[Reddyproc-users] A matter of units

[Jon Paul McCalmont [jpm8]]

Hi Efron,

I don't think it's g C m-2 day-1 anyway, I had a look at a Daily Sum plot from my gapfilling and it extends down to around -300 at the height of the growing season, if this was g C m-2 this would translate to an accumulation of 3 tonnes of carbon per hectare per day which would be very unrealistic. I summed a typical day in umol m-2 s-1 (i.e. half-hour mean multiplied by 1800 to get the half hour sum then sum all half hours for that day) and that comes to nearly 1 million umol so the units are not umol m-2 day-1 either.
You would probably be better to produce your own integration sums from the half hour gapfilled data and produce your own plots, you then know exactly what units you're using.
Remember that original NEE units are a half hour mean (umol m-2 s-1) so must be converted into half hour totals (ideally in g C m2) before summing across the year.
To convert from umol m-2 s-1 to g C m-2 halfhour-1... 
((umol m-2 s-1 *1800)*10^-6)*12

Sorry if you know all this anyway but thought it might be helpful.

Regards,
Jon





-----Original Message-----
From: reddyproc-users-bounces at lists.r-forge.r-project.org [mailto:reddyproc-users-bounces at lists.r-forge.r-project.org] On Behalf Of Efren Lopez Blanco
Sent: 22 April 2015 10:38
To: General information about usage and problems with the REddyProc package
Subject: Re: [Reddyproc-users] A matter of units

Hi Kersin,

I am talking about this:

	EddyProc.C$sPlotDailySumsY('NEE_f','NEE_fsd', Year.i=2013) #Plot of sums with uncertainties

Are the NEE daily sums calculated in umol/m2/day? gC/m2/day? I am interested in the accumulated NEE over a year.

Best,
Efren


On 22 Apr 2015, at 11:03, Kerstin Sickel <ksickel at bgc-jena.mpg.de> wrote:

> Hello Efron,
> 
> unfortunately there is probably a bug, it will be fixed in new version.
> The calculation is in the plotting routines.
> 
> Sorry for no  better answer.
> 
> Have a nice day.
> Kerstin
> 
> On 4/22/2015 10:23 AM, Efren Lopez Blanco wrote:
>> Hello,
>> 
>> Does anyone recognise the units from "Daily sums with uncertainties of NEE_f" graph?. How is it calculated? I should clarify this before I introduce these graphs on my presentation. Thanks in advance!
>> 
>> Best,
>> Efren
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