Questions on simulations using the full forcing possibility

Discussions about the Version 4 concerning the core model simulations
ADrebs
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Questions on simulations using the full forcing possibility

Postby ADrebs » Sun Aug 11, 2019 8:01 pm

Hi ENVI-met team,
I am making research on bio-thermal outdoor condition during July, 31st until August, 2nd 2018 in Vantaa, Finland (60° 17', 25° 3'), 72 hours. For the meteorological forcing observation I use the radiation data (SWDir, SWDiff and LWin from the Finnish Meteorological Institute headquarter about 10 kilometres to the south (quality controlled) beside in-situ observation of air temperature, relative humidity, wind speed and direction. The creation of the .fox-file was a successfully straight-through process. The data appearance in the .fox-file was checked.
After the 72-hour-simulation run the ENVI-met Bio-Met module was used to calculate the human thermal indices (PMV, PET, UTCI, and SET) at 1.4 m height.
By exploring the results I do not understand the high SWin values presented in figure 1, timestamp 1.8.2018, 20:00. According the forcing file the local sunset was approximately around this time (20:00 - 20:30, figure 2). I made a time series of one grid in the area of interest for SWin shown in figure 3. Using these results to calculate for example the PET thermal index is shown in figure 4. The PET values are fare beyond a bio-meteorological definition of 'extreme thermal heat stress'.
What went wrong in the calculation procedure or my way to produce the data?

A-)
Attachments
Figure_4_PET_Heureka_FF_Sommer_2018.png
Figure_3_Leonardo_SWin_Heureka_FF_Sommer_2018.png
Figure_2_FF_01082018_Heureka_Sommer_2018.png
Figure_1_SWDir_Heureka_FF_Sommer_2018.png

Tim
Posts: 913
Joined: Mon May 15, 2017 3:46 pm

Re: Questions on simulations using the full forcing possibility

Postby Tim » Mon Aug 12, 2019 7:52 am

Hi,

I think there are two things about the radiation:
1. The longwave radiation values are too high. They shall represent the downward longwave radiation coming from the sky. Values around 250-300 W/m² are expected.
2. The SW radiation however is not affected by that. Since the input SW radiation values look good, there seems to be a wrong recalculation of the values during the simulation. I'd thus suggest that the parameter whether the values are measured horizontally is not set correctly. You may fix that and see if the output radiation values are then correct.

Best regards,
Tim

ADrebs
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Joined: Sun Sep 04, 2016 7:42 pm
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Re: Questions on simulations using the full forcing possibility

Postby ADrebs » Mon Aug 12, 2019 8:28 am

Hi Tim,

the LWin radiation I used is measured at the FMI main building and quality checked, that I should be sure, that they are right. In the attachment a screen shot from less than half an hour ago from the site I make the research on. LWin values >350W/m2 are more the rule than the exception, times are UTC.

I run the simulation for horizontal and inclined SWin, the results are the same.

As I cannot look into the software, but see the shape of the outcome graph for SWin, it came into my mind, is there an algebraic sign error in the calculation?

A-)
Attachments
iscape_heureka_12082019.png

Tim
Posts: 913
Joined: Mon May 15, 2017 3:46 pm

Re: Questions on simulations using the full forcing possibility

Postby Tim » Mon Aug 12, 2019 8:48 am

Hi,

Ah, I didn't check the legend for longwave radiation but for shortwave radiation. That's why I thought the longwave values to be too high (at 700). With values up to 400 they are definitely fine, yes.

I will check that issue with some simulations.

Best regards,
Tim

Tim
Posts: 913
Joined: Mon May 15, 2017 3:46 pm

Re: Questions on simulations using the full forcing possibility

Postby Tim » Mon Aug 12, 2019 9:13 am

Hi,

Could you zip and upload the csv or fox file?

Best regards,
Tim

ADrebs
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Re: Questions on simulations using the full forcing possibility

Postby ADrebs » Mon Aug 12, 2019 9:21 am

Hi Tim,

here the zipped .fox-file,

A-)
Attachments
ForcingFileHeurekaJuliAugust2018.zip
(137.35 KiB) Downloaded 8 times

helge
Posts: 104
Joined: Mon May 15, 2017 12:27 pm

Re: Questions on simulations using the full forcing possibility

Postby helge » Mon Aug 12, 2019 10:57 am

Dear A-)

We had a look at your FOX-Files: the 20:00:00 and 20:30:00 values from 02th August were missing.
We strongly believe your values are in the "lambert" format. The radiation data is not relative to a horizontal surface but rather to a surface that is always perpendicular to the sun.

Furthermore we found a bug where the information about the reference surface for the radiation is only read from the 1st Jan 00:00:00 - we will fix this bug in the next regular release.

We adjusted your forcing file (see attachment) so it should now yield the correct values.

Also, please make sure that you have the correct reference timezone longitude (I believe 30° E in your case) and georeference in the INX -File. Like all models ENVI-met does not use the day light saving time.

Best
Helge
Attachments
HEUREKA_lambert.zip
(118.03 KiB) Downloaded 9 times

ADrebs
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Re: Questions on simulations using the full forcing possibility

Postby ADrebs » Mon Aug 12, 2019 12:17 pm

Hi Helge,

my original .csv-data file contains the two missing rows and I have no explanation for that why they dropped out. So, thank you for the correction.

Do I have now to wait for a new release?

