Characteristics and Preliminary Causes of Tropical Cyclone Remote Precipitation over China

In this study,the characteristics and preliminary causes of tropical cyclone remote precipitation(TRP)over China during the period from 1979 to 2020 are investigated.Results indicated that approximately 72.42%of tropical cyclones(TCs)in the Western Pacific produce TRP over China.The peak months for TRP are July and August.The four key regions of TRP are the adjacent areas between the Sichuan and Shaanxi Provinces,the northern coast of the Bohai Sea,the coast of the Yellow Sea,and the southern coast area.The typical distance between the station with TRP and the TC center ranges from 1500 to 2500 km.Most of these stations are situated north to 60°west of north of the TC.The south–west water vapor transportation on the west side of the TC is crucial to TRP.TRP has a decreasing trend because of the decrease in the number of TCs that generate TRP.From the perspective of large-scale environmental conditions,a decrease in the integrated horizontal water vapor transport in China' Mainland,the weakening of upward motion at approximately 25°–35°N,which is inconducive to convection,and an increase in low-level vertical wind shear,which is unfavorable for the development of TC in areas with high frequencies of TRP-related TCs,are the factors that result in the decreasing trend of TRP.

Characteristics of Dry and Wet Climate in Shandong Province Based on Standardized Precipitation Index

Based on the monthly precipitation data of 116 meteorological stations in Shandong Province during 1970-2021,standardized precipitation index(SPI)was calculated,and the methods of linear fitting,mutation test and Morlet wavelet analysis were used to analyze the change trend and temporal and spatial distribution characteristics of SPI index in the past 52 years.The results show that there were more normal years in Shandong Province,and the frequency reached 38.46%.There was severe drought in the 1980s and more wet years after 2003.SPI index showed an upward trend in spring,summer and winter but a weak arid trend in autumn.In addition,intense dry weather was more frequent in summer.Spatially,the climate was normal or humid in most areas of Shandong Province.The regions with more wet years were located in the central and northeast Shandong and the peninsula,while the climate was normal in the southwest and north of Shandong.The areas with more dry years were mainly located in the northwest of Shandong Province.There was mainly local and global drought in Shandong Province,and the arid area showed a decreasing trend.In the past 52 years,Shandong Province experienced quasi-4 times of alternation between dry and wet climate.The long period of 21 a was the first main period,and the climate would be still wet in Shandong Province in the future.In terms of mutation,the climate in Shandong Province became humid after 2003,and 2003 was the mutation point.After the abrupt change,the climate changed from gradually drying to wetting.

Analysis on the Variation Characteristics of Precipitation in North China during Recent 30 Years

Based on the monthly precipitation data from 43 stations in North China from 1979 to 2008,the variation characteristics of precipitation in North China in recent 30 years were analyzed by means of empirical orthogonal function(EOF)decomposition,Morlet wavelet transform and Mann-Kendall test.The results showed that the spatial distribution of annual and seasonal precipitation was basically identical in North China,while the annual and summer precipitation from the middle of 1980s to the middle of 1990s were obviously more than these in other periods,and there was great annual variation in spring precipitation in 1990s,while autumn precipitation was higher from 1980s to 1990s and then went down after the beginning of 21st century,which was opposite to winter precipitation,namely there was more winter precipitation from 1980s to 1990s and fewer winter precipitation after the beginning of 21st century.In addition,the annual and summer precipitation changed abruptly in 1997,and there was no obvious change in spring precipitation and autumn precipitation,while winter precipitation had an abrupt change in 2000.Meanwhile,wavelet analysis revealed that the variation period of annual and seasonal precipitation was 3-4 years.

Analysis of the Spatial and Temporal Characteristics of Extreme Precipitation Events in Liaoning Province

Daily precipitation amounts from 1961 to 2005 in 35 observation stations in Liaoning Province were selected in order to study the temporal and spatial distribution of extreme precipitation events.By dint of EOF,REOF,mean-square-error and other ways,the changes in different regions of extreme precipitation and distribution were reflected.The analysis showed that,extreme precipitation in Liaoning Province could be divided into three areas,which were western Liaoning mountains and parts of northern areas,eastern Liaoning mountainous,near-coastal areas of Liaohe River Plain.In the relatively large precipitation areas,extreme precipitation threshold was also higher,and vice versa.The lower frequency of extreme precipitation events had a greater contribution to total precipitation;extreme precipitation,total precipitation and total rain days had the greatest changes in the summer,and the least changes in the winter;number of days of extreme precipitation changes in each season were not great;the change of extreme precipitation was not obvious in the long term.

