1. Perspective on the PUBS Initiative Dennis P. Lettenmaier Department of Civil and Environmental Engineering University of Washington IAHS Preparatory Workshop on Prediction of Ungaged Basins (PUBS) Yamanashi University Kofu, Japan March 28-29, 2002

2. Need and background for PUBS – what has changed in the last decade (or two)? Changing political-scientific landscape (what is the role of IAHS in the post-Cold War era?) Changing scientific needs and interest in hydrologic prediction (e.g., climate/carbon concerns, land cover change) Changing observational considerations (decline of in situ networks, earth observing satellites)

3. Changing political-scientific landscape Need for IAHS/IUGG as a facilitator for east-west scientific exchange is gone Evolution of AGU and EGS (and the role of electronic publication, which effectively makes these organizations global in reach) Emergence of Japan as a scientific leader Growing role of WCRP (and to a lesser extent IGBP) in coordinating hydrologic research

4. Changing scientific demands on hydrologic prediction Global change issues (stationarity assumptions are “out”) The role of the hydrologic system in coupled land- atmosphere prediction (at weather to “short” climate time scales) Importance of vegetation (and more generally spatially distributed data sets, and need for spatially distributed hydrologic prediction)

5. Changing observational constraints and opportunities Decline of in situ networks (surface met as well as hydrological) Role of precipitation radar (and implications for hydrologic models) Remote sensing –Spatially distributed data (vegetation, topography) –Hydrologic forcing data (TRMM/GPM, GOES and other sources for solar radiation) –State variables (snow cover extent, e.g., MODIS, SWE, e.g., AMS, surface T, e.g. TOVS, AVHRR, etc., soil moisture, e.g. SMOS, HYDROS)

6. CEOP (GEWEX Coordinated Enhanced Observing Period) Some excerpts from CEOP Science and Implementation Plans, and March 6-8 (2002) Kickoff Meeting in Tokyo:

7. Global and enhanced observations for the study of monsoon and the water cycle Coordinated Enhanced Observing Period: CEOP CEOS (Committee on Earth Observation Satellites) and WCRP have approved implementation of a joint-observation project for the study of monsoon and the water cycle on a global scale. This project aims to realize enhanced observations of the water cycle on a global scale for a period from 1 October 2001 to 30 September 2004  New generation satellites will support global and enhanced observations. In addition to TRMM, Landsat-7, NOAA-K series and Geostationary satellites, a new generation of earth observation satellites will realize global and enhanced observations for CEOP project: TERRA(USA), AQUA(USA), ENVISAT(Europe) and ADEOS-II(Japan). These satellites will provide Earth observation data of unprecedented volume and quality, providing opportunities for the study of the global water cycle.  Many governments offer observation sites for CEOP project  A prototype information system has already developed by CEOS.

8. Success of global observations by CEOP project is an essential step for the predictability of the global water cycle and water resources. For CEOP project to be implemented effectively, there is a strong need to encourage further cooperation worldwide: ●Further regional cooperation to conduct necessary in-situ observations; ●Further efforts to integrate satellite data among participating Space agencies; ●Cooperation of the meteorological communities in providing outputs of numerical prediction models for the use of the CEOP project. Support of international community is essential to achieve global and enhanced observations for CEOP.

9. Global validation sites – a role for IAHS/PUBS? What is the need (scientific and observational context) Potential for coordination with GEWEX/CEOP (but time is short!) Role for hydrologic validation sites in the context of planned satellite missions (especially GPM).

