The Tropospheric Ozone Assessment Report (TOAR) is an activity of the International Global Atmospheric Chemistry Project. This paper is a component of the report, focusing on the present-day ...distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation. Utilizing the TOAR surface ozone database, several figures present the global distribution and trends of daytime average ozone at 2702 non-urban monitoring sites, highlighting the regions and seasons of the world with the greatest ozone levels. Similarly, ozonesonde and commercial aircraft observations reveal ozone’s distribution throughout the depth of the free troposphere. Long-term surface observations are limited in their global spatial coverage, but data from remote locations indicate that ozone in the 21st century is greater than during the 1970s and 1980s. While some remote sites and many sites in the heavily polluted regions of East Asia show ozone increases since 2000, many others show decreases and there is no clear global pattern for surface ozone changes since 2000. Two new satellite products provide detailed views of ozone in the lower troposphere across East Asia and Europe, revealing the full spatial extent of the spring and summer ozone enhancements across eastern China that cannot be assessed from limited surface observations. Sufficient data are now available (ozonesondes, satellite, aircraft) across the tropics from South America eastwards to the western Pacific Ocean, to indicate a likely tropospheric column ozone increase since the 1990s. The 2014–2016 mean tropospheric ozone burden (TOB) between 60°N–60°S from five satellite products is 300 Tg ± 4%. While this agreement is excellent, the products differ in their quantification of TOB trends and further work is required to reconcile the differences. Satellites can now estimate ozone’s global long-wave radiative effect, but evaluation is difficult due to limited in situ observations where the radiative effect is greatest.
Os sinais GNSS (Global Navigation Satellite System) estão sujeitos a erros sistemáticos causados por diversas fontes, sendo as principais a camada ionosférica, a camada troposférica e o multicaminho. ...A compreensão de como esses efeitos se comportam e relacionam é de grande interesse para a Geodésia Espacial. No Brasil, estudos voltados a esse assunto são possíveis graças às estações da RBMC (Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS), que proporcionam a obtenção de um grande conjunto de dados geodésicos: latitude e longitude geodésicas, altitudes geométrica e ortométrica, Atraso Zenital Troposférico (Zenith Tropospheric Delay - ZTD), índice de irregularidades da ionosfera (FP), níveis de multicaminho (Multipath - MP), dentre outros. Algumas estações são equipadas com barômetros e termômetros, fornecendo também dados meteorológicos. Assim, o trabalho aborda uma análise das relações e comportamentos de dados geodésicos e meteorológicos de 25 estações da RBMC distribuídas pelo território brasileiro, para o dia 2 de agosto de 2013, utilizando as análises multivariadas de componentes principais, fatorial principal e de agrupamentos, visando determinar a contribuição desses dados com as principais fontes de erros sistemáticos, bem como, mostrar o potencial do uso da análise multivariada nos estudos dos erros sistemáticos. Por meio das análises de componentes principais e fatorial, as 12 variáveis analisadas podem ser representadas por apenas quatro variáveis hipotéticas, garantindo 95,9% da variabilidade amostral, sendo três dessas variáveis caracterizadas por cada um dos tipos de erros sistemáticos: variável ionosférica (latitudes geodésica e geomagnética e FP), troposférica (altitudes geométrica e ortométrica, pressão atmosférica, temperatura e ZTD) e multicaminho (MP1 e MP2). Veriï¬ca-se que a pressão atmosférica pode exercer um maior peso que a temperatura na modelagem da camada troposférica. Uma possível influência da ionosfera no ZTD foi identiï¬cada, possibilitando futuras discussões. A não associação das variáveis MP1 e MP2 com as demais foi identiï¬cada, devido o multicaminho ser uma fonte de erro local. O agrupamento de estações por dendrograma possibilita uma nova forma de visualização do comportamento da ionosfera, bem como, a identiï¬cação de estações cujos sinais são mais refletidos.
