The variations in atmospheric warming and cooling result in changes in tropospheric and stratospheric circulation. Ozone depletion also explains much of the observed reduction in stratospheric and upper tropospheric temperatures. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events. This CO, methane, tropospheric ozone, CFCs, and nitrous oxide has increased radiative forcing. The atmosphere appeared highly transparent and lacking thick stratospheric and tropospheric hazes. Low level ozone (or tropospheric ozone) is an atmospheric pollutant. Some ground-based methods provide the possibility to retrieve tropospheric and stratospheric trace gas profiles. Neglecting ionospheric and tropospheric effects, the signal from navigation satellites has a fixed precision. Anthropogenic emissions can be monitored by evaluating data of tropospheric NO2 and SO2. Increased surface UV leads to increased tropospheric ozone. Ground waves "do not" include ionospheric and tropospheric waves. The relevant secondary pollutants include peroxylacyl nitrates (PAN), tropospheric ozone, and aldehydes. NOAA has worked to create a global network of tropospheric ozone measurements using ozonesondes. Therefore, the concentration of tropospheric ozone affects how long these compounds remain in the air. Pesticide use accounts for about 6 percent of total tropospheric ozone levels.