Analysis on Variation Characteristics of Natural Precipitation Resources in Panzhihua City

Affected by southwest monsoon moisture and topography redistribution,natural precipitation in Panzhihua had obvious difference in temporal and spatial distribution.By using precipitation data from Renhe station in Panzhihua during 1965-2009,the variation characteristics of annual precipitation,flood season precipitation and seasonal precipitation were analyzed.The results showed that spring precipitation,summer precipitation,flood season precipitation and annual precipitation changed conformably and significantly since 1970s in 20th century,showing increase trend at present,while autumn precipitation showed decrease tendency.From the 10-year running mean of annual precipitation,it was found that the annual variation of precipitation resources in Panzhihua City had its own regularity,and there was a slowly decrease at present.

Variation Characteristics and Tendency of Precipitation in Chaoyang Area between 1908 and 2008

According to the precipitation sequence of Beijing City from 1900 to 1958,the precipitation sequence of Chengde City were revised and extended.Then the precipitation sequence of Chaoyang City were revised and extended with the precipitation sequence of Chengde City to form 100-years precipitation sequence of Chaoyang.The results showed that the 100-years precipitation sequence of Chaoyang indicated a decreasing trend and obvious periodic variation with the change of age.That is,a 10-year rainy period (approximately 525.0 mm) appeared every 30 a,while the 30-year drought period was approximately 460.0 mm,65.0 mm lower than the former.Moreover,an obviously heavy drought lasting for 2-4 a appeared every 20 a.

Characteristics of Precipitation and Temperature over the Past 40 Years in Zibo City

Based on monthly precipitation and temperature data of Zibo City over the years from 1966 to 2005,the spatial and temporal characteristics of precipitation and temperature in five districts and three counties of Zibo were analyzed by using climatic diagnosis methods including trend analysis and the method of Mexican-hat wavelet transform analysis. The results showed that the precipitation and temperature in Zibo experienced the interdecadal variations. The precipitation slowly increased at an average annual rate of 1.5 mm,and there existed multi-scale oscillation periods such as 32,25-29,10-23 a and quasi-5 a. Meanwhile,significant mutations were showed in 1977 and 1995. The precipitation was on the high side before 1977 and after 1995 while it was on the low side between 1977 and 1995. The yearly average temperature increased at the rate of 0.48 ℃/10 a,and there existed multi-scale oscillation periods such as 21-32,17-21,9-13 and 2-3 a. In addition,the significant mutation was showed in 1991. The temperature was colder before 1991 while after 1991,it was warmer. The results also indicated that the precipitation and temperature of Zibo City varied greatly in regional distribution,i.e.,the precipitation decreased gradually from south to north,and the temperature in the midst of Zibo City was higher than that in the south and the north,which could be divided into 3 types:south-based type,midst-based type and north-based type.

Variations of precipitation characteristics during the period 1960–2014 in the Source Region of the Yellow River,China

Precipitation, a natural feature of weather systems in the Earth, is vitally important for the environment of any region. Under global climate change condition, the characteristics of precipitation have changed as a consequence of enhanced global hydrological cycle. The source region of the Yellow River（SRYR）, locating within the Qinghai-Tibet Plateau, is sensitive to the global climate change due to its complex orography and fragile ecosystem. To understand the precipitation characteristics and its impacts on the environment in the region, we studied the characteristics of rainy days and precipitation amount of different precipitation classes, such as light（0–5 and 5–10 mm）, moderate（10–15, 15–20 and 20–25 mm） and heavy（≥25 mm） rains by analyzing the precipitation data of typical meteorological stations in the SRYR during the period 1961–2014, as well as the trends of persistent rainfall events and drought events. Results showed that annual average precipitation in this area had a non-significant（P〉0.05） increasing trend, and 82.5% of the precipitation occurred from May to September. Rainy days of the 0–5 mm precipitation class significantly decreased, whereas the rainy days of 5–10, 10–15, and 20–25 mm precipitation classes increased and that of ≥25 mm precipitation class decreased insignificantly. The persistent rainfall events of 1-or 2-day and more than 2-day showed an increasing trend, with the 1-or 2-day events being more frequent. Meanwhile, the number of short drought periods（≤10 days） increased while long drought periods（〉10 days） decreased. Since the 0–5 mm precipitation class had a huge impact on the grasslands productivity; the 5–10, 10–15, and 20–25 mm precipitation classes had positive effects on vegetation which rely on the deep soil water through moving nutrients and water into the root zone of these vegetation or through the plant-microbe interactions; the ≥25 mm precipitation class contributed to the floods; and more persistent rainfall events and fewer long drought events inferred positive effects on agriculture. Thus, these results indicate grassland degradation, less risk of floods, and the upgrading impact of climate change on agriculture. This study may provide scientific knowledge for policymakers to sustain the eco-environmental resources in the SYSR.

