Evapotranspiration plugin wrong?

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nikokara - BANNED
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Evapotranspiration plugin wrong?

Post by nikokara - BANNED » Sun Sep 17, 2017 4:30 pm

Hi

Maybe here is samthing wrong

The ETplugin shows constant 5m/s as average wind speed. I really have 0.3 m/s for today.

If i try manualy to enter the 0.3 value Et is the same, i also input 50 m/s Et is the same, even if i input 500m/s (exceptet so far 4000-6000 mm water.

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Re: Evapotranspiration plugin wrong?

Post by nikokara - BANNED » Sun Sep 17, 2017 4:34 pm

Sorry i posted in the blocks problems. This is an plugin problem

Sorry :(
niko

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Re: Evapotranspiration plugin wrong?

Post by Jachym » Sun Sep 17, 2017 5:10 pm

The ET value depends especially on solar radiation, if solar is 0 then it will not change no matter which parameter you change

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Re: Evapotranspiration plugin wrong?

Post by nikokara - BANNED » Sun Sep 17, 2017 5:39 pm

Thank you Yachim for the reply
Can you please move this in the plugins group

My averages are
28.2 °C
82.8 °F

39.4 % Hum

0.3 m/s Wind speed
1.1 km/h
0.7 mph
0.6 kt

1013.0 hPa Presure
29.91 inHg

250 W m-2 SR <-----

4.0 m Alt
13.1 ft

37.95 N Lat

17.09.2017 Date

This gives 4.216 mm
the same as AWS=40m/s

The wind speed is very importand in the FAO Penman-Monteith equation!!!
Maybe more important than solar radiation
niko

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Re: Evapotranspiration plugin wrong?

Post by Jachym » Sun Sep 17, 2017 6:25 pm

The equation is taken directly from NOAA, the wind speed is converted to 2m height, I really dont remember how exactly it is calculated, you can look at the code, but AFAI remeber I checked it and it more or less worked

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Re: Evapotranspiration plugin wrong?

Post by nikokara - BANNED » Tue Sep 19, 2017 9:45 pm

Hi Jachim

I checked the code.

In index.php of ET
@ line 59 and @ line 208, i have changed the variable $w to $f, (from the class file)
and now it swows the average daily wind speed correct.

I have not checked or compared the Eto result yet. I will try to import data to an Eto programm
and post the results here.

Thanks
niko

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Re: Evapotranspiration plugin wrong?

Post by Jachym » Wed Sep 20, 2017 8:44 am

ok thanks

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Re: Evapotranspiration plugin wrong?

Post by nikokara - BANNED » Sat Sep 23, 2017 7:26 am

Hi Jachym

I have compared the results with FAOs Eto calculator

Here the screenshots
with 0.3 m/s wind speed
eto_comp_2017-09-23_093802.jpg
eto_comp_2017-09-23_093802.jpg (340.71 KiB) Viewed 7441 times
and here with zero wind
eto_comp_0wind_2017-09-23_100712.jpg
eto_comp_0wind_2017-09-23_100712.jpg (397.86 KiB) Viewed 7441 times
tsitat --> wind speed totaly ignored (not calculated)

ps i can send you the Eto programm if you want.

have i nice Day :)
niko

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