subject:(Tropospheric delay)

University of Pretoria

1. Isioye, Olalekan Adekunle. An Investigation of Ground-Based GNSS Atmospheric Remote Sensing Techniques for Weather and Climate Monitoring in Nigeria.

Degree: PhD, Geography, Geoinformatics and Meteorology, 2017, University of Pretoria

URL: http://hdl.handle.net/2263/60814

► Radio signals from Global Navigation Satellite Systems (GNSS) satellites suffer delay as they propagate through the atmosphere (neutral and non-neutral) and this delay is partially… (more)

▼ Radio signals from Global Navigation Satellite Systems (GNSS) satellites suffer delay as they propagate through the atmosphere (neutral and non-neutral) and this delay is partially driven by the water vapour content in the atmosphere. The delay component due to the non-neutral atmosphere (ionosphere) is removed through the use of dual frequency GNSS receivers. The main tropospheric parameter is the zenith tropospheric (or total) delay (ZTD), which is a widely accepted parameter with which to express the total delay in the signal from all satellites due to the neutral atmosphere. The ZTD is a measure of the integrated tropospheric condition over a GNSS receiver station. Accordingly, the integrated water vapour or precipitable water vapour (PWV) can be obtained from a portion of the ZTD, if the atmospheric pressure and temperature at the station are known through a concept often referred to as GNSS meteorology. A number of GNSS receivers have been deployed for mapping and geodetic services in Nigeria under the African reference frame initiative, but unfortunately most of these receivers do not have co-located meteorological sensors for pressure and temperature measurements. The prospect of incorporating GNSS meteorology into weather monitoring and climate analysis in Nigeria was investigated and is reported in this thesis. During the first task of this research, the technical basis for ground-based GNSS meteorology was reviewed and the potentials and challenges of the approach to meteorological activities in Africa (including Nigeria) were identified. Thereafter an in-depth analysis of the spatial and temporal variability of ZTD over Nigeria for the period of 2010-2014 was conducted; results revealed weak spatial dependence among the stations. Tidal oscillations (of the diurnal and semidiurnal components) were observed at the GNSS stations of which the diurnal ZTD cycles exhibited significant seasonal dependence, affirming the prospective relevance of ground-based GNSS data to atmospheric studies. Also in this research, the accuracy and suitability of using reanalysis datasets (ERA-Interim and NCEP/NCAR) and a GPT2 neutral model in retrieving PWV from GNSS observations over Nigeria were investigated; results showed that PWV can be retrieved to within a precision of about 1 mm, provided GNSS-derived ZTD is of high precision. A fundamental issue for GNSS meteorology in the West African region was yet again addressed in this research; this is the development of a weighted tropospheric mean temperature model for use in current and future GNSS meteorology activities in the region. A multitechnique comparison of PWV estimates showed good agreement between GNSS estimates and other techniques (i.e. the atmospheric infrared sounder, and ERAInterim reanalysis). This result is suggestive of the potential of assimilating GNSS atmospheric products into reanalysis and climate models. Diurnal and seasonal variability of GNSS PWV estimates exhibits strong correlation with weather events that influence… Advisors/Committee Members: Combrinck, Ludwig (advisor), Botai, J.O. (Joel.

Subjects/Keywords: UCTD; GNSS Meteorology; Zenith Tropospheric Delay (ZTD); Precipitable Water Vapour (PWV); Reanalysis model

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APA (6^th Edition):

Isioye, O. (2017). An Investigation of Ground-Based GNSS Atmospheric Remote Sensing Techniques for Weather and Climate Monitoring in Nigeria. (Doctoral Dissertation). University of Pretoria. Retrieved from http://hdl.handle.net/2263/60814

Chicago Manual of Style (16^th Edition):

Isioye, Olalekan. “An Investigation of Ground-Based GNSS Atmospheric Remote Sensing Techniques for Weather and Climate Monitoring in Nigeria.” 2017. Doctoral Dissertation, University of Pretoria. Accessed April 22, 2021. http://hdl.handle.net/2263/60814.

MLA Handbook (7^th Edition):

Isioye, Olalekan. “An Investigation of Ground-Based GNSS Atmospheric Remote Sensing Techniques for Weather and Climate Monitoring in Nigeria.” 2017. Web. 22 Apr 2021.

Vancouver:

Isioye O. An Investigation of Ground-Based GNSS Atmospheric Remote Sensing Techniques for Weather and Climate Monitoring in Nigeria. [Internet] [Doctoral dissertation]. University of Pretoria; 2017. [cited 2021 Apr 22]. Available from: http://hdl.handle.net/2263/60814.

