Experiment standard description (same all flights) » top »
Summary: The following data are normally collected (for exceptions see end of this text or dataset list): Ozone from two monitors (fast with 0.125 s temporal resolution from the chemiluminescence sensor and with 16 s from the u.v. photometer), CO with a gas chromatograph, submicrometer particles from three counters (CPCs), 14 aerosol samples from an aerosol impactor sampler , and 12 canisters of air samples in WAS (= Whole Air Sampler) for laboratory analysis of CO2, CH4, CO, N2O, SF6, ~40 halocarbons, ~15 hydrocarbons and the isotope composition (13C/12C, 14C/12C, and 18O/16O) of CO. Records describing meteorological conditions during the flight are based on ECMWF analyses. For general information about CARIBIC see the project description. Individual dataset summaries comprise species relevant details such as the instrumentation or the institute in charge. In the particular case of a few flights, data records might be missing or be affected by technical problems.

Species standard description (same for all flights)

Name: CO - carbon monoxide ; Acronym: CO » top »
Summary: Instrument: The CO analyzer for CARIBIC is a modified commercial gas chromatograph. The actual CO detection is based on the reaction of CO with hot mercuric oxide to produce CO2 and elemental mercury, which is sensed by its strong light absorption from a low-pressure mercury vapor lamp at 254 nm. Prior to detection the CO is separated on a gas chromatography column. The detection limit is better than 3 nmole/mole and sufficient to gauge CO in clean remote air masses. The repetition rate of the CO measurement is 130 s. (See also experiment and project summary.) Data format: Dataset consists of eight columns representing Date(UT), Time(UT), Longitude, Latitude, Pressure[hPa], p_height[m], Tpot[K] and CO[ppbv]. Coordinates of data probes are given explicitly while the 'boundary box' meta entries just represent the coordinates of start and destination airports. The data rows are headed by a set of text lines in CARIBIC metadata format - for interpretation cf homepage www.caribic-atmospheric.com.
Here the flight dependent comments from the flight table below will be inserted.
Short description: The CO analyzer for CARIBIC is a modified commercial gas chromatograph. cf www.caribic-atmospheric.com for more detail.
Accuracy: The detection limit is better than 3 nmole/mole and sufficient to gauge CO in clean remote air masses.
Consistency: Dataset covers one measuring flight
Completeness: complete
Process: complete, processed
Aggregation: 130s time resolution
Responsibility: MPCH, Air Chemistry

Name: OZONE (slow) ; Acronym: OM » top »
Summary: Instrument OMCAL (Ozone Monitor CALibrator) is a (modified) u.v. absorption monitor (Environnement O3-41M, Paris, France). It operates automatically. See also experiment summary. Data format: Dataset consists of eight columns representing Date(UT), Time(UT), Longitude, Latitude, Pressure[hPa], p_height[m], Tpot[K] and O3[ppbv]. Coordinates of data probes are given explicitly while the 'boundary box' meta entries just represent the coordinates of start and destination airports. The data rows are headed by a set of text lines in CARIBIC metadata format - for interpretation cf homepage www.caribic-atmospheric.com.
Here the flight dependent comments from the flight table below will be inserted.
Short description: OMCAL (Ozone Monitor CALibrator) is a (modified) u.v. absorption monitor
Accuracy: Detection down to pressures of lower than 150 hPa. After the first 20 min of flight the minimum detection limit is reached: +-4ppbv from 11/97 - 12/98 and +-3ppbv from 01/99 - 04/02 respectively.
Consistency: Dataset covers one measuring flight
Completeness: complete
Process: complete, processed
Aggregation: ~17s time resolution
Responsibility: Forschungszentrum Karlsruhe, Institute for Meteorology and Climate Research

