Trends in Extreme Indices and Seasonal Analysis of Precipitation and Temperature in the Northwest Region of Rio Grande do Sul,Brazil

Probably the most important environmental challenge of this century is to adapt to climate change and develop strategies to minimize its effects. This study aims to conduct an investigation to detect changes in temperature and precipitation in the northwest region of Rio Grande do Sul with the use of different general and regional circulation models (GCMs and RCMs, respectively). Seven distinct locations in the region were considered, for which there were ten different climate projections. Additionally, we investigated the frequency and intensity of extreme rainfall events using different extreme precipitation indices. These projections indicate an increase of mean annual temperature of almost 3°C till the end of the century, as well as an increase in annual precipitation. The seasonal analysis has demonstrated that the largest increases of temperature are projected for winter and early spring and do not coincide with the summer months of the main crop cultivation (soybean) in the region. Additionally, it is expected high amounts of rain during these same months. In general, trends in extreme precipitation indices were detected for the RCM projections in most of locations. It can also be concluded that it is possible that the spatial distribution of the impacts of climate change on agriculture will not be uniform.

Analysis on characteristics of extreme precipitation indices and atmospheric circulation in Northern Shanxi

This article utilizes daily precipitation data from 28 national meteorological stations in northern Shanxi Province spanning from 1972 to 2020,and the US NCEP/NCAR monthly average reanalysis and ERA5 monthly average reanalysis data.The study employs techniques such as empirical orthogonal function(EOF)decomposition,MannKendall mutation and other methods to investigate the spatiotemporal distribution of extreme precipitation index in northern Shanxi and their correlation with atmospheric circulation.The research results show that:the absolute index,relative index,intensity index and sustained dry period index(CDD)in the continuous index appear from southwest to northeast.The spatial distribution characteristics of the central region decrease,while the continuous wet period(CWD)decreases from the central to the east and west.The three indices Rx1day,Rx5day,and CWD mutated in 1978,1975,and 1983 respectively,and other extreme precipitation indices all appeared in a sudden change from a low-value period to a high-value period occurred around 2010.In the high-value years of the summer extreme precipitation index,there is a significant negative anomaly in the height field in the mid-high latitude regions of Eurasia.Northern Shanxi is controlled by a broad low-pressure trough in the Lake Baikal area.Water vapor transported via the east,west,and south routes converges in the northern Shanxi region and encounters cold air from the north.There is a strong upward motion anomaly at 500 hPa in the troposphere,and the dynamic conditions of upper-level divergence and lower-level convergence lead to more summer extreme precipitation in the northern Shanxi region.Conversely,in the low-value years of the summer extreme precipitation index,northern Shanxi is affected by a strong high-pressure ridge north of Lake Baikal.There is a downward motion anomaly at 500 hPa,and the northern Shanxi region lacks water vapor.The cold and warm air cannot converge,and both the water vapor conditions and dynamic conditions are poor,which is not conducive to the production of extreme precipitation in northern Shanxi.

Spatio-temporal Variation Characteristics of Extreme Climate Events and Their Teleconnections to Large-scale Ocean-atmospheric Circulation Patterns in Huaihe River Basin,China During 1959–2019

Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate change.Based on the daily maximum temperature,minimum temperature,and precipitation data of 40 meteorological stations and nine monthly large-scale ocean-atmospheric circulation indices data during 1959–2019,we present an assessment of the spatial and temporal variations of extreme temperature and precipitation events in the HRB using nine extreme climate indices,and analyze the teleconnection relationship between extreme climate indices and large-scale ocean-atmospheric circulation indices.The results show that warm extreme indices show a significant(P < 0.05) increasing trend,while cold extreme indices(except for cold spell duration) and diurnal temperature range(DTR) show a significant decreasing trend.Furthermore,all extreme temperature indices show significant mutations during 1959-2019.Spatially,a stronger warming trend occurs in eastern HRB than western HRB,while maximum 5-d precipitation(Rx5day) and rainstorm days(R25) show an increasing trend in the southern,central,and northwestern regions of HRB.Arctic oscillation(AO),Atlantic multidecadal oscillation(AMO),and East Atlantic/Western Russia(EA/WR) have a stronger correlation with extreme climate indices compared to other circulation indices.AO and AMO(EA/WR) exhibit a significant(P < 0.05) negative(positive)correlation with frost days and diurnal temperature range.Extreme warm events are strongly correlated with the variability of AMO and EA/WR in most parts of HRB,while extreme cold events are closely related to the variability of AO and AMO in eastern HRB.In contrast,AMO,AO,and EA/WR show limited impacts on extreme precipitation events in most parts of HRB.