Analysis on the Variation Characteristics of Temperature and Precipitation in Benxi Area under the Background of Climate Warming

[Objective] The research aimed to study the variation characteristics of temperature and precipitation in Benxi area under the background of climate warming.[Method] Based on the monthly mean temperature and precipitation data of four routine meteorological stations in Benxi area from 1953 to 2010,by using linear tendency rate,linear regression equation,wavelet analysis,Mann-Kendall detection and so on,the variation characteristics of temperature and precipitation under the background of climate warming in the area were analyzed.[Result] The annual average temperature during 1953-2010 in Benxi area presented rise trend,and the linear tendency rate was 0.28 ℃/10 a.It was temperature increase trend in four seasons.The temperature rise rate in winter was the maximum and was the minimum in summer.The annual rainfall presented decrease trend,and the linear tendency rate was-18.16 mm/10 a.Except in spring,it was decrease trend in other seasons.Mann-Kendall mutation detection showed that the mutation of annual average temperature in Benxi area in recent 58 years appeared in 1986.There was no mutation phenomenon in summer.Spring mutation appeared in 1974,and autumn mutation appeared in 1987.Winter mutation was in 1981.The annual and seasonal precipitation didn’t have the mutation phenomenon.The wavelet analysis found that the annual average temperature had the periodic variations of 12-14,5-6 and 2 years in Benxi area in recent 58 years.The annual rainfall had the periodic fluctuations of 8-12,5-6 and 2 years.[Conclusion] The research provided the scientific basis for exploration and sustainable development of the climate resources in the mountain area.

Century-long variability and trends in daily precipitation characteristics at three Finnish stations

Long-term variations and trends in a wide range of statistics for daily precipitation characteristics in terms of intensity, frequency and duration in Finland were analysed using precipitation records during 1908e2008 from 3 meteorological stations in the south(Kaisaniemi),centre(Kajaani) and north(Sodankyl€a). Although precipitation days in northern part were more frequent than in central and southern parts, daily precipitation intensity in the south was generally higher than those in the centre and north of the country. Annual sum of very light precipitation(0 mm < daily precipitation long-term 50 th percentile of daily precipitation more than 0 mm) significantly( p < 0.05) decreased over time,with the highest rate in northern Finland. These decreasing trends might be the result of significant increases in frequency of days with very light precipitation at all the stations, with the highest and lowest rates in northern and southern Finland, respectively. Ratio of annual total precipitation to number of precipitation days also declined in Finland over 1908e2008, with a decreasing north to south gradient. However, annual duration indices of daily precipitation revealed no statistically significant trends at any station. Daily precipitation characteristics showed significant relationships with various well-known atmospheric circulation patterns(ACPs). In particular, the East Atlantic/West Russia(EA/WR)pattern in summer was the most influential ACP negatively associated with different daily precipitation intensity, frequency and duration indices at all three stations studied.

