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"Spin up" vs "Forecast" data

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Page Weil

I want to develop a hydrologic simulation where I use the same values in all scenarios from the beginning of the "spin up" period (say 1/1/2023) through the beginning of the forecast period (1/1/2025, defined in a variable). After that point, I want to use values from historical years to represent each model scenario. This is similar to how ESP forecasts are developed (use observed forcings through present day, and then historic year forcings for each ensemble member)

For example, the "1980" scenario uses 1/1/2023 - 12/31/2024 as spin up and then uses the values from 1/1/1980 through 12/31/1980 for 1/1/2025 through 12/31/2025 in the simulation.

I read through the "Time Shifting" example in the model documentation and this seems to be possible, but I am not sure the exact syntax or model element to use to make this happen.

https://support.goldsim.com/hc/en-us/articles/215241678-Shifting-Time-Series-Data

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    Jason

    Page,

    I have a simple model example that demonstrates how you can run historical to future scenario simulations all in one model. I do this by switching at the present time so that the historical time period relies on the same data but any future parts will rely on scenario based data. Would this be helpful to see?  

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    Page Weil

    Yes, that is exactly what I am trying to do (I just can't figure out the syntax)

    If you can send me this simple conceptual model, that will be all I need.

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    Jason

    Page, I built a simple model that you can easily replicate. Just use a Selector or IF statement to switch from historical to future outputs. Below is a screen capture of the simple setup. In this example, you can imagine that my element called "Forecasted" is your model output that represents the future. In your case, this would be the surrogate years 1/1/1980 through 12/31/1980 you mentioned that represents a future scenario. The key is to use an output like mine called "IsFuture" which is a Boolean true or false. Here is what it looks like:

    In my case, I refer to a special output called "now" which is the current clock time on my computer. In your case, it might be something like "01/01/2025" or whatever you use as your switching time that marks the point of moving from historical to future. Then you have the Selector element to switch from historical to future: 

    In my case, I have 2 scenarios defined. For each scenario, I change the forecast.

    The result is a model that starts with a historical part then transitions to future. Let me know if you want me to send you this model.

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    Page Weil

    Yes, please send me this model. The one thing this is missing though is how to have the model assign a particular historical year to be the forecasted series. Like, how do I assign values from January 1st 1980 to replace values on January 1st 2025?

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    Jason
    • Edited

    Page,

    Okay I sent the model example. Hopefully that helps. Regarding how you assign values from 1980 to replace values in the simulation year of 2025: 

    You can use the Time Shifting functionality on the Time Series for this. It might be good to start here: https://help.goldsim.com/#GS/timeshiftingtimeseriesdata.htm

    Here is an example that shows how you can sample through historical years of data in a future run: Shifting Time Series Data – GoldSim Help Center  

    Please let me know if this helps.

    Jason

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    Page Weil

    Thank you for this. Time Shifting was the concept I did not know about that allowed this to work.

    On suggestion for future enhancements: allow more arbitrary starting dates for time shifting. Right now, it is only available on an annual basis, but it would be good if it could be controlled by a specific date, or a smaller period (monthly/weekly)

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