The Singular Value Decomposition Analysis between Summer Precipitation in the Dongting Lake Region and the Global Sea Surface Temperature

By dint of the summer precipitation data from 21 stations in the Dongting Lake region during 1960-2008 and the sea surface temperature(SST) data from NOAA,the spatial and temporal distributions of summer precipitation and their correlations with SST are analyzed.The coupling relationship between the anomalous distribution in summer precipitation and the variation of SST has between studied with the Singular Value Decomposition(SVD) analysis.The increase or decrease of summer precipitation in the Dongting Lake region is closely associated with the SST anomalies in three key regions.The variation of SST in the three key regions has been proved to be a significant previous signal to anomaly of summer rainfall in Dongting region.

Cluster analysis on summer precipitation field over Qinghai-Tibet Plateau from 1961 to 2004

The summer day-by-day precipitation data of 97 meteorological stations on the Qinghai-Tibet Plateau from 1961 to 2004 were selected to analyze the temporal-spatial distribution through accumulated variance,correlation analysis,regression analysis,empirical orthogonal function,power spectrum function and spatial analysis tools of GIS.The result showed that summer precipitation occupied a relatively high proportion in the area with less annual precipitation on the Plateau and the correlation between summer precipitation and annual precipitation was strong.The altitude of these stations and summer precipitation tendency presented stronger positive correlation below 2000 m,with correlation value up to 0.604（α=0.01）.The subtracting tendency values between 1961-1983 and 1984-2004 at five altitude ranges（2000-2500 m,2500-3000 m,3500-4000 m,4000-4500 m and above 4500 m）were above zero and accounted for 71.4%of the total.Using empirical orthogonal function, summer precipitation could be roughly divided into three precipitation pattern fields：the Southeast Plateau Pattern Field,the Northeast Plateau Pattern field and the Three Rivers＇ Headstream Regions Pattern Field.The former two ones had a reverse value from the north to the south and opposite line was along 35°N.The potential cycles of the three pattern fields were 5.33a,21.33a and 2.17a respectively,tested by the confidence probability of 90%.The station altitudes and summer precipitation potential cycles presented strong negative correlation in the stations above 4500 m,with correlation value of-0.626（α=0.01）.In Three Rivers Headstream Regions summer precipitation cycle decreased as the altitude rose in the stations above 3500 m and increased as the altitude rose in those below 3500 m.The empirical orthogonal function analysis in June precipitation,July precipitation and August precipitation showed that the June precipitation pattern field was similar to the July＇s,in which southern Plateau was positive and northern Plateau negative.But positive value area in July precipitation pattern field was obviously less than June＇s.The August pattern field was totally opposite to June＇s and July＇s.The positive area in August pattern field jumped from the southern Plateau to the northern Plateau.

Stress-Induced Precipitation of Fineγ'-Phase and Thermodynamics Analysis

The microstructures of a single crystal Ni-base superalloy with [001] orientation were observed by means of TEM. Results showed that the fine γ' particles were precipitated in the γ matrix channels during the tensile deformation of the alloy. Thermodynamics analysis indicated that the solubility of elements M(Al,Ta) within the γ matrix may be changed when the alloy was deformed by the external applied stress. The tensile stress reduced the solubility of elements Al and Ta so as to occur the over-saturation and agglomeration of them, which promoted the precipitation of fine γ'-phase in the γ matrix.

The Analysis on the Temporal and Spatial Variation of Strong Precipitation Caused Flood and Agricultural Disaster Loss in Huaihe River Basin of Anhui Province during Meiyu Period of 2007

