Abstract: The diurnal variation characteristics of precipitation (such as hourly precipitation amount, frequency and intensity) of Xinjiang in summer during 2008-2013 were analyzed with 0.1° gridded hourly precipitation dataset merged from automatic weather stations in China and the Climate Precipitation Center Morphing (CMORPH) precipitation product. The results showed that the diurnal variation features of hourly precipitation amount and frequency were similar; both indexes were much larger in northern Xinjiang than in southern Xinjiang and much larger in mountains than in basins, but the higher values of hourly precipitation intensity occurred more in arid basins. The values of hourly precipitation amount, frequency and intensity in most areas of Xinjiang were the largest in June and the least in August. In addition, the peak time of hourly precipitation amount and frequency had a parallel spatial pattern, and the latter was more prominent, in which the peak time of both indexes happened from 18:00 to 23:00 in mountains and from 0:00 to 5:00 in basins. Additionally, the precipitation amount in daytime and nighttime showed a similar spatial pattern. Moreover, the correlation between hourly precipitation amount and frequency was the highest, secondly by the correlation between hourly precipitation amount and intensity, while the correlation between hourly precipitation frequency and intensity was poor, especially in arid basins.

Key words: wetland plant combination, total nitrogen, total phosphorus, chemical oxygen demand, pH, removal efficiency