Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in frequency.In addition,nitrogen(N)deposition occurs simultaneously in arid ...Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in frequency.In addition,nitrogen(N)deposition occurs simultaneously in arid and semi-arid regions.Microbial biomass,diversity,composition,and species interactions are key determinants of ecological functions.We examined the effects of changes in precipitation intensity and N addition on the soil bacterial and fungal communities in a semi-arid grassland in Inner Mongolia,China.Methods The microbial biomass(bacterial PLFAs and fungal PLFAs)was determined through phospholipid fatty acid(PLFA)analysis,and microbial diversity(Shannon index and evenness index)was determined with high-throughput sequencing(16S and ITS).Species interactions were determined using a molecular ecological network analysis.The relationships between microbial community(bacterial community and fungal community)and environmental variables were examined by Mantel tests.Results We found that N addition decreased fungal PLFA under moderate,high,and extreme precipitation intensity treatments and increased fungal community complexity under the high precipitation intensity treatment.Furthermore,N addition increased bacterial diversity under moderate and high precipitation intensity treatments.N addition caused greater environmental stress to the fungal community,which was dominated by deterministic processes.Conclusions The effects of N deposition on soil bacterial and fungal communities were altered by precipitation intensity.The changes in soil bacterial and fungal communities were different,implying that composition and functional traits adapt differently to projected global changes at a regional scale.展开更多
The spectral characteristics of precipitation intensity during warm and cold years are compared in six regions of China based on precipitation data at 404 meteorological stations during 1961-2006.In all of the studied...The spectral characteristics of precipitation intensity during warm and cold years are compared in six regions of China based on precipitation data at 404 meteorological stations during 1961-2006.In all of the studied regions except North China,with the increasing temperature,a decreasing trend is observed in light precipitation and the number of light precipitation days,while an increasing trend appears in heavy precipitation and the heavy precipitation days.Although changes in precipitation days in North China are similar to the changes in the other five regions,heavy precipitation decreases with the increasing temperature in this region.These results indicate that in most parts of China,the amount of precipitation and number of precipitation days have shifted towards heavy precipitation under the background of a warming climate;however,the responses of precipitation distributions to global warming differ from place to place.The number of light precipitation days decreases in the warm and humid regions of China（Jianghuai region,South China,and Southwest China）,while the increasing amplitude of heavy precipitation and the number of heavy precipitation days are greater in the warm and humid regions of China than that in the northern regions（North China,Northwest China,and Northeast China）.In addition,changes are much more obvious in winter than in summer,indicating that the changes in the precipitation frequency are more affected by the increasing temperature during winter than summer.The shape and scale parameters of the Γ distribution of daily precipitation at most stations of China have increased under the background of global warming.The scale parameter changes are smaller than the shape parameter changes in all regions except Northwest China.This suggests that daily precipitation shifts toward heavy precipitation in China under the warming climate.The number of extreme precipitation events increases slightly,indicating that changes in the Γ distribution fitting parameters reflect changes in the regional precipitation distribution structure.展开更多
Using 58 years (1961 to 2018) of daily rainfall data, this study focuses on determining trends in the annual and seasonal precipitation extremes of Jiangxi, China, by choosing four extreme precipitation indices, inclu...Using 58 years (1961 to 2018) of daily rainfall data, this study focuses on determining trends in the annual and seasonal precipitation extremes of Jiangxi, China, by choosing four extreme precipitation indices, including strong precipitation amount (SPA), mean precipitation intensity (MPI), strong precipitation days (SPD), and strong precipitation frequency (SPF). The monotonic trends are tested by using the Mann-Kendall test for the trends and Sen’s method for the magnitude of the trends. The effective sample size (ESS) method was used to eliminate the influence of serial correlation in the Mann-Kendall test. The results indicated that station Zixi had the strongest extreme precipitation, while Wanzai had the weakest. The trends for each index showed an obvious regional feature over Jiangxi. Increasing trends in annual extreme precipitation indices were found at almost all stations, and the annual variability of the extreme precipitation indices was pronounced, especially for the mean precipitation intensity and the strong precipitation frequency;the majority of these positive trends were shown by the statistical tests. In spring, four indices exhibited significant increasing trends in Northeast and Southwest Jiangxi;however, in summer, only MPI had a remarkable positive trend across almost all of Jiangxi. For the other indices, few stations had remarkable trends. In autumn, MPI and SPF showed remarkable increasing trends in most regions of Jiangxi, while SPA and SPD showed increasing trends at only 6 stations and 3 stations, respectively, which were scattered in the northern and middle parts. In winter, the stations with remarkable upward trends in SPA and SPD were mainly located in the middle of the region, whereas the significant patterns of MPI and SPF were located in the south and middle of the region.展开更多
Combined with TRMM products and Tropical Cyclone(TC) best track data in Northwest Pacific from 1 January 2003 to 31 December 2009,a total of 118 TCs,including 336 instantaneous TC precipitation observations are establ...Combined with TRMM products and Tropical Cyclone(TC) best track data in Northwest Pacific from 1 January 2003 to 31 December 2009,a total of 118 TCs,including 336 instantaneous TC precipitation observations are established as the TRMM TC database,and the database is stratified into four intensity classes according to the standard of TC intensity adopted by China Meteorological Administration(CMA):Severe Tropical Storm(STS),Typhoon(TY),Severe Typhoon(STY) and Super Typhoon(SuperT Y).For each TC snapshot,the mean rainfall distribution is computed using 10-km annuli from the TC center to a 300-km radius,then the axisymmetric component of TC rainfall is represented by the radial distribution of the azimuthal mean rain rate;the mean rain rates,rain types occurrence and contribution proportion are computed for each TC intensity class;and the mean quadrantal distribution of rain rates along TCs motion is analyzed.The result shows that:(1) TCs mean rain rates increase with their intensity classes,and their radial distributions show single-peak characteristic gradually,and furthermore,the characteristics of rain rates occurrence and contribution proportion change from dual-peak to single-peak distribution,with the peak rain rate at about 5.0mm/h;(2) Stratiform rain dominate the rain type in the analysis zone,while convective rain mainly occurred in the eye-wall region;(3) The values of mean rain rate in each quadrant along TCs motion are close to each other,relatively,the value in the right-rear quadrant is the smallest one.展开更多