This paper presents a comprehensive description and benchmark evaluation of the tropospheric gas-phase chemistry component of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model ...(NMMBMONARCH), formerly known as NMMB/BSC-CTM, that can be run on both regional and global domains. Here, we provide an extensive evaluation of a global annual cycle simulation using a variety of background surface stations (EMEP, WDCGG and CASTNET), ozonesondes (WOUDC, CMD and SHADOZ), aircraft data (MOZAIC and several campaigns), and satellite observations (SCIAMACHY and MOPITT).We also include an extensive discussion of our results in comparison to other state-of-the-art models. We note that in this study, we omitted aerosol processes and some natural emissions (lightning and volcano emissions). The model shows a realistic oxidative capacity across the globe. The seasonal cycle for CO is fairly well represented at different locations (correlations around 0.3-0.7 in surface concentrations), although concentrations are underestimated in spring and winter in the Northern Hemisphere, and are overestimated throughout the year at 800 and 500 hPa in the Southern Hemisphere. Nitrogen species are well represented in almost all locations, particularly NO2 in Europe (root mean square error - RMSE - below 5 ppb). The modeled vertical distributions of NOx and HNO3 are in excellent agreement with the observed values and the spatial and seasonal trends of tropospheric NO2 columns correspond well to observations from SCIAMACHY, capturing the highly polluted areas and the biomass burning cycle throughout the year. Over Asia, the model underestimates NOx from March to August, probably due to an underestimation of NOx emissions in the region. Overall, the comparison of the modeled CO and NO2 with MOPITT and SCIAMACHY observations emphasizes the need for more accurate emission rates from anthropogenic and biomass burning sources (i.e., specification of temporal variability).
In this study we present an evaluation of the Comprehensive Air Quality Model with extensions (CAMx) for Thessaloniki using radiometric and lidar data. The aerosol mass concentration profiles of CAMx ...are compared against the PM2.5 and PM2. 5−10 concentration profiles retrieved by the Lidar-Radiometer Inversion Code (LIRIC). The CAMx model and the LIRIC algorithm results were compared in terms of mean mass concentration profiles, center of mass and integrated mass concentration in the boundary layer and the free troposphere. The mean mass concentration comparison resulted in profiles within the same order of magnitude and similar vertical structure for the PM2. 5 particles. The mean centers of mass values are also close, with a mean bias of 0.57 km. On the opposite side, there are larger differences for the PM2. 5−10 mode, both in the boundary layer and in the free troposphere. In order to grasp the reasons behind the discrepancies, we investigate the effect of aerosol sources that are not properly included in the model's emission inventory and in the boundary conditions such as the wildfires and the desert dust component. The identification of the cases that are affected by wildfires is performed using wind backward trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model in conjunction with satellite fire pixel data from MODerate-resolution Imaging Spectroradiometer (MODIS) Terra and Aqua global monthly fire location product MCD14ML. By removing those cases the correlation coefficient improves from 0.69 to 0.87 for the PM2. 5 integrated mass in the boundary layer and from 0.72 to 0.89 in the free troposphere. The PM2.5 center of mass fractional bias also decreases to 0.38 km. Concerning the analysis of the desert dust component, the simulations from the Dust Regional Atmospheric Model (BSC-DREAM8b) were deployed. When only the Saharan dust cases are taken into account, BSC-DREAM8b generally outperforms CAMx when compared with LIRIC, achieving a correlation of 0.91 and a mean bias of −29.1 % for the integrated mass in the free troposphere and a correlation of 0.57 for the center of mass. CAMx, on the other hand, underestimates the integrated mass in the free troposphere. Consequently, the accuracy of CAMx is limited concerning the transported Saharan dust cases. We conclude that the performance of CAMx appears to be best for the PM2.5 particles, both in the boundary layer and in the free troposphere. Sources of particles not properly taken into account by the model are confirmed to negatively affect its performance, especially for the PM2. 5−10 particles.
As tecnologias espaciais têm sido amplamente empregadas para fins de posicionamento, a principal e mais moderna é o GNSS (Global Navigation Satellite System). Para alcançar alta acurácia ...(centímetros) no posicionamento GNSS, é imprescindível realizar a modelagem atmosférica (ionosfera e troposfera). No que concerne à troposfera, seus efeitos nos sinais GNSS são modelados considerando duas componentes: a primeira gerada pela influência hidrostática representa cerca de 90% do efeito; a segunda ocasionada pela atmosfera úmida é geralmente menor, porém, sua variação temporal e espacial é muito maior, o que dificulta a sua modelagem. O modelo de Hopfield pode ser utilizado para minimizar os efeitos da troposfera nos sinais GNSS. Mas, dependendo da acurácia almejada, ele pode não ser adequado, principalmente em regiões mais ativas, como pode ser para a realidade brasileira. Para sanar essas limitações, vem sendo utilizado os modelos de Previsão Numérica do Tempo (PNT). Nesse artigo foi avaliada e quantificada a componente úmida do atraso troposférico (ZWD - Zenithal Wet Delay) em diferentes regiões do Brasil empregando dados da RBMC (Rede Brasileira de Monitoramento Contínuo). Foi possível observar que os maiores valores do ZWD foram obtidos na estação SAGA e os menores na estação UFPR. Também foi realizada uma avaliação a respeito do uso do modelo de PNT eta15km no posicionamento por ponto. Os resultados mostraram que o uso do modelo de PNT ao invés de Hopfield traz melhorias significativas no posicionamento.
