L2 Lecture Note

8/11/2019 L2 Lecture Note

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AmeriFlux Standardized Level 2 Data FilesMay 2014

Recognizing the need and convenience for some users to be able to easily obtain data

files containing long-term records from AmeriFlux sites in a common, standardized

format, the AmeriFlux data activity within the Carbon Dioxide Information AnalysisCenter CDIAC! at "a# Ridge $ational %aboratory &roduces the standard files &resented

here' (hese files contain data &rovided by individual site investigators for individual

years that have been chec#ed and reformatted by CDIAC' (hese %evel ) %)! filescontain the same data available from the CDIAC AmeriFlux *ite and Data +x&loration

*ystem htt&ameriflux'ornl'gov!'

.hen using these files /%+A*+ adhere to the AmeriFlux fair-use data &olicy listed on

each data file as &art of the standard header record' If you have 0uestions about the

content, use, or citation of these data, &lease contact (om 1oden bodenta2ornl'gov! or

1ai 3ang yangb2ornl'gov!'

For some sites e'g', 4aira Ranch, California! both ga&-filled files and files with &eriods

of missing data are furnished' *e&arate directories are &rovided for ga&-filledga&5filled! and non ga&-filled with5ga&s! records' (he basic file naming convention

is 6A7F5CCFID5yyyy5%)58854999'csv: or 6A7F5CCFID5yyyy5%)58854999'nc:'

A7F denotes the files are from the AmeriFlux networ#' CC is a two-character countrycode e'g', ;* for the ;nited *tates, CA for Canada!' FID is a uni0ue, three-character

site identifier assigned to all flux sites worldwide e'g', D#< is assigned to the Du#e

Forest loblolly &ine site!' A com&lete list of the AmeriFlux sites and their country code-

site identifiers are &rovided at htt&ameriflux'lbl'govAmeriFlux*ites/ages*ite-7a&'as&x' yyyy is the sam&ling year A'D' or C'+' e'g', =>>?!' %) reflects the AmeriFlux

&roduct level i'e', %evel )!' 88 identifies whether the file contains records with ga&s.@! or offers ga&-filled @F! records' 4999 denotes the release version for this&articular site e'g', 4B re&resents the seventh release of a new set of %) files for site

FID!' (he %) files are &rovided as A*CII text files with each variable se&arated by

commasi'e', comma-se&arated value or 'csv files! or in $etCDF format 'nc files!' +verycsv file contains a =B-line header record followed by data records' (he basic content of

the header record and the order of the variables &resented in the data records are identical

for each file, regardless of whether the files are ga&-filled or not' 7issing values orvalues set to missing by CDIAC during their AC chec#s are denoted by ->>>>'

/arameters not re&orted by the site investigator are denoted by ->>>'

Content and Format of Header Records

%ine = *itename

%ine ) %ocation including latitude and longitude coordinates decimal degrees,$ E + hemis&heres have &ositive values, * E . hemis&heres have

negative values! and elevation masl!

%ine < /rinci&al investigator name%ine +cosystem ty&e according to I@1/ classifications
http://ameriflux.ornl.gov/mailto:[email protected]://ameriflux.lbl.gov/AmeriFluxSites/Pages/Site-Map.aspxhttp://ameriflux.lbl.gov/AmeriFluxSites/Pages/Site-Map.aspxhttp://ameriflux.ornl.gov/mailto:[email protected]://ameriflux.lbl.gov/AmeriFluxSites/Pages/Site-Map.aspxhttp://ameriflux.lbl.gov/AmeriFluxSites/Pages/Site-Map.aspx


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%ine G File creation date

%ines -=< AmeriFlux fair-use data &olicy

%ines =-= File origin and bac#ground%ine =B +-mail contact for 0uestions

%ine =? %isting of the variables and order for each data record

%ine => ;nits for each variable listed in line =G%ine ) *ummary record that identifies the &ercentage of non-missing values for

each column

Content and Format of Data Records

Variable Name Description and Units

3+AR 3ears A'D' or C'+', values range from =>>= to )='

@A/ Indicator used to identify whether C") flux estimates FC! arefurnished for a &articular recordH denotes an FC measurement is

&resent and -= denotes no FC measurement is &resent' *ummaryfiles sitename'html! are also &rovided in each subdirectory to aid

users in determining the availability of data for s&ecific sites and

variables'

D(I7+ %ocal standard time of dayH each half-hour e0uals ')?


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(*) *oil tem&erature ex&ressed in degrees C'

(*)de&th) 7easurement de&th for (*), ex&ressed in cm'

/R+C (otal rainfall or wintertime &reci&itation within the measurement&eriod ex&ressed in mm'

RJ Relative humidity of air, ex&ressed as a &ercentage, measured Lustabove the cano&y'

/R+** 1arometric &ressure ex&ressed in #/a'

C") C") concentration ex&ressed in umolmol'

4/D 4a&or &ressure deficit, as the difference between the saturation

water va&or &ressure and the measured water va&or &ressure,ex&ressed in #/a' 4/D is calculated from relative humidity RJ!

and air tem&erature (A! or from water va&or concentrationJ)"!, (A, and barometric &ressure /R+**!'