Extreme Rainfall Indices in the Hydrographic Basins of Brazil

The authors analyze climate extremes indices (CEI) of rainfall over the largest basins of the Brazilian territory: Amazon (AMA), S?o Francisco (SF), Tocantins (TO) and Paraná (PAR) rivers. The CEI represent the frequency of heavy precipitation events (R30mm and R95p) and short duration extreme rainfall (RX5day and RX1day). Droughts (CDDd) are identified based on two indicators: The longest dry period (CDD) and the annual cycle. The results demonstrate that CDDd, RX1day and RX5day occurred with more frequency and intensity in SF basin during El Ni?o events. CDDd was of greater magnitude in the TO basin during La Ni?a events, while an increase of RX1day occurred in El Ni?o. The strong El Ni?o events (1983 and 1997) caused more intense and frequent RX1day and R30mm over the PAR basin. Amazon droughts occurred in two out of the six El Ni?o events. Moreover, the relationship between the positive (negative) sea superficial temperatures anomalies in North (South) Tropical Atlantic and drought in AMA basin was corroborated. A gradual warming of SST was observed at the start of 2003 until it achieved a maximum in 2005 associated with the southwestern Amazon drought. The second highest anomaly of SST was in 2010 linked with drought that was more spatially extensive than the 2005 drought. The spatial distribution of annual trends showed a significant increase of CDD in south-eastern AMA, Upper SF, northern PAR and throughout the TO basins. R20mm, RX1day and RX5day tend to increase significantly in southwestern (northeast) PAR (AMA) and northwestern TO basins. Comparisons between CEI derived from daily precipitation data from Climate Prediction Center (CPCp) and of the ETA_HadCM3 model showed that the model overestimated RX1day, RX5day and CDD, in the four basins. Future scenarios show that dry periods will occur with greatest magnitude in all the basins until 2071-2099 time slice, while RX1day will be more intense in the TO and SF basins.

Projection of precipitation extremes over South Asia from CMIP6 GCMs

Extreme precipitation events are one of the most dangerous hydrometeorological disasters,often resulting in significant human and socio-economic losses worldwide.It is therefore important to use current global climate models to project future changes in precipitation extremes.The present study aims to assess the future changes in precipitation extremes over South Asia from the Coupled Model Intercomparison Project Phase 6(CMIP6)Global Climate Models(GCMs).The results were derived using the modified Mann-Kendall test,Sen's slope estimator,student's t-test,and probability density function approach.Eight extreme precipitation indices were assessed,including wet days(RR1mm),heavy precipitation days(RR10mm),very heavy precipitation days(RR20mm),severe precipitation days(RR50mm),consecutive wet days(CWD),consecutive dry days(CDD),maximum 5-day precipitation amount(RX5day),and simple daily intensity index(SDII).The future changes were estimated in two time periods for the 21^(st) century(i.e.,near future(NF;2021-2060)and far future(FF;2061-2100))under two Shared Socioeconomic Pathway(SSP)scenarios(SSP2-4.5 and SSP5-8.5).The results suggest increases in the frequency and intensity of extreme precipitation indices under the SSP5-8.5 scenario towards the end of the 21^(st) century(2061-2100).Moreover,from the results of multimodel ensemble means(MMEMs),extreme precipitation indices of RR1mm,RR10mm,RR20mm,CWD,and SDII demonstrate remarkable increases in the FF period under the SSP5-8.5 scenario.The spatial distribution of extreme precipitation indices shows intensification over the eastern part of South Asia compared to the western part.The probability density function of extreme precipitation indices suggests a frequent(intense)occurrence of precipitation extremes in the FF period under the SSP5-8.5 scenario,with values up to 35.00 d for RR1mm and 25.00-35.00 d for CWD.The potential impacts of heavy precipitation can pose serious challenges to the study area regarding flooding,soil erosion,water resource management,food security,and agriculture development.