[Objective] The research aimed to analyze temporal and spatial variation of strong precipitation caused flood and agricultural disaster loss in Huaihe River basin of Anhui Province during Meiyu period of 2007.[Method] On the basis of rainfalls of each station in Huaihe River basin of Anhui,rainfall data during Meiyu period of 2007 and flood disaster data in the same period,the temporal and spatial distribution characteristics of strong precipitation caused flood during Meiyu period of 2007 and its harm on agriculture were analyzed.The variation rule,distribution characteristics of strong precipitation during Meiyu period in Huaihe River basin of Anhui and its relationship with agricultural disaster loss were discussed.[Result] During Meiyu period of 2007 in Huaihe River basin of Anhui,the rainstorm was more,and the rainfall was large.The precipitation variation showed 'three-peak' trend.Rainfall in Huaihe River basin during Meiyu period of 2007 was greatly more than that homochronously in Yangtze River basin.The rain area over 400.0 mm during Meiyu period mainly located in Huaihe River basin,and the rain area over 600.0 mm mainly located from area along Huaihe River to central Huaibei.The rainfall during Meiyu period gradually decreased toward south and north by the north bank of Huaihe River as the symmetry axis.The rainfall in area along Huaihe River showed wavy distribution in east-west direction.The flood disaster loss index and disaster area of crops in Huaihe River basin of Anhui both increased as rainfall in Meiyu period.[Conclusion] The research provided theoretical basis for flood prevention,disaster reduction and agricultural flood-avoiding development in Huaihe River basin.

Cause Analysis on Precipitation Enhancement in the Middle and Lower Yangtze Valley

By means of MICAPS data from China Meteorological Administration,the weather dynamics causing precipitation enhancement in the middle and lower Yangtze Valley on January 19,2008 was analyzed.The results showed that the convergence of cold and warm air was the basic condition of precipitation enhancement,and the influence systems of precipitation enhancement were surface inverse trough,850-700 hPa warm shear and 850-500 hPa low trough,while southwest and southeast low jet were the important dynamic mechanisms of precipitation enhancement,and southwest low jet offered abundant water vapor for precipitation enhancement.

AN ANALYSIS ON INTERDECADAL VARIATIONS OF TROPICAL CYCLONE PRECIPITATION IN GUANGDONG PROVINCE OF CHINA

The interdecadal variations of tropical cyclones(TCs) and their precipitation over Guangdong Province are investigated using the observational data of TCs and precipitation from 26 observational stations in the province from 1951 to 2005.The results show that the TCs precipitation shows an oscillation with a peak value of about 25 years,with both the numbers of the Guangdong-influencing TCs and TCs formed in the western North Pacific oscillating with a peak value of about 23 years.The correlations are highly positive between the interdecadal variation of TC precipitation over the province and these numbers.The interdecadal variation of TC precipitation in the province shows significant negative correlations with the interdecadal variation of annual mean SST in some parts of the western North Pacific and the interdecadal variation of annual mean 500 hPa geopotential heights in some parts of the middle and high latitudes over the North Pacific.In general,there are high mean SSTs on the equator from central to eastern Pacific,low mean SSTs in the middle and high latitudes over the North Pacific and a main strong East Asian trough over the North Pacific in the period of less TC precipitation as compared with the period of more TC precipitation over the province.

Characteristics and Cause Analysis of Variations in Light Precipitation Events in the Central and Eastern Tibetan Plateau,China,During 1961–2019

The Tibetan Plateau(TP)is one of the most sensitive areas and is more susceptible to climate change than other regions in China.The TP also experiences extremely frequent light precipitation events compared to precipitation of other intensities.However,the definition,influencing factors,and characteristics of light precipitation in the TP have not been accurately explained.This study investigated the variation characteristics of light precipitation with intensities(Pre)of 0.1-10.0 mm/d based on climate data from 53 meteorological stations over the central and eastern TP from 1961 to 2019.For detailed analysis,light precipitation events were classified into five grades:G1[0.1-2.0 mm/d),G2[2.0-4.0 mm/d),G3[4.0-6.0 mm/d),G4[6.0-8.0 mm/d),and G5[8.0-10.0 mm/d).The results showed that both the amount of precipitation and number of precipitation days had increased significantly at rates of 4.0-6.0 mm/10 yr and 2.0-4.0 d/10 yr,respectively,and most precipitation events were of low intensity(0.1≤Pre<2.0 mm/d).Light precipitation events mainly occurred in the southeast of the study area,and it showed an increasing trend from the northwest to the southeast.Abrupt changes in light precipitation primarily occurred in the 1980 s.A comprehensive time series analysis using the Mann-Kendall test and Morlet wavelet was performed to characterize the abrupt changes and cycles of light precipitation.During the study period,the main periods of light precipitation corresponded to the 6 yr cycle,with obvious periodic oscillation characteristics,and this cycle coexisted with cycles of other scales.Significant correlations were observed between the amount of light precipitation and temperature over the study area.The findings will enhance our understanding of changes in light precipitation in the TP and provide Scientific basis for the definition of light precipitation in the future.

