Stable water vapour isotope data from ATR flights during EUREC4A
#=================================================================

Level 1 data:
- Picarro cavity ring-down spectrometer installed on ATR, version L2130 from 2012, setup schematic setup_EUREC4A_ATR_PICARRO.jpg
- postprocessed following Aemisegger et al., 2012 and in Sodemann et al. 2017
- VSMOW-SLAP normalisation according to IAEA, 2017
- Standards isotope composition: STANDARD 1, d18O: -11.5 pm 0.2, d2H: -80.0 pm 0.6; STANDARD 2, d18O: -40.46 pm 0.1, d2H: -325.98 pm 0.1, values in permil 
- Samples from standard calibration runs were taken during campaign but have not yet been measured in the lab, will be incldued for level 2 data
- NaN values for missing data points due to instrument failure or calibration runs
- Flags for different parts of flights (subcloud layer, cloud base, stratiform layer) not yet available, will be added for level 2 data


Variables on files:
#================
time in seconds since 19700101_00
d18O in permil, 1 Hz and standard deviation
d2H in permil, 1 Hz and standard deviation
dexc in permil, 1 Hz mean and standard deviation
H2O in ppmv, 1 Hz mean and standard deviation
q in g/kg, 1 Hz mean and standard deviation
lat in deg N
lon in deg W
ALT in m
mr_atr mixing ratio from SAFIRE dew point mirror in g/kg (not on all flights)

Note that in clouds we usually measure total water (water vapour+evaporated cloud water).
Further postprocessing is needed to extract the cloud vapour and cloud liquid water signals.


Contacts for questions:
#================
Franziska Aemisegger: franziska.aemisegger@env.ethz.ch
Leonie Villiger: leonie.villiger@env.ethz.ch

References:
#================

Aemisegger, F., Sturm, P., Graf, P., Sodemann, H., Pfahl, S., Knohl, A., and Wernli, H.: Measuring variations of δ18O and δ2H in atmospheric water vapour using two commercial laser-based spectrometers: an instrument characterisation study, Atmos. Meas. Tech., 5, 1491-1511, https://doi.org/10.5194/amt-5-1491-2012, 2012.

Sodemann, H., Aemisegger, F., Pfahl, S., Bitter, M., Corsmeier, U., Feuerle, T., Graf, P., Hankers, R., Hsiao, G., Schulz, H., Wieser, A., and Wernli, H.: The stable isotopic composition of water vapour above Corsica during the HyMeX SOP1 campaign: insight into vertical mixing processes from lower-tropospheric survey flights, Atmos. Chem. Phys., 17, 6125-6151, https://doi.org/10.5194/acp-17-6125-2017, 2017.

IAEA, Reference sheet for international measurement standards, VSMOW2-SLAP2,
https://nucleus.iaea.org/rpst/Documents/VSMOW2_SLAP2.pdf, 2017.