Assements of the Influence of Rain on Tropospheric Delay of GPS Signals

Abstract

For carrying out GPS measurements with millimeter accuracy, the most important issues of ensuring such measurements are the issues of correct assessment of the effect of water vapor and hydrometeors. It is considered that the "dry" delay of GPS signals usually falls into the category of "systematic" error, which can be eliminated by calculation. Methods and means for measuring water vapor have been currently developed and worked out much more widely than methods for measuring hydrometeors. Taking into account the above, it becomes clear that an accurate assessment of the impact of hydrometeors, and especially rain on the signals of GPS satellites is an urgent task. It is noted that the relevance of the development of technical means for measuring the intensity of rainfall is also explained by the property of rains to greatly attenuate electromagnetic waves with a frequency of 10 GHz and higher. Based on the analysis of the factual material, it is shown that the delay of GPS satellite signals due to the influence of hydrometeors will be 5-8% of the "wet" delay. The process of distrometric measurements of the occurrence frequency of raindrops of various sizes has been optimized. The functional of unconstrained variational optimization has been formulated and its mathematical algorithm has been given.