Inquiry on WRF-Hydro Nudging Experimental Design

[zed li]

Hi everyone,

I hope this email finds you well.

I am currently conducting WRF-Hydro nudging studies in two river basins and, as a beginner, have several questions.

In the first basin, there are two upstream streamflow gauges above my forecast point. Assimilating observations from these two stations has improved the simulation at the forecast point.

For the second basin, there is no upstream gauge above the forecast point. How should I design the experiment for this basin? If I assimilate the flow data from the forecast point itself, the results would appear too perfect. The official documentation states the goal is to "improve model simulation and forecast initial conditions." How should I set up the experiment to properly achieve this objective?

Furthermore, I plan to make the nudging study a core part of my thesis, but I am concerned the content may not be substantial enough. What additional work would you recommend I could undertake?

Thank you for your time and guidance.

Sincerely,
Zed Li

[Arezoo RafieeiNasab]

Hi Zed, 

One goal of why we do nudging (or other techniques) is to improve the model states and therefore the forecasts. For research purposes and verifying that the approach is working as it should, usually we assimilate at a subset of gauges and verify at the remaining locations, similar to what you did with basin 1. However, after you do the proof of concept and you are sure that the methodology works as it should, the next step is to do forecasting. In that step, we want to use ALL available observations (with good quality) and assimilate all, so the forecast quality would be improved to the greatest possible extent. If you would like to verify the impact of assimilation in this setting, you would verify the forecast skill which is the result of improving the model stats. 

Are you a Ms student or PhD? What year of your program you are in? What else is in your thesis? I do recall you were doing some soil moisture DA too. 

Thanks!

Arezoo

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Arezoo Rafieei Nasab, Ph.D.

Scientist V

NSF NCAR Research Applications Laboratory

are...@ucar.edu