Meteorological drought is a natural hazard that can occur under all climatic regimes. Monitoring the drought is a vital and important part of predicting and analyzing drought impacts. Because no single index can repre...Meteorological drought is a natural hazard that can occur under all climatic regimes. Monitoring the drought is a vital and important part of predicting and analyzing drought impacts. Because no single index can represent all facets of meteorological drought, we took a multi-index approach for drought monitoring in this study. We assessed the ability of eight precipitation-based drought indices（SPI（Standardized Precipitation Index）, PNI（Percent of Normal Index）, DI（Deciles index）, EDI（Effective drought index）, CZI（China-Z index）, MCZI（Modified CZI）, RAI（Rainfall Anomaly Index）, and ZSI（Z-score Index）） calculated from the station-observed precipitation data and the Ag MERRA gridded precipitation data to assess historical drought events during the period 1987–2010 for the Kashafrood Basin of Iran. We also presented the Degree of Dryness Index（DDI） for comparing the intensities of different drought categories in each year of the study period（1987–2010）. In general, the correlations among drought indices calculated from the Ag MERRA precipitation data were higher than those derived from the station-observed precipitation data. All indices indicated the most severe droughts for the study period occurred in 2001 and 2008. Regardless of data input source, SPI, PNI, and DI were highly inter-correlated（R^2=0.99）. Furthermore, the higher correlations（R^2=0.99） were also found between CZI and MCZI, and between ZSI and RAI. All indices were able to track drought intensity, but EDI and RAI showed higher DDI values compared with the other indices. Based on the strong correlation among drought indices derived from the Ag MERRA precipitation data and from the station-observed precipitation data, we suggest that the Ag MERRA precipitation data can be accepted to fill the gaps existed in the station-observed precipitation data in future studies in Iran. In addition, if tested by station-observed precipitation data, the Ag MERRA precipitation data may be used for the data-lacking areas.展开更多
Based on daily precipitation data from 163 meteorological stations, this study investigated precipitation changes in the mid-latitudes of the Chinese mainland（MCM） during 1960–2014 using the climatic trend coeffici...Based on daily precipitation data from 163 meteorological stations, this study investigated precipitation changes in the mid-latitudes of the Chinese mainland（MCM） during 1960–2014 using the climatic trend coefficient, least-squared regression analysis, and a non-parametric Mann-Kendall test.According to the effects of the East Asian summer monsoon on the MCM and the climatic trend coefficient of annual precipitation during 1960–2014, we divided the MCM into the western MCM and eastern MCM. The western MCM was further divided into the western MCM1 and western MCM2 in terms of the effects of the East Asian summer monsoon. The main results were as follows：（1） During the last four decades of the 20^（th） century, the area-averaged annual precipitation presented a significant increasing trend in the western MCM, but there was a slight decreasing trend in the eastern MCM, where a seesaw pattern was apparent. However, in the 21^（st） century, the area-averaged annual precipitation displayed a significant increasing trend in both the western and eastern MCM.（2） The trend in area-averaged seasonal precipitation during 1960–2014 in the western MCM was consistent with that in the eastern MCM in winter and spring. However, the trend in area-averaged summer precipitation during1960–2014 displayed a seesaw pattern between the western and eastern MCM.（3） On an annual basis,both the trend in rainstorms and heavy rain displayed a seesaw pattern between the western and eastern MCM.（4） The precipitation intensity in rainstorms, heavy rain, and moderate rain made a greater contribution to changes in the total precipitation than precipitation frequency. The results of this study will improve our understanding of the trends and differences in precipitation changes in different areas of the MCM. This is not only useful for the management and mitigation of flood disasters, but is also beneficial to the protection of water resources across the MCM.展开更多
Characteristics of diurnal cycle precipitation over China are investigated using twice-daily observations by the China Meteorological Administration during 1960–2000. Characteristics investigated include nighttime/da...Characteristics of diurnal cycle precipitation over China are investigated using twice-daily observations by the China Meteorological Administration during 1960–2000. Characteristics investigated include nighttime/daytime precipitation amount(PA), intensity, and frequency. Geographically, the region is separated into western and eastern China by the 110°E longitude. Our analysis shows that there generally is more night-time than daytime precipitation in western China, particularly in the Sichuan Basin. Over eastern China, the opposite holds true, particularly along the southeast coast. Regional average monthly daytime and night-time precipitation peaks in the same month for both western and eastern China. Over western China, monthly night-time precipitation is always greater than that during daytime, but the night-time precipitation frequency(PF) is only greater in non-summer(June–August) months. Over eastern China, daytime precipitation is greater than that in the night-time during the warm season(May–August) in both amount and frequency. The night-day difference(night-time minus daytime) in PA over western China is mainly influenced by precipitation intensity, while over eastern China the night-day difference in rainfall amount is mostly driven by PF.展开更多
Study was carried out on two landfall typhoons Haitang and Matsa, which affected Zhejiang province seriously in 2005. Firstly, the similarity and difference between the two typhoon-induced heavy rains were compared an...Study was carried out on two landfall typhoons Haitang and Matsa, which affected Zhejiang province seriously in 2005. Firstly, the similarity and difference between the two typhoon-induced heavy rains were compared and it was pointed out that both of them brought strong large-scale precipitation and the maximum centers of rainfall were located on the north side of the landfall site. Making landfall on Fujian, Haitang was weaker than Matsa in intensity but surpassed it in rainfall. Then with focus on intensity, moving speed, structure of typhoon, circulation and terrain, the two typhoon-related heavy rains were compared and analyzed. Results show that the asymmetrical distribution of rainfall was closely related to the structure of typhoons themselves, moisture transportation and mesoscale terrain. In contrast to the south side, the north side was hotter and wetter and water vapor was also more abundant. The phenomenon of more rainfall induced by Haitang was in connection with the following reasons. Invading cold air led to rainfall increases, weakened dynamic field and slower movement both benefited precipitation. For the last part, the cold characteristic of air mass over Zhejiang was also a favorable factor for the rain.展开更多