Council of Science Editors:

Isioye O. An Investigation of Ground-Based GNSS Atmospheric Remote Sensing Techniques for Weather and Climate Monitoring in Nigeria. [Doctoral Dissertation]. University of Pretoria; 2017. Available from: http://hdl.handle.net/2263/60814

Delft University of Technology

2. Ku, Ou (author). Estimation of InSAR Tropospheric Delay Using ERA-Interim Global Atmospheric Reanalysis.

Degree: 2017, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:39b60a34-bfe3-4852-a193-ec16c2f94506

► Tropospheric delays are considered to be one of the main performance limitations for Interferometric Synthetic Aperture Radar technology when applied to ground deformation monitoring. In… (more)

Subjects/Keywords: InSAR; tropospheric delay; water vapor mapping; atmosphere correction; ERA-Interim atmospheric reanalysis

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APA (6^th Edition):

Ku, O. (. (2017). Estimation of InSAR Tropospheric Delay Using ERA-Interim Global Atmospheric Reanalysis. (Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:39b60a34-bfe3-4852-a193-ec16c2f94506

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Ku, Ou (author). “Estimation of InSAR Tropospheric Delay Using ERA-Interim Global Atmospheric Reanalysis.” 2017. Thesis, Delft University of Technology. Accessed April 22, 2021. http://resolver.tudelft.nl/uuid:39b60a34-bfe3-4852-a193-ec16c2f94506.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Ku, Ou (author). “Estimation of InSAR Tropospheric Delay Using ERA-Interim Global Atmospheric Reanalysis.” 2017. Web. 22 Apr 2021.

Vancouver:

Ku O(. Estimation of InSAR Tropospheric Delay Using ERA-Interim Global Atmospheric Reanalysis. [Internet] [Thesis]. Delft University of Technology; 2017. [cited 2021 Apr 22]. Available from: http://resolver.tudelft.nl/uuid:39b60a34-bfe3-4852-a193-ec16c2f94506.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ku O(. Estimation of InSAR Tropospheric Delay Using ERA-Interim Global Atmospheric Reanalysis. [Thesis]. Delft University of Technology; 2017. Available from: http://resolver.tudelft.nl/uuid:39b60a34-bfe3-4852-a193-ec16c2f94506

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Curtin University of Technology

3. Lo, Johnny Su Hau. Estimation of tropospheric wet delay from GNSS measurements .

Degree: 2011, Curtin University of Technology

URL: http://hdl.handle.net/20.500.11937/2289

► The determination of the zenith wet delay (ZWD) component can be a difficult task due to the dynamic nature of atmospheric water vapour. However, precise… (more)

▼ The determination of the zenith wet delay (ZWD) component can be a difficult task due to the dynamic nature of atmospheric water vapour. However, precise estimation of the ZWD is essential for high-precision Global Navigation Satellite System (GNSS) applications such as real-time positioning and Numerical Weather Prediction (NWP) modelling.The functional and stochastic models that can be used for the estimation of the tropospheric parameters from GNSS measurements are presented and discussed in this study. The focus is to determine the ZWD in an efficient manner in static mode. In GNSS, the estimation of the ZWD is directly impacted by the choice of stochastic model used in the estimation process. In this thesis, the rigorous Minimum Norm Quadratic Unbiased Estimation (MINQUE) method was investigated and compared with traditional models such as the equal-weighting model (EWM) and the elevationangle dependent model (EADM). A variation of the MINQUE method was also introduced. A simulation study of these models resulted in MINQUE outperforming the other stochastic models by at least 36% in resolving the height component. However, this superiority did not lead to better ZWD estimates. In fact, the EADM provided the most accurate set of ZWD estimates among all the models tested. The EADM also yielded the best ZWD estimates in the real data analyses for two independent baselines in Australia and in Europe, respectively.The study also assessed the validity of a baseline approach, with a reduced processing window size, to provide good ZWD estimates at Continuously Operating Reference Stations (CORS) in an efficient manner. Results show that if the a-priori station coordinates are accurately known, the baseline approach, along with a 2-hour processing window, can produce ZWD estimates that are statistically in good agreement with the estimates from external sources such as the radiosonde (RS), water vapour radiometer (WVR) and International GNSS Service (IGS) solutions. Resolving the ZWD from GNSS measurements in such a timely manner can aid NWP model in providing near real-time weather forecasts in the data assimilation process.In the real-time kinematic modelling of GNSS measurements, the first-order Gauss- Markov (GM) autocorrelation model is commonly used for the dynamic model in Kalman filtering. However, for the purpose of ZWD estimation, it was found that the GM model consistently underestimates the temporal correlations that exist among the ZWD measurements. Therefore, a new autocorrelation dynamic model is proposed in a form similar to that of a hyperbolic function. The proposed model initially requires a small number of autocorrelation estimates using the standard autocorrelation formulations. With these autocorrelation estimates, the least-squares method is then implemented to solve for the model’s parameter coefficients. Once solved, the model is then fully defined. The proposed model was shown to be able to follow the autocorrelation trend better than the GM model. Additionally, analysis of real data at an…

