Global water vapor estimate in the lowest troposphere by attenuation measurements on LEO-LEO satellites at 17.25 GHz

In this work we present the simulation results concerning the possibility to estimate the tropospheric water vapor content along the propagation path between two satellites counter-rotating on two different LEO orbits. The estimation method is based on the measurement of a parameter referring to the differential spectral absorption at 17.25 GHz along the propagation link between the two satellites. The choice of that frequency allows to estimate the water vapor in the lowest troposphere, namely when the propagation path crosses the troposphere at tangent altitudes up to 6 km above the Earth's surface. Effects of different latitudes and atmospheric bending have been accounted for and are presented and discussed.