Statistical characteristics of atmospheric phase fluctuations observed by using same-beam VLBI

Abstract

When the signals from spacecrafts and radio sources transmits through the earths atmosphere and ionosphere, their phase occurs fluctuation, which has great influence on the measurement precision of the ground observing system such as VLBI. Using same beam VLBI data of 1 year which were got from two satellites (Rstar and Vstar) in Japanese lunar exploration project SELENE, we studied the Allan standard deviation and the structure function of correlation phase fluctuations of Rstar and Vstar, and differential correlation phase fluctuation between Rstar and Vstar on six baselines. We also obtained Allan standard deviation of phase fluctuations of Rstar and differential phase fluctuation between Rstar and Vstar at each station based on the 6 baseline data. In addition, we obtained the relationship model between differential phase fluctuations of Rstar and Vstar and its separation angle at each station. In the range of time interval 8 τ τ 0, which obeys Kolmogorov disturbance theory. The relationship model between the root mean square of differential phase fluctuations of Rstar and Vstar and its separation angle at each station is φ =1.967 θ +0.738 deg/deg, and that on six baselines is φ =2.759 θ +1.069 deg/deg.