Study on the Changes of Extreme Temperature in the Southwest of Zhejiang Province during the Period of 1953-2022

Under the background of global warming, extreme temperature occurs frequently around the globe, which has a significant and direct impact on social and economic system. Liuchun Lake is an important ecotourism scenic region in Longyou in the southwest of Zhejiang province, it is very important for the local economic development. Based on the daily mean temperature, maximum and minimum temperature from 15 stations, the 13 extreme temperature indices as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI) were calculated, and the characteristics of extreme temperature in the southwest of Zhejiang province were analyzed. The results showed that: 1) The Warmest day (TXx) and Warmest night (TNx) increased at most of the stations, while the coldest day (TXn) and the coldest night (TNn) basically significantly increased at all the stations;2) The number of frost days (FD0) showed decreased trend, and all the stations passed the 99% significant level, the number of ice days (ID0) also was on downward trend, but it is not significant at all most of the stations, however, both the number of summer days (SU25) and tropical nights (TR20) were on upward trend, and all the stations passed the significant level (p < 0.1);3) Both the number of cold days (TX10P) and cold nights (TN10P) showed a declined trend, while the number of warm days (TX90P) and warm night (TN90P) had an upward trend, especially TN90P had significant increase at all the stations. This implies that the cold events declined and warm events increased in the southwest regions of Zhejiang from 1953 to 2022.

The Spatial-Temporal Change of Extreme Precipitation in the Southwest Region of Zhejiang Province during 1953-2022

Based on the daily precipitation from 17 meteorological stations in the southwest of Zhejiang from 1953 to 2022, 11 extreme precipitation indices were calculated, and the temporal-spatial characteristic of extreme precipitation were analyzed. The results indicate that 1) Except for the number of consecutive dry days (CDD), all the other extreme precipitation indices had low values in the northeast of the study area and high value around Liuchun Lake;2) CDD had a decreasing trend in most part of study area, while the other indices were on the rise, especially at Suichang (SC) and Tonglu (TL) stations, the change was significant (p 0.05);3) The annual variation showed that CDD declined with the trend of 0.83 d/10a, however, all the other indices increased, especially after 2000, the increase was more obvious. In general, the extreme precipitation mount, the extreme precipitation days showed an increasing trend, drought was less likely to happen, and the possibility of heavy precipitation is less, however, at some individual station such as SC, heavy precipitation and storm is much more likely to occur.

Comparison of Daily Extreme Temperatures over Eastern China and South Korea between 1996–2005

This paper examined the decadal mean, seasonal cycle, and interannual variations of mean and extreme temperatures using daily temperature and relative humidity data from 589 stations over eastern China and South Korea between 1996-2005. The results show that the decadal mean Tm （mean daily mean temperature） and the TNn （minimum daily minimum temperature） increase from north to south; the opposite spatial gradient is found in the DTR （diurnal temperature range）; the value of the DTR over South Korea is in- between that over North China and the mid-low Yangtze River valley; the TXx （maximum daily maximum temperature） has a unique spatial distribution, with the largest value over eastern China. The highest standard deviation （STD） is located over northern China and the TNn has the largest area coverage of the high STD. The peak of the seasonal cycle for the Tm, TXx and TNn over South Korea （August） occurs one month later than that over eastern China （July）. The seasonal cycle of the DTR has two peaks （April and October）; the value in the middle-lower reaches of the Yangtze River valley is larger than that in South Korea during July and August owing to the seasonal northward jump of the major monsoon rain band. The interannual variations of summertime temperature indices including the Tin, TXx, and DTR over South Korea are consistent （opposite） to that over northern （southern） China. For the wintertime temperature indices however, the variation over South Korea is consistent with that over eastern China.