The fundamental intention of this investigation is to determine the tropospheric radio attenuation by rain that occurs in radio links in Ciudad Bolivar and Puerto Ayacucho. Based on the annual rain ...data of previous years, by means of the application of the method of prognosis Autoregressive Integrated Moving Average (ARIMA), it was possible to determine the radio attenuation by month as function of the frequency and the intensity of registered rain for years 2009 to 2011 with reliable error indices. This development is directly related to the problems that rain precipitations produce in radio frequencies links, where is observed the loss in the power of the electromagnetic signal because of the dissipation of energy in heat form by the drops of rain. The study is made up of 4 phases of development, based on the compilation of the data of weather stations of the zone, which was provided by the International Center on Research El Niño, followed by the application and analysis of the method of prognosis ARIMA and the estimation of the intensity of rain per foretold hour and finally the results of the radio attenuation for every monthly period appear. The investigation is field and predictive-type and with not experimental design. One concluded that the Cold one is the locality that presents/displays Greater radio attenuation occurs in Puerto Ayacucho.
El propósito fundamental de esta investigación es determinar la radioatenuación troposférica por lluvia que sufren los radioenlaces en Ciudad Bolívar y Puerto Ayacucho. Basados en los datos de lluvia anuales de años anteriores, mediante la aplicación del método de pronóstico de Promedio Móvil Integrado de Auto Regresión (ARIMA), fue posible determinar la radioatenuación en función de la frecuencia y la intensidad de lluvia registrada mensualmente para los años 2009 al 2011 con índices de error confiables. Este desarrollo está relacionado directamente a los problemas que producen las precipitaciones en forma de lluvia en los enlaces de radiofrecuencias, donde se observa la pérdida en la potencia de la señal electromagnética a causa de la disipación de energía en forma de calor por las gotas de lluvia. El estudio está compuesto por 4 fases de desarrollo, basado en la recopilación de los datos de estaciones meteorológicas de la zona, los cuales fueron suministrados por el Centro Internacional de Investigación del Fenómeno del Niño, seguido por la aplicación y análisis del método de pronóstico ARIMA y la estimación de la intensidad de lluvia por hora pronosticada y por último se presentan los resultados de las radioatenuaciones para cada período mensual. El tipo de investigación es de campo y predictiva con diseño no experimental. Se concluyó que Puerto Ayacucho es la ciudad que presenta mayor radioatenuación troposférica debido a la alta intensidad de lluvia.
El propósito fundamental de esta investigación fue determinar la radioatenuación troposférica por lluvia que sufren los radioenlances en localidades del Sur del Lago de Maracaibo. Basados en los ...datos de lluvia de años anteriores, mediante la aplicación del método de pronóstico de Promedio Móvil Integrado de Auto Regresión (ARIMA), fue posible determinar la radioatenuación en función de la frecuencia y la intensidad de lluvia registrada mensualmente para los años 2006 al 2010 con índices de error confiables. Este desarrollo está relacionado directamente a los problemas que producen las precipitaciones en forma de lluvia en los enlaces de radiofrecuencias, donde se observa la pérdida en la potencia de la señal electromagnética a causa de la disipación de energía en forma de calor por las gotas de lluvia. El estudio está compuesto por 4 fases de desarrollo: la recopilación de los datos de estaciones meteorológicas de la zona, los cuales fueron suministrados por el Instituto para la Conservación del Lago de Maracaibo, la aplicación y análisis del método de pronóstico ARIMA, la estimación de la intensidad de lluvia pronosticada y, por último, el cálculo de las radioatenuaciones para cada período mensual. El tipo de investigación es de campo y predictiva con diseño no experimental. Se concluyó que La Fría es la localidad que presenta mayor radioatenuación troposférica debido a la alta intensidad de lluvia.Palabras Clave:pronóstico, lluvia, radioatenuación, troposfera, ARIMA.