10. 1) Eastern Siberian Tundra 2) Eastern Siberian Taiga 3) Mongolian 4) Inner Mongolia 5) Korean Peninsula 6) Korean Jeju 7) Tibet 8) Yangtze River 9) Himalayas 10) Northern South China Sea – Southern Japan 11) Chao-Phraya River 12) North-East Thailand 13) Western Pacific Ocean 14) Equatorial Island 15) Sodankyla 16) Lindenberg 17) Cabauw 18) Niamey 19) Oueme 20) BERMS 21) Fort Peck 22) Bondville 23) SGP 24) Oak Ridge 25) Flona 26) Santarem 27) Manaus 28) Rondonia 29) Brasilia 30) Pantanal CEOP Web Site: monsoon.t.u-tokyo.ac.jp/ceop CEOS Web Site: www.ceos.org

11. ACCOMPLISHMENTS Reviewed status and identified point of contact for each of 30 CEOP Reference Sites Established final CEOP Reference Site Data Policy Set 1-hourly temporal scale as minimum resolution for sampling of CEOP Reference Site Data Concurred on the Requirement for an initial CEOP Seasonal Dataset (1 July to 1 October 2001) to be delivered/released by 30 January 2003. Finalized Brochure “An element of WCRP Initiated by GEWEX with CLIVAR, CliC contributions …” Next meeting tentatively set for Berlin, Germany 31 March-4 April 2003, maximize ESA involvement to compliment NASA/NASDA.

12. ACTIONS/RECOMMENDATIONS Data Management WG Agreed to following actions: -CSE representatives and individual reference site managers will provide reference sites documentation and sample data to CDA at UCAR by 15 April 2002. -CDA at UCAR (Williams) will compile reference site information and sample data, and update CDA website table by 15 May 2002. -In accordance with agreement on resolution (hourly) and decision to formulate minimum requirements from completed CEOP Reference Table as of 15 May 2002 (see above action) the CDA at UCAR will build composite reference site data set by June 2002.

13. Global Precipitation Mission (GPM) TRMM-like precipitation radar, + ~8 “drone” (passive microwave) satellites, to yield 3 hour overpass ~ +/- 60 degrees latitude Spatial resolution ~4-10 km (depending on error) Unlike TRMM, hydrologic science is major focus International in scope (Japan-U.S. TRMM partnership, plus additional partners) Time frame ~2007 Potential hydrologic benefits enormous for under- instrumented portions of the globe, but stronger involvement from the hydrologic community is needed

14. Proposed soil moisture missions SMOS (ESA, ~50 km resolution, n-day overpass) HYDROS (U.S.), ~20 (??) km resolution Both are passive microwave, L-band – hence ~5 (+/-) cm penetration depth Challenges and opportunities for modeling, companion data assimilation strategies will be essential

15. NASA Working Group on Hydrologic Processes of Rivers and Wetlands Principal Investigators: D. Alsdorf, G.D. Emmitt, D. Lettenmaier, L. Smith, C. V ö r ö smarty Amazon Floodplain (L. Hess photo)

16. Solutions from Radar Altimetry Birkett, C.M., Contribution of the TOPEX NASA radar altimeter to the global monitoring of large rivers and wetlands, Water Resources Res.,1223-1239, 1998. Birkett, C.M., L.A.K. Mertes, T. Dunne, M.H. Costa, and M.J. Jasinski, Surface water dynamics in the Amazon Basin: Application of satellite radar altimetry, accepted to Journal of Geophysical Research, 2002. Water surface heights, relative to a common datum, derived from Topex/POSEIDON radar altimetry. Accuracy of each height is about the size of the symbol. Topex/POSEIDON tracks crossing the Amazon Basin. Circles indicate locations of water level changes measured by T/P radar altimetry over rivers and wetlands. Presently, altimeters are configured for oceanographic applications, thus lacking the spatial resolution that may be possible for rivers and wetlands.

17. So what can IAHS/PUBS (and specifically this workshop) accomplish Recognize that IAHS potential role is to coordinate and facilitate, not build (or fund) Develop a coordination role as the voice of international hydrology in related interdisciplinary programs and missions (e.g. CEOP, GPM, soil moisture) Evaluate potential for “qualifying” a set of global hydrology reference sites Identify science needs and opportunities that can help focus attention of the funding agencies