text: * NDSC observations. The [http://www.ndsc.ncep.noaa.gov/ Network for the Detection for Stratospheric Change] (NDSC) is a set of high-quality remote-sounding research stations for observing and understanding the physical and chemical state of the stratosphere. Ozone and key ozone-related chemical compounds and parameters are targeted for measurement. The NDSC is a major component of the international upper atmosphere research effort and has been endorsed by national and international scientific agencies, including the International Ozone Commission, the United Nations Environment Programme (UNEP), and the World Meteorological Organization (WMO). The primary instruments and measurements are: Ozone lidar (vertical profiles of ozone from the tropopause to at least 40 km altitude; in some cases tropospheric ozone will also be measured). Temperature lidar (vertical profiles of temperature from about 30 to 80 km). Aerosol lidar (vertical profiles of aerosol optical depth in the lower stratosphere). Water vapor  lidar (vertical profiles of water vapor in the lower stratosphere). Ozone microwave (vertical profiles of stratospheric ozone from 20 to 70 km). HO microwave (vertical profiles water vapor from about 20 to 80 km). ClO microwave (vertical profiles of ClO from about 25 to 45 km, depending on latitude). Ultraviolet/Visible spectrograph (column abundance of ozone, NO, and, at some latitudes, OClO and BrO). Fourier Transform Infrared spectrometer (column abundances of a broad range of species including ozone, HCl, NO, NO, ClONO, and HNO).
  * MkIV observations. The [http://mark4sun.jpl.nasa.gov/ MkIV] Interferometer is a Fourier Transform Infra-Red (FTIR) Spectrometer, designed and built at the Jet Propulsion Laboratory in 1984, to remotely sense the composition of the Earth's atmosphere by the technique of solar absorption spectrometry. This was born out of concern that man-made pollutants (e.g. chlorofluorocarbons, aircraft exhaust) might perturb the ozone layer. Since 1984, the MkIV Interferometer has participated in 3 NASA DC-8 polar aircraft campaigns, and has successfully completed 15 balloon flights. In addition, the MkIV Interferometer made over 900 days of ground-based observations from many different locations, including McMurdo, Antarctica in 1986.
  * Sonde observations. The [http://www.woudc.org/index_e.html World Ozone and Ultraviolet Radiation Data Centre] (WOUDC) is one of five World Data Centres which are part of the Global Atmosphere Watch (GAW) programme of the World Meteorological Organization (WMO). The WOUDC is operated by the Experimental Studies Division of the Meteorological Service of Canada (MSC) — formerly Atmospheric Environment Service (AES), Environment Canada and is located in Toronto. The WOUDC began as the World Ozone Data Centre (WODC) in 1960 and produced its first data publication of Ozone Data for the World in 1964. In June 1992, the AES agreed to a request from the WMO to add ultraviolet radiation data to the WODC. The Data Centre has since been renamed to the World Ozone and Ultraviolet Radiation Data Centre (WOUDC) with the two component parts: the WODC and the World Ultraviolet Radiation Data Centre (WUDC).