And yes, the time zone is set to CET/ UTC+2 with the reference longitude to 30.

A-)

Tim
Posts: 913
Joined: Mon May 15, 2017 3:46 pm

Re: Questions on simulations using the full forcing possibility

Postby Tim » Mon Aug 12, 2019 12:40 pm

Hi,

Okay!
No, you do not have to wait since all timesteps (even the invalid first timestep which is read unfortunately) hold now the lambert information and will be treated correctly.

Best regards,
Tim

ADrebs
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Joined: Sun Sep 04, 2016 7:42 pm
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Re: Questions on simulations using the full forcing possibility

Postby ADrebs » Mon Aug 12, 2019 9:00 pm

Hi, Tim, Helge,

I continued to test my simulations with the forcing file you provided, and with the standard non-forced option for clear-sky condition. Due to my restricted hardware speed (I don't complain about that), I just finished the 8-hour morning simulations. I started to compare SWin outcomes for forced (Figure 1) and unforced (Figure 2) conditions. As you can see the patterns in colour and shape for both are quite similar. The SWin values instead show still a great difference to the disadvantage of the full-forced simulation. Calculating the PET index based on these values is shown in Figure 3 and 4. The difference in the PET value distribution in these two figures is due to the constant wind speed (5m/s) and direction (225°) in the non-forced simulation. Nevertheless, the non-forced simulation produces still more realistic PET values that the full-forced.

Can you explain me why?

A-)
Attachments
Figure_4_PET_Heureka_notFF_Sommer_2018_0800.png
Figure_3_PET_Heureka_FF_Sommer_2018_0800.png
Figure_2_SWDir_Heureka_notFF_Sommer_2018_0800.png
Figure_1_SWDir_Heureka_FF_Sommer_2018_0800.png

helge
Posts: 104
Joined: Mon May 15, 2017 12:27 pm

Re: Questions on simulations using the full forcing possibility

Postby helge » Tue Aug 13, 2019 1:40 pm

Dear A-),

Thank you for the feedback we will have a look into it by simulating a small test area and will get back to you.

Best Helge

Agnese
Posts: 25
Joined: Mon Feb 18, 2013 3:44 pm

Re: Questions on simulations using the full forcing possibility

Postby Agnese » Tue Sep 24, 2019 2:33 pm

Dear all,

I am using the last release of ENVImet 4.4.3 Summer (downloaded and installed on 12 september 2019) but I have just discovered that I have the same problem discussed here regarding the forcing solar radiation values.

I created a FOX file with measured radiation data (attached), double-checking that I chose the option "on horizontal surface" for the radiation values.
The simulations ran well, but after analysing the radiation outputs it is clear that something went wrong with the forcing direct solar radiation. As you can see form the screenshots below, the values of the direct Sw on top of the model constantly increase until 18pm and then suddenly drop to almost zero at 7pm (I am 100% sure that there is no obstruction to solar radiation in the analysed point).
I've run a simulation for the same day and duration without forcing (i.e. using radiation data calculated by ENVImet -) and the outputs do make sense, with direct Sw decreasing after noon.

I need to run other simulations using measured radiation data and I would rally appreciate if you could explain how I can I fix this?

Many thanks,
Agnese
Attachments
NEW_KENT data 22_23 June 2019.7z
FOX file
(25.16 KiB) Downloaded 2 times
Screeshot4 - Direct Rad output- NO forcing.JPG
direct Sw WITHOUT FORCING
Screeshot3 - direct rad output - WITH FORCING.JPG
Direct Sw when full FORCING is used
Screenshot2 - ENVImet radiation preview.JPG
ENVImet estimated radiation
Screeshot1 - forcing file radiation.JPG
FOX file Radiation from measured data
Screeshot0 - forcing file radiation on horizontal.JPG
option "horizontal surface" activated

Tim
Posts: 913
Joined: Mon May 15, 2017 3:46 pm

Re: Questions on simulations using the full forcing possibility

Postby Tim » Wed Sep 25, 2019 8:19 am

Hi Agnese,

The radiation values are recalculated if they were measured horizontally. As the radiation values are rather low at maximum - such as the values of ADrebs in the beginning of the post - we are pretty sure that the values are not measured horizontally. Uncheck the button in the ForcingManager and the values will be simulated correctly.

Best regards,
Tim

Agnese
Posts: 25
Joined: Mon Feb 18, 2013 3:44 pm

Re: Questions on simulations using the full forcing possibility

Postby Agnese » Wed Sep 25, 2019 9:32 am

Dear Tim,

thanks for your reply.

However we took the measurements with a pyranometer on a horizontal surface, so I am sure they are measured horizontally!

Also, this would not explain why the radiation output "direct SW" grows constantly until 6pm and then drops suddenly at 7pm, in spite of the trend of the direct SW shown in the forcing manager which has maximum intensity at noon. How do you explain that?

Thanks,
Agnese

Tim
Posts: 913
Joined: Mon May 15, 2017 3:46 pm

Re: Questions on simulations using the full forcing possibility

Postby Tim » Wed Sep 25, 2019 10:45 am

Hi Agnese,

Sorry, I think you are right indeed. Maybe there is still some mixup in the code. We will check it immediately!

Edit: At the moment, I'd say the calculations are correct. Are you absolutely sure that location of model area and location of radiation measurements are the same? Is the timestamp correct for sure (thinking about daylight saving time etc.)?

Best regards,
Tim


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