GNSS water vapour tomography – Expected improvements by combining GPS, GLONASS and Galileo observations

Bender, Michael A.; Stosius, Ralf; Zus, Florian; Dick, Galina; Wickert, Jens; Raabe, Armin

doi:10.1016/j.asr.2010.09.011

Cited by 67 publications

(48 citation statements)

References 20 publications

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“…They either process path delays from stations of permanent GNSS networks , or from campaign setups, as in the ESCOMPTE experiment in France (Champollion et al, 2005;Nilsson et al, 2007;Bastin et al, 2007). Further works that exploit the tomographic approach are Nilsson and Gradinarsky (2006), Bender et al ( , 2011b, Rohm and Bosy (2011), Bosy et al (2012), Manning et al (2012) and Rohm (2013).…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

Tropospheric profiles of wet refractivity and humidity from the combination of remote sensing data sets and measurements on the ground

Hurter

Maier

2013

Atmos. Meas. Tech.

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Abstract. We reconstruct atmospheric wet refractivity profiles for the western part of Switzerland with a least-squares collocation approach from data sets of (a) zenith path delays that are a byproduct of the GPS (global positioning system) processing, (b) ground meteorological measurements, (c) wet refractivity profiles from radio occultations whose tangent points lie within the study area, and (d) radiosonde measurements. Wet refractivity is a parameter partly describing the propagation of electromagnetic waves and depends on the atmospheric parameters temperature and water vapour pressure. In addition, we have measurements of a lower Vband microwave radiometer at Payerne. It delivers temperature profiles at high temporal resolution, especially in the range from ground to 3000 m a.g.l., though vertical information content decreases with height. The temperature profiles together with the collocated wet refractivity profiles provide near-continuous dew point temperature or relative humidity profiles at Payerne for the study period from 2009 to 2011.In the validation of the humidity profiles, we adopt a twostep procedure. We first investigate the reconstruction quality of the wet refractivity profiles at the location of Payerne by comparing them to wet refractivity profiles computed from radiosonde profiles available for that location. We also assess the individual contributions of the data sets to the reconstruction quality and demonstrate a clear benefit from the data combination. Secondly, the accuracy of the conversion from wet refractivity to dew point temperature and relative humidity profiles with the radiometer temperature profiles is examined, comparing them also to radiosonde profiles.For the least-squares collocation solution combining GPS and ground meteorological measurements, we achieve the following error figures with respect to the radiosonde reference: maximum median offset of relative refractivity error is −16 % and quartiles are 5 % to 40 % for the lower troposphere. We further added 189 radio occultations that met our requirements. They mostly improved the accuracy in the upper troposphere. Maximum median offsets have decreased from 120 % relative error to 44 % at 8 km height. Dew point temperature profiles after the conversion with radiometer temperatures compare to radiosonde profiles as to: absolute dew point temperature errors in the lower troposphere have a maximum median offset of −2 K and maximum quartiles of 4.5 K. For relative humidity, we get a maximum mean offset of 7.3 %, with standard deviations of 12-20 %.The methodology presented allows us to reconstruct humidity profiles at any location where temperature profiles, but no atmospheric humidity measurements other than from GPS are available. Additional data sets of wet refractivity are shown to be easily integrated into the framework and strongly aid the reconstruction. Since the used data sets are all operational and available in near-realtime, we envisage the methodology of this paper to be a tool for nowcasting of clouds and r...

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Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

Tropospheric profiles of wet refractivity and humidity from the combination of remote sensing data sets and measurements on the ground

Hurter

Maier

2013

Atmos. Meas. Tech.

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“…The ART has been successfully applied to reconstruction of water vapor field (Chen and Liu, 2014;Bender et al, 2011). Its main advantage is the high numerical stability, even under adverse conditions and also relatively easy to incorporate prior knowledge into the reconstruction process.…”

Section: Tomographic Solutionmentioning

confidence: 99%

A new approach for GNSS tomography from a few GNSS stations

Ding

Zhang

et al. 2018

Atmos. Meas. Tech.

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Abstract. The determination of the distribution of water vapor in the atmosphere plays an important role in the atmospheric monitoring. Global Navigation Satellite Systems (GNSS) tomography can be used to construct 3-D distribution of water vapor over the field covered by a GNSS network with high temporal and spatial resolutions. In current tomographic approaches, a pre-set fixed rectangular field that roughly covers the area of the distribution of the GNSS signals on the top plane of the tomographic field is commonly used for all tomographic epochs. Due to too many unknown parameters needing to be estimated, the accuracy of the tomographic solution degrades. Another issue of these approaches is their unsuitability for GNSS networks with a low number of stations, as the shape of the field covered by the GNSS signals is, in fact, roughly that of an upsidedown cone rather than the rectangular cube as the pre-set. In this study, a new approach for determination of tomographic fields fitting the real distribution of GNSS signals on different tomographic planes at different tomographic epochs and also for discretization of the tomographic fields based on the perimeter of the tomographic boundary on the plane and meshing techniques is proposed. The new approach was tested using three stations from the Hong Kong GNSS network and validated by comparing the tomographic results against radiosonde data from King's Park Meteorological Station (HKKP) during the one month period of May 2015. Results indicated that the new approach is feasible for a three-station GNSS network tomography. This is significant due to the fact that the conventional approaches cannot even solve a network tomography from a few stations.

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“…(5), however, is a large sparse matrix. The normal equation of A is singular which leads to numerical problems when using a direct inversion method (Bender et al, 2011a). To overcome this rank deficiency issue, constraint conditions are often introduced to the tomography equation (Flores et al, 2000;Troller et al, 2002;Rohm and Bosy 2009;Bender et al, 2011a).…”

Section: Constraint Conditionsmentioning

confidence: 99%

“…The SWD can be extracted from the slant total delay by excluding slant hydrostatic delay (Davis et al, 1985;Bevis et al, 1994;Bender et al, 2011a). In our study, GAMIT10.5 software is used to process GPS observations (King and Bock, 2001;King and Bock, 2006).…”

Section: Building the Observation Equationmentioning

confidence: 99%

A method to improve the utilization of GNSS observation for water vapor tomography

2016

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Abstract. Existing water vapor tomographic methods useGlobal Navigation Satellite System (GNSS) signals penetrating the entire research area while they do not consider signals passing through its sides. This leads to the decreasing use of observed satellite signals and allows for no signals crossing from the bottom or edge areas especially for those voxels in research areas of interest. Consequently, the accuracy of the tomographic results for the bottom of a research area, and the overall reconstructed accuracy do not reach their full potential. To solve this issue, an approach which uses GPS data with both signals that pass the side and top of a research area is proposed. The advantages of proposed approach include improving the utilization of existing GNSS observations and increasing the number of voxels crossed by satellite signals. One point should be noted that the proposed approach needs the support of radiosonde data inside the tomographic region. A tomographic experiment was implemented using observed GPS data from the Continuously Operating Reference System (CORS) Network of Zhejiang Province, China. The comparison of tomographic results with data from a radiosonde shows that the root mean square error (RMS), bias, mean absolute error (MAE), and standard deviation (SD) of the proposed approach are superior to those of the traditional method.

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GNSS water vapour tomography – Expected improvements by combining GPS, GLONASS and Galileo observations

Cited by 67 publications

References 20 publications

Tropospheric profiles of wet refractivity and humidity from the combination of remote sensing data sets and measurements on the ground

Tropospheric profiles of wet refractivity and humidity from the combination of remote sensing data sets and measurements on the ground

A new approach for GNSS tomography from a few GNSS stations

A method to improve the utilization of GNSS observation for water vapor tomography

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