Subjects/Keywords: zenith wet delay (ZWD); real-time positioning and Numerical Weather Prediction (NWP) modelling; tropospheric wet delay; GNSS measurements

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APA (6^th Edition):

Lo, J. S. H. (2011). Estimation of tropospheric wet delay from GNSS measurements . (Thesis). Curtin University of Technology. Retrieved from http://hdl.handle.net/20.500.11937/2289

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Lo, Johnny Su Hau. “Estimation of tropospheric wet delay from GNSS measurements .” 2011. Thesis, Curtin University of Technology. Accessed April 22, 2021. http://hdl.handle.net/20.500.11937/2289.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Lo, Johnny Su Hau. “Estimation of tropospheric wet delay from GNSS measurements .” 2011. Web. 22 Apr 2021.

Vancouver:

Lo JSH. Estimation of tropospheric wet delay from GNSS measurements . [Internet] [Thesis]. Curtin University of Technology; 2011. [cited 2021 Apr 22]. Available from: http://hdl.handle.net/20.500.11937/2289.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Lo JSH. Estimation of tropospheric wet delay from GNSS measurements . [Thesis]. Curtin University of Technology; 2011. Available from: http://hdl.handle.net/20.500.11937/2289

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

The Ohio State University

4. alojaiman, shahad N M A A. Tropospheric Delay Modeling using GNSS Observations from Continuously Operating Reference Stations (CORS).

Degree: MS, Civil Engineering, 2019, The Ohio State University

URL: http://rave.ohiolink.edu/etdc/view?acc_num=osu1574536144031026

► PPP exhibits through many previous studies the possibility to achieve high accuracy estimation of tropospheric paraments. Either Zenith wet delay (ZWD) or Precipitable Water Vapor… (more)

▼ PPP exhibits through many previous studies the possibility to achieve high accuracy estimation of tropospheric paraments. Either Zenith wet delay (ZWD) or Precipitable Water Vapor (PWV) can be estimated by PPP processing of GNSS data in either real time or post processing mode. PWV is further utilized as a tool from which rainfall forecasting models are established especially in sites where such data may not be available. In this study PPP processing of GNSS data leads to the estimation of ZTD as well as ZWD values. A test is first conducted in which MGEX sites are processed on July 22nd, 2019 and January 11th, 2019 to estimate ZTD values and establish PPP’s accuracy based on IGS final solutions and tropospheric products as reference data. An approach in which the site coordinates are fixed instead of estimated by PPP is then tested on the same MGEX sites to examine its contribution to the accuracy of ZTD estimates. 37 CORS sites around the United States are then processed for three day between August 7th 2019 and August 9th 2019 with PPP and site coordinates fixing to create ZTD, ZWD, and PWV maps of the area from which patterns and models can be generated. The created maps were analyzed alongside NASA’s Goddard Earth Sciences Data and Information Services Center’s precipitation maps of near real time and TRMM Multi-Satellite Precipitation Analysis TMPA products. Finally, PWV reference data was obtained from UCAR’s COSMIC program and daily averaged to be compared with the PWV values extracted from the previously estimated ZWD. The PPP processing of MGEX sites with GPS and GLONASS data resulted in mm level differences between estimated and referenced ZTD data with RMS values as low as 1.55 mm. Site coordinates fixing enhanced ZTD estimates slightly based on the same referenced ZTD data. The examination of maps showed clear consistency between the estimated ZWD as well as PWV maps of the area and the reference precipitation maps of the same day especially as precipitation and weather patterns changed daily. The estimated PWV maps reflected that change from day to day specifically the prominent changes observed around the NESC, NEST, and DSRC sites. PWV validation resulted in PWV errors mostly less than 2 mm and as low as 0.18 mm. The approach has the potential of further CORS network expansion for a more accurate model with location correlated parameters to estimates PWV considered. Future work could also include real time PPP processing with ambiguity fixing to enhance ZWD estimation. Advisors/Committee Members: Wang, Lei (Advisor).

Subjects/Keywords: Civil Engineering; PPP; CORS; Tropospheric delay; Continuously Operating Reference Stations; GNSS; IGS; GPS; MGEX; Zenith total delay; Zenith wet delay; PWV; ZTD; ZWD; Precipitable Water Vapor

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

alojaiman, s. N. M. A. A. (2019). Tropospheric Delay Modeling using GNSS Observations from Continuously Operating Reference Stations (CORS). (Masters Thesis). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1574536144031026

Chicago Manual of Style (16^th Edition):

alojaiman, shahad N M A A. “Tropospheric Delay Modeling using GNSS Observations from Continuously Operating Reference Stations (CORS).” 2019. Masters Thesis, The Ohio State University. Accessed April 22, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574536144031026.

