Troposphere

The troposphere is the lowest layer of the Earth’s atmosphere, extending from the surface up to about 8–15 km in altitude. It contains most of the atmospheric mass and nearly all weather phenomena, including clouds, precipitation, and water vapor.

In geodesy, the troposphere significantly affects the propagation of microwave signals used in space-geodetic techniques such as GNSS, VLBI, and SLR. Variations in temperature, pressure, and especially water vapor content cause signal delays (tropospheric delay), which must be accurately modeled or estimated to achieve millimeter-level positioning accuracy. Tropospheric parameters derived from geodetic observations also contribute to atmospheric and climate research.