Near-Real-Time GPS Sensing of Atmospheric Water Vapour
Bai, Zhengdong (2005) Near-Real-Time GPS Sensing of Atmospheric Water Vapour. PhD thesis, Queensland University of Technology.
An important goal in modern weather prediction is to improve short-term weather
forecasts, especially of severe weather and precipitation. However, the ability to
achieve this goal is hindered by the lack of timely and accurate observations of
atmospheric water vapour, which is one of the most poorly measured and least
understood constituents of the Earth's atmosphere due to its high temporal and spatial
variability. This situation is being addressed by the Global Positioning System (GPS)
technology. GPS radio signals are slowed and bent by changes in temperature,
pressure and water vapour in the atmosphere. Traditionally, the GPS signal
propagation delay is considered a nuisance parameter that is an impediment to
obtaining precise coordinates using GPS. Recent development in GPS precise
positioning and orbit determination has enabled the atmospheric parameters to be
determined to a high degree of accuracy on a routine basis, using continuous tracking
data from ground-based GPS receivers.
The aim of this research is to address several critical scientific challenges in
estimating the atmospheric water vapour content in near-real-time (NRT) in
Australia. Contributions are made to the field of GPS meteorology in the following
First of all, research efforts were made to develop a technical platform for the
ground-based GPS meteorology studies and demonstration of GPS Precipitable
Water Vapour (PWV) estimation using observations from Australian Regional GPS
Networks (ARGN). Methods of estimation of water vapour from GPS and
radiosonde data have been developed and tested. GAMIT-based GPS data processing
strategies and compare analysis with radiosonde water vapour solutions from the
Australia Upper Air Network (AUAN) were undertaken, providing an effective
technical basis for further studies.
Secondly, the research has developed techniques to allow estimation of atmospheric
water vapour from GPS data and surface meteorological observations collected
around the GPS sites. Ideally a dedicated meteorological sensor is installed adjacent
to the GPS antenna. However, meteorological sensors are normally not installed at
most Australian GPS stations. Installing a new meteorological sensor at each GPS
station would involve additional cost at the level of one-third or half of the geodetic
GPS receiver cost. We have experimentally developed and demonstrated
interpolation methods for making use of hourly collected surface meteorological data
from the Australian Automatic Weather Station (AWS) network operated by the
Bureau of Meteorology (BOM) to estimate atmospheric water vapour.
Thirdly, the research has studied ocean tidal loading and its effects on GPS derived
precipitable water vapour estimates. The periodic motion of the Earth's surface due
to ocean loading is one of the largest periodic motions. However, very little work has
been done to quantify their effects on GPS-derived solutions at the GPS sites in the
Australian region surrounded by ocean waters. The research presents the theoretical
analysis and experimental results from the ARGN network, focusing on ocean
loading and its effects on GPS derived precipitable water vapour estimates.
The fourth important effort was the development of techniques for estimating highrate
Slant Water Vapour (SWV) values for future operational meteorological
applications in Australia, including addressing such issues as slant-path delay
recovery from post-fit double-difference residuals, and overcoming site multipath
effects. The experimental results have demonstrated the efficiency of the proposed
Finally, in order to address the meteorological applications with the existing and
anticipated GPS reference stations in the Australian region, and measure the
atmospheric water vapour content in near-real-time, the technical issues to
implement NRT GPS water vapour estimation were identified and discussed,
including the data requirements for meteorological and climate applications, NRT
data processing and quality control procedures for GPS orbits. The experimental
GPS PWV results from NRT and post data processing are compared and presented.
Impact and interest:
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|Item Type:||QUT Thesis (PhD)|
|Supervisor:||Feng, Yanming & Moody, Miles|
|Keywords:||GPS, Global positioning system, NRT, near-real-time, PWV, Precipitable Water Vapour, ARGN, Australian Regional GPS Networks, GAMIT-based, AUAN, Australia Upper Air Network|
|Divisions:||Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering|
|Department:||Faculty of Built Environment and Engineering|
|Institution:||Queensland University of Technology|
|Copyright Owner:||Copyright Zhengdong Bai|
|Deposited On:||03 Dec 2008 03:55|
|Last Modified:||28 Oct 2011 19:42|
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