MESOSCALE ANALYSIS OF YUNNAN SUCCESSIVE HEAVY PRECIPITATION AROUSED BY THE STORM OVER THE BAY IN EARLY SUMMER

By using regular meteorological data, physical quantity fields, satellite pictures and Doppler radar echo data, we analyze the mesoscale features and the conditions of 4 successive heavy precipitation processes in Yunnan aroused by the storm over the Bay in the early summer. The results show that the life of the storm over the Bay is usual 2 or 3 days and the cloud top temperature of the storm is always below -65℃. The storm over the Bay affects Yunnan by mesoscale convective cloud clusters, cloud system in peripheral or weaken itse,fmoving to the northeast. The Tibetan Plateau shear lines and vortexes, NE-SW convergence channels and southwest wind convergence supply favorable circulation background and dynamical conditions. There are many common features about Doppler radar echoes, the flocculent echoes with intensity about 35-45 dBZ move to the east to produce successive precipitation in Yunnan, and the mesoscale features of southwest jet and wind veering with altitude not only are favorable to transport warm and moist airflow brought to the north by the storm over the Bay. but also are favorable to convective development.

THE ANALYSIS OF TROPICAL CYCLONE PRECIPITATION AFFECTING THE LIAODONG PENINSULA

1 INTRODUCTION Tropical cyclones （TCs） moving north and getting to the Liaodong Peninsula and waters of the Yellow and Bohai Seas are in their late phase of life cycle. While weakening rapidly, TCs carry a large amount of warm and humid air that forms heavy rainfall by itself on the one hand and interact with westerlies in the middle latitudes on the other. With their warm-core structure destroyed by intruded cooler air, TCs absorb baroclinic energy while it weakens and experiences extratropical transition （ET）. With right conditions and complicated topographic features of the peninsula, the transformed extratropical cyclone evolves to intensify heavy rainfall in most cases and even results in secondary disasters like storm surges. Therefore, the extratropical transition of TCs is usually responsible for more serious damage in mid-latitude areas. For the forecast of heavy rain associated with north-going TCs experiencing extratropical transition, it not only involves their own intensity and structure but also the distribution of the surrounding field and its interactions with TCs. Most of the present studies discuss TCs-inflicted heavy rains or those taking place south of the Shandong Peninsula. Focusing on intense precipitation resulted from TCs over the Liaodong Peninsula, this work analyzes the distribution of the ambient field and physical quantities hoping to help forecast TCs-related heavy rains accurately.

Climate Prediction and Diagnostic Analysis of Typhoon Precipitation in Midsummer of Yongzhou

By consulting the typhoon yearbook and restoring the historical weather chart,technical separation of typhoon precipitation in Yongzhou from July to September of 1981-2015 was conducted.On this basis,climatic characteristics of typhoon precipitation in midsummer of Yongzhou were analyzed,and climate prediction and diagnostic analysis were carried out.The research results showed that typhoon precipitation was an important component of midsummer precipitation in Yongzhou,but its contribution to total precipitation was not as much as precipitation of the westerly belt system.When the ridge line of the western Pacific subtropical high was northward,typhoon precipitation was more than westerly precipitation in midsummer of Yongzhou;when the subtropical high was southward,there were more patterns of westerly precipitation year;when the subtropical high was normally northward,typhoon precipitation and westerly precipitation were less,with more dry years.In summer,abnormal cold sea surface temperature(SST)in tidal zone and warm pool zone of western Pacific and abnormal warm SST in NinoZ zone(strong El Nino event)were favorable for that the ridge line of the western Pacific subtropical high was southward,and there were more patterns of westerly precipitation year in midsummer of Yongzhou.On the contrary,when subtropical high was northward or normally northerly,there was less westerly precipitation.In non La Nina years when the subtropical high was northward,most of them were typhoon precipitation years.In La Nina years when the subtropical high was northward,most of them were dry years.

