[13 December 2008] First IGCP 565 Workshop took place: The First Workshop of the IGCP 565 Project "Developing the Global Geodetic Observing System into a Monitoring System for the Global Water Cycle" took place on December 12, 2008 in San Francisco, California, USA. This first workshop focused on a review of the state of the art in understanding the quantitative fluxes in the global water cycle and considered the relation between geodetic observations and mass changes in the main reservoirs of the water cycle in oder to clarify the open science questions that the geodetic observations can help to reconcile. The workshop was attended by fifteen participants from geodesy and hydrology. By bringing together leading experts from two separate scientific fields, the workshop provided an excellent frame for the interdisciplinary dialog between geodesy and hydrology. The state of the art in the two fields as related to the other field was reviewed in invited key notes and these presentations led to extensive discussions. Issues addressed in discussions included the modeling of the signals of water mass redistribution in the geodetic observations, the improvements in data processing and geophysical modeling inherent in geodetic analysis that are required in order to preserve the unbiased water mass signals in the geodetic observations and products, the integration of in situ and geodetic remote sensing products, and the relation between the geodetic signals and mass redistribution in the terrestrial hydrosphere. As a result of these discussion a list of questions was identified and considered in more detail. It was concluded that deep groundwater is one of the major uncertainties in the budget of the water cycle, and that this uncertainty is highly relevant and an obstacle for regional water management. In order to utilize the geodetic techniques for closing this gap, a hybrid approach of local implementation and global observations was proposed. Assimilation of the geodetic observations in hydrological models was identified as the ultimate goal. Immediate outcome of the meeting was a report presentation given on December 13, 2008 at the GRACE Science Team Meeting at the same venue. In this presentation, the project was introduced to a larger community as a framework for the dialog between geodesy and hydrology with the particular objective of making best use of the geodetic observations and products for regional water management. The main scientific findings of the IGCP 565 Workshop were also reported.

The full program of the workshop, which included seven invited key note lectures and four contributed project reports, and copies of the presentations are available at http://www.iag-ggos.org/igcp565/workshops/ (under the link 'Program').