Statistical Downscaling of Summer Temperature Extremes in Northern China

Two approaches of statistical downscaling were applied to indices of temperature extremes based on percentiles of daily maximum and minimum temperature observations at Beijing station in summer during 1960-2008. One was to downscale daily maximum and minimum temperatures by using EOF analysis and stepwise linear regression at first, then to calculate the indices of extremes; the other was to directly downseale the percentile-based indices by using seasonal large-scale temperature and geo-potential height records. The cross-validation results showed that the latter approach has a better performance than the former. Then, the latter approach was applied to 48 meteorological stations in northern China. The cross- validation results for all 48 stations showed close correlation between the percentile-based indices and the seasonal large-scale variables. Finally, future scenarios of indices of temperature extremes in northern China were projected by applying the statistical downsealing to Hadley Centre Coupled Model Version 3 （HadCM3） simulations under the Representative Concentration Pathways 4.5 （RCP 4.5） scenario of the Fifth Coupled Model Inter-comparison Project （CMIP5）. The results showed that the 90th percentile of daily maximum temperatures will increase by about 1.5℃, and the 10th of daily minimum temperatures will increase by about 2℃ during the period 2011- 35 relative to 1980-99.

Quantile Trends in Temperature Extremes in China

A number of recent studies have examined trends in extreme temperature indices using a linear regression model based on ordinary least-squares. In this study, quantile regression was, for the first time, applied to examine the trends not only in the mean but also in all parts of the distribution of several extreme temperature indices in China for the period 1960–2008. For China as a whole, the slopes in almost all the quantiles of the distribution showed a notable increase in the numbers of warm days and warm nights, and a significant decrease in the number of cool nights. These changes became much faster as the quantile increased. However, although the number of cool days exhibited a significant decrease in the mean trend estimated by classical linear regression, there was no obvious trend in the upper and lower quantiles. This finding suggests that examining the trends in different parts of the distribution of the time-series is of great importance. The spatial distribution of the trend in the 90 th quantile indicated that there was a pronounced increase in the numbers of warm days and warm nights, and a decrease in the number of cool nights for most of China, but especially in the northern and western parts of China, while there was no significant change for the number of cool days at almost all the stations.

Determination of Physiological and Biochemical Indices of Hailan Chickens at 20 Weeks of Age

[Objective]This study aimed to determine physiological and biochemical indices of Hailan chickens at 20 weeks of age.[Method]T,P,BT,CT,ESR,systolic pressure,diastolic pressure,RBC,HCT,MCV,RDW,HGB,MCH,MCHC,PLT,MPV,WBC,N,E,B,L,M,TP,Alb,AST,ALT,Glu and TG and CHO of 20 weeks-old male and female Hailan chickens were determined with various methods.[Result]According to the determined blood physiological and biochemical indices,RBC,HGB,Glu and ALB in male chickens were higher compared with female chickens,exhibiting extremely significant differences（P〈0.01）;B,M and TP in male chickens were significantly higher compared with female chickens（P〈0.05）;other physiological and biochemical indices exhibited no significant differences between males and females（P〉0.05）.[Conclusion]Physiological and biochemical indices of 20 weeks-old Hailan chickens varied between males and females,which were generally higher in male chickens than in female chickens.

Trends in Seasonal Precipitation over China during 1961-2007

Trends in six indices of precipitation in China for seasons during 1961-2007 were analyzed based on daily observations at 587 stations. The trends were estimated by using Sen's method with Mann-Kendall's test for quantifying the significance. The geographical patterns of trends in the seasonal indices of extremes were similar to those of total precipitation. For winter, both total and extreme precipitation increased over nearly all of China, except for a small part of northern China. Increasing trends in extreme precipitation also occurred at many stations in southwestern China for spring and the midlower reaches of the Yangtze River and southern China for summer. For autumn, precipitation decreased in eastern China, with an increasing length of maximum dry spell, implying a drying tendency for the post-rainy season. Wetting trends have prevailed in most of western China for all seasons. The well-known 'flood in the south and drought in the north' trend exists in eastern China for summer, while a nearly opposite trend pattern exist for spring.