Name: Isotopes and GC air sample analyses ; Acronym: IS » top »
Summary: Instrument: Air samples from CARIBIC flights were analysed for CH4, CO2, N2O, SF6, isotopic composition of CO (13CO, C18O, 14CO) and CO2 (13CO2, CO18O). For completeness and to aid interpretation, the continuously measured CO and O3 concentrations integrated over the sampling interval are also given (see CO and OM). CH4, CO2, N2O, and SF6 were determined by a gas chromatograph.Uncertainties are given as standard deviations of typically 20 replicate analyses. The delta13C(CO), delta18O(CO), delta13C(CO2), and delta18O(CO2) values were determined by an isotope ratio mass spectrometer [Brenninkmeijer, C.A.M., J. Geophys. Res. 98, 10595-10614,1993; Brenninkmeijer and Roeckmann, Geophys. Res. 102, 25477-25485, 1997; Brenninkmeijer et al., Chemosphere: Global Change Sci. 1, 33-52, 1999]. 14CO concentration was determined by an accelerator mass spectrometry (AMS) [Brenninkmeijer, C.A.M., J. Geophys. Res. 98, 10595-10614, 1993]. Data format: Dataset consists of 35 columns representing: Sample #, date, time, lon, lat (start, end, middle of the sampling interval), pressure[hPa], p_height[m], T[K], Tpot[K], CH4[ppb], uncertainty of CH4[ppb], CO2[ppm], uncertainty of CO2[ppm], N2O[ppbv], uncertainty of N2O[ppb], SF6[ppt], uncertainty of SF6[ppt], delta13C(CO)[0/00], delta18O(CO)[0/00], 14CO[molecule/cm3], delta 13C(CO2)[0/00], uncertainty of delta13C(CO2)[0/00], delta18O(CO2)[0/00], uncertainty of delta18O(CO2)[0/00], O3[ppb], CO[ppb]. Delta13C is given relative to V-PDB. For CO2, delta18O relative to V-PDB-CO2, for CO V-SMOW is used. Coordinates of data probes are given explicitly while the 'boundary box' meta entries just represent the coordinates of start and destination airports. The data rows are headed by a set of text lines in CARIBIC metadata format - for interpretation cf www.caribic-atmospheric.com
Here the flight dependent comments from the flight table below will be inserted.
Short description: Air samples taken during the CARIBIC flights were analysed for CH4, CO2, N2O, SF6, isotopic composition of CO (13CO, C18O, 14CO) and CO2 (13CO2, CO18O)
Accuracy: The CH4, CO2, and N2O measurements were calibrated using a standard gas mixture from NOAA. SF6 measurements were calibrated using a standard gas mixture from Heidelberg. The uncertainty in delta13C for CO is 0.2 0/00, for CO2 0.05 0/00. The uncertainty in delta18O for CO is 0.4 0/00, for CO2 0.1 0/00. Note that delta18O of CO2 has been affected by exchange with water vapor in the aircraft sampling cylinders. Note that delta18O of CO has been affected by the formation of CO in the aircraft sampling cylinders due to reaction of O3 with carbonaceous material. Details can be supplied separately.
Consistency: Dataset covers one measuring flight
Completeness: complete
Process: complete, processed
Aggregation: 20 min sampling mean.
Responsibility: MPCH, Air Chemistry