INFLUENCES OF LOW-FREQUENCY MOISTURE TRANSPORTATION ON LOW FREQUENCY PRECIPITATION ANOMALIES IN THE ANNUALLY FIRST RAINY SEASON OF SOUTH CHINA IN 2010

85-station daily precipitation data from 1961-2010 provided by the National Meteorological Information Center and the NCEP/NCAR 2010 daily reanalysis data are used to investigate the low-frequency variability on the precipitation of the first rain season and its relationships with moisture transport in South China,and channels of low-frequency water vapor transport and sources of low-frequency precipitation are revealed.The annually first raining season precipitation in 2010 is mainly controlled by 10-20 d and 30-60 d oscillation.The rainfall is more(interrupted) when the two low-frequency components are in the same peak(valley) phase,and the rainfall is less when they are superposed in the inverse phase.The 10-20 d low-frequency component of the moisture transport is more active than the 30-60 d.The10-20 d water vapor sources lie in the South India Ocean near 30° S,the area between Sumatra and Kalimantan Island(the southwest source),and the equatorial middle Pacific region(the southeast source),and there are corresponding southwest and southeast moisture transport channels.By using the characteristics of 10-20 d water vapor transport anomalous circulation,the corresponding low-frequency precipitation can be predicted 6 d ahead.

CHARACTERISTICS OF ZONAL ANOMALY OF ANNUAL PRECIPITATION IN THE NORTHEASTERN CHINA

The characteristics of zonal anomaly and change rule of temporal distribution of annual precipitation in the northeastern China are revealed in this paper with EOF (Empirical Orthogonal Function) and REOF (Rotated Empirical Orthogonal Function) methods and results are drawn in the standard relief maps with GIS technology for practical application. Data used in the study were obtained from 208 meteorological stations over the northeastern China from 1961 to 2001. EOF results show that the first 3 loading vectors could give entire spatial anomaly structure of annual precipitation. In the Northeast Plain including the Songneng Plain and the Liaohe Plain, there is a regional compatibility (whether wet or dry) of annual precipitation change and this precipitation pattern has occurred since the late 1980s to the present. There also exist annual precipitation patterns of wet (or dry) in south and dry (or wet) in north and wet (or dry) in east and dry (or wet) in west. REOF results display 8 principal precipitation anomaly areas by the first 8 rotated loading vectors: the west plain, the Liaodong hills, the Sanjiang Plain, the Liaoxi hills, the Changbai Mountains, the Hulun Buir Plateau, the southwest plateau and the Liaodong Peninsula.

Morphological Characteristics of Precipitation Areas over the Tibetan Plateau Measured by TRMM PR

The multidimensional morphological characteristics(including scale, horizontal shape and 3 D morphology) of precipitation areas over the Tibetan Plateau in summer were studied using 15 years(1998–2012) of observational data from the precipitation radar onboard the Tropical Rainfall Measuring Mission satellite. As the scale of the precipitation area increased from 20 to 150 km, the near-surface rain rate(RRav) of the precipitation area increased by up to 78%(from ~1.12 to ~2 mm h~(-1)). Linear precipitation areas had the lowest median RRav(~1 mm h~(-1) over the eastern Tibetan Plateau),whereas square-shaped precipitation areas had the highest median RRav(~1.58 mm h~(-1) over the eastern Tibetan Plateau).The 3D morphology was defined as the ratio of the average vertical scale to the average horizontal scale, where a large value corresponds to thin and tall, and a small value corresponds to plump and short. Thin-and-tall precipitation areas and plump-and-short precipitation areas had a greater median RRav, whereas the precipitation areas with a moderate 3D morphology had the lowest median RRav. The vertical structure of the precipitation-area reflectivity was sensitive to both size and 3D morphology, but was not sensitive to the horizontal shape. The relationship between RRav and the morphological characteristics was most significant over the southern slopes of the Tanggula Mountains and the Tibetan Plateau east of 100°E. The morphological characteristics of precipitation areas are therefore closely related to the intensity of precipitation and could potentially be used to forecast precipitation and verify numerical models.

SPATIO-TEMPORAL VARIATION CHARACTERISTICS OF EXTREMELY HEAVY PRECIPITATION FREQUENCY OVER SOUTH CHINA IN THE LAST 50 YEARS

