the northeast and central and western regions.The spatial distribution of the rate of change in DFAI shows an obvious difference, i.e., increasing in the middle and north, and decreasing in the east and west. Figures and Tables | References | Related Articles | Metrics

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Prediction of changes in mean and extreme climate events in Northeast China under different warming scenarios Xue AO, Qing-fei ZHAI, Yan CUI, Chun-yu ZHAO, Tao WANG, Xiao-yu ZHOU, Yi-ling HOU 2020, 36 (5):  40-51.  doi: 10.3969/j.issn.1673-503X.2020.05.006 Abstract ( 360 )   HTML ( 13 )   PDF (3386KB) ( 130 )   Save Using the daily temperature and precipitation data from the regional climate model RegCM4, the changes in the average climate and extreme climate events in the Northeast China region under the 1.5℃ and 2.0℃ heating scenarios were estimated.The results show that under the RCP4.5 (Representative Concentration Pathway 4.5) emission scenario, the model is expected to stabilize 1.5℃ and 2.0℃ warmings around 2030 and 2044.Under the two warming scenarios, the temperature, accumulated temperature, and the length of the growing season in the Northeast China all show an increasing trend.The increasing rate increases with the increase in the warming threshold.In the case of 1.5℃ warmings, the annual average temperature increases by 1.19℃, the anomaly percentage in annual average precipitation increases by 5.78%, the average accumulated temperature increases by 247.1℃·d, and the length of the growing season extends by 7.0 days.The temperature, accumulated temperature, and the length of the growing season increase significantly under the warming condition of 2℃compared with that under the warming condition of 1.5℃.However, annual and seasonal precipitation generally decreases, and the annual precipitation anomaly decreases by 1.96%.Under the two warming scenarios, extreme high-temperature events increase significantly, extremely low-temperature events decrease significantly, and extreme precipitation events generally increase.The number of frost and freezing days decreases significantly, and the duration of heatwaves increases significantly.In the future, precipitation extremes in Northeast China will increase.Not only will the magnitude of a single precipitation process increase, but the magnitude of the extreme precipitation process also increases significantly.With the increase of the temperature threshold, intensity of the extreme precipitation will also gradually increase. Figures and Tables | References | Related Articles | Metrics

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Impact of indirect effects of sulfate aerosol on winter climate in East China Dong-dong WANG, Bin ZHU, Xu-jiang WAN 2020, 36 (5):  52-61.  doi: 10.3969/j.issn.1673-503X.2020.05.007 Abstract ( 154 )   HTML ( 2 )   PDF (5126KB) ( 40 )   Save The indirect effects (IE) of aerosols affect the climate through clouds, which is complex and uncertain.Based on the CAM5.1 (Community Atmosphere Model, V5.1) model developed by the NCAR (National Center for Atmospheric Research), sensitivity experiments of the IE of sulfate aerosols were designed to investigate the influence of the IE on a cloud, precipitation and the intensity of monsoon in winter in East China in this paper by changing the number concentrations of the sulfate aerosols that can serve as the cloud condensation nuclei number concentration.The results show that sulfate aerosols play a dominant role in the formation of cloud condensation nuclei (CCN) in East Asia.The indirect effects of sulfate aerosols result in a significant increasing concentration of CCN and cloud droplet number in winter in East China, decrease the effective radius of cloud droplet in the low layer of ocean and land, and increase the total cloud liquid water path, resulting in an increasing albedo of a cloud.The negative radiation effect forces to cool the surface and lower atmosphere, increases the sea level press.The increasing sea-land pressure gradient leads to the intensification of the East Asian winter monsoon and the reduction of the total precipitation rate in southern China.The indirect effects of sulfate aerosols may not be responsible for the decadal weakening of East Asian winter monsoon in the mid-1980s. Figures and Tables | References | Related Articles | Metrics

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Variation characteristics of acid rain and its relationship with meteorological factors in Urumqi Yun-ling MIAO,Jun ZHANG,Yu-ping ZHENG,Meng-jiao CHEN,Yun-hui ZHANG 2020, 36 (5):  62-68.  doi: 10.3969/j.issn.1673-503X.2020.05.008 Abstract ( 235 )   HTML ( 4 )   PDF (775KB) ( 68 )   Save Using the acid rain monitoring data of 1316 samples from the national basic meteorological stations in Urumqi from 1992 to 2018, the variation characteristics of the pH and K values in precipitation samples and their relationship with meteorological factors were analyzed.The results showed that in recent 27 years, the average annual pH value is 6.64.The acid rain frequency is only 4.56% and the precipitation in Urumqi is mainly neutral and alkaline.The average annual pH values show a slightly increasing trend and change abruptly in 1998.During the sampling period, the average annual K value is 90.40 μs·cm-1 and shows a decreasing trend.The mutation occurs in 2001.The sequence of K values from high to low in the four seasons are opposite to the pH value, namely, winter, spring, autumn, and summer.When acid rain occurs in Urumqi, the northerly wind direction on the ground and at the upper layer is dominant.The pH value is positively correlated with wind speed, while the K value is negatively correlated with precipitation.In recent years, the implementation of "replacing coal with gas" in the heating season in Urumqi has greatly reduced the consumption of coal, resulting in a significant reduction of sulfur compounds such as SO2 in the atmosphere.Besides, the municipal government has intensified its control of environmental pollution in recent years, and the frequency of acid rain has been significantly reduced compared with that before 2007. Figures and Tables | References | Related Articles | Metrics

