Relationship between sub-cloud secondary evaporation and stable isotope in precipitation in different regions of China

Falling to the ground from the bottom of clouds, rain experiences evaporation process, which has a very important role for accurate analysis of isotope water cycle information and the improvement of isotope hydrology system. As an integral part of the water cycle research, this evaporation process gradually arise people’s attention. Based on the precipitation isotope data obtained from GNIP site or some observation and literature, the existence and influence factors of secondary evaporation effects are studied in different regions of China. The study areas are divided into four regions (northwest arid region, southeast monsoon region, southwest monsoon region, and the Tibetan Plateau region), and the results show that the four regions exist the secondary evaporation effect. The seasonal change is obvious in the northwest arid areas and the north of the southeast monsoon region, and it is strong in summer and weak in winter. In the northwest arid areas and the monsoon region in dry season, it has a strong secondary evaporation effect when rainfall is less, and there is no significant correlation between monsoon rainfall and the secondary evaporation effect during the rainy season. The relationship between temperature and secondary evaporation is not obvious in the north of the southeast monsoon region during rainy season, while the sub-cloud secondary evaporation is more intense in high temperatures in other areas. In addition to the northwest arid region and north of the southeast monsoon region in the dry season, the relationship between the secondary evaporation effect and the relative humidity is significant. In high relative humidity, the secondary evaporation effect gradually weakens with the increase in the relative humidity.