MLA Handbook (7^th Edition):

alojaiman, shahad N M A A. “Tropospheric Delay Modeling using GNSS Observations from Continuously Operating Reference Stations (CORS).” 2019. Web. 22 Apr 2021.

Vancouver:

alojaiman sNMAA. Tropospheric Delay Modeling using GNSS Observations from Continuously Operating Reference Stations (CORS). [Internet] [Masters thesis]. The Ohio State University; 2019. [cited 2021 Apr 22]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1574536144031026.

Council of Science Editors:

alojaiman sNMAA. Tropospheric Delay Modeling using GNSS Observations from Continuously Operating Reference Stations (CORS). [Masters Thesis]. The Ohio State University; 2019. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1574536144031026

University of Western Ontario

5. Samadi Alinia, Hadis. New GPS Time Series Analysis and a Simplified Model to Compute an Accurate Seasonal Amplitude of Tropospheric Delay.

Degree: 2017, University of Western Ontario

URL: https://ir.lib.uwo.ca/etd/4956

► Horizontal and vertical deformation of the Earth’s crust is due to a variety of different geophysical processes that take place on various spatiotemporal scales. The… (more)

▼ Horizontal and vertical deformation of the Earth’s crust is due to a variety of different geophysical processes that take place on various spatiotemporal scales. The quality of the observations from spaced-based geodesy instruments such as Global Positioning System (GPS) and differential interferometric synthetic aperture radar (DInSAR) data for monitoring these deformations are dependent on numerous error sources. Therefore, accurately identifying and eliminating the dominant sources of the error, such as troposphere error in GPS signals, is fundamental to obtain high quality, sub-centimeter accuracy levels in positioning results. In this work, I present the results of double-differenced processing of five years of GPS data, between 2008 and 2012, for sparsely distributed GPS stations in southeastern Ontario and western Québec. I employ Bernese GPS Software Version 5.0 (BSW5.0) and found two optimal sub-networks which can provide high accuracy estimation of the position changes. I demonstrate good agreement between the resulted coordinate time series and the estimates of the crustal motions obtained from a global solution. In addition, I analyzed the GPS position time series by using a complex noise model, a combination of white and power-law noises. The estimated spectral index of the noise model demonstrates that the flicker noise is the dominant noise in most GPS stations in our study area. The interpretation of the observed velocities suggests that they provide an accurate constraint on glacial isostatic adjustment (GIA) prediction models. Based on a deeper analysis of these same GPS stations, I propose a model that accurately estimates the seasonal amplitude of zenith tropospheric delay (ZTD) error in the GPS data on local and regional spatial scales. I process the data for the period 2008 through 2012 from eight GPS stations in eastern Ontario and western Québec using precise point positioning (PPP) online analysis available from Natural Resource Canada (NRCan) (https://webapp.geod.nrcan.gc.ca/geod/tools-outils/ppp.php). The model is an elevation-dependent model and is a function of the decay parameter of refractivity with altitude and the seasonal amplitude of refractivity computed from atmospheric data (pressure, temperature, and water vapor pressure) at a given reference station. I demonstrate that it can accurately estimate the seasonal amplitude of ZTD signals for the GPS stations at any altitude relative to that reference station. Based on the comparison of the observed seasonal amplitudes of the differenced ZTD at each station and the estimates from the proposed model, it can provide an accurate estimation for the stations under normal atmospheric conditions. The differenced ZTD is defined as the differences of ZTD derived from PPP at each station and ZTD at the reference station. Moreover, I successfully compute a five-year precipitable water vapor (PWV) at each GPS site, based on the ZTD derived from meteorological data and GPS processing. The results provide an accurate platform to monitor long-term…

Subjects/Keywords: GPS data processing; GIA; meteorological data; zenith tropospheric delay; precipitable water vapor; elevation-dependent seasonal amplitude; Geophysics and Seismology

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APA (6^th Edition):

Samadi Alinia, H. (2017). New GPS Time Series Analysis and a Simplified Model to Compute an Accurate Seasonal Amplitude of Tropospheric Delay. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/4956

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Samadi Alinia, Hadis. “New GPS Time Series Analysis and a Simplified Model to Compute an Accurate Seasonal Amplitude of Tropospheric Delay.” 2017. Thesis, University of Western Ontario. Accessed April 22, 2021. https://ir.lib.uwo.ca/etd/4956.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Samadi Alinia, Hadis. “New GPS Time Series Analysis and a Simplified Model to Compute an Accurate Seasonal Amplitude of Tropospheric Delay.” 2017. Web. 22 Apr 2021.

