Dry Troposphere Correction

Dry Troposphere Correction

The dry troposphere correction (DTC) deals with the hydrostatic (i.e., dry gases, such as nitrogen and oxygen) component of atmospheric refraction. With approximately 90 % of tropospheric delay coming from hydrostatic components, the DTC is the largest adjustment applied to altimeter measurements. Dry gases account for ~99 % of the atmospheric; thus, DTC is closely related to both atmospheric and sea level pressure. For practical reasons, sea level pressure is determined using weather prediction / reanalysis models. Additionally, the DTC depends on local acceleration due to gravity, local temperature, and the refractive index of dry air. Unlike the wet atmosphere, the dry atmosphere can be modelled using the laws of ideal gases, simplifying calculations considerably.

Uncertainties associated with DTC were not investigated during the first phase of ASELSU.