Based on the ERA reanalysis winds data, the multi-time scale variations of Somali jet are analyzed synthetically. The jet's influences on rainfall in China on interannual, interdecadal and sub-monthly scales are a...Based on the ERA reanalysis winds data, the multi-time scale variations of Somali jet are analyzed synthetically. The jet's influences on rainfall in China on interannual, interdecadal and sub-monthly scales are also studied using correlation and composite analyses. The results demonstrate that the interdecadal variations of the jet are significant.The Somali jet became weaker in the 1960 s and became the weakest in the early 1970 s before enhancing slowly in the late 1970 s. Moreover, the relation between the Somali jet and summer precipitation in China is close, but varies on different timescales. Preliminary analysis shows that the intensity variations in May and June during the early days of establishment are well correlated with summer precipitation in China. The Somali jet intensity on the interdecadal scale is closely related with interdecadal variations of the precipitation in China. Regardless of leading or contemporaneous correlation, the correlations between the Somali jet intensity and the rainfall in northern and southern China show obvious interdecadal variations. Moreover, the link between the anomalies of the jet intensity in May-August and precipitation evolution on synoptic scale in China is further studied. China has more rainfall with positive anomalies of the Somali jet but less rainfall with negative anomalies during the active period of the jet. The influence of positive Somali jet anomalies on China precipitation is more evident.展开更多
Idealized supercell storms are simulated with two aerosol-aware bulk microphysics schemes(BMSs),the Thompson and the Chen-Liu-Reisner(CLR),using the Weather Research and Forecast(WRF)model.The objective of this study ...Idealized supercell storms are simulated with two aerosol-aware bulk microphysics schemes(BMSs),the Thompson and the Chen-Liu-Reisner(CLR),using the Weather Research and Forecast(WRF)model.The objective of this study is to investigate the parameterizations of aerosol effects on cloud and precipitation characteristics and assess the necessity of introducing aerosols into a weather prediction model at fine grid resolution.The results show that aerosols play a decisive role in the composition of clouds in terms of the mixing ratios and number concentrations of liquid and ice hydrometeors in an intense supercell storm.The storm consists of a large amount of cloud water and snow in the polluted environment,but a large amount of rainwater and graupel instead in the clean environment.The total precipitation and rain intensity are suppressed in the CLR scheme more than in the Thompson scheme in the first three hours of storm simulations.The critical processes explaining the differences are the auto-conversion rate in the warm-rain process at the beginning of storm intensification and the low-level cooling induced by large ice hydrometeors.The cloud condensation nuclei(CCN)activation and auto-conversion processes of the two schemes exhibit considerable differences,indicating the inherent uncertainty of the parameterized aerosol effects among different BMSs.Beyond the aerosol effects,the fall speed characteristics of graupel in the two schemes play an important role in the storm dynamics and precipitation via low-level cooling.The rapid intensification of storms simulated with the Thompson scheme is attributed to the production of hail-like graupel.展开更多
The Three-River Headwaters(TRH)region in the Tibetan Plateau is vulnerable to climate change;changes in summer(June–August)precipitation have a significant impact on water security and sustainability in both local an...The Three-River Headwaters(TRH)region in the Tibetan Plateau is vulnerable to climate change;changes in summer(June–August)precipitation have a significant impact on water security and sustainability in both local and downstream areas.However,the changes in summer precipitation of different intensities over the TRH region,along with their influencing factors,remain unclear.In this study,we used observational and ERA5 reanalysis data and employed a precipitation categorization and water vapor budget analysis to quantify the categorized precipitation variations and investigate their possible linkages with the water vapor budget.Our results showed an increasing trend in summer precipitation at a rate of 0.9 per year(p<0.1)during 1979–2020,with a significant dry-to-wet transition in 2002.The category‘very heavy precipitation’(10 mm d−1)contributed 65.1%of the increased summer precipitation,which occurred frequently in the northern TRH region.The dry-to-wet transition was caused by the effects of varied atmospheric circulations in each subregion.Southwesterly water vapor transport through the southern boundary was responsible for the increased net water vapor flux in the western TRH region(158.2%),while southeasterly water vapor transport through the eastern boundary was responsible for the increased net water vapor flux in the central TRH(155.2%)and eastern TRH(229.2%)regions.Therefore,we inferred that the dry-to-wet transition of summer precipitation and the increased‘very heavy precipitation’over the TRH was caused by increased easterly and southerly water vapor transport.展开更多
Acoustic interference of atmosphere has been an attractive research area because of its potential effect on environment,water resources,ecology,agriculture,and other areas.However,it is also a controversial topic beca...Acoustic interference of atmosphere has been an attractive research area because of its potential effect on environment,water resources,ecology,agriculture,and other areas.However,it is also a controversial topic because of the difficulty of quantitative assessment and high operating costs.In this study,a novel acoustic interference technology is proposed that uses strong lowfrequency sound waves.There is no chemical pollution or dependence on airborne vehicles,and it can be remotely controlled at low cost.A complete equipment system for acoustic atmospheric interference technology is established,based on which a series of experimental studies on cloud and precipitation response under acoustic action are performed,mainly including the radar echo intensity,cloud microphysical characteristics and the spatial distribution of ground rainfall intensity.The trigger and periodic effect of the acoustic waves on the cloud are proposed to be the key responses of acoustic atmospheric interference.This study is important to further research on atmosphere interference technology based on low frequency strong sound waves.展开更多
