Zimmerman parameters

[Wokkeltje]

I use my OS to control driplines.
With the current Zimmerman algoritm, there needs to be around 12mm (0,5inch) of rain to prevent irrigation.
For me irrigation schould be posponed if it has rained 5 or 6mm.

It would be nice if we could modify some more parameters of the Zimmerman method. the latest update to modify the weight of temp, humidity and rainfall was already a good step, but didn’t solve my problem

Since the weather adjustment was 1 of the most important reasons to buy the OS, it would be nice if I could have more impact on algorithm.

thanks already

ps: any news when a new version will be released? I am alway curious for new features.

[Ray]

Any specific suggestions on how you’d like to improve the Zimmerman algorithm?

[Wokkeltje]

The zimmerman calculation is

The formula used to set the scale is as follows:
• Humidity: Average humidity for the previous day above 30% is subtracted from the weather adjustment, below 30% is added to it. Example: 77% Max Humidity + 26% Min Humidity / 2 = 51% Avg Humidity, 30% – 51% Avg Humidity = -21% Humidity Adjustment
• Temperature: +4% for each degree Fahrenheit above 70, and -4% for each degree Fahrenheit below 70.
• Precipitation: -2% for each hundredth of an inch precipitation from today and yesterday. Example: 0.12″ rain today + 0.05″ rain yesterday * 100 = 17 hundredths of an inch of rain * -2 = -34% Precipitation Adjustment

So I would suggest to have the 3 parameters configurable:
* For Humidity: be able to modify the 30%
* For temp: be able to modify the +-4%
* For Precep: be able to modify the +-2%

With this extra addition, I think everybody can build its own custom Zimmerman method that fits his needs.

The ultimate would be to have also more impact of historical rain (in my region). Because sometimes it rains during a thunderstorm 30l, so this means the next couple of days no irrigation is needed. With the Zimmerman method only the previous day is taken into account.
But I know it is difficult to create a rule for this because going more days in the past has a lot more items that will influence the decision how much to water.

[peter]

I would really like it to look at the forecast for the day: [pop] * [qpf_allday] * [some factor]

forecast/

“simpleforecast”: {
“forecastday”: [
…
“period”:1,
…
“pop”:20,
“qpf_allday”: {
“in”: 0.02,
“mm”: 1
},
},

[Ray]

@Wokkeltje: the second and third you mentioned:
* For temp: be able to modify the +-4%
* For Precep: be able to modify the +-2%
are already possible in the latest firmware. Specifically, you can change the weight of each factor. For example, by using a 50% weight for the temperature factor, it essentially changes +/-4% to +/- 2%.

The first one you mentioned: changing the threshold of 30% is currently not possible.

Note that if the algorithm doesn’t fit your need, you can always host the weather script on a different server and that way you can modify the weather algorithm in any way you want.

[Wokkeltje]

I don’t think changing the weight to 50% does the trick, since changing it to 50% wil modify the impact of 1l of rain to only 0,5l. It would work if I could change the weight for rain to 200% but this is not supported in the GUI.

Can I run the weather script on my rasparyPI? This would be great.
Where do I need to modifythe setting to not use the script on your server but on a local server?

[Samer]

To clarify on Ray’s comment about hosting the weather service, this is something we will be supporting in 2.1.6 but currently is not supported.

When 2.1.6 is out, you will have a field to input your weather script URL and we will also provide documentation on setting up the weather service.

Thanks!

[Wokkeltje]

any idea for the release date? (days, weeks, months, …) ?

just to have an idea, not to pin you to a date

[Ray]

We are actively working on 2.1.6 at the moment. Because this version involves a number of changes, it’s take a while. But we hope to get it done within a couple of weeks.

[Boris]

I agree with the ultimate idea “historical rain” from wokkeltje and it would be great if it can be done by weather script or something like this in 2.1.6. I have irrigation lines which are opened only 1 Day a week. If there was enough precipitation in the week it is not necessary to open the line.

[Peter]

I have been using the Zimmerman method for a while now but the baseline weather conditions (Temp = 70F, Humidity = 30% and Rain = 0) aren’t a great match for London, UK where average temp is 50F and Humidity is up around 80%. I have been using a 0% sensitivity setting on temp/humidity to pretty much ignore any weather fluctuations except for rainfall.

But over the weekend, I modified the UI and weather server script to accept a custom baseline for my location. In essence allowing me to set the reference temp/humidity/rain to average London conditions. This means that I can set my program duration to an “average day” scenario and have Zimmerman adjust for daily offsets in all three variables.
Be interesting to see how it works out in practice but back testing on a year’s worth of historical data suggests a much better fit. The code changes are pretty minimal and backwards compatible. Curious, if this is of interest to others ?

Attachments:

1. 

   Zimmerman.jpg
   

[Wokkeltje]

I am interested.

I live in Belgium, so I am thinking about °C and l/m but the idea looks good to be able to tweak a bit the Zimmerman method.

[Peter]

So I figured out how to add imperial/metric detection and conversion and seems to be working. I’ll put to Samer to see if he is interested in taking into the weather and app master branch.

I have written this as an upgrade to the existing Zimmerman adjustment method rather than adding a new Zimmerman2 to the pick list. I could change the approach and implement this as a new method if that would be preferred. I guess it depends whether current Zimmerman users believe this is a natural enhancement or an unnecessary complexity 8) Thoughts?

Attachments:

1. 

   Zimmerman.jpg
   

[Samer]

Feel free to submit a pull request if you have it working and I’ll review it and get it added in. I need to push an update out for the app for the various changes over the past month or so and this might be a good thing to include.

Thank you!

[Wokkeltje]

+1

[insight3fl]

Here in southwest Florida, most lawn types are irrigated based upon so many inches of water per week. So I also agree the best parameter for us to be able to set is the rainfall based upon the average of the last 7 days. It may have rained 2 inches today (typical in the summer) and then in three days, I do not need to irrigate again as I have far exceed my Empire Zoysia requirement of 1 inch per week. If the formula only looks at today and yesterday, our typical 1-2 inches of rain every few days will still allow Opensprinkler to run.

[RottenMutt]

+1 for considering forecast
+1 seven day a week rain average

[Author]

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