Instrumentation
The instruments that produced the measurements in this dataset, and the periods over which each was in place. Sensor identities here come from three sources, in order of authority for a given question:
- the datalogger programs, which name the channel, its sensor and its conversion constants, and are the only source that says how a raw signal became a value;
- the GIN fieldbook device columns (
Device Name,Device Model), which name the physical unit and its serial number at a location; - Yearly Notes, whose
Setup ECtable is the authority for the eddy covariance setup periods, sensor separations and flux-run configuration.
The GIN export records when an entry was written, which is not when a device was installed. Entries dated 1 January 2016 (and 2003, 2006) are backdated inventory imports made when GIN was introduced, so a device whose earliest entry carries one of those dates was already at the site and its true installation date is not in the export. Only entries describing an event — a replacement, a repair, a device marked defective — date anything.
Eddy covariance system, 47 m
Two gas analysers were operated at this level, and the dataset is built per analyser rather than per year.
| instrument | role | period |
|---|---|---|
| Gill HS-50 sonic anemometer | wind components, sonic temperature | 2004-present, orientation 209° |
LI-COR LI-7500 (open path, IRGA75) |
CO2 and H2O densities | 2004 until removal on 12 December 2017 |
LI-COR LI-7200 (enclosed path, IRGA72) |
CO2 and H2O mole fractions | from 11 January 2016 |
The two analysers ran in parallel from January 2016. The LI-7500 was removed from the site on 12 December 2017 but continued to write empty values into the data stream until it was taken out of it on 31 January 2018, which is why the setup table lists it for two further periods with no flux run. IRGA72 itself spans two physical LI-7200 units, exchanged inside the long 2019 gap; the second has a different column set in the raw stream. The analyser also moved on the boom in 2023, changing its separation from the sonic. All of this is dated per setup period in Yearly Notes, which should be read there rather than summarised.
The fieldbook records the enclosed-path system at this level as an LI-7200RS head with an LI-7550 analyser unit and an LI-7200-101 flow module.
Meteorological sensors, 47 m
These produce the tower series documented under Meteorological data.
| variable | instrument | period | source |
|---|---|---|---|
TA, RH |
Rotronic MP101A, read as a single-ended analog voltage (multiplier 0.1, offset 0) | until 21 January 2016 | CR10X logger program |
TA, RH |
Campbell Scientific CS215, on SDI-12 (multiplier 1) | from 21 January 2016 | CR1000 logger program |
SW_IN, LW_IN |
Kipp & Zonen CNR1, SN 020484, sensitivity 10.03 µV W-1 m2 (multiplier 99.7009, offset 0) | 14 September 2005 until December 2021 | CR10X and CR1000 logger programs |
SW_IN, LW_IN |
Kipp & Zonen CNR4, SN 212965, sensitivities 13.89 (SW in), 14.38 (SW out), 10.85 (LW in), 11.33 (LW out) µV W-1 m2 | installed 14 December 2021 | fieldbook |
PPFD_IN |
Kipp & Zonen PAR LITE, SN 050590, sensitivity 5.65 µV µmol-1 m2 s (primary, incoming) | installed 8 January 2016 | fieldbook |
PPFD_OUT |
Kipp & Zonen PAR LITE, SN 050603, sensitivity 5.26 µV µmol-1 m2 s (secondary, outgoing) | installed 8 January 2016 | fieldbook |
| PAR, total and diffuse | Delta-T BF2 sunshine sensor, SN BF2116 | entries 2016-2024, active | fieldbook |
| PAR | Kipp & Zonen PQS-1, SN 110145 | at this level from July 2011, inactive in every later entry | fieldbook |
| wind speed | Vector Instruments A100LK cup anemometer, SN 16697, replacing a broken A100L | installed 8 January 2016 | fieldbook |
| — | Campbell Scientific CR1000 datalogger | from January 2016 (CR10X before) | fieldbook, logger programs |
The 8 January 2016 date covers three of these rows because they were one visit: the boom was retracted that morning and the LI-7200 with its analyser and flow-module box, the replacement cup anemometer, both Kipp & Zonen PAR sensors and a new tower box were installed together. The LI-7200’s first raw binary is three days later, on 11 January 2016. A new reflected-PAR sensor had been fitted once before, at the end of June or beginning of July 2008; that entry is a remark added after the fact and dates the work only to within about a fortnight.
Two things about this table are worth stating plainly.
The temperature and humidity sensor is identified from the logger programs alone. The fieldbook records no temperature or humidity device at the 47 m level for the whole period of this dataset; the first such entry is a Campbell HygroVUE10 in June 2026, after the record ends. The MP101A and CS215 identifications, and the January 2016 date at which they changed, rest on the CR10X and CR1000 programs and on the step the data themselves show. See Air temperature, where that step is quantified and corrected.