Applying constant precipitation intensity,which does not occur in natural events,is one of the main limitations concerning rainfall simulators in soil erosion studies.The present work evaluated the InfiAsper rainfall ...Applying constant precipitation intensity,which does not occur in natural events,is one of the main limitations concerning rainfall simulators in soil erosion studies.The present work evaluated the InfiAsper rainfall simulator operating with a new control panel to program rainfalls with different precipitation intensities(PI).Infiltration rates and soil and water losses were evaluated in a Distrophic Acrisol(clay loam texture)with simulated rainfalls of 30 mm and duration of 40 min,considering advanced(AD),intermediate(IN),delayed(DE),and inverted intermediate(II)patterns,all with PI peaks of 110 mm h^(-1),and a constant(CT)pattern.The experimental design was in randomized blocks with five treatments(rainfall patterns)and experimental units measuring 2.5×2.5 m.The simulator worked satisfactorily,applying the rainfall according to the preconfigured programs.The simulated rainfall with the CT and II patterns did not promote runoff nor soil loss.Infiltration and runoff rates varied according to the applied rainfall pattern,reaching 97.8 and 27.3 mm h^(-1)(AD),82.1 and 39.5 mm h^(-1)(IN),and 76.2 and 49.7 mm h^(-1)(DE),respectively.Soil loss and surface runoff totaled each 4.77 g m^(-2)and 3.9 mm(AD),6.70 g m^(-2)and 6.8 mm(IN),and 6.03 g m^(-2)and 7.0 mm(DE).The InfiAsper simulator modified enables varying precipitation intensity besides obtaining satisfactory results in the field and information consistent with the expected characteristics of natural rainfall patterns.In the intermediate and delayed rainfall patterns,soil and water losses are higher than in the advanced.展开更多
The Hekou-Longmen reach, together with local floods, is the main source area for coarse sedimenta- tions into the Yellow River. When total rainfall slightly increased in the area, discharge dramatically decreased by 4...The Hekou-Longmen reach, together with local floods, is the main source area for coarse sedimenta- tions into the Yellow River. When total rainfall slightly increased in the area, discharge dramatically decreased by 40%-70% after the year of 2000, and attracting extensive attention in the context of global climate change. High temporal resolution precipitation （timescales between 1 and 4 h） data from the June to September period from 270 rain gauges over the past three decades was mined in order to help explain the phenomenon. Each rainfall event was classified as light/moderate rain, large rain, heavy rain or rainstorm by the event＇s rainfall amount, and further classified as low intensity rain, medium intensity rain and high intensity rain by the event＇s rainfall intensity. The Mann-Kendall trend test was applied to detect the presence and significance of monotonic trends, and to find the change points in the mean and variance of the precipitation characteristics series, including the amount, intensity, frequency and duration of each rainfall category. Results show that although the total amount of precipitation has slightly increased, the average rainfall intensity has significantly decreased. The larger change happened in light/moderate rain events and low/medium intensity rain events, and the intensity changes have a great extent occurred around the threshold of Non-Runoff Rainfall regime, which was proposed for the approximate calcula- tion of initial losses. Changes in rainfall distribution between different classes of the Runoff Rainfall regime in the 2000s could lead to 0.9 mm less runoffdepth （17.3% of the total reduction） than the 1980-1999 period. The study indicates that changes in hourly precipitation may be responsible for the sharp reduction of discharge.展开更多
In the Lancang‒Mekong River basin(LMRB),agriculture,dominating the local economy,faces increasing challenges in water supply under climate change.The projection of future precipitation in this basin is essential for u...In the Lancang‒Mekong River basin(LMRB),agriculture,dominating the local economy,faces increasing challenges in water supply under climate change.The projection of future precipitation in this basin is essential for understanding the challenges.In this study,the Weather Research and Forecasting(WRF)model was applied to project the LMRB precipitation.Comparing with the historical period(1986e2005),we analyzed the changes of both the projected precipitation amount and the frequency of rainless(<0.1 mm d1),light rain(0.1e10 mm d1),moderate rain(10e25 mm d1),heavy rain(25e50 mm d1),rainstorm(50e100 mm d1),and heavy rainstorm(>100 mm d1)for three periods,namely the near-term(2016e2035),mid-term(2046e2065),and long-term(2080e2099).The results indicate that the precipitation amount during the wet season(AprileOctober)is expected to increase in most areas of the basin for the three periods.As for the precipitation during the dry season(NovembereMarch),an increase is projected in most areas for the near-term,while an increase in the lower reach of the basin and a decrease in the upper and middle reach for the mid-term and long-term.The precipitation reduction is expected to be greatest in Myanmar,Laos,Thailand,and Yunnan province of China for the mid-term.The frequency of precipitation in different intensities has prominent regional and temporal differences.During the wet season,the days of rainless and light rain are expected to decrease in the middle reach,whereas the days of rainstorm and heavy rainstorm increase.This feature is especially strong in southern Thailand,southern Laos and Cambodia in the near-term and in Laos and Thailand for the mid-term and long-term.During the dry season,there are projected increasing rainless days and decreasing days of precipitation for the other intensities in the middle reach,and opposite in the rest area of the basin.These projected precipitation changes have potential various impact in different parts of the basin.The middle reach would likely face increasing flood risks because of more days of rainstorm and heavy rainstorm,as well as more precipitation.Yunnan,Myanmar,Thailand and Laos would probably be the center of drought threatens during the dry season due to the increment of rainless days and the precipitation reduction.Besides,the seawater intrusion during the dry season in the near-term and mid-term would be more serious as a result of the precipitation decrease in southern Vietnam.展开更多
Analyzing the impact of radio interference(RI)variation during foul weather conditions is an area that has received limited study.This paper provides a statistical analysis of RI measurements obtained from a long-term...Analyzing the impact of radio interference(RI)variation during foul weather conditions is an area that has received limited study.This paper provides a statistical analysis of RI measurements obtained from a long-term observation station close to the world’s first commercially operating 1000 kV UHV AC double-circuit transmission line in China.During six months of observations,the impact of RI was studied on the line during fog,drizzle,and light snow and rain.It was found that RI increases linearly with the natural logarithm of the precipitation intensity.The Levenberg-Marquardt algorithm(LMA)is employed to fit the RI value with the precipitation intensity.The reasonable distribution of RI in different foul weather is verified by one-sample K-S test.This test is seen as beneficial for further RI prediction based on statistical weather mode.展开更多
基金supported by the National Natural Science Foundation of China(NSFC-31970410)Liaoning Revitalization Talents Program(XLYC2002083)+1 种基金Liaoning Province Science and Technology Plan Project(2018103004)Department of Science and Technology of Liaoning Province(2022JH5/10400111).
