scholarly journals A method for predicting short‐time changes in fine particulate matter (PM 2.5 ) mass concentration based on the global navigation satellite system zenith tropospheric delay

2019 ◽  
Vol 27 (1) ◽  
Author(s):  
Min Guo ◽  
Hanwei Zhang ◽  
Pengfei Xia
Keyword(s):  
Mass Concentration ◽  
Fine Particulate Matter ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Pm 2.5 ◽  
Zenith Tropospheric Delay ◽  
Fine Particulate ◽  
Time Changes ◽  
Global Navigation Satellite ◽  
Short Time

scholarly journals Estimación de parámetros troposféricos en tiempo casi real para Sudamérica mediante técnicas GNSS

2020 ◽  
Author(s):  
◽  
Juan Manuel Aragón Paz
Keyword(s):  
Water Vapor ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Navigation Satellite ◽  
Total Delay ◽  
Zenith Tropospheric Delay ◽  
Zenith Total Delay ◽  
El Sistema ◽  
Sociedad Civil ◽  
Global Navigation Satellite

En el presente trabajo de tesis se desarrolla el diseño e implementación de un sistema de cálculo, en tiempo casi real, de parámetros troposféricos mediante técnicas de navegación global por satélite (GNSS, del inglés Global Navigation Satellite System) para Sudamérica. El desarrollo de la llamada Meteorología GNSS se remonta a principios de la década del 90 donde se encuentran los trabajos fundacionales de esta disciplina. Con el correr de los años, nuevas contribuciones han ido definiendo los reales alcances de esta técnica, poniendo en práctica metodologías cada vez más contrastadas con los métodos de medición tradicionales. En los últimos años los esfuerzos se han enfocado en el desarrollo de procedimientos de cálculo que permitan la utilización de los datos GNSS, cada vez más numerosos, en la asimilación para modelos meteorológicos (en especial los de corto plazo), permitiendo así anticipar eventos con alto impacto a la sociedad civil (tormentas con granizo, inundaciones repentinas, eventos convectivos de mesoescala, etc). Numerosos trabajos se han centrado en la implementación de la meteorología GNSS en Europa, Estados Unidos y Japón. Para la región Sudamericana existen pocos y recientes antecedentes de la aplicación de estas metodologías. Se desarrolló un sistema de cálculo, que permite hacer uso de infraestructura existente en la región, tanto meteorológica como geodésica, enfocado en la obtención de las variables de interés meteorológico como son el retardo troposférico cenital (ZTD, del inglés Zenith Total Delay) y el vapor de agua integrado (IWV, del inglés Integrated Water Vapor). Por otra parte, se han realizado estudios en la aplicación del ZTD y el IWV a índices que permitan dar información rápida acerca de posibles eventos meteorológicos severos. En este trabajo se desarrollan las estrategias diseñadas para la adquisición de los datos, su disponibilidad y alcance. Las problemáticas en la disponibilidad de los mismos, de acuerdo a su procedencia, son descriptas y sorteadas. Seguidamente se brinda una detallada descripción de la metodología de estimación de las observaciones, haciendo especial foco en los parámetros de retardo troposférico cenital (ZTD, del ingles Zenith Tropospheric Delay) y vapor de agua integrado (IWV, del inglés Integrated Water Vapor) mediante el procesamiento de las observaciones GNSS y meteorológicas. Una vez que se tienen los resultados, la presentación de los mismos y los posibles formato de intercambio con las instituciones potenciales usuarias del dato son discutidos. Finalizando esta sección se hace un análisis de la performance del sistema de procesamiento contra las técnicas de radio sondeo (convencionales) y alguno de los modelos de reanálisis mas utilizados. En una segunda etapa se explora las distintas capacidades del IWV GNSS para representar las variaciones temporales y espaciales de la distribución del vapor de agua atmosférico frente a distintas situaciones meteorológicas. También, se describe el desarrollo de posibles índices de alerta que hagan utilización de la información disponible a partir del IWV GNSS. Basándose en bibliografía actualizada se comparan las distintas posibilidades de aplicación a la región de estudio en función de la frecuencia temporal y espacial de las observaciones. Los resultados son presentados analizando un evento de interés meteorológico para la región central de Argentina. Finalmente, los puntos mas salientes del presente trabajo son presentados en las conclusiones. Las mismas abarcan desde el sistema de descarga de datos hasta la implementación de los índices de alerta. Se formulan las posibles derivaciones del trabajo y sus implicancias en la mejora continua de este sistema, que en tiempo casi real, provee información sobre los parámetros de ZTD e IWV. Una sección final describe cuáles son las recomendaciones que permitirían mejoras en la utilización de los datos provistos para conseguir un máximo aprovechamiento de los mismos.