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Comparative analysis of the gale characteristics in the strongest wind area along Lanzhou-Xinjiang railway Ping JIANG, Xin-min PAN, Jun-mei XUE, Yan-ping SHA 2020, 36 (5):  69-75.  doi: 10.3969/j.issn.1673-503X.2020.05.009 Abstract ( 293 )   HTML ( 7 )   PDF (1227KB) ( 102 )   Save Based on the hourly wind speed data of 32 monitoring stations along Lanzhou-Xinjiang railway from 2015 to 2018, the gale characteristics in the two strongest wind region of Lanzhou-Xinjiang railway i.e.the 100-kilometer wind area and the pre-hundred kilometer wind area were comparatively analyzed through investigating the average number of gale days, duration of gale, the contribution rate of different wind speed, and the variation of time scales and geographical distribution of strong wind by means of statistical methods and spatial analysis.The results show that the extreme gale whose rank is greater than 11 is more likely to occur in the pre-hundred kilometer wind zone than in the hundred kilometer wind zone, which indicates some characteristics in the pre-hundred kilometer wind area under the influence of its downstream terrain relative to in hundred kilometer wind area.Specifically, in the pre-hundred kilometer wind area, the mean hourly wind speed is bigger in the nighttime (20:00 to 08:00 the following day) than in the daytime (08:00 to 20:00), and its variability in spatial distribution is larger, and the dominant wind direction is basically perpendicular to Lanzhou-Xinjiang railway, which leads to strong transversal wind.This paper can fill in the gaps of exploration of weather patterns in the pre-hundred kilometer wind area, and provide the basis for the analysis of change rules of gale in special regions, the fine forecast of hourly gale in the key regions, special experimental study and the determination of the warning threshold of wind-induced disaster. Figures and Tables | References | Related Articles | Metrics

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Suitability evaluation of ice-snow climate resources in Liaoning province Xiao-yu ZHOU,Qiang GONG,Chun-yu ZHAO,Yan CUI,Ming-yan LIU,Xue AO,Xin-yi ZHANG 2020, 36 (5):  76-85.  doi: 10.3969/j.issn.1673-503X.2020.05.010 Abstract ( 260 )   HTML ( 9 )   PDF (3599KB) ( 92 )   Save In order to fully exploit the advantages of ice-snow resources of Liaoning province, scientifically develop and plan cold region ice-snow resources, the meteorological data of 61 stations were used to evaluate the suitability of ice-snow climate resources in Liaoning province using statistical, qualitative or quantitative indicators and other analytical methods.The results show that ice-snow resources are distributed in all parts of Liaoning province, and are the richest in the eastern mountainous area.The western Liaoning province has less snowfall and a long icing period.Whereas, there are relatively few ice-snow resources in the coastal areas of Dalian.The suitable temperature and sunshine conditions and low wind speed are in favour of the outdoor ice and snow activities in the area with the rich ice-snow resources in winter.The risk of meteorological disasters such as high temperature inducing snow melting, fog, strong wind and low visibility is low in winter.From the mid-November to early March, the artificial snow-making can be conducted in the whole province.Most areas of Fushun, Benxi, Tieling, Shenyang, Dandong, and Liaoyang are the optimal regions for ice-snow tourism and sports in Liaoning province.However, the western Liaoning with less snowfall is more suitable to develop ice tourism relative to snow tourism.Inversely, the coastal areas such as Huludao and Dalian have short ice and snow periods and can be explored in developing small-scale ice-snow and sea-ice tourism projects. Figures and Tables | References | Related Articles | Metrics

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Spatio-temporal evolution of vegetation coverage and its responses to climatic factors in Liaoning province Yu-hong LI,Su-lin TAO,Rong-ping LI,Lin-lin LI,Ting WANG,Bin ZHOU,Jing LI 2020, 36 (5):  86-90.  doi: 10.3969/j.issn.1673-503X.2020.05.011 Abstract ( 254 )   HTML ( 5 )   PDF (2043KB) ( 179 )   Save Based on the estimated vegetation coverage (VC) in Liaoning province using MODIS-NDVI data and mixed pixel decomposition model, the spatio-temporal evolution of VC and its responses to climatic factors were investigated.The results show that the VC experiences a fluctuating increasing trend with an average annual rate of 0.38% from 2000 to 2018.The region with increasing trend accounts for 92.3% of the vegetated area.The bare land and low-coverage area decrease year by year, and the percentages of the middle-low, middle and high coverage areas increase by 11.35%, 11.00% and 9.22%, respectively, since 2000.The relationships between the VC and climatic factors show significant spatial variability.Specifically, the VC in the west of Liaoning which is drought prone region is negatively correlated with temperature and positively correlated with precipitation.However, the VC in the east of Liaoning has positive and negative relationships with temperature and precipitation, respectively.Besides, the VC has a lag response of one month to the precipitation, but not to the temperature in Liaoning province. Figures and Tables | References | Related Articles | Metrics