Spatio-Temporal Analysis of Drought in the North-Eastern Coastal Region of Vietnam Using the Standardized Precipitation Index (SPI)

Spatio-temporal analysis of drought provides valuable information for drought management and damage mitigation. In this study, the Standardized Precipitation Index at the time scale of 6 months (SPI-6) is selected to reflect drought conditions in the North-Eastern coastal region of Vietnam. The drought events and their characteristics from 1981 to 2019 are detected at 9 meteorological stations and 10 Chirps rainfall stations. The spatio-temporal variation of drought in the study region is analyzed on the basis of the number, duration, severity, intensity, and peak of the detected drought events at the 19 stations. The results show that from 1981 to 2019 the drought events mainly occurred with 1-season duration and moderate intensity and peak. The number, duration, severity, and peak of the drought events were the greatest in the period 2001-2010 and were the smallest in the period 2011-2019. Among the 19 stations, the drought duration tends to decrease at 11 stations, increase at 7 stations, and has a slight variant at 1 station;the drought severity tends to decrease at 14 stations, increase at 4 stations, and has not a significant trend at 1 station;the drought intensity tends to decrease at 17 stations, increase at 1 station, and has a slight variant at 1 station;and the drought peak tends to decrease at 18 stations and increase at 1 station.

Comparative Analysis of Automatic Observation Data of DSG3 Precipitation Phenomenon Instrument and Manual Observation Data

The observation data collected by DSG3 precipitation phenomenon observation instrument and the manual parallel observation data in 5 stations of Gansu Province from January 2018 to December 2019 were compared and analyzed.The results show that the missing observation rate of the observation instrument was 0%,and the performance of the equipment was good;the empty forecast rate of drizzle was the highest;the false forecast rate of hail was the highest,and the accuracy of automatic observation records was relatively poor;the capture rate and empty forecast rate of rain and snow were higher,while their false forecast rate and missing forecast rate were lower.The capture rate and missing forecast rate of sleet were higher,and its missing forecast rate was low;the accuracy of automatic observation was better.It shows that the empty forecast and false forecast of DSG3 precipitation phenomenon observation instrument mainly occurred in weak precipitation phenomena,and the recognition of drizzle and hail was poor.

Comparative Analysis of Climate Characteristics of Extremely Short-Time Severe Precipitation in Guizhou Based on Two Types of Rainfall Data

In order to fill the gaps of the research on the data of automatic weather stations(referred to as automatic stations)not used for the climate characteristics of extremely short-time severe precipitation in Guizhou Province,the climate characteristics of extremely short-time severe precipitation in Guizhou Province were compared and analyzed based on the hourly precipitation data of the automatic stations and the national weather stations(referred to as the national stations)from April to September during 2010-2019.The results show that the average state of maximum hourly precipitation of all stations(the automatic stations and the national stations)and national stations both are representative,but the data of all stations are more representative when the maximum hourly precipitation is extreme.The 99.5 th quantile is the most reasonable threshold of extremely short-time severe precipitation in each station.The spatial distribution of extremely short-time severe precipitation intensity in all stations and national stations is generally that the southern region is stronger than the northern region,and the intensity values are concentrated in the range of 40-50 mm/h.All stations data can better reflect the distribution characteristics of<40 and≥50 mm/h.The national stations data underestimates the precipitation intensity in the southern and northeastern marginal areas of Guizhou,and slightly exaggerates the precipitation intensity in the northern part of Guizhou.The monthly and diurnal variations of the frequency of extremely short-time severe precipitation in all stations and national stations are very obvious and the variation trend is the same,but the intensity of extremely short-time severe precipitation has no obvious monthly variation characteristics.There is no significant diurnal variation in the intensity of extremely short-time severe precipitation in all stations,but the diurnal variation in the data of national stations is significant.Since the frequency of extremely short-time severe precipitation in national stations is less,the diurnal variation in the intensity of extremely short-time severe precipitation in all stations is more statistically significant.