scholarly journals A Regional Zenith Tropospheric Delay (ZTD) Model Based on GPT3 and ANN

2021 ◽  
Vol 13 (5) ◽  
pp. 838
Author(s):  
Fei Yang ◽  
Jiming Guo ◽  
Chaoyang Zhang ◽  
Yitao Li ◽  
Jun Li
Keyword(s):  
Satellite System ◽  
Reference Station ◽  
Tropospheric Delay ◽  
Neutral Atmosphere ◽  
Zenith Tropospheric Delay ◽  
Satellite Positioning ◽  
Proposed Model ◽  
Radio Signals ◽  
Global Navigation Satellite ◽  
Gnss Data

The delays of radio signals transmitted by global navigation satellite system (GNSS) satellites and induced by neutral atmosphere, which are usually represented by zenith tropospheric delay (ZTD), are required as critical information both for GNSS positioning and navigation and GNSS meteorology. Establishing a stable and reliable ZTD model is one of the interests in GNSS research. In this study, we proposed a regional ZTD model that makes full use of the ZTD calculated from regional GNSS data and the corresponding ZTD estimated by global pressure and temperature 3 (GPT3) model, adopting the artificial neutral network (ANN) to construct the correlation between ZTD derived from GPT3 and GNSS observations. The experiments in Hong Kong using Satellite Positioning Reference Station Network (SatRet) were conducted and three statistical values, i.e., bias, root mean square error (RMSE), and compound relative error (CRE) were adopted for our comparisons. Numerical results showed that the proposed model outperformed the parameter ZTD model (Saastamoinen model) and the empirical ZTD model (GPT3 model), with an approximately 56%/52% and 52%/37% RMSE improvement in the internal and external accuracy verification, respectively. Moreover, the proposed method effectively improved the systematic deviation of GPT3 model and achieved better ZTD estimation in both rainy and rainless conditions.

scholarly journals Assessment of GNSS PPP-Based Zenith Tropospheric Delay

2020 ◽  
Vol 55 (4) ◽  
pp. 171-184
Author(s):  
Mohamed Abdelazeem ◽  
Ahmed El-Rabbany
Keyword(s):  
Precise Point Positioning ◽  
Satellite System ◽  
Tropospheric Delay ◽  
International Gnss Service ◽  
Zenith Tropospheric Delay ◽  
Global Navigation Satellite ◽  
The University ◽  
Globally Distributed ◽  
By Products ◽  
Gnss Observations

AbstractThis study assesses the precision of zenith tropospheric delay (ZTD) obtained through triple-constellation global navigation satellite system (GNSS) precise point positioning (PPP). Various ZTD estimates are obtained as by-products from GPS-only, GPS/Galileo, GPS/BeiDou, and triple-constellation GPS/Galileo/BeiDou PPP solutions. Triple-constellation GNSS observations from a number of globally distributed reference stations are processed over a period of seven days in order to investigate the daily performance of the ZTD estimates. The estimated ZTDs are then validated by comparing them with the International GNSS Service (IGS) tropospheric products and the University of New Brunswick (UNB3m) model counterparts. It is shown that the ZTD estimates agree with the IGS counterparts with a maximum standard deviation (STD) of 2.4 cm. It is also shown that the precision of estimated ZTD from the GPS/Galileo and GPS/Galileo/BeiDou PPP solutions is improved by about 4.5 and 14%, respectively, with respect to the GPS-only PPP solution. Moreover, it is found that the estimated ZTD agrees with the UNB3m model with a maximum STD of 3.1 cm. Furthermore, the GPS/Galileo and GPS/Galileo/BeiDou PPP enhance the precision of the ZTD estimates by about 6.5 and 10%, respectively, in comparison with the GPS-only PPP solution.