*.C= *oil water content, based on time-domain measurement methodssensitive to dielectric &ermittivity, at de&th = ex&ressed as a

&ercentage'

*.C) *oil water content, based on time-domain measurement methodssensitive to dielectric &ermittivity, at de&th ) ex&ressed as a

&ercentage'

7easurement de&ths and column de&ths in cm for *.C= and

*.C) are &rovided in a table at the bottom of this document'

Rn $et radiation ex&ressed in .m)' /ositive values denote

downwards'

/AR Incoming &hotosynthetically active radiation i'e', radiation in the' to 'B micrometer waveband!, measured above the cano&y, and

ex&ressed in umolm)s'

Rg Incoming global solar radiation shortwave radiation, '=G to '

micrometer waveband! including both direct radiation and diffuse

radiation, measured above the cano&y, and ex&ressed in .m)'

Rgdif Incoming diffuse global solar radiation including reflected and

scattered radiation from all &ortions of the s#y, measured above the

cano&y, and ex&ressed in .m)'


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/ARout Reflected &hotosynthetically active radiation ex&ressed inumolm)s'

Rg"ut "utgoing global solar radiation shortwave radiation, '=G to '

micrometer waveband!, measured above the cano&y, ex&ressed in.m)'

Rgl Incoming longwave radiation i'e', radiation in the to =micrometer waveband!, measured above the cano&y, ex&ressed in

.m)'

Rgl"ut "utgoing longwave radiation, measured above the cano&y,ex&ressed in .m)'

J)" .ater va&or concentration above the cano&y ex&ressed in

mmolmol'

R+ (otal ecosystem res&iration ex&ressed in umolm)s'

@// @ross &rimary &roduction, including total ecosystem res&iration

R+! and net ecosystem exchange $++!, ex&ressed in umolm)s'@// is calculated as @// K R+ - $++

C")to& If more than one concentration is re&orted by the site investigator

the measurement closest to the surface is &resented above as C")and the measurement from the highest sam&ling &oint is re&orted

here as C")to& in umolmol'

C")height Indicates the height of the C")to& measurement ex&ressed in

meters'

A/AR (he amount of &hotosynthetically active radiation /AR!

assimilated by the cano&y and understory as determined by the

difference between above-cano&y /AR measurements and ground-

level /AR measurements' A/AR values are ex&ressed inumolm)s'

/ARdif Incoming diffuse &hotosynthetically active radiation i'e', radiationin the ' to 'B micrometer waveband!, measured above the

cano&y, and ex&ressed in umolm)s' Diffuse /AR includes

reflected and scattered radiation in the ' to 'B micrometerwavebands from all &ortions of the s#y'


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A/AR&ct (he &ercentage of incoming &hotosynthetically active radiation

/AR! assimilated by the cano&y and understory' A/AR&ct values

are ex&ressed as &ercentages'

M% Atmos&heric stability &arameter calculated from M% where M is

the measurement height and % is the 7onin-"bu#hov length' M%is unitless'


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Measurement heights expressed in meters !or the edd"#covariance s"stems$

Site name Measurement height %m&

Ai#en )G'

Ana#tuvu# River moderate burn site )'BAna#tuvu# River severe burn site )'B)

Ana#tuvu# River unburned site )'G

AR7 *@/ site ')?

AR7 burn site G

At0asu# )'

Audubon @rasslands '

Austin Cary


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Flagstaff managed forest site )'Jarvard Forest hemloc# site )B'

Jeritage %and Conservancy >'

Jowland east tower harvest site )>'

Jowland main )>'

Jowland west tower site )>'

Imnavait Cree# heath tundra


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;CI =>>? burn site '

;CI )< burn site '

;71* '

;71* Disturbance

.alnut River )'=

.illow Cree# )>'

.ind River B'

.isconsin Clearcut Red /ine '

.isconsin Clearcut 3oung Jardwoods '

.isconsin 7ature Jardwoods )'

.isconsin 7ature Red /ine )


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Measurement depths and integration depths expressed in cm !or S()* and

S()2' $A denotes cases where only one soil moisture value was re&orted by the

&rinci&al investigator'

Site name S()* S()2

Ana#tuvu# River moderate burn site )'G $AAna#tuvu# River severe burn site )'G $A

Ana#tuvu# River unburned site )'G $A

AR7 *@/ site = G before

=


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Florida +verglades (aylor *lough short

hydro&eriod marsh

-=G $A

Fort /ec# G )-

)?! =)


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"hio "a# "&enings - wet burn site )G ?= burn site > $A

;CI =>?> burn site = $A

;CI =>>? burn site == >

;71* -

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