The SIA method for spatial analysis of precipitation in the upper-middle reaches of the Yangtze River

Using geographic information system (GIS) techniques and the newest seasonal and annual average precipitation data of 679 meteorological stations from 1971 to 2000, the multiple regressions equations of the precipitation and topographical variables are established to extract the effect of topography on the annual and seasonal precipitation in the upper-middle reaches of the Yangtze River. Then, this paper uses a successive interpolation approach (SIA), which combines GIS techniques with the multiple regressions, to improve the accuracy of the spatial interpolation of annual and seasonal rainfall. The results are very satisfactory in the case of seasonal rainfall, with the relative error of 6.86%, the absolute error of 13.07 mm, the average coefficient of variation of 0.070, and the correlation coefficient of 0.9675; in the case of annual precipitation, with the relative error of 7.34%, the absolute error of 72.1 mm, the average coefficient of variation of 0.092, and the correlation coefficient of 0.9605. The analyses of annual mean precipitation show that the SIA calculation of 3-5 steps considerably improves the interpolation accuracy, decreasing the absolute error from 211.0 mm to 62.4 mm, the relative error from 20.74% to 5.97%, the coefficient of variation from 0.2312 to 0.0761, and increasing the correlation coefficient from 0.5467 to 0.9619. The SIA iterative results after 50 steps identically converge to the observed precipitation.

Innovative trend analysis of annual and seasonal precipitation in Ningxia,China

Based on daily rainfall data from 26 station records,spatial and temporal variations in annual and seasonal precipitation of different rainfall intensities from 1961 to 2018 in Ningxia,China are investigated using the innovative trend analysis(ITA)method.The results show that annual precipitation increases on the northern plain but decreases in the southern mountainous area.The increase in regional annual precipitation is mainly due to an increase in weak precipitation,while the decrease in regional annual rainfall is a result of a reduction in heavy precipitation.Lowintensity precipitation shows an upward trend,while high-intensity precipitation shows a downward trend.The variation trend of extreme precipitation is more obvious.The contributions of different types of extreme precipitation vary by season.During spring,the increase in regional rainfall is mainly caused by the increase in heavy precipitation,while the decrease in regional precipitation is mainly caused by the decrease in weak precipitation.During summer and autumn,the increase in regional precipitation is caused by the increase in light precipitation,while the reduction in regional rainfall is caused by the decrease in heavy precipitation.This study provides support for water resources planning and addressing droughts and floods.

Complexity analysis of precipitation in changing environment in Chien River Basin,China

The hydrological processes influenced by the multiple factors of climate, geography, vegetation, and human activities are becoming more and more complex, which is an important characteristic of hydrological systems. The different complexity distributions of precipitation processes of the Chien River Basin （a sub-basin of the Minjiang Basin） in two periods （from 1952 to 1980, and from 1981 to 2009） are illustrated using the fractal based on the continuous wavelet transform （CWT）. The results show that （1） at the basin scale the precipitation process in the latter period is more complex than in the former period; （2） the maximum value of the complexity distribution moved from the east to the middle; and （3） through analysis of the time-information and space-information concealed in this complexity change, the precipitation characteristics in the changing environment in the basin can be illuminated. This study could provide a reference for research on disaster pre-warning in changing environments and for integrated water resources management in the local basin.

SEOF Analysis on the Precipitation and Temperature in China during 1951-1999

[Objective] The research aimed to study the seasonal variation characteristics of precipitation and temperature in China during 1951-1999. [Method] Based on the monthly average precipitation and temperature data in 160 stations from January, 1951 to February, 1999, which were provided by China Meteorological Administration, the spatial-temporal variation characteristics of precipitation and temperature in 48 years were studied by using SEOF method. [Result] SEOF analysis of precipitation:SEOF analysis of the first modal showed the four-season propulsion of rain belt in China from south to north. Seen from the time coefficient, as a whole, the precipitation in China decreased slightly during the 1960s-1970s. After the 1970s, the precipitation had the increase trend and was the decrease trend after the 1980s. SEOF analysis of temperature:the first modals of precipitation and temperature configured well in the space. In the dry zone where the precipitation was less, the temperature variation was obvious. Seen from the time sequence, the temperature in China during 1951-1999 was low, and it was the low temperature period in the 1950s. The temperature rose slightly during the 1950s-1960s, and it entered into the low temperature period again from the middle and latter periods of 1960s to early the 1970s. From the metaphase of 1970s to the end of 1990s, the temperature increased relatively and stably. [Conclusion] The research provided the theory basis for studying the climate variation in China.