Vancouver:

Samadi Alinia H. New GPS Time Series Analysis and a Simplified Model to Compute an Accurate Seasonal Amplitude of Tropospheric Delay. [Internet] [Thesis]. University of Western Ontario; 2017. [cited 2021 Apr 22]. Available from: https://ir.lib.uwo.ca/etd/4956.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Samadi Alinia H. New GPS Time Series Analysis and a Simplified Model to Compute an Accurate Seasonal Amplitude of Tropospheric Delay. [Thesis]. University of Western Ontario; 2017. Available from: https://ir.lib.uwo.ca/etd/4956

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

RMIT University

6. Yuan, Y. Real-time retrieval of precipitable water vapour from GNSS precise point positioning.

Degree: 2015, RMIT University

URL: http://researchbank.rmit.edu.au/view/rmit:161611

► Global Positioning System (GPS) meteorology (GPS-MET) as a novel approach for precipitable water vapour (PWV) sounding using ground-based GPS receivers has been conducted since earlier… (more)

▼ Global Positioning System (GPS) meteorology (GPS-MET) as a novel approach for precipitable water vapour (PWV) sounding using ground-based GPS receivers has been conducted since earlier 1990s. Further research to date is based on post-processing or near-real-time processing using differenced GPS observations. It still remains a challenging task at high temporal resolutions and in real time. In addition, new Global Navigation Satellite Systems (GNSS) are under development quickly. This has the potential to improve the retrieval of PWV, leading GPS-MET research to a new stage of GNSS-MET. This study aims to take these aspects into account and investigates the retrieval of zenith total delay (ZTD) and PWV using real-time precise point positioning (PPP) approach. The PPP processing in this study is conducted using the BKG (the Federal Agency for Cartography and Geodesy) NTRIP Client (BNC) software platform which is substantially modified. The modifications include the modelling of tropospheric delay in which GPT2 is implemented and the corrections of error sources such as solid Earth tides, ocean tide loading and the antenna-related. The retrieved ZTD is then converted into PWV by multiplying a dimensionless proportionality which is derived from the Forecast Vienna Mapping Functions 1 (VMF1-FC) model. The retrievals of ZTD and PWV are validated using GPS observations in a one-month period at 20 globally distributed stations. The derived real-time ZTDs at most stations agree well with the tropospheric products from the International GNSS Service (IGS) and the root mean square (RMS) errors are <12 mm. The RMS errors of the PWVs in comparison with the radiosonde data are ≤3 mm. Note that 15 mm accuracy is the threshold if ZTDs are input to Numerical Weather Prediction (NWP) models and 3 mm accuracy is the threshold if PWVs are inputs to weather nowcasting according to the document by World Meteorological Organization (WMO). Furthermore, the theoretical accuracy of PWVs in various conditions is analysed. The RMS error of PWV is proved to be a strictly increasing function of zenith wet delay (ZWD) and weighted mean temperature. Hence the retrieval of PWV is more challenging in higher temperature and humidity conditions. This research proves that even in poor retrieval conditions, i.e., high humidity and temperature, an accuracy of PWV at 3 mm level is still achievable using the real-time ZTD from PPP and the empirical models for the determination of weighted mean temperature. A preliminary study of the ZTD retrieval using multi-GNSS data is also conducted in this study. The addition of GLONASS (GLObal NAvigation Satellite System) observations will significantly increase the number of visible satellites and improve the Dilution of Precision (DOP) indices like Positional DOP (PDOP) and Geometric DOP (GDOP). However, a test of ZTD retrieval at 12 global IGS stations shows that adding GLONASS data degrades the accuracy of ZTD. A further analysis implies that the multi-GNSS processing can be improved by the…

Subjects/Keywords: Fields of Research; GPS meteorology; GNSS meteorology; Zenith total delay; Precipitable water vapour; Precise point positioning; Multiple GNSS; Tropospheric delay; Zenith wet delay; NTRIP; Numerical weather prediction; Weather nowcasting; Global Navigation Satellite System

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APA (6^th Edition):

Yuan, Y. (2015). Real-time retrieval of precipitable water vapour from GNSS precise point positioning. (Thesis). RMIT University. Retrieved from http://researchbank.rmit.edu.au/view/rmit:161611

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Yuan, Y. “Real-time retrieval of precipitable water vapour from GNSS precise point positioning.” 2015. Thesis, RMIT University. Accessed April 22, 2021. http://researchbank.rmit.edu.au/view/rmit:161611.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Yuan, Y. “Real-time retrieval of precipitable water vapour from GNSS precise point positioning.” 2015. Web. 22 Apr 2021.