scholarly journals Development and evaluation of the refined zenith tropospheric delay (ZTD) models

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Fei Yang ◽  
Xiaolin Meng ◽  
Jiming Guo ◽  
Debao Yuan ◽  
Ming Chen
Keyword(s):  
Back Propagation ◽  
Mapping Function ◽  
Temporal Analysis ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Distribution Analysis ◽  
Residual Distribution ◽  
Zenith Tropospheric Delay ◽  
Accuracy Difference ◽  
Global Navigation Satellite

AbstractThe tropospheric delay is a significant error source in Global Navigation Satellite System (GNSS) positioning and navigation. It is usually projected into zenith direction by using a mapping function. It is particularly important to establish a model that can provide stable and accurate Zenith Tropospheric Delay (ZTD). Because of the regional accuracy difference and poor stability of the traditional ZTD models, this paper proposed two methods to refine the Hopfield and Saastamoinen ZTD models. One is by adding annual and semi-annual periodic terms and the other is based on Back-Propagation Artificial Neutral Network (BP-ANN). Using 5-year data from 2011 to 2015 collected at 67 GNSS reference stations in China and its surrounding regions, the four refined models were constructed. The tropospheric products at these GNSS stations were derived from the site-wise Vienna Mapping Function 1 (VMP1). The spatial analysis, temporal analysis, and residual distribution analysis for all the six models were conducted using the data from 2016 to 2017. The results show that the refined models can effectively improve the accuracy compared with the traditional models. For the Hopfield model, the improvement for the Root Mean Square Error (RMSE) and bias reached 24.5/49.7 and 34.0/52.8 mm, respectively. These values became 8.8/26.7 and 14.7/28.8 mm when the Saastamoinen model was refined using the two methods. This exploration is conducive to GNSS navigation and positioning and GNSS meteorology by providing more accurate tropospheric prior information.

scholarly journals Geostatistical Modelling and Mapping of the Concentration of Gaseous Pollutants

2018 ◽  
Vol 2 (2) ◽  
pp. 219-232
Author(s):  
J. S. Okpoko ◽  
H. A. P. Audu
Keyword(s):  
Root Mean Square ◽  
Gas Flow ◽  
Fine Particulate Matter ◽  
Satellite System ◽  
Gaseous Pollutants ◽  
Mean Square ◽  
Kriging Method ◽  
Geospatial Modelling ◽  
Gis Environment ◽  
Global Navigation Satellite

In this study, the prediction of the concentration of gaseous pollutants around Ughelli West gas flow station in Delta State of Nigeria was carried out using Geostatistical technique in GIS environment. Since air pollutants negatively affect quality of air, lives and the environment, there is therefore the need to frequently monitor air quality, have thorough understanding of the pollutants’ concentration and their spatial distribution in an environment. The gaseous pollutants data of volatile organic compounds (VOCs), methane (CH4), nitrogen dioxide (NO2), sulphur dioxide (SO2) and ozone (O3), were obtained using Multi-parameter gas monitor while that of fine particulate matter (PM2.5) was obtained with SPM meter for a period of three months. Thermo Anemometer was used to obtain the values of wind speed, ambient temperature, atmospheric pressure and relative humidity. Artificial Neural Network designer software (Pythia) was used to validate the acquired field data; predict the concentration of the gaseous pollutants at selected distances from the flow station. The geospatial coordinates of the flow station were obtained using Global Navigation Satellite System (GNSS) receivers; the geospatial modelling and analysis were performed with ArcGIS software and ordinary kriging method of Geostatistical techniques. The results of the maximum concentration for the gaseous pollutants in the study area were 28.17 µg/m3, 19.44 µg/m3, 0.37 µg/m3, 49.81 µg/m3, 0.061 µg/m3 and 0.047µg/m3 for VOCs, CH4, NO2, PM2.5, O3 and SO2 respectively. The root mean square error for the concentration of the gaseous pollutants, ozone and sulphur (IV) oxide in the study area were 0.01618 and 0.008417 indicating a good interpolation model, while their root mean square standard errors, which show the reliability of the predicted values, were 0.70513551 and 0.8459251 respectively. These results conform with the report of other researchers that a better kriging method yields a smaller root mean square and a standard root mean square closer to one. The developed prediction maps for the gaseous pollutants in this study revealed that the study area will experience lower concentration of gaseous pollutants at a distance of 400 m and above.