Rietveld Quantitative Analysis of Carbides Precipitation in Normalized-tempered 2.25Cr-1Mo-0.25V Steel

The quantitative determination of the mass fractions of precipitates in steels is very difficult using traditional materials characterization techniques. The Rietveld full-pattern fitting algorithm was introduced to solve this problem. The precipitated multicomponents’ mass fraction of M3C, MC, M7C3 and M23C6 were evaluated precisely and relatively quickly. It is found evolution of carbides apparently occurs during tempering at high temperatures, and a two-step transformation mechanism is proposed for M7C3 during early tempering treatment. The method is an effective way on the investigation of precipitation kinetics, which may play a promising role in propertities’ enhancement and design of the heat-resistant steels.

A Case Study of Impact of FY-2C Satellite Data in Cloud Analysis to Improve Short-Range Precipitation Forecast

Chinese FengYun-2C(FY-2C) satellite data were combined into the Local Analysis and Prediction System(LAPS) model to obtain three-dimensional cloud parameters and rain content. These parameters analyzed by LAPS were used to initialize the Global/Regional Assimilation and Prediction System model(GRAPES) in China to predict precipitation in a rainstorm case in the country. Three prediction experiments were conducted and were used to investigate the impacts of FY-2C satellite data on cloud analysis of LAPS and on short range precipitation forecasts. In the first experiment, the initial cloud fields was zero value. In the second, the initial cloud fields were cloud liquid water, cloud ice, and rain content derived from LAPS without combining the satellite data. In the third experiment, the initial cloud fields were cloud liquid water, cloud ice, and rain content derived from LAPS including satellite data. The results indicated that the FY-2C satellite data combination in LAPS can show more realistic cloud distributions, and the model simulation for precipitation in 1–6 h had certain improvements over that when satellite data and complex cloud analysis were not applied.

THE DIAGNOSTIC ANALYSIS OF THE TRACK AND PRECIPITATION OF TYPHOON “RANANIM” AFTER LANDFALL

Over the past few years, landfall and track,intensity, sustaining mechanisms of tropical cyclones （hereafter TCs） and associated weather changes have become heated topics of research, From the viewpoints of energy transformation, moisture transfer, midlatitude baroclinic frontal zones and ambient wind fields, Chen et al.Le et al.and Zeng et al.studied the sustaining mechanism of TCs that have made landfall. Li et al.also pointed out that the intensification of TCs during transition was associated with the disturbance and downward transportation of high-level potential vortexes, low-level frontal zones and low-pressure circulation around TCs, after explaining the difference in TCs transition following the theory of wet potential vortexes. With large-scale diagnostic study of two types of TCs that unexpectedly weaken or enhance just before landfall in southern China, Hu et al.noted that enhancing TCs were usually to the southwest or south of the subtropical high with low levels featured by well-defined southwesterly inflow inside TCs and sufficient supply of water vapor. Liang et al.not only analyzed the changes in convective cloud bands, precipitation, track and temperature and humidity structure in the course of TC Vongfang landfall, but the effect of cold air and Southwest Monsoon on its intensity in particular. As also shown in numerical experiments conducted both at home and abroad and relevant studies,saturated humidity and large-sized bodies of water are favorable for the maintenance and enhancement of landfall TCs circulation. All of the above research achievements not only help broaden the understanding of the patterns by which TCs behave but are positive in improving the forecast of the track, winds and rains after landfall. It is.however, not much addressed in the field or evounon of landfall TCs when they are with special underlying surface and circulation background. TC Rananim （0414） was the most serious typhoon that ever affected Zhejiang province after landfall in the 48 years from 1956 to 2004, which was also the storm that caused heavy rains in the most widespread area in Jiangxi province in the past 20 years. There are two points about Rananim that stand out from the other storms. The first was the sudden westward turning of its track and the second the significant enhancement of precipitation after moving above the Boyang Lake.What kind of mechanism caused such remarkable change in the storm？ With 6-hourly 1×1°NECP global reanalysis data, real-time upper-level observations and TCs location reports by the Central Observatory, the above two points and possible causes are studied in terms large-scale circulation background, underlying surface, cold air and diagnosis of physical quantity fields. New understanding has been made about the behavioral pattern of landfall TCs and related results will offer effective help in operational forecast.