Diurnal Variation Characteristics Of Precipitation In Summer Of Xinjiang During 2008-2013

Studies on diurnal variation characteristics of precipitation are conducive to investigate the mles of precipitation to provide relevant scientific proof for evaluating numerical modeling reliability in diverse regions, and can contribute to fuel the cognition to thermodynamic processes in climate change. The diurnal variation characteristics of precipitation in summer of Xinjiang during 2008-2013 is analyzed by hourly merged precipitation product, and some indexes are used, such as hourly precipitation amount, frequency and intensity. Among the major findings are as follows:(1) The reliability of hourly merged precipitation product in Xinjiang is evaluated by ground precipitation daily observation dataset and automatic meteorological stations data. The results indicated that there is a significant correlation between the gridded dataset and station observation data though the underestimate value and overestimate value are existed, in which the value of mean bias error (MBE) and root-mean-square error (RMSE) are much lower, the hourly average precipitation data of automatic meteorological stations conform with the corresponding interpolated gridded data, and the change process of typical precipitation events can be accurately depicted by gridded data, so the gridded dataset is highly credible in this study area.(2) There is similar feature between hourly precipitation amount and frequency. In specific terms, the values of hourly precipitation amount and frequency in northern Xinjiang are higher than those in southern regions of Xinjiang, and the values in mountains are higher than those in basins. The features of hourly precipitation intensity are different from each other, and the regions with higher values distribute in the arid basins, such as the midwest of Tarim Basin and the middle and central region of Junggar Basin. Moreover, the values of hourly precipitation amount, frequency and intensity in most areas of Xinjiang are the largest in June, and the least in August.(3) Percentage of gridded number of peak time to hourly precipitation amount, frequency and intensity at some time in total gridded number of sub regions exist prominent regional differences, in which the peak time of hourly precipitation amount in mountains and basins focuses on 18:00-23:00 and 0:00-5:00, respectively. The peak time of hourly precipitation amount and frequency have parallel spatial pattern, but the peak time features of hourly precipitation intensity are not obvious.(4) The precipitation amount of daytime and nighttime concentrates in mountains, and exists an increasing trend, particularly much larger to the increasing magnitude at daytime. In addition, the precipitation amount of daytime and nighttime in northern Xinjiang is larger than that in southern regions of Xinjiang. The daytime precipitation in mountains and neighboring areas is more abundant than precipitation at night, particularly the difference value exceeds 0.5mm in west mountains of Junggar and the northwest of Altay Basin. However, the precipitation al night is more plenty than that at daytime in Junggar Basin and other arid basins. Moreover, the precipitation amount of daytime and night in most areas of Xinjiang is the largest in June, and the least in August.(5) The average precipitation relative variation of different hours in Xinjiang ranges from 17.6% to 75.6%, and shows prominent regional differences. In addition, the value of most sub regions except west mountains of the Junggar and the middle of Tianshan mountains is the least around 8:00, so the precipitation stability is prominent. Moreover, the correlation between hourly precipitation amount and frequency is the highest, and the correlation coefficient between hourly precipitation amount and intensity is just behind the former, while poor for the correlation coefficient between hourly precipitation frequency and intensity, particularly in arid basins.