The primary purpose of this investigation was to determine the tropospheric radio attenuation by rain that occurs in radio links in southern Maracaibo Lake locations. Based on previous year’s rainfall data, using the forecasting method AutoRegressive Integrated Moving Average (ARIMA), it was possible to determine the radio attenuation depending on the frequency and the intensity of monthly predicted rainfall for the years 2006 to 2010 with reliable error rates. This development is directly linked to the problems caused by rainfall in radio links, since there is a loss in signal strength due to the electromagnetic energy dissipation in the form of heat by the raindrops. The study consisted of 4 stages of development: the collection of data from weather stations in the area, which were provided by the Institute for the Conservation of the Maracaibo Lake, the application and analysis of ARIMA forecasting method, the estimation of the intensity of forecasted rain and, finally, the computation of radio attenuation for each monthly period. The investigation has field and predictive model whit not experimental design. It was concluded that La Fría is the town with higher tropospheric radio attenuation due to the higher rain intensity. Words key: forecast, rain, radioattenuation, troposphere, ARIMA.
The primary purpose of this investigation was to determine the tropospheric radio
attenuation by rain that occurs in radio links in southern Maracaibo Lake locations.
Based on previous year`s ...rainfall data, using the forecasting method AutoRegressive
Integrated Moving Average (ARIMA), it was possible to determine the radio attenuation depending on the frequency and the intensity of monthly predicted rainfall for the years
2006 to 2010 with reliable error rates. This development is directly linked to the
problems caused by rainfall in radio links, since there is a loss in signal strength due to
the electromagnetic energy dissipation in the form of heat by the raindrops. The study
consisted of 4 stages of development: the collection of data from weather stations in
the area, which were provided by the Institute for the Conservation of the Maracaibo
Lake, the application and analysis of ARIMA forecasting method, the estimation of the
intensity of forecasted rain and, finally, the computation of radio attenuation for each
monthly period. The investigation has field and predictive model whit not experimental
design. It was concluded that La Fría is the town with higher tropospheric radio
attenuation due to the higher rain intensity.
El propósito fundamental de esta investigación fue determinar la radioatenuación
troposférica por lluvia que sufren los radioenlances en localidades del Sur del Lago de
Maracaibo. Basados en los datos de lluvia de años anteriores, mediante la aplicación
del método de pronóstico de Promedio Móvil Integrado de Auto Regresión (ARIMA),
fue posible determinar la radioatenuación en función de la frecuencia y la intensidad
de lluvia registrada mensualmente para los años 2006 al 2010 con índices de error
confiables. Este desarrollo está relacionado directamente a los problemas que
producen las precipitaciones en forma de lluvia en los enlaces de radiofrecuencias,
donde se observa la pérdida en la potencia de la señal electromagnética a causa de la
disipación de energía en forma de calor por las gotas de lluvia. El estudio está
compuesto por 4 fases de desarrollo: la recopilación de los datos de estaciones
meteorológicas de la zona, los cuales fueron suministrados por el Instituto para la
Conservación del Lago de Maracaibo, la aplicación y análisis del método de
pronóstico ARIMA, la estimación de la intensidad de lluvia pronosticada y, por último,
el cálculo de las radioatenuaciones para cada período mensual. El tipo de
investigación es de campo y predictiva con diseño no experimental. Se concluyó que
La Fría es la localidad que presenta mayor radioatenuación troposférica debido a la
alta intensidad de lluvia.
This investigation project has the purpose to determine the tropospheric
radioattenuation of monthly rain in the city of Maracay, using the rain data for annual
periods obtained from the forecasting ...methods for temporary series. As well, the
intention for the development of this project is related directly to the problems that produce rain form precipitations in the links of radio frequencies, where it is observed
that the loss in the power of the electromagnetic signal is by the dissipation of
energy in the form of heat by drops of rain. In this sense, the intensity of rain per
hour is determined and the results of the radioattenuation for every monthly period
appear. Using the field data, this study allows us by design to be a predictive and not
experimental type. In conclusion, and according to the analyzed forecasting methods
used in this investigation, it is possible to forecast for the following 5 years the rain
data with a reliable index of error for this climatologic phenomenon; also, it is verified
that the effect of rain in the connections of radio frequencies from the 5 GHz, is
affected significantly according to the intensity of rain registered, being due mainly to
the dissipation of the power of the signal by drops of rain.
