Location and format of L4 Ameriflux Observations have changed

[braczka]

Describe the bug

The repository for the L4 Ameriflux data used for land modeling has changed and the current documentation page for the L4 obs converter data sources link is broken. (broken link)

As far as i can tell the current repository has been migrated to here: https://fluxnet.org/data/download-data/ or https://ameriflux.lbl.gov/data/download-data/.

This is really two issues: the documentation needs to be updated, and the observation converter needs to be updated to reflect the change in repository and change in file format.

Which model(s) are you working with?

Relevant to CLM or any land model using carbon, water land-atmosphere fluxes.

Have you modified the DART code?

I have not made any modifications to the ~/observations/obs_converters/Ameriflux/level4_to_obs.f90 code yet, but the file format of the repository has changed, thus changes are required..

[hkershaw-brown]

Note for building the Ameriflux observation converter:

cd DART/observations/obs_converters/Ameriflux/work
./quickbuild.csh

Running the converter:

./level4_to_obs  

The converter reads a bunch of options from the file input.nml. The level4_to_obs options are in the &level4_to_obs_nml section of the file:

input.nml

 26 &level4_to_obs_nml
 27    text_input_file = '../data/USHa12003_L4_h.txt'
 28    obs_out_file    = 'obs_seq.out'
 29    year            = 2003
 30    timezoneoffset  = -6
 31    latitude        =  42.5378
 32    longitude       = -72.1715
 33    elevation       = 353
 34    flux_height     = 29
 35    maxgoodqc       = 3
 36    verbose         = .TRUE.
 37    /

[hkershaw-brown]

@braczka @nancycollins Are there any of the old format files hanging around, e.g. '../data/USHa12003_L4_h.txt' ? Maybe on Cheyenne?

[braczka]

I did not locate any of these files the last time I looked at this -- but I didn't give it a thorough look because I knew the file formatting had likely changed. I agree, It would be helpful to have these to test the existing obs_converter though......will see if I can locate some.

[hkershaw-brown]

@mjs2369 added a Makefile to https://ncar.github.io/dart-developers-guide/documentation.html in case you want to build the documentation on your machine with Sphinx

[nancycollins]

sorry - i didn't ever work with the ameriflux converter, and don't know of any input files.

[nancycollins]

i did a bit of poking around. i did not find any input data, but in the observations/obs_converters/Ameriflux/shell_scripts is a script that creates a series of obs_seq files from what i presume was Ameriflux data. the output files are on cheyenne, here:

/glade/p/cisl/dares/Observations/FluxTower

this is based on the filenames matching up with the names used in the script. they might be useful in validating any input files that are found.

[braczka]

Thank you Nancy -- I did a bit of poking around as well, and apparently the old L4 style format is still hosted by the University of Montana Terrasystems group. I downloaded a few of the test files here if you want them: /glade/scratch/bmraczka/AmerifluxL4_oldformat

[nancycollins]

i believe this is going to be marlee's project, so i'm going to back away slowly and not make eye contact!! :)

[braczka]

Yes ! Agreed -- Marlee was assigned to this fun project :-)

[mjs2369]

Thank you, Brett and Nancy, for locating those files for me! I will look into it :)

[braczka]

I have been able to make some headway on other site-level land DA PR's (e.g. #461) and have circled back to this one. It would be useful to have an updated Ameriflux L4 obs converter given interest in site level land DA work, including state and parameter estimation using CLM. Given the complexity of eddy covariance data with the new Ameriflux format (e.g. temporal resolution, uncertainty, QA/QC) it makes sense for me to lead this project. (I have a lot of experience working with land-atmosphere flux data). I will start working on a PR in near future, and will assign @mjs2369 to review to help with the software implementation.

[mjs2369]

@braczka sounds great, thanks for taking the lead on this

[braczka]

This issue fixed in #478 .