The Role of Atmospheric Circulation Patterns in Controlling the Regional Distribution of Stable Isotope Contents in Precipitation: Preliminary results from two transects in the Ecuadorian Andes

摘要

Spatial and temporal variability of oxygen-18 and deuterium contents in precipitation in the equatorial zone of the Pacific coast of South America is reviewed based on a network of 13 meteorological stations collecting composite monthly rainfall samples. The meteorological stations are situated along two latitudinal transects (1deg S and 3deg S) from the Pacific coast of Ecuador to the Amazon Basin. The Andes, blocking the free transport of water vapour from the Amazon basin to the Pacific Ocean, and the seasonal displacement of the Intertropical Convergence Zone (ITCZ) are the two main factors controlling the precipitation regime and the isotope composition of precipitation in the region.