Application of expectation–maximization algorithm to estimate random walk process noise for GNSS tropospheric delay

GNSS (Global Navigation Satellite Systems) tropospheric delay, specifically zenith wet delay (ZWD), shows clear spatial–temporal variations and is usually modeled as RWPN (random walk process noise). However, because RWPN does not take the geographical position of GNSS stations and local weather con...

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Bibliographic Details
Published in:GPS solutions Vol. 28; no. 4; p. 204
Main Authors: Zhang, Xinggang, Li, Pan, Wang, Miaomiao, Ge, Maorong, Schuh, Harald
Format: Journal Article
Language:English
Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2024
Springer Nature B.V
Subjects:
Algorithms
Atmospheric Sciences
Automotive Engineering
Delay
Earth and Environmental Science
Earth Sciences
Electrical Engineering
Estimates
Geophysics/Geodesy
Global navigation satellite system
Maximization
Optimization
Original Article
Parameter estimation
Position measurement
Random walk
Satellite observation
Space Exploration and Astronautics
Space Sciences (including Extraterrestrial Physics
Troposphere
Weather
Precise point positioning
Severe weather
GNSS
Kalman filter
Troposphere
Random walk process noise
Expectation–maximization algorithm
ISSN:1080-5370, 1521-1886
Online Access:Get full text
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Summary:GNSS (Global Navigation Satellite Systems) tropospheric delay, specifically zenith wet delay (ZWD), shows clear spatial–temporal variations and is usually modeled as RWPN (random walk process noise). However, because RWPN does not take the geographical position of GNSS stations and local weather conditions into account for precise point positioning (PPP), it may lead to biased ZWD estimates. To address the scientific problem and improve ZWD estimates, we adopt the Expectation–Maximization algorithm (EM algorithm) to validate the feasibility of estimating RWPN using only GNSS measurements. Numerical experiments reveal that using only GNSS observations is capable of determining the RWPN parameter, although it could take several days to reach a stable solution if the initial guess deviates far away from the truth. It is also shown that estimating RWPN can almost always effectively improve ZWD estimates by several millimeters in contrast with traditional PPP results. If the ambiguities are fixed to their integer values correctly, the accuracy of RWPN estimates for ZWD can be greatly reduced by 2 mm / hour .
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ISSN:1080-5370
1521-1886
DOI:10.1007/s10291-024-01714-7