Environmental controls on stable isotopes of precipitation in Lanzhou, China: An enhanced network at city scale.

Stable hydrogen and oxygen isotopes in precipitation are very sensitive to environmental changes, and can record evolution of water cycle. The Lanzhou city in northwestern China is jointly influenced by the monsoon and westerlies, which is considered as a vital platform to investigate the moisture regime for this region. Since 2011, an observation network of stable isotopes in precipitation was established across the city, and four stations were included in the network.

[Effect of Below-cloud Secondary Evaporation in Precipitations over the Loess Plateau Based on the Stable Isotopes of Hydrogen and Oxygen].

Based on stable isotopes in 409 precipitation samples provided by GNIP and meteorological records at the eight stations in Loess Plateau from January 1985 to December 2004, as well as the trajectory model of HYSPLIT 4.9, the spatial and temporal variations of d-excess and Δ18O were analyzed. The spatial distribution of secondary evaporation rate and the impact of meteorological factors on below-cloud secondary evaporation were also discussed.

[Characteristics of delta18O in precipitation and water vapor sources in Lanzhou City and its surrounding area].

Based on the 243 daily precipitation samples and meteorological statistics at the four stations at Lanzhou city and its surrounding area (Yongdeng, Gaolan and Yuzhong) from April 2011 to March 2012, the characteristics of stable isotopes in precipitation, as well as the correlation between stable isotopes and meteorological records, were analyzed. The precipitation equation of Lanzhou city and its surrounding area were calculated through the regression analysis, and the water vapor source of the four sites was tracked by the HYSPLIT 4. 9 model, and water vapor transmission regime was established.