Thirty Years of the Network for Detection of Atmospheric Composition Change (NDACC): Contributions to Metrology
by Dr. Anne Thompson, Dr. Irina Petropavlovskikh, Dr. Martine DeMaziere, Dr. Jeannette Wild, Mrs./Ms. Kathy Thompson

Abstract

The Network for the Detection of Atmospheric Composition Change (NDACC, ndacc.org), an international global monitoring network of more than 108 stations was established in 1991. The original aim was to support the Montreal Protocol's charge to monitor stratospheric ozone depletion and related key variables that are measured from the ground (in-situ, balloon-borne, by remote sensing). Over the past 30+ years, NDACC's goals have broadened to detect climate changes related to natural and anthropogenic variability in the chemical and physical states of the stratosphere and upper troposphere. Since its inception, NDACC has delivered high-quality reference observations (www.ndacc.org; Menu selections DATA, then protocols) subject to strict measurement protocols to the global science community. NDACC's Working Groups are organized by observational techniques (i.e. Brewer, Dobson, lidar, microwave radiometry, sondes, spectral UV, and Infrared and UV/Visible spectrometry). In addition, NDACC has Satellite and Theory and Analysis Working Groups and has established formal collaborative agreements with 10 other Cooperating Networks, e.g., AERONET, TCCON, AGAGE, SHADOZ. To meet societal needs for climate mitigation, NDACC continuously works on assessing its strategy for the further development of the Network’s geographical coverage and representativeness of its observations to meet societal demands for information and mitigation. An important achievement of NDACC has been in quality assurance, the promulgation of standards, and prescribed data protocols across all the working groups and Cooperative Agreements, and in collaborations with Metrology organizations and WMO GAW’s expert teams. Examples include intercomparison campaigns as for the World Traveling Dobson spectrometer standard; promulgation of uniform software for determining chemical species concentrations from lidar, UV/Vis and infrared signals and spectra; conformity of data formats and archiving to evolving requirements of satellite user communities and according to FAIR data principles. Several NDACC targets are considered Fiducial Reference Measurements by the satellite community and serve satellite and model validation purposes.