Observed precipitation trends in the Yangtze river catchment from 1951 to 2002

The monthly, seasonal, and annual precipitation trends in the Yangtze river catchment have been detected through analysis of 51 meteorological stations' data between 1950-2002 provided by National Meteorological Administration. Results reveal that: 1) Summer precipitation in the Yangtze river catchment shows significant increasing tendency. The Poyanghu lake basin, Dongtinghu lake basin and Taihu lake basin in the middle and lower reaches are the places showing significant positive trends. Summer precipitation in the middle and lower reaches experienced an abrupt change in the year 1992; 2) The monthly precipitation in months just adjoining to summer shows decreasing tendency in the Yangtze river catchment. The upper and middle reaches in Jialingjiang river basin and Hanshui river basin are the places showing significant negative trends; 3) Extreme precipitation events show an increasing tendency in most places, especially in the middle and lower reaches of the Yangtze river catchment.

IMPACT OF URBANIZATION IN DIFFERENT REGIONS OF EASTERN CHINA ON PRECIPITATION AND ITS UNCERTAINTY

Climate effect caused by urbanization has been an indispensable anthropogenic factor in the research on regional climate change.Based on daily precipitation data,possible effects of precipitation on the development of three city groups in eastern China are discussed.With three classification methods(TP,PD and MODIS land cover),urban and rural stations are identified.The main findings are as follows.Climate effects caused by urbanization are different from place to place.In 1960 to 2009,the urbanization brought more precipitation to the Yangtze River Delta and Pearl River Delta city groups but had no obvious effect on the precipitation of the Beijing-Tianjin-Tangshan city group.The difference of precipitation is slight between urban and suburban areas during slow period of the urbanization from 1960 to 1979.It is more evident in the rapid period(1980 to 2009) that urbanization has positive effects on precipitation in every city group.The difference of precipitation between urban and rural stations is sensitive to the ways of distinguishing rural from urban area,which may cause uncertainties in 1960 to 1979,while it is very different in 1980 to 2009 in which urbanization favors more precipitation in all city groups and their differences in precipitation are not sensitive to the division methods.

Trends in the indices of precipitation phases under current warming in Poland,1966e2020

In Poland the phase in which precipitation occurs impacts the availability of water in its reservoirs,the potential for hydrological droughts,snowfall flooding and winter recreation.The influence of warming on the occurrence of precipitation phases on the Polish scale has not been studied so far.Based on data from 42 synoptic stations for the period 1966-2020,this study discusses trends in the indices of liquid(Lq),mixed(Mx)and solid(Sd)precipitation describing their totals(T),frequencies(Nd)and contribution to overall precipitation totals(T%)and a number of days with overall precipitation(Nd%)from a seasonal perspective.Moreover,the influence of seasonal and daily air temperatures on longterm variability in the precipitation phase indices was assessed.The precipitation phase was discriminated based on the observations of weather phenomena noted as current and past weather considering days with precipitation
0.1 mm.Precipitation phases significantly reacted to current warming.The strongest and widespread were increasing trends in rains(+1.74 for LqNd,+5.35 mm for LqT,+3.51%for LqNd%,+4.08%for LqT%per decade)and decreasing trends in snowfalls(-1.92 for SdNd,-3.12 mm for SdT,-3.65%for SdNd%,-3.26%for SdT%per decade)in winter when the warming was weakest but average temperature was close to freezing point.In winter,air temperature explained 60%e80%of the variance in the frequency of snowfall and rainfall.Daily air temperature>-2℃ contributed to trends in winter rainfall while daily air temperature>1C most contributed to trends in winter snowfall.No trends in winter mixed precipitation were due to opposite changes in its frequency above and below 1℃.In spring,the increase in a liquid phase was due more to the melting of a solid and mixed phase,while in autumn,it was due more to the transformation of a mixed phase into a liquid phase.In spring,air temperature explained at most 30%-50%of the variance in the indices of snowfall frequency.Negative trends in mixed precipitation were significant in transitional seasons,being more prominent in spring than in autumn and were mostly driven by changes in daily air temperatures between 0 and 5℃.A diminished percentage of summer rains on days with air temperatures below 15℃ was compensated by their increase above that threshold thus producing no long-term trends.Warming significantly weakened the relationships between precipitation phases and average seasonal air temperatures except for summer rainfalls.

Climatological Characteristics of Summer Precipitation over East Asia Measured by TRMM PR:A Review

Precipitation is an important indicator of climate change and a critical process in the hydrological cycle, on both the global and regional scales. Methods of precipitation observation and associated analyses are of strategic importance in global climate change research. As the first space-based radar, the Tropical Rainfall Measuring Mission （TRMM） Precipitation Radar （PR） has been in operation for almost 17 years and has acquired a huge amount of cloud and pre- cipitation data that provide a distinctive view to help expose the nature of cloud and precipitation in the tropics and subtropics. In this paper we review recent advances in summer East Asian precipitation climatology studies based on long-term TRMM PR measurements in the following three aspects： （1） the three-dimensional structure of precipita- tion, （2） the diurnal variation of precipitation, and （3） the recent precipitation trend. Additionally, some importantprospects regarding satellite remote sensing of precipitation and its application in the near future are discussed.

Precipitation variability in Portugal from 1960 to 2011

This study analyses spatial variab （amount and concentration） based on data lity and trends in annual and monthly precipitation from 42 stations in mainland Portugal during the period 1960-2011. Relationships between certain geographic variables （elevation, latitude and longitude） and precipitation variability were also determined in order to check for specific dependencies and spatial patterns in precipitation distribution, concentration and changing trends. Trends and relationships have been analysed using both parametric and non-parametric tests. The results showed that annual precipitation had decreased in all stations and that this trend is statistically significant for most of the time series （70% of the stations showed nega- tive trends with at least a 0.1 significance level）. The Annual Precipitation Concentration In- dex revealed an opposite behaviour pattern, suggesting that even though the annual trend for precipitation amount was negative overall, more than half of the udometric stations registered a more marked seasonality for precipitation during the period 1960-2011. However, only one station showed statistical significant time trend. Regarding the influence of geographical features, latitude is the most important variable, governing spatial distribution and variations in annual precipitation as well as its intra-annual changeability. These important changes in precipitation, involving both amount and concentration, may have severe consequences for ecosystems and societies.