B-spline function-based approach for GPS tropospheric tomography

Haji-Aghajany, Saeid; Amerian, Yazdan; Verhagen, Sandra

doi:10.1007/s10291-020-01005-x

Cited by 32 publications

(23 citation statements)

References 41 publications

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“…The results of the research also indicate that the ANES approach improves the accuracy of tomographic reconstructions compared to the conventional approach. In addition to the approach proposed in this paper, many other influential developments have also improved the accuracy of tomographic reconstruction compared to the conventional approach [15,[34][35][36][37]. Table 3 presents the tomographic strategies of the developments mentioned above and the optimal strategy in this paper.…”

Section: Discussionmentioning

confidence: 99%

An Adaptive Non-Uniform Vertical Stratification Method for Troposphere Water Vapor Tomography

2021

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Global Navigation Satellite System (GNSS) water vapor tomography provides a four-dimensional (4-D) distribution of water vapor in the atmosphere for weather monitoring. It has developed into a widely used technique in numerical weather prediction (NWP). Vertical stratification is essential in discretizing the tomographic region. Traditional discretization methods divide the tomographic area into regular voxels with an equal height interval, which ignores the dynamic exponential distribution of water vapor. In recent years, non-uniform stratification methods have been widely validated by tomographic experiments. However, such experiments have not proposed a specific calculation method for stratification thickness. Therefore, in this paper, we introduced an adaptive non-uniform stratification method that follows the exponential distribution of water vapor in the tomographic region and presented the process of iterative calculation to acquire the optimal stratification interval. The proposed approach was applied based on the exponential decreasing trend in water vapor with increasing altitude. Moreover, it could adaptively calculate the interval of stratification height according to water vapor content. The tomographic experiments were performed using Global Positioning System (GPS) data from 19 ground-based stations in the Hong Kong Satellite Positioning Reference Station Network (SatRef) from 1 to 31 August 2019. The results indicated that, compared to the traditional stratification method, the root mean square error derived from the proposed approach was reduced by 0.26 g/m3. Additionally, severe weather can negatively affect the accuracy of the tomographic results. The results also showed that the accuracy of the tomographic results was reduced with increasing altitude. Moreover, the performance of the tomographic water vapor fields below 3000 m was improved by the proposed approach.

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Section: Discussionmentioning

confidence: 99%

An Adaptive Non-Uniform Vertical Stratification Method for Troposphere Water Vapor Tomography

2021

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“…According to the above definitions for PCA, only patients with tumors “involving the hilar bile duct (defined as the duct located topologically between the right side of the umbilical portion of the left portal vein and the left side of the origin of the right posterior portal vein)” were included into our analysis [ 23 , 24 , 25 ].…”

Section: Methodsmentioning

confidence: 99%

“…Pathologic tumor staging of the PHC based on the newest 8th TNM classification of the UICC and AJCCC [ 23 , 24 ].…”

Section: Methodsmentioning

confidence: 99%

Impact of Body Mass Index on Tumor Recurrence in Patients Undergoing Liver Resection for Perihilar Cholangiocarcinoma (pCCA)

Hau

Devantier

Jahn

et al. 2021

Cancers

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Background: The association of body mass index (BMI) and long-term prognosis and outcome of patients with perihilar cholangiocarcinoma (pCCA) has not been well defined. The aim of this study was to evaluate clinicopathologic and oncologic outcomes with pCCA undergoing resection, according to their BMI. Methods: Patients undergoing liver resection in curative intention for pCCA at a tertiary German hepatobiliary (HPB) center were identified from a prospective database. Patients were classified as normal weight (BMI 18.5–24.9 kg/m2), overweight (BMI 25.0–29.9 kg/m2) and obese (>30 kg/m2) according to their BMI. Impact of clinical and histo-pathological characteristics on recurrence-free survival (RFS) were assessed using Cox proportional hazard regression analysis among patients of all BMI groups. Results: Among a total of 95 patients undergoing liver resection in curative intention for pCCA in the analytic cohort, 48 patients (50.5%) had normal weight, 33 (34.7%) were overweight and 14 patients (14.7%) were obese. After a median follow-up of 4.3 ± 2.9 years, recurrence was observed in totally 53 patients (56%). The cumulative recurrence probability was higher in obese and overweight patients than normal weight patients (5-year recurrence rate: obese: 82% versus overweight: 81% versus normal weight: 58% at 5 years; p = 0.02). Totally, 1-, 3-, 5- and 10-year recurrence-free survival rates were 68.5%, 44.6%, 28.9% and 13%, respectively. On multivariable analysis, increased BMI (HR 1.08, 95% CI: 1.01–1.16; p = 0.021), poor/moderate tumor differentiation (HR 2.49, 95% CI: 1.2–5.2; p = 0.014), positive lymph node status (HR 2.01, 95% CI: 1.11–3.65; p = 0.021), positive resection margins (HR 1.89, 95% CI:1.02–3.4; p = 0.019) and positive perineural invasion (HR 2.92, 95% CI: 1.02–8.3; p = 0.045) were independent prognostic risk factors for inferior RFS. Conclusion: Our study shows that a high BMI is significantly associated with an increased risk of recurrence after liver resection in curative intention for pCCA. This factor should be considered in future studies to better predict patient’s individual prognosis and outcome based on their BMI.

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“…A prior constraint of the 3D structure of the water vapor needs to be applied in this vector, based on radiosonde data. A test [43] with a 17-station network in California was carried out, comparing the conventional, voxelbased method, and this new B-spline function method, both validated against radiosonde observations. RMSE was reported to reduce by about 0.3 g m −3 .…”

Section: Tomographymentioning

confidence: 99%

Review on the Role of GNSS Meteorology in Monitoring Water Vapor for Atmospheric Physics

Vaquero-Martínez

Antón

2021

Remote Sensing

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After 30 years since the beginning of the Global Positioning System (GPS), or, more generally, Global Navigation Satellite System (GNSS) meteorology, this technique has proven to be a reliable method for retrieving atmospheric water vapor; it is low-cost, weather independent, with high temporal resolution and is highly accurate and precise. GNSS ground-based networks are becoming denser, and the first stations installed have now quite long time-series that allow the study of the temporal features of water vapor and its relevant role inside the climate system. In this review, the different GNSS methodologies to retrieve atmospheric water vapor content re-examined, such as tomography, conversion of GNSS tropospheric delay to water vapor estimates, analyses of errors, and combinations of GNSS with other sources to enhance water vapor information. Moreover, the use of these data in different kinds of studies is discussed. For instance, the GNSS technique is commonly used as a reference tool for validating other water vapor products (e.g., radiosounding, radiometers onboard satellite platforms or ground-based instruments). Additionally, GNSS retrievals are largely used in order to determine the high spatio-temporal variability and long-term trends of atmospheric water vapor or in models with the goal of determining its notable influence on the climate system (e.g., assimilation in numerical prediction, as input to radiative transfer models, study of circulation patterns, etc.).

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B-spline function-based approach for GPS tropospheric tomography

Abstract: Important noteTo cite this publication, please use the final published version (if applicable). Please check the document version above.

Cited by 32 publications

References 41 publications

An Adaptive Non-Uniform Vertical Stratification Method for Troposphere Water Vapor Tomography

An Adaptive Non-Uniform Vertical Stratification Method for Troposphere Water Vapor Tomography

Impact of Body Mass Index on Tumor Recurrence in Patients Undergoing Liver Resection for Perihilar Cholangiocarcinoma (pCCA)

Review on the Role of GNSS Meteorology in Monitoring Water Vapor for Atmospheric Physics

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