Water vapor tomography using GPS phase observations: simulation results

Nilsson, Tobias; Gradinarsky, Lubomir

doi:10.1109/tgrs.2006.877755

Cited by 83 publications

(50 citation statements)

References 19 publications

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“…This method has been developed by many other scientists for troposphere tomography [12][13][14][15][16][17]. Other approaches to retrieve the 3D WV include algebraic reconstruction techniques [18,19] and estimating WV directly from raw GPS phase observations [20].…”

Section: Introductionmentioning

confidence: 99%

An Improved Tomography Approach Based on Adaptive Smoothing and Ground Meteorological Observations

et al. 2017

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Using the Global Navigation Satellite System (GNSS) to sense three-dimensional water vapor (WV) has been intensively investigated. However, this technique still heavily relies on the a priori information. In this study, we propose an improved tomography approach based on adaptive Laplacian smoothing (ALS) and ground meteorological observations. By using the proposed approach, the troposphere tomography is less dependent on a priori information and the ALS constraints match better with the actual situation than the constant constraints. Tomography experiments in Hong Kong during a heavy rainy period and a rainless period show that the ALS method gets superior results compared with the constant Laplacian smoothing (CLS) method. By validation with radiosonde and European Centre for Medium-Range Weather Forecasts (ECMWF) data, we found that the introduction of ground meteorological observations into tomography can solve the perennial problem of resolving the wet refractivity in the lower troposphere and thus significantly improve the tomography results. However, bad data quality and incompatibility of the ground meteorological observations may introduce errors into tomography results.

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Section: Introductionmentioning

confidence: 99%

An Improved Tomography Approach Based on Adaptive Smoothing and Ground Meteorological Observations

et al. 2017

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“…Knowing precise information about the spatiotemporal distribution of water vapour is a prerequisite for atmospheric research (Emanuel et al, 1995;Park et al, 1999;Bauer et al, 2011;Ducroco et al, 2002). With the rapid development of the global navigation satellite system (GNSS), the GNSS troposphere tomographic technique has become a potentially powerful method for obtaining three-dimensional distributions of water vapour with high spatio-temporal resolution (Braun, et al, 1999;Flores et al, 2000;Troller, et al, 2002;Nilsson and Gradinarsky, 2006;Perler et al, 2011;Brenot et al, 2014;. In recent years, the integration of GNSS data and NWP has given better results in the field of GNSS meteorology (Douša and Václavovic, 2014;Douša et al, 2016;Wilgan et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Tropospheric tomography is used to discretise the tomographic area into a large number of voxels and established the integral equation using the signal observations which cross the whole tomographic area (Flores et al, 2000). In addition, some constraint conditions are also imposed on the tomographic modelling so as to overcome the ill-posed problem caused by the unfavourable geometric distribution of ground-based receivers as well as the constellation of the GNSS satellites (Flores et al, 2000;Skone and Houle, 2005;Nilsson and Gradinarsky, 2006;Bender and Raabe, 2007;Brenot et al, 2014). Recently, some external information was exploited which tries to improve the initial fields used in tomographic modelling.…”

Section: Introductionmentioning

confidence: 99%

An improved troposphere tomographic approach considering the signals coming from the side face of the tomographic area

Zhao¹,

Yao²

2017

Ann. Geophys.

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Abstract. The spatio-temporal distribution of atmospheric water vapour information plays a crucial role in the establishment of modern numerical weather forecast models and description of the different weather variations. A troposphere tomographic method has been proposed considering the signal rays penetrating from the side of the area of interest to solve the problem of the low utilisation rate of global navigation satellite system (GNSS) observations. Given the method above needs the establishment of a unit scale factor model using the radiosonde data at only one location in the research area, an improved approach is proposed by considering the reasonability of modelling data and the diversity of the modelling parameters for building a more accurate unit scale factor model. The new established model is established using grid point data derived from the European Centre for Medium-Range Weather Forecasts (ECMWF) and evenly distributed in the tomographic area, which can enhance the number of calculated initial water vapour density values with high accuracy. We validated the improved method with respect to the previous methods, as well as the result from a radiosonde using data from 12 stations from the Hong Kong Satellite Positioning Reference Station Network. The obtained result shows that the number of initial values estimated by the new model is increased by 6.83 %, while the internal and external accuracies are 0.08 and 0.24 g m −3 , respectively. Integrated water vapour (IWV) and water vapour density profile comparisons show that the improved method is superior to previous studies in terms of RMS, MAE, and bias, which suggests higher accuracy and reliability.

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“…In the tomography model, the grid is usually divided in an even vertical height with a constant top height of 10 km and the water vapor density is considered to be same inside each voxel (Flores et al, 2000;Hirahara, 2000;Troller et al, 2006;Nilsson and Gradinarsky, 2006;Bastin et al, 2007). However, such a grid model does not take into account the significant difference of actual water vapor distribution inside or outside each voxel for the vertical direction.…”

Section: Introductionmentioning

confidence: 99%

Optimization of GPS water vapor tomography technique with radiosonde and COSMIC historical data

Xia

Cai

2016

Ann. Geophys.

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Abstract. The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in numerical weather prediction. GPS tomography technique has been proved effectively for three-dimensional water vapor reconstruction. In this study, the tomography processing is optimized in a few aspects by the aid of radiosonde and COSMIC historical data. Firstly, regional tropospheric zenith hydrostatic delay (ZHD) models are improved and thus the zenith wet delay (ZWD) can be obtained at a higher accuracy. Secondly, the regional conversion factor of converting the ZWD to the precipitable water vapor (PWV) is refined. Next, we develop a new method for dividing the tomography grid with an uneven voxel height and a varied water vapor layer top. Finally, we propose a Gaussian exponential vertical interpolation method which can better reflect the vertical variation characteristic of water vapor. GPS datasets collected in Hong Kong in February 2014 are employed to evaluate the optimized tomographic method by contrast with the conventional method. The radiosonde-derived and COSMICderived water vapor densities are utilized as references to evaluate the tomographic results. Using radiosonde products as references, the test results obtained from our optimized method indicate that the water vapor density accuracy is improved by 15 and 12 % compared to those derived from the conventional method below the height of 3.75 km and above the height of 3.75 km, respectively. Using the COSMIC products as references, the results indicate that the water vapor density accuracy is improved by 15 and 19 % below 3.75 km and above 3.75 km, respectively.

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Water vapor tomography using GPS phase observations: simulation results

Cited by 83 publications

References 19 publications

An Improved Tomography Approach Based on Adaptive Smoothing and Ground Meteorological Observations

An Improved Tomography Approach Based on Adaptive Smoothing and Ground Meteorological Observations

An improved troposphere tomographic approach considering the signals coming from the side face of the tomographic area

Optimization of GPS water vapor tomography technique with radiosonde and COSMIC historical data

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