Trends in extreme climatic indices across the temperate steppes of China from 1961 to 2013

Aims Extreme climate events have become more severe and frequent with global change in recent years.The Chinese temperate steppes are an important component of the Eurasian steppes and highly sensitive and vulnerable to climatic change.As a result,the occur-rence of extreme climate events must have strong impacts on the temperate steppes.Therefore,understanding the spatio-temporal trends in extreme climate is important for us to assess the sensitivity and vulnerability of Chinese temperate steppes to climatic changes.This research had two specific objects to(i)specify the temporal changes in extreme climate events across the whole steppe and(ii)compare the trend differences for extreme climate events in differ-ent types of steppes-meadow steppe,typical steppe and desert steppe.Methods To investigate extreme climate trends in the temperate steppes of China,82 meteorological stations with daily temperature and precipi-tation data(1961-2013)were used.Meanwhile,eight core extreme climate indices(extreme high-temperature threshold,extreme low-temperature threshold,frost days,heatwave duration,heavy rain-fall threshold,percentage of heavy rainfall,heavy rainfall days and consecutive dry days)from the Statistical and Regional Dynamical Downscaling of Extremes for European Regions(STARDEX)project were selected to analyse the trends in extreme climate across the whole temperate steppe and the three main types(meadow steppe,typical steppe and desert steppe)through time and space.Important Findings The results showed that(i)the changes in extreme climatic tem-perature events across the whole temperate steppe were obvi-ous during 1961-2013.The frost days(−3.40 days/10 year[yr])decreased significantly,while the extreme high-temperature thresh-old(0.24℃/10 yr),extreme low-temperature threshold(0.52℃/10 yr),and heatwave duration(0.58 days/10 yr)increased notably.The annual changes in extreme precipitation were small and not sig-nificant.(ii)Differences appeared in the extreme climatic trends in different types of steppes.The desert steppe showed strong climate extremes and underwent the most significant asymmetric warming compared with the meadow steppe and typical steppe.At the same time,the heatwave duration(0.62 days/10 yr)increased.In terms of the extreme precipitation,there was no significant trend among the three types of steppes.However,the fluctuations in extreme precipi-tation were the largest in the desert steppe compared to those in the typical steppe and meadow steppe.

Noninvasive treatment efficacy monitoring and dose control for high-intensity focused ultrasound therapy using relative electrical impedance variation

As an effective therapeutic modality, high-intensity focused ultrasound（HIFU） can destroy tumour tissues by thermocoagulation with less metastasis, but it is still limited by inaccurate non-invasive temperature monitoring and efficacy evaluation. A model of electrical impedance measurement during HIFU therapy was established using the temperatureimpedance relationship. Based on the simulations of acoustic pressure, temperature, and electrical conductivity, the impedance of the phantom was calculated and experimentally demonstrated for different values of acoustic power values and treatment time. We proved that the relative impedance variation（RIV） increases linearly with the increasing treatment time at a fixed acoustic power, and the relative impedance variation rate shows a linear relationship with the acoustic power.The RIV and treatment time required for HIFU treatment efficacy are inversely proportional to the acoustic power and the square of acoustic power, respectively. The favourable results suggest that RIV can be used as an efficient indicator for noninvasive temperature monitoring and efficacy evaluation and may provide new strategy for accurate dose control of HIFU therapy.

Assessment of Climate Change over South America under RCP 4.5 and 8.5 Downscaling Scenarios

Four sets of downscaling simulations based on the Eta Regional Climate Model forced by two global climate models, the HadGEM2-ES and the MIROC5, and two RCP scenarios—8.5 and 4.5, have been carried out. The objective of this work is to assess the climate change over South America based on the Eta simulations. The future changes are shown in timeslices of 30 years: 2011-2040;2041-2070 and 2071-2100. The climate change response of the Eta simulations nested in HadGEM2-ES is larger than the Eta nested in MIROC5. Major warming area is located in the central part of Brazil. In austral summer, the reduction of precipitation in the central part and the increase in the southeastern part of the continent are common changes in these simulations, while the EtaHadGEM2-ES intensifies the decrease of precipitation in central Brazil, the Eta-MIROC5 expands the area of increase of precipitation in southern Brazil toward the end of the century. In austral winter, precipitation decrease is found in the northern part of South America and in most of Central America, whereas the reduction in southeastern South America is limited to near coastal region. The time series of temperatures show that warming trends are larger in the Eta-HadGEM2-ES than in the Eta-MIROC5 simulations. Heavier precipitation rates are projected in the Central-South of Brazil toward the end of the century. Increase in the length of consecutive dry days (CDD) in Northeast of Brazil and the decrease of consecutive wet days (CWD) in the Amazon region are common features in these simulations.