The radiometer change is dated by the fieldbook, the calibration by the logger programs. The CNR1 has no device entry of its own — it predates GIN — but a 2008 entry recording a relay replacement for it on the tower’s CR10X meteo logger confirms it was in service then. The CNR4 was installed on 14 December 2021. Neither instrument change moved the shortwave series measurably, which is asserted rather than assumed — see Incoming shortwave radiation.
The CNR4 was installed on 14 December 2021, and the installing entry notes that the logger script still needed to be adapted to the new calibration constants. The logger program was updated on 7 January 2022, adding the four CNR4 sensitivities and new raw-voltage variables.
The two dates are 24 days apart. What the logger recorded in between has not yet been established: if the CNR4 was read through the CNR1’s multiplier, the radiation values of that period are wrong by the ratio of the two sensitivities. Anyone using December 2021 or early January 2022 radiation data should treat that window as unverified until it has been checked against the screened series. This is a question about a 24-day window, and the continuity checks in Incoming shortwave radiation work on seasonal and annual ratios, which would not necessarily resolve it.
Soil profile, forest floor (FF1)
The soil sensors were replaced as a set on 19 March 2020, which is the single most important date for the soil variables: it is a change of sensor generation with no overlap, so the step across it cannot be calibrated away.
| variable | instrument | depths | period |
|---|---|---|---|
| soil water content | Decagon ECH2O EC-20 | 0.05, 0.1, 0.2, 0.3 m | until 19 March 2020 |
| soil water content | METER TEROS 12 | 0.05, 0.1, 0.2, 0.3, 0.5 m | from 19 March 2020 |
| water potential | Decagon MPS-2 | 0.05, 0.1, 0.6 m | until 19 March 2020 for the shallow depths |
| water potential | METER TEROS 21 | 0.2, 0.3, 0.5 m | from 19 March 2020 |
| soil temperature | Campbell 107 thermistor | 0.05 m | until March 2021 |
| soil temperature | Campbell 109 thermistor | 0.05 m | from 24 March 2021 |
| soil heat flux | Hukseflux HFP01 | 0.05 m | throughout |
The 0.5 m depth exists only in the TEROS 12 generation, which is why the soil-water-content product carries a homogenised second column at four depths and deliberately none at 0.5 m. A second profile, FF2, carries MPS-2 water potential sensors at 0.05, 0.1, 0.15, 0.2 and 0.3 m. Coverage, flags and the sensor-generation step are documented under Soil water content and Soil temperature.
The subcanopy station (M1_2) carries a CS215 temperature and humidity sensor, installed on 26 March 2021 to replace a Rotronic MP100, alongside an Apogee SQ-521 and a LI-COR LI-190SA quantum sensor, an Apogee SN-500-SS net radiometer and a W200P wind vane. Forest-floor acquisition is a CR1000 with an AM16/32B multiplexer until March 2021 and an ARK-1124C from October 2021.
Profile masts
A temperature, humidity and wind profile is operated on the tower and on satellite masts at the site (T1_17.5, T1_35, M2, M3, M4). Its temperature and humidity sensors are Rotronic units of several generations — MP101, MP400H and MP402H transmitters with HygroClip S2, S3 and HC2-S3 probes, with individual heads replaced repeatedly between 2015 and 2021 — and its wind sensors are Gill WindSonics. None of these profile sensors contributes to this dataset, which takes its meteorology from the 47 m level and the forest floor. They are listed here only because published descriptions of the site sometimes name them.
Published descriptions that disagree
Three sensor identities given in the literature do not match the fieldbook or the logger programs. They are recorded here so that a reader comparing this dataset against those papers is not left to wonder which is right.
Shekhar et al. (2024) give the site’s temperature and humidity sensor as a Rotronic HygroClip HC2-S3. The fieldbook does hold HygroClip HC2-S3 units at CH-LAE, but on the profile masts (M3, M4, T1_35), never at the 47 m level that supplies this dataset, and the logger programs give the MP101A and CS215 above.
The same study gives soil moisture as a Decagon ECH2O EC-5. The string EC-5 does not occur anywhere in the fieldbook export; the CH-LAE profile is EC-20 and then TEROS 12, as above. The study assigns EC-20 to the subalpine site it compares against, so the two sites’ sensors appear to have been transposed.
The same study assigns the Delta-T BF2 radiation sensor, serial BF2116, to the subalpine site. That serial is registered in the fieldbook at CH-LAE at the 47 m level.
None of this affects the values in either dataset; it affects only what a reader concludes about which instrument produced them.