文摘Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in frequency.In addition,nitrogen(N)deposition occurs simultaneously in arid and semi-arid regions.Microbial biomass,diversity,composition,and species interactions are key determinants of ecological functions.We examined the effects of changes in precipitation intensity and N addition on the soil bacterial and fungal communities in a semi-arid grassland in Inner Mongolia,China.Methods The microbial biomass(bacterial PLFAs and fungal PLFAs)was determined through phospholipid fatty acid(PLFA)analysis,and microbial diversity(Shannon index and evenness index)was determined with high-throughput sequencing(16S and ITS).Species interactions were determined using a molecular ecological network analysis.The relationships between microbial community(bacterial community and fungal community)and environmental variables were examined by Mantel tests.Results We found that N addition decreased fungal PLFA under moderate,high,and extreme precipitation intensity treatments and increased fungal community complexity under the high precipitation intensity treatment.Furthermore,N addition increased bacterial diversity under moderate and high precipitation intensity treatments.N addition caused greater environmental stress to the fungal community,which was dominated by deterministic processes.Conclusions The effects of N deposition on soil bacterial and fungal communities were altered by precipitation intensity.The changes in soil bacterial and fungal communities were different,implying that composition and functional traits adapt differently to projected global changes at a regional scale.
基金Supported by the National Natural Science Foundation of China(41230528)National (Key) Basic Research and Development (973) Program of China(2012CB955204)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The spectral characteristics of precipitation intensity during warm and cold years are compared in six regions of China based on precipitation data at 404 meteorological stations during 1961-2006.In all of the studied regions except North China,with the increasing temperature,a decreasing trend is observed in light precipitation and the number of light precipitation days,while an increasing trend appears in heavy precipitation and the heavy precipitation days.Although changes in precipitation days in North China are similar to the changes in the other five regions,heavy precipitation decreases with the increasing temperature in this region.These results indicate that in most parts of China,the amount of precipitation and number of precipitation days have shifted towards heavy precipitation under the background of a warming climate;however,the responses of precipitation distributions to global warming differ from place to place.The number of light precipitation days decreases in the warm and humid regions of China（Jianghuai region,South China,and Southwest China）,while the increasing amplitude of heavy precipitation and the number of heavy precipitation days are greater in the warm and humid regions of China than that in the northern regions（North China,Northwest China,and Northeast China）.In addition,changes are much more obvious in winter than in summer,indicating that the changes in the precipitation frequency are more affected by the increasing temperature during winter than summer.The shape and scale parameters of the Γ distribution of daily precipitation at most stations of China have increased under the background of global warming.The scale parameter changes are smaller than the shape parameter changes in all regions except Northwest China.This suggests that daily precipitation shifts toward heavy precipitation in China under the warming climate.The number of extreme precipitation events increases slightly,indicating that changes in the Γ distribution fitting parameters reflect changes in the regional precipitation distribution structure.
文摘Using 58 years (1961 to 2018) of daily rainfall data, this study focuses on determining trends in the annual and seasonal precipitation extremes of Jiangxi, China, by choosing four extreme precipitation indices, including strong precipitation amount (SPA), mean precipitation intensity (MPI), strong precipitation days (SPD), and strong precipitation frequency (SPF). The monotonic trends are tested by using the Mann-Kendall test for the trends and Sen’s method for the magnitude of the trends. The effective sample size (ESS) method was used to eliminate the influence of serial correlation in the Mann-Kendall test. The results indicated that station Zixi had the strongest extreme precipitation, while Wanzai had the weakest. The trends for each index showed an obvious regional feature over Jiangxi. Increasing trends in annual extreme precipitation indices were found at almost all stations, and the annual variability of the extreme precipitation indices was pronounced, especially for the mean precipitation intensity and the strong precipitation frequency;the majority of these positive trends were shown by the statistical tests. In spring, four indices exhibited significant increasing trends in Northeast and Southwest Jiangxi;however, in summer, only MPI had a remarkable positive trend across almost all of Jiangxi. For the other indices, few stations had remarkable trends. In autumn, MPI and SPF showed remarkable increasing trends in most regions of Jiangxi, while SPA and SPD showed increasing trends at only 6 stations and 3 stations, respectively, which were scattered in the northern and middle parts. In winter, the stations with remarkable upward trends in SPA and SPD were mainly located in the middle of the region, whereas the significant patterns of MPI and SPF were located in the south and middle of the region.
基金National Nature Science Foundation of China(41205017)Pre-Research Foundation of General Equipment Department(9140A22060215JB09349)
文摘Combined with TRMM products and Tropical Cyclone(TC) best track data in Northwest Pacific from 1 January 2003 to 31 December 2009,a total of 118 TCs,including 336 instantaneous TC precipitation observations are established as the TRMM TC database,and the database is stratified into four intensity classes according to the standard of TC intensity adopted by China Meteorological Administration(CMA):Severe Tropical Storm(STS),Typhoon(TY),Severe Typhoon(STY) and Super Typhoon(SuperT Y).For each TC snapshot,the mean rainfall distribution is computed using 10-km annuli from the TC center to a 300-km radius,then the axisymmetric component of TC rainfall is represented by the radial distribution of the azimuthal mean rain rate;the mean rain rates,rain types occurrence and contribution proportion are computed for each TC intensity class;and the mean quadrantal distribution of rain rates along TCs motion is analyzed.The result shows that:(1) TCs mean rain rates increase with their intensity classes,and their radial distributions show single-peak characteristic gradually,and furthermore,the characteristics of rain rates occurrence and contribution proportion change from dual-peak to single-peak distribution,with the peak rain rate at about 5.0mm/h;(2) Stratiform rain dominate the rain type in the analysis zone,while convective rain mainly occurred in the eye-wall region;(3) The values of mean rain rate in each quadrant along TCs motion are close to each other,relatively,the value in the right-rear quadrant is the smallest one.
