1. Assimilation of Streamflow and Surface Soil Moisture Observations into a Land Surface Model Christoph Rüdiger, Jeffrey P. Walker Dept. of Civil & Env. Engineering., University of Melbourne Jetse D. Kalma School of Engineering, University of Newcastle Garry R. Willgoose Earth & Biosphere Institute, School of Geography, University of Leeds Paul R. Houser Hydrological Sciences Branch, NASA Goddard Space Flight Center, Now: George Mason University & Center for Research on Environment and Water

2. Christoph Rüdiger EGU05 Background Koster et al., JHM, 2000

3. Christoph Rüdiger EGU05 State of Art

4. Christoph Rüdiger EGU05 Location of Study Catchment Melbourne Newcastle Sydney 1000km0km

5. Christoph Rüdiger EGU05 Location of Study Catchment Streamgauge Soil Moisture Climate www.sasmas.unimelb.edu.au

6. Christoph Rüdiger EGU05 Methodology (NLFIT) Kuczera, 1982

7. Christoph Rüdiger EGU05 Streamflow Assimilation - Single catchement - DischargeSoil Moisture

8. Christoph Rüdiger EGU05 Streamflow Assimilation - Single catchement - Root ZoneSurface Layer

9. Christoph Rüdiger EGU05 Surface Soil Moisture Assimilation Eg. Walker et al. (2001) have shown that surface soil moisture assimilation is generally a viable tool for SM updating. Can remote sensing data then be used to further constrain variational type assimilations?

10. Christoph Rüdiger EGU05 Adjustments to Experiment Runs First initial state estimates are set to average values, rather than extremes Maximum and minimum values are not allowed to be violated Observation errors of forcing data are made more “realistic” by changing pure bias to bias and white noise errors (Turner et al., in review)

11. Christoph Rüdiger EGU05 Errors and Biases of Forcing Data BiasError Rainfall25% Radiation0%15%

12. Christoph Rüdiger EGU05 Variational-type Surface Soil Moisture Assimilation Surface SM Runoff Root Zone SM Profile SM

13. Christoph Rüdiger EGU05 Focus Catchments Upper Catchment Lower Catchment

14. Christoph Rüdiger EGU05 Unmonitored Catchments Upper Catch. Lower Catch. TruthDegrad.Assim. Catchment Deficit 221.744 270.119 150.461 148.909 228.773 253.190 Root Zone Excess -5.76858 -3.607990.0 0.0 -3.21003 Surface Excess -0.00615 -0.46736 0.79978 0.97535 0.51269 -6.7E-05

15. Christoph Rüdiger EGU05 Summary Streamflow Assimilation in subhumid catchments can produce adequate estimates of initial moisture states. DA of surface soil moisture observations can act as an additional constraint for the observed catchment. Assimilation of both observations has potential for use in finding initial lumped moisture states for a LSM for ungauged upstream catchments.

16. Christoph Rüdiger EGU05 Conclusions States of ungauged upstream basins can be retrieved to a certain extent. Length of assimilation window will have to be variable for different conditions, esp. if errors in forcing are large and biased. Some states may not have an impact on the objective function, but may be retrieved using additional observations of other variables. First estimate of initial states can potentially be crucial to success of the proposed DA scheme, hence have to handled appropriately.

17. Christoph Rüdiger EGU05 Acknowledgment Australian Research Council (ARC-DP grant 0209724) Hydrological Sciences Branch, National Aeronautics and Space Administration (NASA), USA University of Melbourne –Melbourne International Fee Remission Scholarship (MIFRS) –Postgraduate Overseas Research Experience Scholarship (PORES)