Vancouver:

Yuan Y. Real-time retrieval of precipitable water vapour from GNSS precise point positioning. [Internet] [Thesis]. RMIT University; 2015. [cited 2021 Apr 22]. Available from: http://researchbank.rmit.edu.au/view/rmit:161611.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Yuan Y. Real-time retrieval of precipitable water vapour from GNSS precise point positioning. [Thesis]. RMIT University; 2015. Available from: http://researchbank.rmit.edu.au/view/rmit:161611

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

7. Masoumi, Salim. GPS tropospheric modelling: new developments and insights .

Degree: 2017, Australian National University

URL: http://hdl.handle.net/1885/148041

► GPS is widely used to monitor temporal and spatial variations of Earth’s crust, oceans and atmosphere. Of particular interest to this research is the use… (more)

▼ GPS is widely used to monitor temporal and spatial variations of Earth’s crust, oceans and atmosphere. Of particular interest to this research is the use of GPS for studying variations in the Earth’s lower atmosphere. While there have been significant advances in the techniques and models used in GPS analyses over the past two decades, there is still room for improvement. In particular, observations at very low elevation angles still suffer greatly from modelling errors. These low-elevation observations provide useful information about the moisture content of the atmosphere and its variability around a GPS station, and are thus valuable data for meteorological studies if properly modelled. The main focus of this thesis is on optimization of the techniques and models used in GPS analysis for more accurate estimates of the tropospheric delays. Particular attention is paid to modelling low-elevation observations and challenging weather conditions. Throughout the thesis, we investigate several different aspects of modelling techniques and how each of them affect the tropospheric estimates. By applying a previously developed empirical model [Moore, 2015], the site-specific errors are shown to have large impacts on the tropospheric delay estimates: empirical mitigation of site-specific errors leads to improved repeatabilities of heights and tropospheric zenith delays for the majority of the stations in our analysis. The empirical site-specific model also significantly reduces the sensitivity of tropospheric zenith delay estimates to the choice of elevation cut-off. Another important potential source of error, the GPS estimates of tropospheric horizontal gradients are shown to be more accurate than the model values currently available. However, the conventional two-axis planar model of gradients does not accurately represent the actual gradients of the refractivity under weather conditions with asymmetric horizontal changes of refractivity. Such abnormal conditions may occur due to topography-driven gravity waves in the troposphere, and the mismodelled tropospheric horizontal gradients induce errors in the parameter estimates, sometimes leading to skewed position time series and inaccurate tropospheric zenith delays. A new parametrization of tropospheric gradients whereby an arbitrary number of gradients are estimated as discrete directional wedges is shown via both simulations and real case studies to largely improve the accuracy of recovered tropospheric zenith delays in asymmetric gradient scenarios. The new directional model significantly improves the repeatabilities of the station height time series in asymmetric gradient situations while causing slightly degraded repeatabilities for the stations …

Subjects/Keywords: Global Positioning System; Tropospheric delay; Site-specific errors; Tropospheric horizontal gradients; Directional gradient model; Temporal constraints

…have large impacts on the tropospheric delay estimates: empirical mitigation of site-specific… …reduces the sensitivity of tropospheric zenith delay estimates to the choice of elevation cut… …Background 2.1 GPS observables, modelling and parameters . 2.2 Tropospheric delay modelling in GPS… …for tropospheric delay estimation . . . . . . . . . . . 3.2.4 Impact of the ESM on the… …25 xiii LIST OF FIGURES xiv 3.5 The differences between the tropospheric zenith delay…

10 more images…

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APA (6^th Edition):

Masoumi, S. (2017). GPS tropospheric modelling: new developments and insights . (Thesis). Australian National University. Retrieved from http://hdl.handle.net/1885/148041

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Masoumi, Salim. “GPS tropospheric modelling: new developments and insights .” 2017. Thesis, Australian National University. Accessed April 22, 2021. http://hdl.handle.net/1885/148041.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Masoumi, Salim. “GPS tropospheric modelling: new developments and insights .” 2017. Web. 22 Apr 2021.

Vancouver:

Masoumi S. GPS tropospheric modelling: new developments and insights . [Internet] [Thesis]. Australian National University; 2017. [cited 2021 Apr 22]. Available from: http://hdl.handle.net/1885/148041.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Masoumi S. GPS tropospheric modelling: new developments and insights . [Thesis]. Australian National University; 2017. Available from: http://hdl.handle.net/1885/148041

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

8. Korak, Saha. Propagation of Microwaves in the Troposphere with Potential Application to GPS based Navigation and Meteorology with emphasis on Indian region.

Degree: 2008, Cochin University of Science and Technology

URL: http://dyuthi.cusat.ac.in/purl/2715

► Global Positioning System (GPS), with its high integrity, continuous availability and reliability, revolutionized the navigation system based on radio ranging. With four or more GPS… (more)

