Seminar: Viviana Horna

ATTO, the Amazon Tall Tower Observatory, is a German-Brazilian research collaboration dedicated to investigating the importance of intact Amazon forests in the changing Earth system. At ATTO, most components of the water cycle are measured: precipitation, eddy covariance ET, soil moisture. In the new ATTO phase, sap flow (to estimate transpiration T), water storage in tree trunks, dew formation and loss through seepage into deep soil, and estimation of soil water evaporation are added. A unique instrument at ATTO is the measurement of continuous water vapor isotopes. With the isotope and flux measurements, we have several ways to separate E and T from ET and estimate the total water return of these forests to the atmosphere and its variations between dry and rainy seasons. Estimates of stand transpiration based on xylem flow data will be used to compare them with transpiration estimates from isotope measurements on a daily, seasonal, and interannual time scale. Calculating water storage in the trunks will help refine transpiration estimates and identify possible effects of drought and seasonal differences. Regional influences will be evaluated as a separate model component.