文摘Meteorological drought is a natural hazard that can occur under all climatic regimes. Monitoring the drought is a vital and important part of predicting and analyzing drought impacts. Because no single index can represent all facets of meteorological drought, we took a multi-index approach for drought monitoring in this study. We assessed the ability of eight precipitation-based drought indices（SPI（Standardized Precipitation Index）, PNI（Percent of Normal Index）, DI（Deciles index）, EDI（Effective drought index）, CZI（China-Z index）, MCZI（Modified CZI）, RAI（Rainfall Anomaly Index）, and ZSI（Z-score Index）） calculated from the station-observed precipitation data and the Ag MERRA gridded precipitation data to assess historical drought events during the period 1987–2010 for the Kashafrood Basin of Iran. We also presented the Degree of Dryness Index（DDI） for comparing the intensities of different drought categories in each year of the study period（1987–2010）. In general, the correlations among drought indices calculated from the Ag MERRA precipitation data were higher than those derived from the station-observed precipitation data. All indices indicated the most severe droughts for the study period occurred in 2001 and 2008. Regardless of data input source, SPI, PNI, and DI were highly inter-correlated（R^2=0.99）. Furthermore, the higher correlations（R^2=0.99） were also found between CZI and MCZI, and between ZSI and RAI. All indices were able to track drought intensity, but EDI and RAI showed higher DDI values compared with the other indices. Based on the strong correlation among drought indices derived from the Ag MERRA precipitation data and from the station-observed precipitation data, we suggest that the Ag MERRA precipitation data can be accepted to fill the gaps existed in the station-observed precipitation data in future studies in Iran. In addition, if tested by station-observed precipitation data, the Ag MERRA precipitation data may be used for the data-lacking areas.
基金financially supported by the National Natural Science Foundation of China (91644226)the National Key Research Project of China (2016YFA0602004)Industry of National Public Welfare (Meteorological) Scientific Research (GYHY201206004)
文摘Based on daily precipitation data from 163 meteorological stations, this study investigated precipitation changes in the mid-latitudes of the Chinese mainland（MCM） during 1960–2014 using the climatic trend coefficient, least-squared regression analysis, and a non-parametric Mann-Kendall test.According to the effects of the East Asian summer monsoon on the MCM and the climatic trend coefficient of annual precipitation during 1960–2014, we divided the MCM into the western MCM and eastern MCM. The western MCM was further divided into the western MCM1 and western MCM2 in terms of the effects of the East Asian summer monsoon. The main results were as follows：（1） During the last four decades of the 20^（th） century, the area-averaged annual precipitation presented a significant increasing trend in the western MCM, but there was a slight decreasing trend in the eastern MCM, where a seesaw pattern was apparent. However, in the 21^（st） century, the area-averaged annual precipitation displayed a significant increasing trend in both the western and eastern MCM.（2） The trend in area-averaged seasonal precipitation during 1960–2014 in the western MCM was consistent with that in the eastern MCM in winter and spring. However, the trend in area-averaged summer precipitation during1960–2014 displayed a seesaw pattern between the western and eastern MCM.（3） On an annual basis,both the trend in rainstorms and heavy rain displayed a seesaw pattern between the western and eastern MCM.（4） The precipitation intensity in rainstorms, heavy rain, and moderate rain made a greater contribution to changes in the total precipitation than precipitation frequency. The results of this study will improve our understanding of the trends and differences in precipitation changes in different areas of the MCM. This is not only useful for the management and mitigation of flood disasters, but is also beneficial to the protection of water resources across the MCM.
基金supported by the National Basic Research Program of China(2012CB956201)the Knowledge Innovation Program of the Chinese Academy of Sciences(KZCX2-EW-202)the Special Fund for Public Welfare Industry(Meteorology)(GYHY201106028)
文摘Characteristics of diurnal cycle precipitation over China are investigated using twice-daily observations by the China Meteorological Administration during 1960–2000. Characteristics investigated include nighttime/daytime precipitation amount(PA), intensity, and frequency. Geographically, the region is separated into western and eastern China by the 110°E longitude. Our analysis shows that there generally is more night-time than daytime precipitation in western China, particularly in the Sichuan Basin. Over eastern China, the opposite holds true, particularly along the southeast coast. Regional average monthly daytime and night-time precipitation peaks in the same month for both western and eastern China. Over western China, monthly night-time precipitation is always greater than that during daytime, but the night-time precipitation frequency(PF) is only greater in non-summer(June–August) months. Over eastern China, daytime precipitation is greater than that in the night-time during the warm season(May–August) in both amount and frequency. The night-day difference(night-time minus daytime) in PA over western China is mainly influenced by precipitation intensity, while over eastern China the night-day difference in rainfall amount is mostly driven by PF.
文摘Study was carried out on two landfall typhoons Haitang and Matsa, which affected Zhejiang province seriously in 2005. Firstly, the similarity and difference between the two typhoon-induced heavy rains were compared and it was pointed out that both of them brought strong large-scale precipitation and the maximum centers of rainfall were located on the north side of the landfall site. Making landfall on Fujian, Haitang was weaker than Matsa in intensity but surpassed it in rainfall. Then with focus on intensity, moving speed, structure of typhoon, circulation and terrain, the two typhoon-related heavy rains were compared and analyzed. Results show that the asymmetrical distribution of rainfall was closely related to the structure of typhoons themselves, moisture transportation and mesoscale terrain. In contrast to the south side, the north side was hotter and wetter and water vapor was also more abundant. The phenomenon of more rainfall induced by Haitang was in connection with the following reasons. Invading cold air led to rainfall increases, weakened dynamic field and slower movement both benefited precipitation. For the last part, the cold characteristic of air mass over Zhejiang was also a favorable factor for the rain.