An assessment method of annual climatic status in China using extreme climate indices:2021 as an example

A proper assessment of annual climatic status(ACS)is conducive to rationally formulating disaster prevention and mitigation measures.The former definition of ACS lacks either information on extreme climate or an intuitive grade feature service to the public.The ACS defined in the National Standard of the People's Republic of China(GBACS)only considers the accumulated climate effects of each weighted 10-d temperature/precipitation anomaly in a year.Under global warming,the losses caused by extreme climate events often have a significant impact on the grades of ACS,but this impact cannot be reasonably reflected by GBACS.This study proposed the assessment of ACS using extreme climate indices(extreme climate-based ACS(ECACS))and compared it with GBACS.The results indicated that GBACS and ECACS can be used to evaluate the ACS from different angles.The ECACS is an important supplement to the GBACS,especially considering the years with frequently occurring extreme climate events.The sum of GBACS and ECACS is a reasonable and comprehensive way to evaluate the ACS.The empirical orthogonal function(EOF)analysis indicated a uniform mode(EOF1)and a dipole mode(EOF2)in GBACS and ECACS in China.The interannual variation characteristics of ECACS in northern and southern China(EOF2 pattern)are consistent with real climate features,which is conducive to providing better and more detailed regional information in the ACS forecast service.The results have essential instructive and application value for ACS assessment and government decision making.

Evaluation of the Eta Simulations Nested in Three Global Climate Models

To provide long-term simulations of climate change at higher resolution, Regional Climate Models (RCMs) are nested in global climate models (GCMs). The objective of this work is to evaluate the Eta RCM simulations driven by three global models, the HadGEM2-ES, BESM, and MIROC5, for the present period, 1961-1990. The RCM domain covers South America, Central America, and Caribbean. These simulations will be used for assessment of climate change projections in the region. Maximum temperatures are generally underestimated in the domain, in particular by MIROC5 driven simulations, in summer and winter seasons. Larger spread among the simulations was found in the minimum temperatures, which showed mixed signs of errors. The spatial correlations of temperature simulations against the CRU observations show better agreement for the MIROC5 driven simulations. The nested simulations underestimate precipitation in large areas over the continent in austral summer, whereas in winter overestimate occurs in southern Amazonia, and underestimate in southern Brazil and eastern coast of Northeast Brazil. The annual cycle of the near-surface temperature is underestimated in all model simulations, in all regions in Brazil, and in most of the year. The temperature and precipitation frequency distributions reveal that the RCM and GCM simulations contain more extreme values than the CRU observations. Evaluations of the climatic extreme indicators show that in general hot days, warm nights, and heat waves are increasing in the period, in agreement with observations. The Eta simulations driven by HadGEM2-ES show wet trends in the period, whereas the Eta driven by BESM and by MIROC5 show trends for drier conditions.

Characterizing the Spatio-temporal Dynamics and Variability in Climate Extremes over the Tibetan Plateau during 1960–2012

