# Update\_param! for temp in FUND

**URL:** <https://forum.mimiframework.org/t/update-param-for-temp-in-fund/156>\
**Category:** Uncategorized\
**Created:** [March 30, 2021, 1:56am UTC](https://forum.mimiframework.org/t/update-param-for-temp-in-fund/156 "2021-03-30T01:56:14Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![KGregory](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.mimiframework.org/kgregory/32/32_2.png) [@KGregory](https://forum.mimiframework.org/u/KGregory)\
**Post date:** [March 30, 2021, 1:56am UTC](https://forum.mimiframework.org/t/update-param-for-temp-in-fund/156/1 "2021-03-30T01:56:14Z")

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The FUND “climatedynamics” component calculates too much temperature rise for a given ECS and emissions scenario than the climate models when ECS is less than 3 C. I created a spreadsheet with a 2-box climate model that matches the climate model behavior. I created a new temperature profile of 1051 years and attempted to use the update\_param! function in each component, such as;  
update\_param!(m, :ocean, :temp, Tempcor)  
where “temp” is the global average temperature from FUND and “Tempcor” is my temperature from 2-box climate model, both parameter have the length 1051 and are one dimensional. However, this gives this error:  
MethodError: no method matching update\_param!(::Model, ::Symbol, ::Symbol, ::Array{Float64,1})  
Closest candidates are:  
update\_param!(::Model, ::Symbol, ::Any; update\_timesteps) at C:\Users\Ken.julia\packages\Mimi\mHt54\src\core\delegate.jl:54  
update\_param!(!Matched::Mimi.AbstractCompositeComponentDef, ::Symbol, ::Any; update\_timesteps) at C:\Users\Ken.julia\packages\Mimi\mHt54\src\core\connections.jl:480  
update\_param!(!Matched::Mimi.ModelInstance, ::Symbol, ::Any) at C:\Users\Ken.julia\packages\Mimi\mHt54\src\core\connections.jl:484  
…  
Stacktrace:  
[1] top-level scope at In[85]:1  
[2] include\_string(::Function, ::Module, ::String, ::String) at .\loading.jl:1091

Can you tell me why the update\_param! line doesn’t work?

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<div class="post-metadata">

**Author:** ![lrennels](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.mimiframework.org/lrennels/32/6_2.png) [@lrennels](https://forum.mimiframework.org/u/lrennels)\
**Post date:** [March 31, 2021, 7:20am UTC](https://forum.mimiframework.org/t/update-param-for-temp-in-fund/156/2 "2021-03-31T07:20:32Z")

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**Sorry in advance for length, but I wanted to be comprehensive and clear here!**

You can only call `update_param!` on an existing model parameter that was previously created by calling `set_param!`.

In the original FUND model created with

```auto
m = MimiFUND.get_model()

```

the `temp` parameter in components such as `ocean` is never set with `set_param!`, so there is no model parameter `:temp` holding values that can be updated. The values are instead **computed** within the `climatedynamics` component as the `temp` **variable** and then connected to the `temp` parameter in various components, including `ocean`, with a call to `connect_param!`.

There are several options for changing how temperature is calculated and passed to components within FUND depending on your goals as written below, and the Mimi API is [here](https://www.mimiframework.org/Mimi.jl/stable/ref/ref_API/) for reference and clarification.

* * *

* * *

If you want to **remove** the `climatedynamics` component entirely, you can do so with `delete_comp!`. You will then need to fix up any missing connections that used to flow throw `climatedynamics` using new connections for dynamic computation, or `set_param!` to force with external values.

* * *

* * *

If you want to **edit** the `climatedynamics` component’s computation of temperature, you can create your own component from scratch or derived from the FUND `climatedynamics` component and then use the `replace_comp!` functionality. This could, for example, adapt FUND’s `climatedynamics` `:temp` variable to be computed in a different way, which would then automatically flow through the model.

* * *

* * *

If you want to **leave the FUND components as they are** but just force some components with your new `Tempcor` values, you could break the connections between `climatedynamics` and the various components like `ocean` and then call `set_param!` to set their values to your externally computed `Tempcor`.

**Generally** , the easiest way to do this would be to first disconnect all the component parameters you want to use your external values with `disconnect_param!`, so they no longer pull from `climate dynamics`, and then use `set_param!` create a new model parameter `temp` with values `Tempcor`, which at run time will set the value for parameter `temp` in any component with a parameter of that name that is not yet connected.

```auto
m = MimiFUND.get_model()
disconnect_param(m, :ocean, :temp)
disconnect_param(m, :other_component, :temp)
set_param!(m, :temp, Tempcor)

```

**However** , in FUND `temp` is a parameter in several components, not all of which use the same values (ie. in `ocean` it only has the `time` dimension but in others it has both `time` and `regions`), so Mimi cannot safely make the assumption that any component parameter `:temp` that is not unconnected at build time can be set to the same model parameter.

Instead, we must call `set_param!` for each component and be explicit about what we want the model parameter name to be using the longer `set_param!` method `set_param!(m, comp_name, param_name, unique_param_name, value)`, so your code would be

```auto
m = MimiFUND.get_model()
disconnect_param(m, :ocean, :temp) # optional, the line below will do this automatically
set_param!(m, :ocean, :temp, :ocean_temp, Tempcor)

```

This will break any connections `ocean`'s parameter `temp` has to other variables, create a new model parameter with the name `ocean_temp` (normally defaults to the `temp`) with value `Tempcor`, and then set `ocean`'s parameter `:temp` to the have the values of the model parameter `ocean_temp`, which in this case are `Tempcor`.

Then if you want to update `ocean`'s `temp` parameter in the future you would use

```auto
update_param!(m, :ocean_temp, new_values)

```

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<div class="post-metadata">

**Author:** ![KGregory](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.mimiframework.org/kgregory/32/32_2.png) [@KGregory](https://forum.mimiframework.org/u/KGregory)\
**Post date:** [April 3, 2021, 1:49am UTC](https://forum.mimiframework.org/t/update-param-for-temp-in-fund/156/3 "2021-04-03T01:49:51Z")

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Thanks you for the detailed reply. It was very helpful and the code worked fine! Yes, I was aware that the parameter temp is a 1 dimensional vector in 3 components and a 2 dimensional array in 8 components. ‘temp’ is global average temperature anomaly, so it is the same in all 16 regions, so there is no point in having temp as an array. It appears to be just a waste of memory.

Of course, setting ‘temp’ from an Excel file calculation is a poor solution. I will now attempt to create a new climatedynamics component to include my 2-box climate model from Excel. I won’t be able to do that for a few days.