▼ Global Positioning System (GPS), with its high integrity, continuous availability and reliability, revolutionized the navigation system based on radio ranging. With four or more GPS satellites in view, a GPS receiver can find its location anywhere over the globe with accuracy of few meters. High accuracy - within centimeters, or even millimeters is achievable by correcting the GPS signal with external augmentation system. The use of satellite for critical application like navigation has become a reality through the development of these augmentation systems (like W AAS, SDCM, and EGNOS, etc.) with a primary objective of providing essential integrity information needed for navigation service in their respective regions. Apart from these, many countries have initiated developing space-based regional augmentation systems like GAGAN and IRNSS of India, MSAS and QZSS of Japan, COMPASS of China, etc. In future, these regional systems will operate simultaneously and emerge as a Global Navigation Satellite System or GNSS to support a broad range of activities in the global navigation sector.Among different types of error sources in the GPS precise positioning, the propagation delay due to the atmospheric refraction is a limiting factor on the achievable accuracy using this system. The WADGPS, aimed for accurate positioning over a large area though broadcasts different errors involved in GPS ranging including ionosphere and troposphere errors, due to the large temporal and spatial variations in different atmospheric parameters especially in lower atmosphere (troposphere), the use of these broadcasted tropospheric corrections are not sufficiently accurate. This necessitated the estimation of tropospheric error based on realistic values of tropospheric refractivity. Presently available methodologies for the estimation of tropospheric delay are mostly based on the atmospheric data and GPS measurements from the mid-latitude regions, where the atmospheric conditions are significantly different from that over the tropics. No such attempts were made over the tropics. In a practical approach when the measured atmospheric parameters are not available analytical models evolved using data from mid-latitudes for this purpose alone can be used. The major drawback of these existing models is that it neglects the seasonal variation of the atmospheric parameters at stations near the equator. At tropics the model underestimates the delay in quite a few occasions. In this context, the present study is afirst and major step towards the development of models for tropospheric delay over the Indian region which is a prime requisite for future space based navigation program (GAGAN and IRNSS). Apart from the models based on the measured surface parameters, a region specific model which does not require any measured atmospheric parameter as input, but depends on latitude and day of the year was developed for the tropical region with emphasis on Indian sector.Large variability of atmospheric water vapor content in short spatial and/or temporal scales…

Subjects/Keywords: Microwaves; Tropospheric Delay; GPS; Navigation; Meteorology; Mapping; Indian region; Physics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Korak, S. (2008). Propagation of Microwaves in the Troposphere with Potential Application to GPS based Navigation and Meteorology with emphasis on Indian region. (Thesis). Cochin University of Science and Technology. Retrieved from http://dyuthi.cusat.ac.in/purl/2715

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Korak, Saha. “Propagation of Microwaves in the Troposphere with Potential Application to GPS based Navigation and Meteorology with emphasis on Indian region.” 2008. Thesis, Cochin University of Science and Technology. Accessed April 22, 2021. http://dyuthi.cusat.ac.in/purl/2715.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Korak, Saha. “Propagation of Microwaves in the Troposphere with Potential Application to GPS based Navigation and Meteorology with emphasis on Indian region.” 2008. Web. 22 Apr 2021.

Vancouver:

Korak S. Propagation of Microwaves in the Troposphere with Potential Application to GPS based Navigation and Meteorology with emphasis on Indian region. [Internet] [Thesis]. Cochin University of Science and Technology; 2008. [cited 2021 Apr 22]. Available from: http://dyuthi.cusat.ac.in/purl/2715.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Korak S. Propagation of Microwaves in the Troposphere with Potential Application to GPS based Navigation and Meteorology with emphasis on Indian region. [Thesis]. Cochin University of Science and Technology; 2008. Available from: http://dyuthi.cusat.ac.in/purl/2715

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

North-West University

9. Combrink, Adriaan Zacharias Albertus. Detection of atmospheric water vapour using the Global Positioning System / A.Z.A. Combrink .

Degree: 2003, North-West University

URL: http://hdl.handle.net/10394/184

► The Global Positioning System (GPS) has been used for more than a decade for the accurate determination of position on the earth's surface, as well… (more)

Subjects/Keywords: Global Positioning System; Zenith tropospheric delay; Total electron content; Precipitable water vapour; Ionosphere; Troposhere

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Combrink, A. Z. A. (2003). Detection of atmospheric water vapour using the Global Positioning System / A.Z.A. Combrink . (Thesis). North-West University. Retrieved from http://hdl.handle.net/10394/184

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Combrink, Adriaan Zacharias Albertus. “Detection of atmospheric water vapour using the Global Positioning System / A.Z.A. Combrink .” 2003. Thesis, North-West University. Accessed April 22, 2021. http://hdl.handle.net/10394/184.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Combrink, Adriaan Zacharias Albertus. “Detection of atmospheric water vapour using the Global Positioning System / A.Z.A. Combrink .” 2003. Web. 22 Apr 2021.

