How to output PAR (Photosyntherically active radiation) in EMEP

[Yuanlin29]

Hello,

Currently we'd like to output at the stomatal conductance for VOC species (MVK and MACR) on different landtype, meanwhile we also want to output the PAR values. I'm a bit confused that there are both PARSun and PARShade in EMEP model. It would be appreciated that if there is someone can tell me if I need to output them seperately or just need to sum, also how can I output these variables since they can't be added to the namelist directly.

Many thanks,

Yuanlin

[mifads]

Hi Yuanlin!
Sorry about the slow response here. I wanted to test some PAR outputs at least before responding, but I'm buried in other jobs. I'll try to get back to this later today, or this week at least.
Best Regards,
Dave

[Yuanlin29]

Hello Dave, Thank you for your reply and these tests. No worries at all and I am looking forward to hearing from you. Cheers, Yuanlin From: mifads ***@***.***> Sent: 10 March 2025 08:39 To: metno/emep-ctm ***@***.***> Cc: Yuanlin Wang ***@***.***>; Author ***@***.***> Subject: Re: [metno/emep-ctm] How to output PAR (Photosyntherically active radiation) in EMEP (Issue #130) CAUTION: This email originated from outside of the organisation. Do not click links or open attachments unless you recognise the senders email address and know the content is safe. Hi Yuanlin! Sorry about the slow response here. I wanted to test some PAR outputs at least before responding, but I'm buried in other jobs. I'll try to get back to this later today, or this week at least. Best Regards, Dave — Reply to this email directly, view it on GitHub<#130 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ASTIU7CHNLAAKMEMDQFQED32TVFTJAVCNFSM6AAAAABYMK2UCKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDOMBZHAYDIOJVG4>. You are receiving this because you authored the thread.Message ID: ***@***.***> [Image removed by sender. mifads]mifads left a comment (metno/emep-ctm#130)<#130 (comment)> Hi Yuanlin! Sorry about the slow response here. I wanted to test some PAR outputs at least before responding, but I'm buried in other jobs. I'll try to get back to this later today, or this week at least. Best Regards, Dave — Reply to this email directly, view it on GitHub<#130 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ASTIU7CHNLAAKMEMDQFQED32TVFTJAVCNFSM6AAAAABYMK2UCKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDOMBZHAYDIOJVG4>. You are receiving this because you authored the thread.Message ID: ***@***.***> This email and any attachments are intended solely for the named recipients and are confidential. If you are not the intended recipient, please reply to the email to highlight the error and delete this email from your system; you must not use, disclose, copy, or distribute this email or any of its attachments. UK Centre for Ecology & Hydrology (UKCEH) has taken reasonable precautions to minimise risk of this email or any attachments containing viruses or malware, but the recipient should carry out its own virus and malware checks before opening the attachments. UKCEH does not accept any liability for any losses or damages which the recipient may sustain due to presence of any viruses. Opinions, conclusions or other information in this message and attachments that are not related directly to UKCEH business are solely those of the author and do not represent the views of UKCEH. We process your personal data in accordance with our Privacy Notice, available on the UKCEH website. https://www.ceh.ac.uk/privacy-notice Registered office address; Maclean Building Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, United Kingdom, OX10 8BB Companies Registered Name; UK Centre for Ecology & Hydrology Place of Registration; England Registered Company Number; 11314957

[mifads]

Hi Yuanlin,

Again, sorry about the delay, but now I have had a quick look at the code. I'm afraid we don't have a method to output those variables for different land-cover types, so you will have to code this yourself. In Mosaics_mod you can see how we do this for Fst of O3, LAI, etc., so I guess one would start there if you need fields of these parameters. Alternatively, if you just want the data for individual sites then one could just add extra printouts from e.g. Rsurface_mod.

About PARsun and PARshade, then check out their usage in DO3SE_mod. They are used for leaves in the sun, and leaves in the shade, respectively, so can't be simply summed. If it is enough with PAR above the canopy, then in Derived_mod I recently added an output for the "above canopy height" PAR, which applies for all vegetation:

case ( "PARach_Wm2" ) ! PAR above canopy, through horizontal
forall ( i=1:limax, j=1:ljmax )
d_2d( n, i,j,IOU_INST) = PARdbh(i,j)+PARdif(i,j)
end forall

This was for TFMM grid-scale outputs however, not for in-canopy usage.
Best Regards,
Dave

[Yuanlin29]

Hello Dave,

Thanks very much for your reply. I have recently added PARsun and PARshade in the Mosaic_mod, like what you did for LAI. Meanwhile I also tried to output LAI, PARsun, PARshade, Rs for deciduous and coniferous land types, below is what have been added in the config_namelist:

NewMosaic =
'Mosaic', 'Rs', 'MVK', 'Grid', 'sm', 'YMDH',
'Mosaic', 'Rs', 'MACR', 'Grid', 'sm', 'YMDH',
'Mosaic', 'Rs', 'MVK', 'DF', 'sm', 'YMDH',
'Mosaic', 'Rs', 'MACR', 'DF', 'sm', 'YMDH',
'Mosaic', 'Rs', 'MVK', 'CF', 'sm', 'YMDH',
'Mosaic', 'Rs', 'MACR', 'CF', 'sm', 'YMDH',

MOSAIC_METCONCS=
'LAI',
'PARsun'
'PARshade'

MET_LCS =
'DF',
'CF',

Mosaic_timefmt =
'YMDH'

I have run only one day (12 July, 2022) for EU domain and managed to output these successfully, however, I met some issues:
(1) Stomatal resistance (Rs) values are very big (>7000 s/m) across Spain and Portugal compared to another model (GEOS-Chem) whose values are between 0-300 s/m;
(2) PARshade values are also very strange, daily average can reach 100,000 w/m2 across thw whole continent, much more than PARsun which are only from 0 to 300 w/m2
I have no idea why these values are so big and wonder whether it is normal in the EMEP model. I would greatly appreciate if you can help me anwser these questions.

Best wishes,
Yuanlin

[mifads]

Hi Yuanlin,
Good that the model produced numbers at least, but there must be bugs:

1. It is better to compare Gs (=1/Rs) than Rs since the latter can approach infinity or some random big number (e.g. 9999) as deposition rates (Gs) approach zero. Big Rs means nothing. A typical Rs in daytime would be ca. 1cm/s = 0.01 m/s though, at which point Rs = 100 s/m.
2. Those values are not possible. I would also check for bugs, and maybe also check that PARshade is actually calculated at night - maybe also set to some big number when it doesn't matter.

As well as a careful check of the code, I would start with some print outs every time-step of the values for a certain location. That might help identify if things are actually being calculated at night time, and to check that daytime values are reasonable.
Best wishes
Dave