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Characteristics of lightning activity and its response to the surface relative humidity in Heilongjiang province Xiang-ling YUAN, Hong-xu MA, Shi-ding CHEN, Chun-fang LIU 2020, 36 (5):  91-96.  doi: 10.3969/j.issn.1673-503X.2020.05.012 Abstract ( 176 )   HTML ( 2 )   PDF (1228KB) ( 113 )   Save The lightning location and daily mean surface relative humidity (RH) data in Heilongjiang province during 2006-2017 were used to analyze the relationships between the density and intensity of lightning and RH based on mathematical statistics, Pearson correlation analysis and GIS spatial analysis methods.The results indicate that the smaller or larger RH is disadvantageous to the generation of lightning activity.Specifically, the lightning hardly occurs if RH is less than 25%, and it is gradually easily triggered with the increase of RH between 25% and 77%.However, the lightning is decreasing with the increase of RH if the latter is larger than 79%.In addition, RH less than 77% has positive and negative correlation with density and intensity of lighting, respectively.Inversely, RH larger than 79% shows negative and positive correlation with density and intensity of lighting, respectively.The threshold of RH is between 77% and 79%.The interval of 70%-90% is the lightning-prone RH, where the lightning density is closely related to RH and the lightning tends to occur in clusters. Figures and Tables | References | Related Articles | Metrics

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A study on the variation of building climate zones and heating climate conditions in China Yu-lian LIU,Li CHEN,Heng-yuan KANG,Shuang SUN,Yong-ji ZHOU,Heng-chong ZHANG 2020, 36 (5):  97-104.  doi: 10.3969/j.issn.1673-503X.2020.05.013 Abstract ( 294 )   HTML ( 5 )   PDF (1607KB) ( 312 )   Save This paper compared the changes in climate zoning for buildings between 1951-1980 and 1981-2010 using monthly average temperature data and discussed the change characteristics of climatic conditions for heating from 1951 to 2018 using daily average temperature data.The results show that compared with the period from 1951 to 1980, the range of severe cold area decreases from 1981 to 2010, and the southern boundary moves northward.The cold area, the hot-summer and cold-winter area, the hot-summer and warm-winter area move northward.However, the mild area expands westward, and the range of hot-summer and warm-winter area becomes larger.From 1951 to 2018, the heating degree day in all building climate zones decreases significantly.The largest reduction rate is in the severe cold area and the smallest is in the mild area.The anomaly percentage of heating degree day has a big fluctuate in the hot-summer and cold-winter area, and has a small fluctuate in the severe cold area.During the period of 1998 to 2012, the heating degree day and the average daily heating intensity of all building climate zones increased, and the trend of hot-summer and warm-winter area passes the 0.05 significance test. Figures and Tables | References | Related Articles | Metrics

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Temporal and spatial pattern of soil respiration pattern in urban green spaces of Shenyang Jie BAI,Zhi-ping FAN,Li-tao LIN,Qun LI,Xue-kai SUN,Xi-ping MA,Dan-dan LI 2020, 36 (5):  105-112.  doi: 10.3969/j.issn.1673-503X.2020.05.014 Abstract ( 146 )   HTML ( 3 )   PDF (1152KB) ( 33 )   Save Basing on 24 urban green spaces of four vegetation configurations in Shenyang, this study aimed to examine the temporal and spatial dynamics of soil respiration and its influencing factors.Results show that soil respiration has obviously seasonal variation patterns.Partial correlation analysis indicates that soil temperature is the vital factor affecting temporal variation of soil respiration.In addition, respiration of four vegetation types are 5.68 μmol·m-2·s-1 (Sparse trees), 5.66 μmol·m-2·s-1 (Tree-grasses), 4.75 μmol·m-2·s-1 (Tree-shrubs), and 3.84 μmol·m-2·s-1 (Tree-shrub-grasses), respectively.The soil respiration of Sparse trees and Tree-grasses are significantly higher than that of Tree-shrub-grasses.Spatial heterogeneity analysis shows that the difference of soil temperature caused by the degree of dialysis, combined with the diverse nutrient conditions such as soil organic matter, would be the main factors contributing to the soil respiration rate difference among vegetation configurations.The winter and summer regressions both show that soil temperature is the principle factor affecting the spatial heterogeneity of carbon emission among urban green spaces.Therefore, reasonable vegetation configuration which contributes to the reduction of direct surface illumination and soil temperature, would be an important method to achieve urban green space CO2 emission reduction. Figures and Tables | References | Related Articles | Metrics