Submitted to: Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2013
Publication Date: 10/16/2013
Citation: Liu, Z., Yoshimura, K., Kennedy, C.D., Wang, X., Pang, S. 2013. Water vapor d2H dynamics over China derived from SCIAMACHY satellite measurements. Science China Earth Sciences. 57(4):813-823. Interpretive Summary: Novel satellite-based isotope measurements were used to evaluate atmospheric patterns controls over China. These data represent a unique tool for regional assessment of climatological process, particularly in remote areas such as East Asia. In China, isotopically-distinct geographic patterns were linked to both monsoonal moisture source and post-precipitation evaporation.
Technical Abstract: This study investigates water vapor isotopic patterns and controls over China using high-quality water vapor delta2H data retrieved from Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) observations. The results show that water vapor delta2H values on both annual and seasonal time-scales broadly exhibit a continental effect, with values largely decreasing northwest from coastal lowlands to high-elevation mountainous regions. However, region-specific analysis revealed spatially distinct patterns of water vapor delta2H exist between seasons. In the monsoon domain (e.g., China south of 35 degrees N), depletion in delta2H in the summer and fall seasons is closely tied to monsoon moisture sources (the Indian and Pacific oceans) and subsequent amount effect, but higher delta2H values in winter and spring are a result of isotopically-enriched continental-sourced moisture proceeded by less rainout. In contrast, farther inland in eastern Asia (non-monsoon domain), moisture is derived overwhelmingly from the dry continental air masses and local evaporation, and delta2H values are largely controlled by the temperature effect, exhibiting a summer-enriched and winter/spring-depleted seasonality. The fact that, in the summer season, the spatial pattern of water vapor delta2H is the opposite to that of precipitation isotopes also suggests that partial evaporation of falling raindrops is a key driver of water vapor isotope in the non-monsoon domain. This study highlights the importance of non-Rayleigh factors in governing water vapor isotope, and provides constraints on water precipitation isotope interpretation and modern isotope hydrological processes over eastern Asia.