基金National Basic Research Program of China(973 Program,2012CB957804)Natural Science Foundation of China(41175051)
文摘Based on the ERA reanalysis winds data, the multi-time scale variations of Somali jet are analyzed synthetically. The jet's influences on rainfall in China on interannual, interdecadal and sub-monthly scales are also studied using correlation and composite analyses. The results demonstrate that the interdecadal variations of the jet are significant.The Somali jet became weaker in the 1960 s and became the weakest in the early 1970 s before enhancing slowly in the late 1970 s. Moreover, the relation between the Somali jet and summer precipitation in China is close, but varies on different timescales. Preliminary analysis shows that the intensity variations in May and June during the early days of establishment are well correlated with summer precipitation in China. The Somali jet intensity on the interdecadal scale is closely related with interdecadal variations of the precipitation in China. Regardless of leading or contemporaneous correlation, the correlations between the Somali jet intensity and the rainfall in northern and southern China show obvious interdecadal variations. Moreover, the link between the anomalies of the jet intensity in May-August and precipitation evolution on synoptic scale in China is further studied. China has more rainfall with positive anomalies of the Somali jet but less rainfall with negative anomalies during the active period of the jet. The influence of positive Somali jet anomalies on China precipitation is more evident.
基金supported by the National Key Research and Development Program of China(Grant Nos.2016YFE0109700 and 2017YFC150190X)Research Program from Science and Technology Committee of Shanghai(Grant No.19dz1200101)National Science Foundation of China(Grant Nos.41575101 and 41975133)。
文摘Idealized supercell storms are simulated with two aerosol-aware bulk microphysics schemes(BMSs),the Thompson and the Chen-Liu-Reisner(CLR),using the Weather Research and Forecast(WRF)model.The objective of this study is to investigate the parameterizations of aerosol effects on cloud and precipitation characteristics and assess the necessity of introducing aerosols into a weather prediction model at fine grid resolution.The results show that aerosols play a decisive role in the composition of clouds in terms of the mixing ratios and number concentrations of liquid and ice hydrometeors in an intense supercell storm.The storm consists of a large amount of cloud water and snow in the polluted environment,but a large amount of rainwater and graupel instead in the clean environment.The total precipitation and rain intensity are suppressed in the CLR scheme more than in the Thompson scheme in the first three hours of storm simulations.The critical processes explaining the differences are the auto-conversion rate in the warm-rain process at the beginning of storm intensification and the low-level cooling induced by large ice hydrometeors.The cloud condensation nuclei(CCN)activation and auto-conversion processes of the two schemes exhibit considerable differences,indicating the inherent uncertainty of the parameterized aerosol effects among different BMSs.Beyond the aerosol effects,the fall speed characteristics of graupel in the two schemes play an important role in the storm dynamics and precipitation via low-level cooling.The rapid intensification of storms simulated with the Thompson scheme is attributed to the production of hail-like graupel.
基金supported by Science and Technology Project of China Huaneng Research on Integrated Meteorology and Hydrology Forecasting System in Lancang River Basin(HNKJ21-HF241)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0207-02)+1 种基金the Research Programme of the Kunming Engineering Corporation Limited(DJ-HXGG-2021-04)the Key Research and Development Programme of Yunnan(202203AA080010)as part of the Science and Technology Plan Project of Yunnan Provincial Department of Science and Technology.Support from Swedish STINT(CH 2019-8377 and CH 2020-8767)is also acknowledged.
文摘The Three-River Headwaters(TRH)region in the Tibetan Plateau is vulnerable to climate change;changes in summer(June–August)precipitation have a significant impact on water security and sustainability in both local and downstream areas.However,the changes in summer precipitation of different intensities over the TRH region,along with their influencing factors,remain unclear.In this study,we used observational and ERA5 reanalysis data and employed a precipitation categorization and water vapor budget analysis to quantify the categorized precipitation variations and investigate their possible linkages with the water vapor budget.Our results showed an increasing trend in summer precipitation at a rate of 0.9 per year(p<0.1)during 1979–2020,with a significant dry-to-wet transition in 2002.The category‘very heavy precipitation’(10 mm d−1)contributed 65.1%of the increased summer precipitation,which occurred frequently in the northern TRH region.The dry-to-wet transition was caused by the effects of varied atmospheric circulations in each subregion.Southwesterly water vapor transport through the southern boundary was responsible for the increased net water vapor flux in the western TRH region(158.2%),while southeasterly water vapor transport through the eastern boundary was responsible for the increased net water vapor flux in the central TRH(155.2%)and eastern TRH(229.2%)regions.Therefore,we inferred that the dry-to-wet transition of summer precipitation and the increased‘very heavy precipitation’over the TRH was caused by increased easterly and southerly water vapor transport.
基金supported by the National Key R&D Program of China(Grant No.2017YFC0403600)the National Natural Science Foundation of China(Grant Nos.91847302 and 51879137)+1 种基金the Special Finance of Qinghai Provincethe State Key Laboratory of Hydro-science and Engineering(Grant No.2017-KY-04)。
文摘Acoustic interference of atmosphere has been an attractive research area because of its potential effect on environment,water resources,ecology,agriculture,and other areas.However,it is also a controversial topic because of the difficulty of quantitative assessment and high operating costs.In this study,a novel acoustic interference technology is proposed that uses strong lowfrequency sound waves.There is no chemical pollution or dependence on airborne vehicles,and it can be remotely controlled at low cost.A complete equipment system for acoustic atmospheric interference technology is established,based on which a series of experimental studies on cloud and precipitation response under acoustic action are performed,mainly including the radar echo intensity,cloud microphysical characteristics and the spatial distribution of ground rainfall intensity.The trigger and periodic effect of the acoustic waves on the cloud are proposed to be the key responses of acoustic atmospheric interference.This study is important to further research on atmosphere interference technology based on low frequency strong sound waves.
