READ ME for EUREC4A_M161_Picarro_1min_v1.2.nc

netcdf EUREC4A_M161_Picarro_1min_v1.2 {
dimensions:
        time = UNLIMITED ; // (0 currently)
variables:
        double time(time) ;
                time:units = "seconds since 2020-01-01 00:00:00 UTC" ;
        double lon(time) ;
                lon:long_name = "Longitude" ;
                lon:units = "degrees_east" ;
        double lat(time) ;
                lat:long_name = "Latitude" ;
                lat:units = "degrees_north" ;
        double ppmv_H2O(time) ;
                ppmv_H2O:long_name = "H2O Concentration" ;
                ppmv_H2O:units = "ppmv" ;
                ppmv_H2O:missing_value = 9.969209968386869e+36 ;                
        double q_H2O(time) ;
                q_H2O:long_name = "Specific Humidity" ;
                q_H2O:units = "kg/kg" ;
                q_H2O:missing_value = 9.969209968386869e+36 ;
        double d18O(time) ;
                d18O:long_name = "Oxygen 18/16 isotope delta value of water vapor" ;
                d18O:units = "delta per mil" ;
                d18O:missing_value = 9.969209968386869e+36 ;
        double dD(time) ;
                dD:long_name = "D/H isotope delta value of water vapor" ;
                dD:units = "delta per mil" ;
                dD:missing_value = 9.969209968386869e+36 ;
        double qc_flag(time) ;
                qc_flag:long_name = "Data Quality Control Flag" ;
                qc_flag:key = "1 = Normal, 2 = Rain Occurring, 3 = Post Rain, 4 = Smokestack/Wind Mask, 5 = NaN/Missing/Unusable "                 
 
// global attributes:
                :Title = "EUREC4A M161 Continuous In-Situ Water Vapor Isotopic Composition 1-min v1.2" ;
                :Author = "Sebastian Los <slos@unm.edu  https://orcid.org/0000-0002-6310-6414"  ;
                :PI = "Dr. Joseph Galewsky <galewsky@unm.edu  https://orcid.org/ 0000-0001-8236-6839"   ;
                :Collector = "Sebastian Los <slos@unm.edu" ;                
                :Experiment = "EUREC4A Field Campaign" ;
                :Platform = "RV Meteor" ;
                :Instrument = "Picarro L2130-i Cavity Ring-Down Spectroscopy (CRDS) Water Vapor Isotopic Analyzer
                :Collected = "2020 Jan 18 00:01:00 - 2020 Feb 21 23:59:00" ;
                :Created = "Aug 23, 2020"       ;
                :Updated = "March 17, 2022, July 1, 2022"  
                :Description = "Continuous water vapor isotopic time series. Delta values per mil on VSMOW-SLAP scale. Bulk uncertainties: d18O = 0.29, dD = 1.24. READ ME available at DOI." ;
                :History = "Verison 1.0: Original Level 1 data, Version 1.1 improves the calibration of isotopic time series, Version 1.2 updates the quality control flag"   ;                
                :version = "1.2" ;
                :DOI =  "https://doi.org/10.25326/83"
}

#=================================================================

Level 1 data (Version 1.0):
- Picarro L2130-i cavity ring-down spectrometer deployed aboard the Research Vessel Meteor during research cruise M161 of EUREC4A
- Inlet sampled relatively undisturbed air from above the air chemistry lab with a forward facing fetch (above the bow)
- Inlet sampling height was 20.3 m above the mean sea surface, from downward facing funnel to minimize rain and seaspray effects
- Inlet line of 505 cm length was heated to prevent condensation
- Daily calibration runs done throughout the cruise using a rotation of four reference standards
- Post-processing includes water vapor concentration dependence correction and VSMOW-SLAP normalisation
- Averaged from 1 Hz to 1 minute resolution
Version 1.1
- Calibration updated to remove 4 problematic calibration runs. Bulk uncertainies estimated at 0.29 and 1.24 per mil for d18O and dD respectively.
Version 1.2
- Qualtiy control flag updated. Previously masked wind/ship emission times now unmasked and flagged.
		qc_flag = 1 --> Normal conditions, high quality
		qc_flag = 2 --> Periods with rain occurring
		qc_flag = 3 --> Post rain periods (rain ending + 3 hours). Generally higher than typical delta values affected by precipitation processes that may or may not represent ambient conditions (rain evaporation from ship surfaces, cold pool air mass, etc.)
		qc_flag = 4 --> Periods with wind from 120 and 250 degrees relative to the bow (behind instrument). These may be contaminated by ship smokestack or other ship emissions
		qc_flag = 5 --> NaN values for missing data points due to instrument issues, calibration runs, measurement restrictions. Fill Value 9.969209968386869e+36

Variables in file:
#================
time, seconds since 01.01.2020 00:00:00 (UTC)
latitude, deg N, 1 min mean
longitude,  deg E, 1 min mean
ppmv_h20, Water vapor concentration ppmv, 1 min mean
q_h2o, Specific humidity g/kg, 1 min mean
d18O Oxygen ratio (18/16)in permil, 1 min mean
dD, Deuterium/Hydrogen (D/H) ratio in permil, 1 min mean

Contacts for questions:
#================
Dr. Joseph Galewsky, galewsky@unm.edu,  https://orcid.org/ 0000-0001-8236-6839
Sebastian Los, slos@unm.edu,  https://orcid.org/0000-0002-6310-6414

DOI:
#================
https://doi.org/10.25326/83