The total column amount of ozone and other trace gases are measured with mm-wave instruments, FT-IR and DOAS spectrometers, at IRF in Kiruna (Table 6, #8.1). With the sun or moon as infrared light sources, FT-IR spectrometers can quantify the total column amounts of many important trace gases in the troposphere and stratosphere. At present the following species are retrieved from the Kiruna data: O3 (ozone), ClONO2, HNO3, HCl, CFC-11, CFC-12, CFC- 22, NO2, N2O, NO, HF, C2H2, C2H4, C2H6, CH4, CO, COF2, H2O, HCN, HO2NO2, NH3, N2, and OCS. Together with Russian and Finnish institutes at the same latitude, IRF studies the stratospheric ozone and its dependence on polar atmospheric circulation and precipitation of charged particles. The ground-based instruments are also used to validate satellite measurements of vertical ozone distribution (Odin, SAGE III, and GOME). Aerosols and thin clouds are measured at IRF in Kiruna. For example, researchers use Lidars (Light Detection and Ranging) to measure polar stratospheric and noctilucent clouds. Winds and structures are measured with ESRAD MST radar at IRF in Kiruna. At IRF in Kiruna measurements are used to assess the physical and chemical state of the stratosphere and upper troposphere and the impact of changes on the global climate. Particle precipitation is measured by relative ionospheric opacity meters (riometers) at IRF in Kiruna. Riometers measure the absorption of cosmic noise at 30 and 38 MHz and provide information about particles with energies larger than 10 keV. The electron density of the ionosphere is measured by ionosonds and digisondes at IRF in Kiruna.