This paper comprehensively studies the spatio-temporal characteristics of the frequency of extremely heavy precipitation events over South China by using the daily precipitation data of 110 stations during 1961 to 2008 and the extremely heavy precipitation thresholds determined for different stations by REOF, trend coefficients, linear trend, Mann-Kendall test and variance analysis. The results are shown as follows. The frequency distribution of extremely heavy precipitation is high in the middle of South China and low in the Guangdong coast and western Guangxi. There are three spatial distribution types of extremely heavy precipitation in South China. The consistent anomaly distribution is the main type. Distribution reversed between the east and the west and between the south and the north is also an important type. Extremely heavy precipitation events in South China mainly occurred in the summer-half of the year. Their frequency during this time accounts for 83.7% of the total frequency. In the 1960 s and 1980 s, extremely heavy precipitation events were less frequent while having an increasing trend from the late 1980 s. Their climatological tendency rates decrease in the central and rise in the other areas of South China, and on average the mean series also shows an upward but insignificant trend at all of the stations. South China's frequency of extremely heavy precipitation events can be divided into six major areas and each of them shows a different inter-annual trend and three of the representative stations experience abrupt changes by showing remarkable increases in terms of Mann-Kendall tests.

Characteristics of Drought and Humidification Based on Standardized Precipitation Index in Weifang City during the Past 50 Years

[Objective] This study aimed to analyze the evolution characteristics and occurrence patterns of droughts and floods in Weifang City. [Method] Based on the monthly precipitation data during 1961-2010 obtained from nine meteorological sta- tions of Weifang City, by using standardized precipitation index, monthly SPI index of Weifang City during the past 50 years was calculated to analyze the spatial and temporal distribution characteristics of drought and humidification in Weifang City. [Result] The results showed that the variation of drought and humidification had stage characteristics in Weifang City, which was relatively humid in the 1960s and 1970s and developed from extremely humid in early 1960s to dry in late 1970s, persistent drought was observed throughout the range of Weifang City in the 1980s, and the variation tended to be smooth during the 1990s-2000s. Spatial distribution of drought and humidification in Weifang City showed certain regional characteristics. In the 1960s, the mid-west region of Weifang City was relatively humid, while the southeastern region was relatively dry; in the 1970s, there was little difference among the drought and humidification extent in each region; in the 1980s, each region of Weifang City was generally dry, specifically, drought in the southeastern region was the most severe, while drought in the northern region was the slightest; in the 1990s and 2000s, variation of drought and humidification in each region of Weifang City was basically the same. The uneven spatial and temporal distribution of precipi- tation led to abnormal distribution of drought and humidification in some areas, such as the abnormal phenomenon in 1999; the spatial distribution of drought and humidi- fication duration in each generation had their own characteristics, which brought diffi- culties to the unified deployment of drought and flood control departments. [Conclu- sion] This study provided theoretical basis for the drought resistance, waterlogging prevention and disaster reduction in Weifang City under the background of climate change.

Effect of Precipitation Characteristics on Spatial and Temporal Variations of Landslide in Kermanshah Province in Iran

Landslide can be defined as the mass movement of sloping slopes under the influence of mass gravity and its stimuli such as earthquakes,floods and flood plains.This phenomenon is one of the natural hazards that every year causes a lot of financial and financial losses in mountainous,rain-fed and seismic areas.Detection of time and the magnitude of landslides are necessary to understand the causes of landslide and to warn potential hazards.In this research,the amount of landslide displacement in Kermanshah province was evaluated by the characteristics of rainfall.To this end,a network of fixed points in and out of the slipping mass of 20 points was created to monitor the amount of displacement on different slip load users and the amount of displacement of each point in 5 time intervals using the Global Positioning System for two-dimensional GPS measurement.The results of the 511-day follow-up showed that the total horizontal displacement of the moving points in the 5 intervals measured at 1658 mm has a monthly displacement rate of 112 mm.Also,the total vertical displacement of moving points at the same time is 899 mm,with a monthly movement rate of 71 mm.Then,precipitation variances such as rainfall,rainfall,precipitation duration,maximum rainfall intensity in the intervals of 10,20,30 and 60 minutes and the average rainfall intensity were calculated and extracted for each of the 5 time periods.The drawing of the vectors of points on the topographic map of the area indicated that the direction of mass movement is in the direction of elevation gradient of the region.The results showed that only the precipitation severity with the landslide had a good correlation.The landslide movement had the highest correlation with average rainfall intensity(R=0.85)and with maximum 30 minutes rainfall(R=0.67),respectively,and other rainfall characteristics like amount,duration,and type of rainfall had not significantly correlated with movement of landslides.