Exposure and Income: Preliminary Findings on Labor Supply on High Pollution Days

2021 ◽  
Author(s):  
Bridget Hoffmann ◽  
Juan Pablo Rud
Keyword(s):  
Air Pollution ◽  
Labor Supply ◽  
Low Income ◽  
Fine Particulate Matter ◽  
Working Hours ◽  
Pm 2.5 ◽  
Pollution Levels ◽  
Fine Particulate ◽  
High Pollution ◽  
Average Worker

We study labor supply decisions on days with high levels of air pollution in Mexico City's metropolitan area using hourly levels of fine particulate matter (PM 2.5) air pollution at the locality level. We document a negative, non-linear relationship between PM 2.5 levels and daily labor supply, with strong effects on days with extremely high pollution levels. On these days, the average worker experiences a reduction of around 7.5% of working hours. Workers partially compensate for lost hours by increasing their labor supply on days that follow high pollution days. We provide evidence that income constraints may play an important role in workers labor supply decisions, as we find more moderate responses among informal and low-income workers.

scholarly journals AVALIAÇÃO ROBUSTA DA MODELAGEM NEUTROSFÉRICA SOBRE O TERRITÓRIO BRASILEIRO BASEADA EM MODELOS DE PREVISÃO NUMÉRICA DE TEMPO DA AMÉRICA DO SUL

2014 ◽  
Vol 20 (3) ◽  
pp. 481-503 ◽  
Author(s):  
TAYNÁ APARECIDA FERREIRA GOUVEIA ◽  
LUIZ FERNANDO SAPUCCI ◽  
JOÃO FRANCISCO GALERA MONICO ◽  
DANIELE BARROCA MARRA ALVES
Keyword(s):  
Global Navigation Satellite System ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Navigation Satellite ◽  
Global Navigation ◽  
Para Determinar ◽  
Global Navigation Satellite

O posicionamento com o sistema GNSS (Global Navigation Satellite System) é atualmente a técnica mais utilizada para se obter a localização sobre a superfície terrestre ou próxima a essa. Depois dos efeitos causados pela ionosfera, a refração que o sinal sofre ao ultrapassar a neutrosfera pode ser considerada como uma das maiores fontes de erro no sinal, a qual gera um atraso, que rebatida na direção zenital é denominado atraso zenital neutrosférico (ZND), ou ainda atraso zenital troposférico (ZTD - Zenithal Tropospheric Delay). Esse atraso gera erros no posicionamento GNSS quando o mesmo não é devidamente modelado. Os modelos de Previsão Numérica de Tempo (PNT) são boas alternativas para a modelagem do ZND, pois como são alimentados diariamente por observações da atmosfera, os mesmos, geram previsões do ZND capazes de captar suas oscilações espaciais e temporais. No CPTEC/INPE são desenvolvidos e operacionalizados modelos de PNT globais e regionais, sendo os últimos dedicados ao melhor detalhamento sobre a América do Sul. No Brasil está operacional no CPTEC/INPE um processo que gera tais previsões com resolução espacial de 15 km e temporal de 3 horas, além de outras versões que contemplam outras sofisticações. Para determinar o impacto dessas melhorias na qualidade das previsões do ZND, o presente trabalho apresenta uma avaliação robusta das versões disponibilizadas, utilizando como referência os valores de ZND estimados a partir dos dados GNSS coletados pelas estações da RBMC (Rede Brasileira de Monitoramento Contínuo), levando em consideração: a variação sazonal, a continentalidade e a variação da altitude e latitude.

scholarly journals Space-Time-Frequency Adaptive Processor for Multiple Interference Suppression in GNSS Applications

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Qiang Guo ◽  
Lian-gang Qi ◽  
Jianhong Xiang
Keyword(s):  
Interference Suppression ◽  
Satellite System ◽  
Space Time ◽  
Similar Frequency ◽  
Time Frequency ◽  
Weight Calculation ◽  
Global Navigation Satellite ◽  
Short Time ◽  
Multiple Interference ◽  
Adaptive Processor