Name: non-methane hydrocarbons (NMHC) ; Acronym: NH » top »
Summary: Air samples were taken during the CARIBIC flights by a whole air sampler (WAS) into 21 l stainless steel canisters. Since most of the sample (typically at about 20 bar, i.e. about 400 l) was consumed by the isotope analysis, an aliquot of the sample (usually about 10 l) was taken into a 2 l stainless steel canister. These aliquots were within 2 weeks after the flight analysed for non-methane hydrocarbons (NMHCs) at the Max-Planck-Institute for Chemistry, Mainz and then sent for halocarbon analysis to University of East Anglia. The NMHCs were cryogenically enriched, desorbed, separated on capillary column, and detected by a mass spectrometer. The NMHC measurements started with the flight # 21 and were continued since. Data for alkanes, ethyne, and benzene are reported here. Data format: Dataset consists of 40 columns representing: Sample #, Date(UT), Time(UT), Lon., Lat. of sampling begin, Date(UT), Time(UT), Lon., Lat.of sampling end, Time(UT), Lon., Lat. of middle of the sampling interval, corresp. Pressure[hPa], Barometric height[m], T[C], Tpot[K], O3 [ppb], CO [ppb] both averaged over sampling interval (for completeness and to aid the interpretation), Ethane [pptv], Uncertainty (SD) of ethane measurement [pptv], Propane [pptv], SD of propane [pptv], Butane [pptv], SD of butane [pptv], Pentane [pptv], SD of Pentane [pptv], Hexane [pptv], SD of hexane, [pptv], 2-methyl propane [pptv], SD of 2-methyl propane [pptv], 2-methyl butane [pptv], SD of 2-methyl butane [pptv], 2-methyl pentane [pptv], SD of 2-methyl pentane [pptv], 3-methyl pentane [pptv], SD of 3-methyl pentane [pptv], Cyclohexane [pptv], SD of cyclohexane [pptv], Ethyne [pptv], SD of ethyne [pptv], Benzene [pptv], SD of benzene [pptv]. Coordinates of data probes are given explicitly while the 'boundary box' meta entries just represent the coordinates of start and destination airports. The data rows are headed by a set of text lines in CARIBIC metadata format - cf website www.caribic-atmospheric.com
Here the flight dependent comments from the flight table below will be inserted.
Short description: Air samples taken during the CARIBIC flights were analysed for non-methane hydrocarbons (NMHCs)
Accuracy: Internal consistency checks were applied to CARIBIC measurements to test their plausibility. They revealed implausibly high alkene concentrations probably due to contamination during sampling and/or storage. In addition, toluene could not be measured reliably. Thus only data for alkanes, ethyne, and benzene are reported here. Multicomponent NMHC standard gas mixtures prepared by National Physical Laboratory (NPL, 30 components, C2-C9) and National Center for Atmospheric Research (NCAR, 39 components, C2-C8) were used to calibrate the apparatus.
Consistency: Dataset covers usually 12 samples taken during the return flight.
Completeness: complete
Process: complete, processed
Aggregation: The data represent a mean value over a sampling interval of typically 20 min.
Responsibility: MPCH, Air Chemistry

Name: Submicrometer aerosol particles or condensation nuclei ; Acronym: CN » top »
Summary: Instrument: Three Condensation Particle Counters (CPCs, TSI Model 7610) with different lower threshold diameters (4, 12, and 18 nm) measure the number concentration of submicrometer aerosol particles in three different size ranges. The three CPCs were modified for low-pressure and aircraft application. The counting efficiency of the instruments was determined in the pressure range 160-1000 hPa. Data format: Dataset consists of 11 columns representing: Date, Time (UT), Lon., Lat., Alt.(feet), Static Press.(hPa), Static Temp.(K), Particle Number Concentrations in the size ranges N4-12: 4 nm to 12 nm, N12: 12 nm to 1300 nm, N18: 18 nm to 135 nm or 1300 nm, and a column containing a binary information about airmass origin: measurement in UT airmasses = 0, measurement in LS airmasses = 100. This classification was made using either in situ measured ozone data or, if these were not available, model derived PV values. The upper threshold diameter of the particle measurements (1300 nm) is determined by the 50 % sampling efficiency point of the inlet system. For some flights (99.03.13 - 00.08.17), a pre-impactor was used upstream of the third CPC. For these flights the smaller upper threshold diameter of 135 nm is valid. As the concentration of ultrafine particles (N4-12) is determined by subtracting the readings of the first two CPCs, for statistical reasons, N4-12 can show negative values (difference is normally smaller 10 % and within the experimental error). Using the data, you can assume N4-12 equal to zero in such cases. Given number concentrations are corrected for pressure dependent counting efficiency, coincidence, particle losses in the sampling line, and inlet sampling efficiency. Concentrations are given as "particles/cm^3" at standard conditions (1013.25 hPa, 273.15 K). Only data obtained during level flight are included, data from aircraft ascent and descent were omitted. Data points for which no reliable values are available are indicated by "-9999".
Here the flight dependent comments from the flight table below will be inserted.
Short description: aerosol particle number concentrations in three size ranges: N4-12 : 4 nm to 12 nm; N12 : 12 nm to 1300 nm; N18 : 18 nm to 135 nm or 1300 nm;
Accuracy: N4-12 ~35 %, N12 and N18 +- 10 %
Consistency: Dataset covers one measuring flight
Completeness: complete
Process: complete, processed
Aggregation: 2 or 4 s time resolution
Responsibility: IFT, Physics

