EC Raw Binary Format (CH-LAE)


See here for more info about the EC raw binary format.

 

Setup since 2004

wdt_ID Year FRMT GA1S Binaries From Binaries To SA GA 1 GA 2 SA Hei/Ori GA1 Sep GA2 Sep Notes
Year FRMT GA1S Binaries From Binaries To SA GA 1 GA 2 SA Hei/Ori GA1 Sep GA2 Sep Notes

Notes

(1) SA: “axis” orientation

(2) 2 extra bytes in data stream Note 19 Oct 2018 (LH): I am not sure what the problem here was, data look like they have the same structure despite the 2 extra bytes mentioned. Needs check in case of recalculations. For now, this is listed as the same format as 2015-3.

(3) QCL: ver1 var0

(4) correct # of bytes

(5) (1) For some reason 2007 is a special case, because using the Horst (1997) spectral correction yielded unrealistic results, i.e. the spectral correction factor for CO2 was far too high (up to 11 instead of 1.05). Therefore, this year was calculcated using the spectral correction by Massman (2000, 2001). This was a problem only with EddyPro version 521, Flux Run v2015-03, and was solved in later versions of EddyPro.

(6) QCL: ver1 var2

(7) QCL: ver1 var2 EMPTY

(8) There was (is?) an error in the raw binary filename timestamp between 2013-07-06 and 2013-07-12. relevant fieldbook entry: “2013-07-12: time on moxa was wrong. changed on 16:44 from 22:43:50 to 15:44”, i.e. 6 hours + I renamed all files from 2013070615.b02 until (incl.) 2013071214.b00 manually by subtracting 6 hours. For example: 2013070802.b00 was renamed to 2013070720.b00.

(9) Removed IRGA75 from site on 2017-12-12, see entry in GIN.

(10) IRGA75 is not on site anymore, but still part of the data stream, i.e. logged data for IRGA75 are empty.

(11) IRGA75 is now removed from the data stream. Since Wed Jan 31 11:25:37 2018 we only have the Licor 7200 running.

(12) SA orientation is possibly 206° from here on until now. In case of recalculations, please check.

(13) From now on: In addition to the normal lag time between IRGA and sonic we have an artificial lag time of 12 seconds due to the buffer, which needs to be considered when processing the files when searching for the best correlation between vertical wind speed and CO2/H2O concentration. For more info see here. This also affects all following time periods.

(14) IRGA72+ installed, IRGA75 was removed from the site.
IRGA72+ has now 13 columns instead of 12 columns. New: diag_val and signal_strength. Not logged anymore: status_byte.

(15) Calibration gas: There was an issue with the calibration gas used to calibrate the IRGA72. As a consequence, the CO2 concentrations in the raw data files have to be multiplied by 0.974 before flux calculations. This can be directly done during the conversion of the raw data binary files to CSV files when using the FCT Flux Calc Tool. Note the provided EddyPro settings under Downloads at the end of this page: these settings already consider the correction and apply the gain to the CO2 concentration measurements during the conversion from raw binary to CSV. For more info about this issue see here: Wrong Calibration Gas 2017. Affected time period: all IRGA72 CO2 concentrations between 2017121417.L22and 2019031523.L20.

(16) IRGA75 temporarily installed as replacement for the defective IRGA72. The IRGA75 is not affected by the calibration gas issue described in (15). IRGA72 was dismounted and removed from site. However, I found this info on GL-PROCESSING (in the fluxes Level-0 folder): “Problems with LI-7200 starting on December 22nd 2018. Replaced by LI-7500 in January 2019. The LI-7500 consistently displays IRGA AGC too low and there seems to be a problem with the fluxes. LI-7500 replaced on March 20 2019 with the LI-7200, and the fluxes are back to normal.” (written by unknown)

(17) The IRGA72 was replaced with another IRGA72 on 11 Jan 2019, the data stream is the same. However, it seems like both IRGA72 were defective. In this time period, there are mostly incomplete files and it is possible that no reasonable fluxes can be calculated.

(18) From now on: The calibration gas issue described in (15) is now solved, the correct gas was used this time.

(19) During this time period there was an issue with the IRGA72: no clear lag time could be found (tested in search windows 0-20s and -50 to +50s) in contrast to the period before and after. On 7 Jun 2018, the flow module of the IRGA72 was replaced and after the replacements lag time detection again worked as expected. It is likely that the IRGA72 flow module was broken during this whole period. If e.g. CO2 fluxes are calculated during this period, they look somewhat like CO2 fluxes until incl. 30 May, but then start to fluctuate around zero between 31 May and 7 Jun. For the H2O flux, the problematic time period seems to start even earlier on 13 May.

 

Legend

  • Binaries From … The first valid file that contains the first data for the respective year.
  • Binaries To … The last valid file that contains the last data for the respective year.
  • Format … The format settings that were used. FRMT files contain information about the sequence of incoming data, e.g. first the SA, then GA1. Generally, the FRMT files contain correct information about these data sequences, but not necessarily about processing settings because the settings are different depending on the use case (e.g. preliminary fluxes use settings that speed up processing time).
  • GA … Gas analyzer
  • GA1 Sep … Northward, Eastward and Vertical separation of the GA inlet in relation to the SA center, given in mm (Note: EddyPro needs distances in cm), for more info see here
  • HS50 … Gill HS-50 sonic anemometer
  • IRGA72 … LI-COR 7200 enclosed path infrared gas analyzer.
  • SA … Sonic anemometer.
  • SA Hei/Ori … Height and orientation of SA. Orientation is the direction in which the north arrow of the SA points.
  • Year … Given with an underscore, whereby the underscore denotes a change in the data format. For example, in 2015_2 the QCL was added to the data file, but the QCL was not installed in 2015_1.

 

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