Extreme climate events play an important role in studies of long-term climate change. As the Earth’s Third Pole, the Tibetan Plateau(TP) is sensitive to climate change and variation. In this study on the TP, the spatiotemporal changes in climate extreme indices(CEIs) are analyzed based on daily maximum and minimum surface air temperatures and precipitation at 98 meteorological stations, most with elevations of at least 4000 m above sea level, during 1960–2012. Fifteen temperature extreme indices(TEIs) and eight precipitation extreme indices(PEIs) were calculated. Then, their long-term change patterns, from spatial and temporal perspectives, were determined at regional, eco-regional and station levels. The entire TP region exhibits a significant warming trend, as reflected by the TEIs. The regional cold days and nights show decreasing trends at rates of-8.9 d(10 yr)-1(days per decade) and-17.3 d(10 yr)-1, respectively. The corresponding warm days and nights have increased by 7.6 d(10 yr)-1 and 12.5 d(10 yr)-1, respectively. At the station level, the majority of stations indicate statistically significant trends for all TEIs, but they show spatial heterogeneity. The eco-regional TEIs show patterns that are consistent with the entire TP. The growing season has become longer at a rate of 5.3 d(10 yr)^-1. The abrupt change points for CEIs were examined, and they were mainly distributed during the 1980 s and 1990 s. The PEIs on the TP exhibit clear fluctuations and increasing trends with small magnitudes. The annual total precipitation has increased by 2.8 mm(10 yr)^-1(not statistically significant). Most of the CEIs will maintain a persistent trend, as indicated by their Hurst exponents. The developing trends of the CEIs do not show a corresponding change with increasing altitude. In general, the warming trends demonstrate an asymmetric pattern reflected by the rapid increase in the warming trends of the cold TEIs, which are of greater magnitudes than those of the warm TEIs. This finding indicates a positive shift in the distribution of the daily minimum temperatures throughout the TP. Most of the PEIs show weak increasing trends, which are not statistically significant. This work aims to delineate a comprehensive picture of the extreme climate conditions over the TP that can enhance our understanding of its changing climate.

Variability and change of climate extremes from indigenous herder knowledge and at meteorological stations across central Mongolia

In semi-arid regions,air temperatures have increased in the last decades more than in many other parts of the world.Mongolia has an arid/semi-arid climate and much of the population are herders whose livelihoods depend upon limited water resources that fluctuate with a variable climate.Herders were surveyed to identify their observations of changes in climate extremes for two soums of central Mongolia,Ikh-Tamir in the forest steppe north of the Khangai Mountains and Jinst in the desert steppe south of the mountains.The herders’indigenous knowledge of changes in climate extremes mostly aligned with the station-based analyses of change.Temperatures were warming with more warm days and nights at all stations.There were fewer cool days and nights observed at the mountain stations both in the summer and winter,yet more cool days and nights were observed in the winter at the desert steppe station.The number of summer days is increasing while the number of frost days is decreasing at all stations.The results of this study support further use of local knowledge and meteorological observations to provide more holistic analysis of climate change in different regions of the world.

Heterogeneous Trends of Precipitation Extremes in Recent Two Decades over East Africa

East Africa is so vulnerable to the impacts of precipitation extremes varying from frequent floods to prolonged droughts.However,systematic regional assessment of precipitation extremes across seasons has received little attention,and most previous studies of precipitation extremes have employed many indices and sparse gauge observations giving marginalized details.In this study,we use three precipitation extreme indices to examine the intensity of the highest single-day rainfall record(rx1day),prevalence of very heavy rainfalls(r30mm),and persistence of successive wet days(cwd)at both annual and seasonal scales over recent two decades(1998-2018)based on the Tropical Rainfall Measuring Mission(TRMM)Multisatellite Precipitation Analysis data.The results show that the most intensive and frequent precipitation extremes are noticeable from January to May across the areas extending from Madagascar to the Tanzanian coastal zone.These areas also exhibit patches of significant increasing trends in frequency,duration,and intensity of precipitation extremes annually and seasonally.However,significant declines in frequency and intensity of precipitation extremes are observed from western Ethiopia to Congo-Uganda,especially in June-September.The October-December season witnesses higher interannual variability amounting to overall weak and less significant trends.Further subregional assessment shows overall declining intensity and frequency of precipitation extremes in northern part of the study areas.Mean wetness duration increased,with persistence of moderate wet days and slight reduction of severe events.This study unveils higher susceptibility of the East African region to the widely observed hotspots of precipitation extremes posing threats to food security,water resource,and human well-being.The region should consider upscaling irrigation schemes in addition to planning resilient and supportive infrastructures to withstand the upsurging precipitation extremes,especially along the coastal zone.