Vancouver:

Combrink AZA. Detection of atmospheric water vapour using the Global Positioning System / A.Z.A. Combrink . [Internet] [Thesis]. North-West University; 2003. [cited 2021 Apr 22]. Available from: http://hdl.handle.net/10394/184.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Combrink AZA. Detection of atmospheric water vapour using the Global Positioning System / A.Z.A. Combrink . [Thesis]. North-West University; 2003. Available from: http://hdl.handle.net/10394/184

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

10. Ugur, Mehmet Ali. Modeling the Neutral Atmosphere in Continuously Operating GNSS Networks using OPUS-Projects.

Degree: MS, Civil Engineering, 2013, The Ohio State University

URL: http://rave.ohiolink.edu/etdc/view?acc_num=osu1357277355

► The Height Modernization Program, which has been designed and is being implemented by the National Geodetic Survey (NGS), is an ongoing operation focused on… (more)

▼ The Height Modernization Program, which has been designed and is being implemented by the National Geodetic Survey (NGS), is an ongoing operation focused on forming accurate, reliable heights using the Global Navigation Satellite System (GNSS) technology. The determination of GPS-derived ellipsoidal heights is one of the most critical components in the Height Modernization Program and subject to potentially significant error sources in GPS. The GPS error sources may reduce the accuracy of GPS-derived coordinates and ellipsoidal heights. The height component is primarily affected by inherent geometric weakness and by un-modeled part of the neutral atmosphere (troposphere). Some recent studies have shown that tropospheric delay is one of the most challenging and essential error sources in space-based geodetic applications; especially, in the determination of ellipsoidal height, if it is not sufficiently accounted for. This thesis focuses on possible improvements in the accuracy of the GPS-derived ellipsoidal height, and addresses the effects of tropospheric delay, pertinent to the NGS web-based GPS processing engine, OPUS-Projects, based on the national Continuously Operating Reference Station (CORS) network. This thesis validates that the effect of tropospheric delay, through the combination of the national and global permanent GNSS networks (CORS and International GNSS Service (IGS)), can be reduced, resulting in the improved accuracy of GPS-derived ellipsoidal heights. Specific experiments have been designed and performed to illustrate the improvements. The experiments presented in this study were conducted in the State of Ohio and used the Ohio CORS stations to generate case studies with variable GPS data spans, baseline lengths, and network designs. In addition to CORS stations, IGS stations are included to improve the accuracy of the estimated tropospheric corrections. The experimental results show that the reliability of tropospheric corrections is highly correlated to the length of the baseline, the duration of GPS data, and the network configuration. The experiments attempt to investigate the required baseline length with respect to the duration of GPS data and determine the optimal network configuration to assure proper estimation of tropospheric corrections, and, ultimately, ellipsoidal heights. The experiments carried out in this study prove that the optimal network design is based on the multiple base approach that utilizes the IGS stations. Not only this approach improves the accuracy and consistency of tropospheric corrections, but it also improves the accuracy of the ellipsoidal heights determination. In conclusion, this thesis demonstrates the importance of proper accommodation of the tropospheric effect in the determination of ellipsoidal heights. More importantly, this thesis illustrates that the tropospheric effect can be accurately modeled and, subsequently, correction can be applied to improve the accuracy of GPS positioning using permanent GPS networks;… Advisors/Committee Members: Grejner-Brzezinska, Dorota A. (Advisor).

Subjects/Keywords: Atmosphere; Civil Engineering; Engineering; Geotechnology; GPS; the neutral atmosphere; troposphere modeling; tropospheric delay; GPS-derived ellipsoidal heights

…17 2.4. 2.5. 3. The Tropospheric Propagation Delay and Refractivity… …19 From the Tropospheric Refractivity to Delay… …28 3.1. Modeling the Tropospheric Delay… …28 3.2. Tropospheric Delay Modeling Techniques… …15 Figure 2.5: The Neutral Atmosphere Propagation (Tropospheric) Delay L…

10 more images…

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ugur, M. A. (2013). Modeling the Neutral Atmosphere in Continuously Operating GNSS Networks using OPUS-Projects. (Masters Thesis). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1357277355

Chicago Manual of Style (16^th Edition):

Ugur, Mehmet Ali. “Modeling the Neutral Atmosphere in Continuously Operating GNSS Networks using OPUS-Projects.” 2013. Masters Thesis, The Ohio State University. Accessed April 22, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357277355.

MLA Handbook (7^th Edition):

Ugur, Mehmet Ali. “Modeling the Neutral Atmosphere in Continuously Operating GNSS Networks using OPUS-Projects.” 2013. Web. 22 Apr 2021.

Vancouver:

Ugur MA. Modeling the Neutral Atmosphere in Continuously Operating GNSS Networks using OPUS-Projects. [Internet] [Masters thesis]. The Ohio State University; 2013. [cited 2021 Apr 22]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1357277355.

Council of Science Editors:

Ugur MA. Modeling the Neutral Atmosphere in Continuously Operating GNSS Networks using OPUS-Projects. [Masters Thesis]. The Ohio State University; 2013. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1357277355

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Open Access Theses and Dissertations