Name: Position and Meteorology ; Acronym: PM » top »
Summary: These datasets represent meteorological information prepared by KNMI (Peter van Velthoven) for the CARIBIC project. The meteorological analysis of the CARIBIC measurement flights is based on ECWMF first guess fields (6-hour forecasts) with a resolution of 1x1 degree on ECMWF model levels. First guess fields from ECMWF were used until 13 September 2000, because ECMWF used a 3D-var assimilation scheme until then. For 3D-var, first guess fields are somewhat smoother than analyses. After 13 September 2002 ECMWF used 4D-var assimilation and its analyses were used, as first guess fields were no longer available. With 4D-var the analyses are much smoother than in 3D-var. Data format: ECMWF model data interpolated linearly in longitude, latitude, log(pressure) and time to the aircraft location. The following parameters are interpolated: Temperature (K), Potential vorticity (PVU), Potential temperature (K), Equivalent potential temperature (K), Specific humidity (10e-3 g/kg), Eastward wind component U (m/s), Northward wind component V (m/s), Vertical wind component W=dp/dt (1e-3 mbar/s, 0.1 Pa/s), Wind speed (m/s), Wind direction (deg), Water vapour volume mixing ratio, H2O (ppmv), Relative Humidity (%).
Here the flight dependent comments from the flight table below will be inserted.
Short description: ECMWF Model data along flight tracks: Temp./ windvelocity/ humidity .
Accuracy: The quality of ECMWF analyses is monitored and documented at ECMWF (http://www.ecmwf.int). The following expresses a subjective view by Peter van Velthoven: The accuracy of model parameters that are also measured can easily be checked. See e.g. http://www.knmi.nl/~/velthove/CARIBIC. The difference between modelled and measured temperatures and potential temperatures is usually less than 2 K, mostly less than 1 K. The horizontal wind speeds are relatively less accurate than temperatures. Measured and modelled wind speeds can deviate up to about 10 m/s. The modelled wind directions are usually quite accurate (within 20 degrees) except when the wind speed is very low, so that the direction is badly defined. The relative and specific humidities are not very accurate because the radiosonde humidity measurements are quite inaccurate still. Errors in RH of 30 % are no exception.
Consistency: Dataset covers one measuring flight
Completeness: complete
Process: complete, processed
Aggregation: 1x1deg, 60 hybrid sigma levels, 6 h Interpol. to flight position every min.
Responsibility: KNMI, Atmospheric Composition Research


Name: Cloudcover ; Acronym: CL » top »
Summary: These datasets represent meteorological information prepared by KNMI (Peter van Velthoven) for the CARIBIC project. The meteorological analysis of the CARIBIC measurement flights is based on ECWMF first guess fields (6-hour forecasts) with a resolution of 1x1 degree on ECMWF model levels. First guess fields from ECMWF were used until 13 September 2000, because ECMWF used a 3D-var assimilation scheme until then. For 3D-var, first guess fields are somewhat smoother than analyses. After 13 September 2002 ECMWF used 4D-var assimilation and its analyses were used, as first guess fields were no longer available. With 4D-var the analyses are much smoother than in 3D-var. Data format: ECMWF model data interpolated linearly in longitude, latitude, log(pressure) and time to the aircraft location. The following parameters are interpolated: Cloud cover (dimensionless 0-1), Cloud liquid water content (g/kg), Cloud ice water content (g/kg).
Here the flight dependent comments from the flight table below will be inserted.
Short description: ECMWF Model data along flight tracs: Cloud cover / water content.
Accuracy: The quality of ECMWF analyses is monitored and documented at ECMWF (http://www.ecmwf.int). The following expresses a subjective view by Peter van Velthoven: The accuracy of model parameters that are also measured can easily be checked. See e.g. http://www.knmi.nl/~/velthove/CARIBIC. Errors in cloud cover and ice and water content are quite large, even more so than in humidity. Only the large scale variations correspond to real atmospheric variability.
Consistency: Dataset covers one measuring flight
Completeness: complete
Process: complete, processed
Aggregation: 1x1deg, 60 hybrid sigma levels, 6 h Interpol. to flight position every min.
Responsibility: KNMI, Atmospheric Composition Research