Observations for the GHG evaluation

Various observational data sets, including measurements at surface monitoring stations, ship cruises, various aircraft programmes, AirCore balloon soundings, and surface based total column measurements are available. Examples of the type of observations that can be used for the evaluation of CH4 mole fractions are shown in Figure 1. A brief description of each of these data is given below. 

•   ObsPack (Observation Package (ObsPack) Data Products, which are processed for the surface discrete measurements, aircraft measurements, and measurements of discrete air samples collected along the lines of ship cruises

• Aircraft campaigns data 
  1. HIPPO (HIAPER Pole-to-Pole Observations) programme) consists in aircraft cross-sections measurements of atmospheric concentrations of greenhouse gases (including CH₄) approximately pole-to-pole, from the surface to the lower stratosphere
  2.  ORCAS (("O₂/N₂ Ratio and CO₂ Airborne Southern Ocean Study") aircraft campaigns took place over the Southern Ocean (35^oN -75^oS region) and within 0-13 km altitude during January until early March 2016. 

• Data along commercial flights
  1. CARIBIC. CARIBIC (("Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container") is programme that collects air samples collected onboard a Lufthansa Airbus A340-600 passenger aircraft. The CARIBIC flights start from Frankfurt (Germany) to various destinations around the world. The CARIBIC measurements cover mainly the upper troposphere and lower stratosphere (8-13 km altitude)  
  2. CONTRAIL. CONTRAIL ("Comprehensive Observation Network for TRace gases by AIrLiner") is jointly conducted by NIES (National Institute for Environmental Studies), the MRI (Meteorological Research Institute), JAL (Japan Airlines), and JAMCO (JAMCO Corporation) and JAL-F (JAL Foundation). The JAL flights start from Tokyo (Japan) to Asia, Australia, Europe, and Hawaii. The measurements were conducted mainly between 10-12 km altitude and partly below 10 km. 

• AirCore measurements. The AirCore instrument developed by NOAA/ESRL is an atmospheric sampling system that can be launched on balloons and that consists of a long stainless steel tube, which can sample the surrounding atmosphere and preserve a profile of the trace gas of interest from the middle stratosphere to the ground. The AirCore measurements are useful for the evaluation of modelled CH₄ mole fractions especially in the lower and middle stratosphere. The Aircore data can be found from the ObsPack web site  

• TCCON (Total Carbon Column Observing Network) is a global network of ground-based Fourier Transform Spectrometers (FTS) that record spectra of the sun in the near-infrared. From these spectra, column-averaged abundances of atmospheric constituents including CO₂ and CH₄ are retrieved.