Este proyecto de investigación tiene como finalidad determinar la radioatenuación
troposférica por lluvia mensual para la ciudad de Maracay, utilizando los datos de
lluvia para períodos anuales posteriores, derivados a partir de los métodos de
pronóstico para series temporales. Asimismo, el propósito para su desarrollo está
relacionado directamente a los problemas que producen las precipitaciones en
forma de lluvia en los enlaces de radiofrecuencias, donde se observa la pérdida en
la potencia de la señal electromagnética a causa de la disipación de energía en
forma de calor por las gotas de lluvia. En este sentido, se determina la intensidad de
lluvia por hora pronosticada y se presentan los resultados de las radioatenuaciones
para cada período mensual. Para este proyecto con modalidad de campo, se
considera según su diseño de tipo predictiva y no experimental. Como conclusión,
es posible estimar los datos de lluvia con índices de error confiables de este
fenómeno climatológico para 5 años siguientes, utilizando el método de pronóstico
de Promedio Móvil Integrado de Auto Regresión (ARIMA); del mismo modo, se
comprueba que el efecto de la lluvia en los enlaces de radiofrecuencias a partir de
los 5 GHz se ve afectado significativamente según la intensidad de lluvia registrada,
debiéndose principalmente a la disipación de la potencia de la señal por las gotas.
Le PPP (Precise Point Positioning) est une méthode GNSS (Global Navigation Satellite Systems), basée sur le concept SSR (State Space Representation). Grâce aux améliorations récentes des modèles ...atmosphériques, le PPP en temps réel (RT-PPP) peut être également amélioré. L'objectif principal de ce travail est d'étudier le RT-PPP et l'infrastructure optimisée en termes de coûts et d'avantages pour réaliser la méthode en utilisant des corrections atmosphériques. Pour cela, différentes configurations d'un réseau GNSS dense et régulier existant en France, le réseau Orphéon, sont utilisées. Ce réseau compte environ 160 sites, propriété de Geodata-Diffusion (Hexagon Geosystems). Dans un premier temps, le mode «PPP-RTK flottant» a été évalué, il correspond au RT-PPP avec des améliorations issues des corrections de réseau, mais avec les ambiguïtés flottantes. Ensuite, des corrections de réseau sont appliquées pour améliorer le mode « PPP-RTK » où les ambiguïtés sont fixées à leurs valeurs entières. Pour le PPP-RTK flottant, une version modifiée du package RTKLib 2.4.3 (beta) est utilisée pour prendre en compte les corrections réseau. Les effets ionosphériques de premier ordre ont été éliminés par la combinaison iono-free et le retard troposphérique zénithal est estimé. Les corrections ont été appliquées en introduisant des paramètres troposphériques a priori contraints. Une modélisation adaptative basée sur les OFCs (Optimal Fitting Coefficients) a été mise en place pour décrire le comportement de la troposphère, en utilisant des estimations des retards troposphériques pour les stations Orphéon. Cette solution permet une communication monodirectionnelle entre le serveur et l'utilisateur. Les gains réalisés sur le temps de convergence pour obtenir un positionnement de 10 centimètres de précision ont été quantifiés statistiquement. La topologie du réseau a été évaluée, en réduisant le nombre de stations de référence (jusqu'à 75%), via une configuration de réseau lâche. Dans la deuxième étape, le PPP-RTK est réalisé grâce au logiciel PPP-Wizard 1.3 et avec les produits temps réel CNES (Centre Nacional de Estudes Spatiales) pour les orbites, les horloges et les biais de phase des satellites. Le RT-IPPP (RT-Integer PPP) est réalisé avec estimation des délais troposphériques et ionosphériques. Les corrections ionosphériques et troposphériques sont introduites en tant que paramètres a priori contraints au PPP-RTK. Pour générer des corrections ionosphériques, il a été mis en place un algorithme d'interpolation à distance inversée (IDW–Inverse Distance Weighting). Les améliorations apportées au positionnement horizontal dues aux corrections atmosphériques SSR externes provenant d’un réseau (dense ou lâche) sont prometteuses et peuvent être utiles pour les applications qui dépendent principalement du positionnement horizontal.
