Weather adjustment factors?


#1

Continuing the discussion from 2016 Flex chronicle (aka eating your own dog food):

Franz, I am wondering if you are thinking of adding any controls to adjusting for differences between selected weather station and local observed weather. The advantage over fudging other variables like crop coefficient, is that when tweaking the crop type or other zone information, the adjustment for weather station is not wiped out. I was thinking of multipliers for either temp, humidity or precipitation, or maybe just a simple multiplier for ET.

I am 8 miles from the nearest non-personal weather station, and it is close to the ocean, so records lower temps and probably more humidity than my local conditions. I find that my perennial beds do not water on flex unless i manually empty the zone. I could adjust advanced zone settings (such as crop coefficient to increase the ET), but think they are realistic.


#2

I have been kicking around the idea of a logarithmic adjustment to et based on temp. I’m just findin some of plants that behave well on flex daily when temps are 80-90 but once temps break 95, dry out much quicker than flex predicts.

I probably need to these plants to a new valve and schedule, but just toying with it for now.


#3

I’ll be very interested in what you come up with. I’m seeing the same problems most drastically with my perennials and annual beds.

What about also kicking around having the coefficient change monthly as well. I had read articles where it changes drastically for vegetable crops throughout the season, but then found there is a pretty large difference for grass as well (http://irrigationtoolbox.com/ReferenceDocuments/TechnicalPapers/IA/2008/2127translated.pdf

And I would also like to see something where schedules could be run more than once a day to handle the negative moisture levels.

Somehow these three seem all intertwined to me for handling the really hot, nasty days.


#4

@jkb Thanks for the feedback, interesting concepts that we will ultimately/eventually end up building something closer to in the future.

The original flex had a semi-static coefficient for each month (just for grass) that did move at the beginning of each month. The one issue was no manipulation by the user, and it is one of our biggest levers. If you do have automatic adjustments for crop coefficient, also need a way for people to disable that feature that want to set their own, so the UI gets more confusing. I think what we have now for crop coefficient is a good compromise throughout the year. If becomes a real issue, we could potentially add that automatic monthly adjustment in some regard.

Definitely helpful for Dante’s Inferno. Until this season we’ve really not had anyone pushing the flex limits quite like this bunch :wink:

:cheers:


#5

Oh, I agree with you – As far as coefficients changing throughout the year, I was just putting on my visionary hat and looking into the future, after you get the rest of this nailed down to where you/we want it! :wink: If you could do it at one point in the far off future, it will just be another plus to differentiate your software from the others.


#6

Wondering if this has gone anywhere with the product team…?

I was looking for weather adjustments to dial in localized climate compared to the weather station, not crop adjustments as others were mentioning. For example, if temps are higher than ‘seasonal’ then exaggerate the impact of higher temps in the ET calculations.