Appendix X: IUGG Presentation

A REVIEW OF GLOBAL HYDROLOGIC DATA SETS IN RELATION TO THE GCOS/GTOS PLAN FOR TERRESTRIAL CLIMATE-RELATED OBSERVATIONS^[8]

Jurate Landwehr (USGS, 431 National Center, Reston VA 20192, USA;

e-mail: [email protected])

Josef Cihlar (Canada Centre for Remote Sensing, 588 Booth Street, Ottawa, Ontario, Canada

K1A 0Y7; e-mail: [email protected])

TOPC (Terrestrial Observation Panel for Climate) is a joint activity of the Global Climate Observing System (GCOS) and the Global Terrestrial Observing System(GTOS), both of which are initiatives of WMO, UNEP, and ICSU. IOC of UNESCO also sponsors GCOS, and UNESCO and the FAO, GTOS. The purpose of GCOS is to provide a forum for the development of a comprehensive long-term global observing system to improve our capability to detect, predict and assess climate change. GTOS was established to provide policy-makers, resource managers, and researchers data needed to detect, quantify, and give early warning of changes in the capacity of terrestrial ecosystems to support sustainable development and improvements in human welfare. TOPC has produced an analysis of data and actions needed to address these goals jointly. The GCOS/GTOS PLAN FOR TERRESTRIAL CLIMATE-RELATED OBSERVATIONS has been published and is available via the internet at http://www.wmo.ch/web/gcos/pub/topv2_1.html The TOPC plan not only identifies key hydrospheric, cryospheric and biospheric parameters but also compares their relative importance for their respective climate purposes and suggests methods and actions for obtaining this information. For example, for the hydrologic sector, the plan provides a detailed rationale for the following variables: atmospheric water content near the surface (relative humidity), biogeochemical transport from land to oceans, discharge (runoff), evapotranspiration, groundwater storage fluxes, precipitation, sediment load at large river mouths, snow cover area and snow water equivalent, soil moisture and surface water storage. TOPC is actively seeking to identify which data is available digitally to satisfy the above requirements. In this presentation, we will review which hydrologic data sources have been identified globally, and discuss the general availability and compatibility of this information, as well as gaps in the geographic or thematic coverage for the above variables.