PPP (Precise Point Positioning) is a GNSS (Global Navigation Satellite Systems) method, based on SSR (State Space Representation) concept. Thanks to recent improvements in atmospheric models, Real-time PPP (RT-PPP) can also be improved. The main objective of this work is to study the RT-PPP and the optimized infrastructure in terms of costs and benefits to realize the method using atmospheric corrections. Therefore, different configurations of a dense and regular GNSS network existing in France, the Orpheon network, are used. This network has about 160 sites and is owned by Geodata-Diffusion (Hexagon Geosystems). Initially, ‘float PPP-RTK’ was evaluated, it corresponds to RT-PPP with improvements resulting from network corrections, although with ambiguities kept float. Further on, network corrections are applied to improve “PPP-RTK” where ambiguities are fixed to their integer values. For the float PPP-RTK, a modified version of the RTKLib 2.4.3 (beta) package is used to apply network corrections. First-order ionospheric effects were eliminated by the iono-free combination and zenith tropospheric delay estimated. The corrections were applied by introducing a priori constrained tropospheric parameters. Adaptive modeling based on OFCs (Optimal Fitting Coefficients) has been developed to describe the behavior of the troposphere, using estimates of tropospheric delays for Orpheon stations. This solution allows one-way communication between the server and the user. The gains achieved in convergence time to 10 centimeters accuracy were statistically quantified. Network topology was assessed by reducing the number of reference stations (up to 75%) using a sparse network configuration. In the second step, PPP-RTK is realized using the PPP-Wizard 1.3 software and CNES (Centre National d'Etudes Spatiales) real-time products for orbits, clocks and phase biases of satellites. The RT-IPPP (RT-Integer PPP) is performed with estimation of tropospheric and ionospheric delays. Ionospheric and tropospheric corrections are introduced as a priori parameters constrained in PPP-RTK. To generate ionospheric corrections, it was implemented an Inverse Distance Weighting (IDW) algorithm. Improvements achieved in horizontal positioning due to external SSR corrections from a (dense or sparse) network are promising and may be useful for applications that depend primarily on horizontal positioning.
O PPP (Precise Point Positioning) é um método GNSS (Global Navigation Satellite Systems) baseado no conceito SSR (State Space Representation). Graças às melhorias recentes nos modelos atmosféricos, o PPP em tempo real (RT-PPP) também pode ser aprimorado. O objetivo principal deste trabalho é estudar o RT-PPP e a infraestrutura otimizada em termos de custos e benefícios para realizar o método usando correções atmosféricas. Portanto, são utilizadas diferentes configurações de uma rede GNSS densa e regular existente na França, a rede Orphéon. Esta rede tem cerca de 160 estações, sendo propriedade da Geodata-Diffusion (Hexagon Geosystems). Inicialmente, foi avaliado o "float PPP-RTK", que corresponde ao RT-PPP com melhorias resultantes de correções de rede, embora mantendo as ambiguidades como float. Em um segundo momento, as correções de rede são aplicadas para aprimorar o "PPP-RTK", onde ambiguidades são fixadas para seus valores inteiros. Para o float PPP-RTK, uma versão modificada do software RTKLib 2.4.3 (beta) é empregada de modo a levar em consideração as correções de rede. Os efeitos ionosféricos de primeira ordem foram eliminados pela combinação iono-free e o atraso troposférico é estimado. As correções são aplicadas introduzindo parâmetros troposféricos a priori injuncionados. Uma modelagem adaptativa baseada em OFCs (Optimal Fitting Coefficients) foi implementada para descrever o comportamento da troposfera, utilizando estimativas de atraso troposférico para estações da rede Orpheon. Tal solução permite a comunicação unidirecional entre o servidor e o usuário. Os ganhos alcançados no tempo de convergência para acurácia de 10 centímetros foram quantificados estatisticamente. A topologia de rede foi avaliada reduzindo o número de estações de referência (até 75%) usando uma configuração de rede esparsa. Na segunda etapa, o PPP-RTK é realizado usando o software PPP-Wizard 1.3, bem como os produtos para tempo real do CNES (Centre National d’Etudes Spatiales) de órbitas, relógios e biases de fase de satélites. O RT-IPPP (RT-Integer PPP) é realizado com estimativa de atrasos troposféricos e ionosféricos. As correções ionosféricas e troposféricas são introduzidas como parâmetros a priori injuncionados no PPP-RTK. Para gerar correções ionosféricas, foi implementado um algoritmo baseado na ponderação pelo inverso da distância (IDW–Inverse Distance Weighting). As melhorias alcançadas no posicionamento horizontal com o uso das correções SSR externas de uma rede (densa ou esparsa) são promissoras e podem ser úteis para aplicações que dependem principalmente do posicionamento horizontal.
PDF
