Leick, A. (2004) GPS Satellite Surveying. 3rd Edition, John Wiley and Sons, Hoboken.

has been cited by the following article:

• TITLE: Impact of Tropospheric Delay Gradients on Total Tropospheric Delay and Precise Point Positioning

  AUTHORS: Mohamed Elsobeiey, Mohamed El-Diasty

  KEYWORDS: Precise Point Positioning, Electromagnetic Waves, Tropospheric Delay, Tropospheric Gradients

  JOURNAL NAME: International Journal of Geosciences, Vol.7 No.5, May 18, 2016

  ABSTRACT: GPS signals are electromagnetic waves that are affected by the Earth’s atmosphere. The Earth’s atmosphere can be categorized, according to its effect on GPS signals, into the ionosphere (ionospheric delay) and neutral atmosphere (tropospheric delay). The first-order ionospheric delay can be eliminated by linear combination of GPS observables on different frequencies. However, tropospheric delay cannot be eliminated because it is frequency-independent. Thetotal tropospheric delay can be divided into three components. The first is the dry component, the second part is the wet component, and the third part is the horizontal gradients which account for the azimuthal dependence of tropospheric delay. In this paper, the effect of modeling tropospheric gradients on the estimation of the total tropospheric delay and station position is investigated. Long session, one month during January 2015, of GPS data is collected from ten randomly selected globally distributed IGS stations. Two cases are studied: thefirst case, the coordinates of stations are kept fixed to their actual values and the tropospheric delay is estimated twice, with and without tropospheric gradients. In the second case, the station position is estimated along with the total tropospheric delay with and without tropospheric gradients. It is shown that the average bias of the estimated total tropospheric delay when neglecting tropospheric gradients ranges from ?1.72 mm to 2.14 mm while the average bias when estimating gradients are ?0.898 mm to 1.92 mm which means that the bias is reduced by about 30%. In addition, the average standard deviation of the bias is 4.26 mm compared with 4.52 mm which means that the standard deviation is improved by about 6%.