To enhance the multiple interference suppression performance of global navigation satellite system (GNSS) receivers without extra antenna elements, a space-time-frequency adaptive processor (STFAP) is investigated. Firstly, based on the analysis of the autocorrelation function of the multicomponent signal, we propose a common period estimation and data block technique to segment the received signal data into blocks. Secondly, the signal data in each block are short-time Fourier transformed into time-frequency (TF) domain, and the corresponding TF points with similar frequency characteristics are regrouped to structure space-time-frequency (STF) data matrixes. Finally, a space-time-frequency minimum output power- (STF-MOP) based weight calculation method is introduced to suppress multiple interfering signals according to their sparse characteristics in TF and space domains. Simulation results show that the proposed STFAP can effectively combat more wideband periodic frequency-modulated (WBPFM) interferences even some of them arriving from the same direction as GNSS signals without increasing the number of antenna elements.

scholarly journals Estimation of diameter at breast height from mobile laser scanning data collected under a heavy forest canopy

2017 ◽  
Vol 63 (No. 9) ◽  
pp. 433-441 ◽  
Author(s):  
Čerňava Juraj ◽  
Tuček Ján ◽  
Koreň Milan ◽  
Mokroš Martin
Keyword(s):  
Laser Scanning ◽  
Forest Canopy ◽  
Mean Squared Error ◽  
Satellite System ◽  
Tree Level ◽  
Efficient Technology ◽  
Mobile Mapping ◽  
Mobile Mapping System ◽  
Global Navigation Satellite ◽  
Short Time

Mobile laser scanning (MLS) is time-efficient technology of geospatial data collection that proved its ability to provide accurate measurements in many fields. Mobile innovation of the terrestrial laser scanning has a potential to collect forest inventory data on a tree level from large plots in a short time. Valuable data, collected using mobile mapping system (MMS), becomes very difficult to process when Global Navigation Satellite System (GNSS) outages become too long. A heavy forest canopy blocking the GNSS signal and limited accessibility can make mobile mapping very difficult. This paper presents processing of data collected by MMS under a heavy forest canopy. DBH was estimated from MLS point cloud using three different methods. Root mean squared error varied between 2.65 and 5.57 cm. Our research resulted in verification of the influence of MLS coverage of tree stem on the accuracy of DBH data.

scholarly journals Analysis and Comparison of GPS Precipitable Water Estimates between Two Nearby Stations on Tahiti Island

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5578
Author(s):  
Fangzhao Zhang ◽  
Jean-Pierre Barriot ◽  
Guochang Xu ◽  
Marania Hopuare
Keyword(s):  
Mapping Function ◽  
Precipitable Water ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Horizontal Distance ◽  
International Gnss Service ◽  
Weighted Mean Temperature ◽  
The Difference ◽  
Global Navigation Satellite ◽  
The Impact

Since Bevis first proposed Global Positioning System (GPS) meteorology in 1992, the precipitable water (PW) estimates retrieved from Global Navigation Satellite System (GNSS) networks with high accuracy have been widely used in many meteorological applications. The proper estimation of GNSS PW can be affected by the GNSS processing strategy as well as the local geographical properties of GNSS sites. To better understand the impact of these factors, we compare PW estimates from two nearby permanent GPS stations (THTI and FAA1) in the tropical Tahiti Island, a basalt shield volcano located in the South Pacific, with a mean slope of 8% and a diameter of 30 km. The altitude difference between the two stations is 86.14 m, and their horizontal distance difference is 2.56 km. In this paper, Bernese GNSS Software Version 5.2 with precise point positioning (PPP) and Vienna mapping function 1 (VMF1) was applied to estimate the zenith tropospheric delay (ZTD), which was compared with the International GNSS Service (IGS) Final products. The meteorological parameters sourced from the European Center for Medium-Range Weather Forecasts (ECMWF) and the local weighted mean temperature ( T m ) model were used to estimate the GPS PW for three years (May 2016 to April 2019). The results show that the differences of PW between two nearby GPS stations is nearly a constant with value 1.73 mm. In our case, this difference is mainly driven by insolation differences, the difference in altitude and the wind being only second factors.

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