HYDROLOGIC APPLICATIONS AT THE UNIVERSITY OF WASHINGTON

1. HYDROLOGIC APPLICATIONS AT THE UNIVERSITY OF WASHINGTON Dennis P. Lettenmaier Department of Civil and Environmental Engineering CDEP/ARCS Council State College, PA October 25, 2005

2. UW ARCS Activity • Part of Center for Study of the Earth System • Joint CDEP/ARCS and RISA support (merger of former Hayes Center with Climate Impacts Group • ARCS activity now oriented toward support of science interface of CIG • CIG has both climate change and climate information transfer (S/I) aspects • One activity (formerly under ARCS flex funding) was development of (experimental) Westwide Seasonal Hydrologic Forecast System

3. Brief review of • Westwide forecast system • National Surface Water Monitor

4. Background: UW west-wide system • where did it come from? 1997 COE Ohio R. basin/NCEP -> -> UW East Coast 2000 (NCEP/ENSO) -> -> UW PNW 2001 -> UW west-wide 2003 • what are its objectives? • evaluate climate forecasts in hydrologic applications • seasonal: CPC, climate model, index-based (e.g., SOI, PDO) • 16-day: NCEP EMC Global Forecast System (GFS) • evaluate assimilation strategies • MODIS snow covered area; AMSR-E SWE • SNOTEL/ASP SWE • evaluate basic questions about predictability • evaluate hydrologic modeling questions • role of calibration, attribution of errors, multiple-model use • evaluate downscaling approaches • what are its components?

5. soil moisture snowpack streamflow, soil moisture, snow water equivalent, runoff local scale (1/8 degree) weather inputs INITIAL STATE Hydrologic model spin up Hydrologic forecast simulation NCDC met. station obs. up to 2-4 months from current LDAS/other real-time met. forcings for spin-up gap ensemble forecasts ESP traces (40) CPC-based outlook (13) NCEP CFS ensemble (20) NSIPP ensemble (9) SNOTEL / MODIS* Update SNOTELUpdate Now 1-2 years back Month 6 - 12 Background: UW west-wide system * experimental, not yet in real-time product

6. Background: UW west-wide system Snowpack Initial Condition Soil Moisture Initial Condition

7. monthly hydrographs MAP LINKS TO FLOW FORECASTS

8. Expansion to multiple-model framework Seasonal Climate Forecast Data Sources CCA NOAA CAS OCN CPC Official Outlooks SMLR CA Coupled Forecast System CFS VIC Hydrology Model NASA NSIPP/GMAO dynamical model ESP ENSO UW ENSO/PDO

9. LDAS Models An LDAS intercomparison conclusion: Model results, using default parameters, have a wide spread for some states and fluxes. Every model is doing something better than other models in some parts of the country NOAH VIC MOSAIC SAC Dag Lohmann, HEPEX

10. Multi-model framework Multiple Hydrologic Models Schaake Shuffle (Clark et al) CCA NOAA CAS OCN CPC Official Outlooks NWS SAC SMLR CA Wood et al., 2002 Coupled Forecast System (CFS) VIC Hydrology Model NASA NSIPP-1 dynamical model NOAH LSM NWS: Day et al; Twedt et al ESP Hamlet et al., Werner et al. weightings calibrated via retrospective analysis ENSO UW ENSO/PDO

11. Test Case Salmon River basin upstream of Whitebird, ID

12. Individual model results

13. Individual model results Monthly Avg Flow Monthly RMSE

14. Individual model results • VIC appears to be best “overall” • Captures base flow, timing of peak flow • Lowest RMSE except for June • Magnitude of peak flow a little low • SAC is second “overall” • No base flow • peak flow is early but magnitude is close to observed* • NOAH is last • No base flow • peak flow is 1-2 months early and far too small (high evaporation)

15. Ongoing work RESEARCH -- RESEARCH -- RESEARCH • assimilation of MODIS & other remote sensing • climate forecast (CPC outlooks, climate model, index-based) • downscaling • shorter term forecasts (GFS-based) • multiple-model exploration • further development of SW Monitor • generally, water / energy balance questions in face of climate change / variability • HEPEX support

16. SW Monitor Background • directly related to retrospective drought reconstruction Andreadis et al. (“Twentieth Century drought in the conterminous U.S., JHM, Dec. 2005) and westwide forecast system • enabled by recent NCDC extension of digital data archives back to 1915 • makes use of real-time forcing creation methods from the west-wide forecast system • will be used as platform for drought and hydrologic variability analyses in real-time • forecasts that can be used in drought outlook type analysis

17. Monitor Webpage daily updates 1-2 day lag soil moisture & SWE percentiles ½ degree resolution archive from 1915-current uses ~2130 index stns

19. Index Station Method Gridded Forcing Creation SW Monitor Information Flow NOAA ACIS Prcp Tmax Tmin Coop Stations 1930s 1955+ VIC Retrospective Simulation Daily, 1915 to Near Current Hydrologic State VIC Real-time Simulation (~1 month long) Hydrologic State (-1 Day) Hydrologic values, anom’s, %-iles w.r.t. retrospective PDF climatology (PDF) of hydrologic values w.r.t. defined period vals, anoms %-iles w.r.t. PDF

20. Future Research • Real-time applications!

21. Examples of UW (SW Monitor / Forecast System) Interactions with Operational Groups • soil moisture estimates have featured in US Drought Monitor panel/author discussions during Drought Monitor map synthesis. • NRCS National Water and Climate Center (NWCC) has requested UW spatial hydrologic mapping data for the upcoming forecast season. • UW recently demonstrated alternate web-based interface for NWCC forecasts • UW Forecast system approaches to enter into comparative analyses with Colorado RFC forecasts (K. Werner) and with NWCC forecasts (T. Pagano). • UW forecasts in Colorado R. basin were supplied to NWCC for forecast coordination discussions with RFCs last winter (one UW forecast used directly) • UW forecast system spatial maps used in pre-forecast discussions with NWCC forecasters