Temporal-spatial Variation Characteristics of the Extreme Precipitation Days over South China from 1961 to 2010

[ Objective] The research aimed to analyze temporal-spatial variation characteristics of the extreme precipitation days over South China from 1961 to 2010. [ Method] Based on the daily precipitation data in meteorological stations over South China, extreme precipitation thresholds were determined according to the percentiles distribution for different stations. Temporal-spatial variation characteristics of the extreme precipitation days over South China were studied by the methods of fuzzy clustering, trend coefficient, wavelet analysis and cross spectrum analysis, etc. [ Re- suit] Four sub-regions were identified over South China. They were respectively Nanling area, west Guangxi area, Coast area and Hainan area. Occurrence seasons of the extreme precipitations in each sub-region were significantly different. Extreme precipitation clays in four sub-regions all had increase trends, and those of Nanling area and Coast area were significant. From wavelet analysis and cress spectrum analysis, there were significant periodic variation characteristics. Extreme precipitation days in each sub-region all had significant same-phase evolution trends at the peri- od of 2 -5 years, but backward time length was different. [ Conclusion] The research provided background materials for forecast and influence as- sessment of the extremely heavy precipitation over South China.

Chemical characteristics of precipitation and wet deposition of major ions in Liaozhong County of Liaoning Province,Northeast China

The chemical characteristics of precipitation were analyzed based on the chemical composition of principal ionic within acid rain(from February 2007 to January 2008)of Liaozhong Meteorological Station located in Malong Village in Liaozhong County of Northeast China,meteorological conditions on the corresponding period ground,and variation of several air pollutants concentration.The results indicated that:(1)The precipitation average pH value of all samples was4.76;the frequency of acid rain during the observation period was 70.7%;the frequency was 82.8%in summer and autumn.(2)In the chemical composition of precipitation,the primary anions were SO_4^(2-)and NO_3^-;the primary cations were NH_4^+and Ca^(2+).(3)All concentration of anions was higher in summer and winter,but relatively low in spring and autumn.This showed that the relationship between regional rainfall acidification and pollution was not significant.(4)Rainwater acidity and nearly floor gaseous pollution concentration were different from each other,and pH and NO_x,CO,NO_2 and O_3concentrations showed significant negative correlation,but was not obvious with SO_2 concentration.However,the pH and alkaline pollutants,such as particulate,was positively correlative.

Structural and Regulating Characteristics of Adjustable Annulus-clearance Nozzle Used in Supercritical Fluid Precipitation

A new type of adjustable nozzle with an annulus clearance between the surfaces of a revolved solid and the matched hole was analyzed, which contained matching parts, regulating parts, guiding elements, and sealing part. The general regulating function of the adjustable nozzle was derived and the regulating and matching characteristics were also analyzed. Through the analysis, it was concluded that the matching-profile curve of either the revolved body or matched hole should be chosen as a straight line in order to keep the linear regulating feature. Moreover, the multi-annulus-clearance nozzle was designed, and some experiments were carried out on preparing budesonide particles with the nozzle. According to the experimental results, it was proved that the annulus nozzles is practical in preparing micro-particles by supercritical fluid precipitation method.

Analysis on Climatic Characteristics of the Precipitation Anomaly in Southwest China in Recent 60 Years

[Objective] The research aimed to analyze temporal-spatial distribution characteristics of the precipitation anomaly in southwest China from 1951 to 2010. [Method] Based on monthly precipitation data at 44 stations of southwest China and 160 stations of China from 1951 to 2010, by using EOF analysis, wavelet analysis and composite analysis, monthly and seasonal change rules of the precipitation in southwest China were analyzed. Corresponding spatial-temporal distribution characteristics of the precipitation in drought and flood years were studied. Temporal-spatial distribution characteristics of the precipitation anomaly in southwest China in recent 60 years were revealed. [Result] Seasonal distribution of the precipitation in southwest China was uneven and was typical single-peak type. Precipitation concentrated from May to September, and peak appeared in July. In recent years, rainfall in autumn significantly became less, while that in other seasons had no obvious change. Precipitation in summer had the cycle of 14 years, another for 6 years and 3-4 years of periodic oscillations. In wet years, precipitation in southwest China had same phase with that in southern China, and anti-phase with that in the junction of Qinghai, Gansu, Xinjiang and Tibet. In dry years, precipitation in southwest China had same phase with that in the eastern part of northwest China and northern China. [Conclusion] The research provided reference basis for prediction and pre-warning of the precipitation in the zone.