基金We acknowledge the Conselho Nacional de Desenvolvimento Científico e Tecnologico e Brasil(CNPq)for the financial support(Process 422394/2018-1)This study was financed in part by the Coordenaçao de Aperfeiçoamento de Pessoal de Nível Superior-Brasil(CAPES)-Finance Code 001。
文摘Applying constant precipitation intensity,which does not occur in natural events,is one of the main limitations concerning rainfall simulators in soil erosion studies.The present work evaluated the InfiAsper rainfall simulator operating with a new control panel to program rainfalls with different precipitation intensities(PI).Infiltration rates and soil and water losses were evaluated in a Distrophic Acrisol(clay loam texture)with simulated rainfalls of 30 mm and duration of 40 min,considering advanced(AD),intermediate(IN),delayed(DE),and inverted intermediate(II)patterns,all with PI peaks of 110 mm h^(-1),and a constant(CT)pattern.The experimental design was in randomized blocks with five treatments(rainfall patterns)and experimental units measuring 2.5×2.5 m.The simulator worked satisfactorily,applying the rainfall according to the preconfigured programs.The simulated rainfall with the CT and II patterns did not promote runoff nor soil loss.Infiltration and runoff rates varied according to the applied rainfall pattern,reaching 97.8 and 27.3 mm h^(-1)(AD),82.1 and 39.5 mm h^(-1)(IN),and 76.2 and 49.7 mm h^(-1)(DE),respectively.Soil loss and surface runoff totaled each 4.77 g m^(-2)and 3.9 mm(AD),6.70 g m^(-2)and 6.8 mm(IN),and 6.03 g m^(-2)and 7.0 mm(DE).The InfiAsper simulator modified enables varying precipitation intensity besides obtaining satisfactory results in the field and information consistent with the expected characteristics of natural rainfall patterns.In the intermediate and delayed rainfall patterns,soil and water losses are higher than in the advanced.
文摘The Hekou-Longmen reach, together with local floods, is the main source area for coarse sedimenta- tions into the Yellow River. When total rainfall slightly increased in the area, discharge dramatically decreased by 40%-70% after the year of 2000, and attracting extensive attention in the context of global climate change. High temporal resolution precipitation （timescales between 1 and 4 h） data from the June to September period from 270 rain gauges over the past three decades was mined in order to help explain the phenomenon. Each rainfall event was classified as light/moderate rain, large rain, heavy rain or rainstorm by the event＇s rainfall amount, and further classified as low intensity rain, medium intensity rain and high intensity rain by the event＇s rainfall intensity. The Mann-Kendall trend test was applied to detect the presence and significance of monotonic trends, and to find the change points in the mean and variance of the precipitation characteristics series, including the amount, intensity, frequency and duration of each rainfall category. Results show that although the total amount of precipitation has slightly increased, the average rainfall intensity has significantly decreased. The larger change happened in light/moderate rain events and low/medium intensity rain events, and the intensity changes have a great extent occurred around the threshold of Non-Runoff Rainfall regime, which was proposed for the approximate calcula- tion of initial losses. Changes in rainfall distribution between different classes of the Runoff Rainfall regime in the 2000s could lead to 0.9 mm less runoffdepth （17.3% of the total reduction） than the 1980-1999 period. The study indicates that changes in hourly precipitation may be responsible for the sharp reduction of discharge.
基金the model data,and the support from Li Chongyin Academician Workstation of Yunnan province.This work was supported by the National Natural Science Foundation of China(U1902209)the Chinese Academy of Sciences and the Key Science Foundation of Yunnan Province(2016FA041)+1 种基金the External Cooperation Program of Bureau of International Cooperation(GJHZ1729)the Science and Technology Project of SGCC(State Grid Corporation of China)[Research and application of multi-spatial scale variation of photovoltaic output characteristics considering complex factors such as cloud and floating dust](NY71-19-013).
文摘In the Lancang‒Mekong River basin(LMRB),agriculture,dominating the local economy,faces increasing challenges in water supply under climate change.The projection of future precipitation in this basin is essential for understanding the challenges.In this study,the Weather Research and Forecasting(WRF)model was applied to project the LMRB precipitation.Comparing with the historical period(1986e2005),we analyzed the changes of both the projected precipitation amount and the frequency of rainless(<0.1 mm d1),light rain(0.1e10 mm d1),moderate rain(10e25 mm d1),heavy rain(25e50 mm d1),rainstorm(50e100 mm d1),and heavy rainstorm(>100 mm d1)for three periods,namely the near-term(2016e2035),mid-term(2046e2065),and long-term(2080e2099).The results indicate that the precipitation amount during the wet season(AprileOctober)is expected to increase in most areas of the basin for the three periods.As for the precipitation during the dry season(NovembereMarch),an increase is projected in most areas for the near-term,while an increase in the lower reach of the basin and a decrease in the upper and middle reach for the mid-term and long-term.The precipitation reduction is expected to be greatest in Myanmar,Laos,Thailand,and Yunnan province of China for the mid-term.The frequency of precipitation in different intensities has prominent regional and temporal differences.During the wet season,the days of rainless and light rain are expected to decrease in the middle reach,whereas the days of rainstorm and heavy rainstorm increase.This feature is especially strong in southern Thailand,southern Laos and Cambodia in the near-term and in Laos and Thailand for the mid-term and long-term.During the dry season,there are projected increasing rainless days and decreasing days of precipitation for the other intensities in the middle reach,and opposite in the rest area of the basin.These projected precipitation changes have potential various impact in different parts of the basin.The middle reach would likely face increasing flood risks because of more days of rainstorm and heavy rainstorm,as well as more precipitation.Yunnan,Myanmar,Thailand and Laos would probably be the center of drought threatens during the dry season due to the increment of rainless days and the precipitation reduction.Besides,the seawater intrusion during the dry season in the near-term and mid-term would be more serious as a result of the precipitation decrease in southern Vietnam.
基金supported in part by the National Basic Research Program(973 Program)under Grant 2011CB209402-3the Science and Technology Project of the State Grid Corporation of China under Grant GY71-15-033.
文摘Analyzing the impact of radio interference(RI)variation during foul weather conditions is an area that has received limited study.This paper provides a statistical analysis of RI measurements obtained from a long-term observation station close to the world’s first commercially operating 1000 kV UHV AC double-circuit transmission line in China.During six months of observations,the impact of RI was studied on the line during fog,drizzle,and light snow and rain.It was found that RI increases linearly with the natural logarithm of the precipitation intensity.The Levenberg-Marquardt algorithm(LMA)is employed to fit the RI value with the precipitation intensity.The reasonable distribution of RI in different foul weather is verified by one-sample K-S test.This test is seen as beneficial for further RI prediction based on statistical weather mode.
