scholarly journals The use of products from ground-based GNSS observations in meteorological nowcasting

2010 ◽  
Vol 26 ◽  
pp. 77-82 ◽  
Author(s):  
E. Terradellas ◽  
B. Téllez
Keyword(s):  
Water Vapour ◽  
Horizontal Distribution ◽  
Global Navigation Satellite Systems ◽  
Full Potential ◽  
Atmospheric Humidity ◽  
Satellite Systems ◽  
Close Relationship ◽  
Integrated Water Vapour ◽  
Global Navigation Satellite ◽  
Gnss Observations

Abstract. Convective rainfall is often focalized in areas of moisture convergence. A close relationship between precipitation and fast variations of vertically-integrated water vapour (IWV) has been found in numerous cases. Therefore, continuous monitoring of atmospheric humidity and its spatial distribution is crucial to the operational forecaster for a proper nowcasting of heavy rainfall events. The microwave signals continuously broadcasted by the Global Navigation Satellite Systems (GNSS) satellites are influenced by the water vapour as they travel through the atmosphere. Estimates of IWV retrieved from ground-based GNSS observations may, then, constitute a source of information on the horizontal distribution and the time evolution of atmospheric humidity. At the Spanish Meteorological Agency (AEMET), a near-real-time map of IWV estimates retrieved from ground GNSS measurements in the Iberian Peninsula and West Mediterranean region is operationally built and presented to the forecaster. The maps are generated every 15 minutes following a one-dimensional variational assimilation scheme with the previous map as the background state. A case study is presented in order to illustrate some strengths and weaknesses of the product, to assess the potential benefit of using GNSS products in nowcasting and to define the steps to be done in order to make use of the full potential of the method.

scholarly journals GNSS-Based Machine Learning Storm Nowcasting

2020 ◽  
Vol 12 (16) ◽  
pp. 2536 ◽  
Author(s):  
Marcelina Łoś ◽  
Kamil Smolak ◽  
Guergana Guerova ◽  
Witold Rohm
Keyword(s):  
Machine Learning ◽  
Severe Weather ◽  
Global Navigation Satellite Systems ◽  
Vertical Profiles ◽  
Satellite Systems ◽  
Weather Events ◽  
Machine Learning Approach ◽  
Integrated Water Vapour ◽  
Global Navigation Satellite ◽  
Gnss Observations

Nowcasting of severe weather events and summer storms, in particular, are intensively studied as they have great potential for large economic and societal losses. Use of Global Navigation Satellite Systems (GNSS) observations for weather nowcasting has been investigated in various regions. However, combining the vertically integrated water vapour (IWV) with vertical profiles of wet refractivity derived from GNSS tomography has not been exploited for short-range forecasts of storms. In this study, we introduce a methodology to use the synergy of IWV and tomography-based vertical profiles to predict 0–2 h of storms using a machine learning approach for Poland. Moreover, we present an analysis of the importance of features that take part in the prediction process. The accuracy of the model reached over 87%, and the precision of prediction was about 30%. The results show that wet refractivity below 6 km and IWV on the west of the storm are among the significant parameters with potential for predicting storm location. The analysis of IWV demonstrated a correlation between IWV changes and storm occurrence.

scholarly journals Integrated water vapour content retrievals from ship-borne GNSS receivers during EUREC<sup>4</sup>A

2020 ◽  
Author(s):  
Pierre Bosser ◽  
Olivier Bock ◽  
Cyrille Flamant ◽  
Sandrine Bony ◽  
Sabrina Speich
Keyword(s):  
Water Vapour ◽  
Weather Forecast ◽  
Global Navigation Satellite Systems ◽  
Water Vapour Content ◽  
Medium Range Weather Forecast ◽  
Satellite Systems ◽  
Infra Red ◽  
Integrated Water Vapour ◽  
Global Navigation Satellite ◽  
Gnss Data

Abstract. In the framework of the EUREC4A (Elucidating the role of clouds-circulation coupling in climate) campaign that took place in January and February 2020, integrated water vapour (IWV) contents were retrieved over the open Tropical Atlantic Ocean using Global Navigation Satellite Systems (GNSS) data acquired from three research vessels (R/Vs): R/V Atalante, R/V Maria S. Merian, and R/V Meteor. This paper describes the GNSS processing method and compares the GNSS IWV retrievals with IWV estimates from the European Center for Medium-range Weather Forecast (ECMWF) fifth ReAnalysis (ERA5), from the Moderate-Resolution Imaging Spectroradiometer (MODIS) infra-red products, and from terrestrial GNSS stations located along the tracks of the ships. The ship-borne GNSS IWVs retrievals from R/V Atalante and R/V Meteor compare well with ERA5, with small biases (−1.62 kg m−2 for R/V Atalante and +0.65 kg m−2 for R/V Meteor) and a root mean square (RMS) difference about 2.3 kg m−2. The results for the R/V Maria S. Merian are found to be of poorer quality, with RMS difference of 6 kg m−2 which are very likely due to the location of the GNSS antenna on this R/V prone to multipath effects. The comparisons with ground-based GNSS data confirm these results. The comparisons of all three R/V IWV retrievals with MODIS infra-red product show large RMS differences of 5–7 kg m−2, reflecting the enhanced uncertainties of this satellite product in the tropics. These ship-borne IWV retrievals are intended to be used for the description and understanding of meteorological phenomena that occurred during the campaign, east of Barbados, Guyana and northern Brazil. Both the raw GNSS measurements and the IWV estimates are available through the AERIS data center (https://en.aeris-data.fr/). The digital object identifiers (DOIs) for R/V Atalante IWV and raw datasets are https://doi.org/10.25326/71 (Bosser et al., 2020a) and https://doi.org/10.25326/74 (Bosser et al., 2020d), respectively. The DOIs for the R/V Maria S. Merian IWV and raw datasets are https://doi.org/10.25326/72 (Bosser et al., 2020b) and https://doi.org/10.25326/75 (Bosser et al., 2020e), respectively. The DOIs for the R/V Meteor IWV and raw datasets are https://doi.org/10.25326/73 (Bosser et al., 2020c) and https://doi.org/10.25326/76 (Bosser et al., 2020f), respectively.

scholarly journals Validating HY-2A CMR Precipitable Water Vapor Using Ground-based and Shipborne GNSS Observations

2020 ◽  
Author(s):  
Zhilu Wu ◽  
Yanxiong Liu ◽  
Yang Liu ◽  
Jungang Wang ◽  
Xiufeng He ◽  
...  
Keyword(s):  
Water Vapor ◽  
Microwave Radiometer ◽  
Precipitable Water ◽  
Global Navigation Satellite Systems ◽  
High Temporal Resolution ◽  
Satellite Systems ◽  
The Indian Ocean ◽  
Global Navigation Satellite ◽  
Gnss Data ◽  
Gnss Observations

Abstract. The calibration microwave radiometer (CMR) onboard Haiyang-2A satellite provides wet tropospheric delays correction for altimetry data, which can also contribute to the understanding of climate system and weather processes. Ground-based Global Navigation Satellite Systems (GNSS) provide precise PWV with high temporal resolution and could be used for calibration and monitoring of the CMR data, and shipborne GNSS provides accurate PWV over open oceans, which can be directly compared with uncontaminated CMR data. In this study, the HY-2A CMR water vapor product is validated using ground-based GNSS observations of 100 IGS stations along the coastline and 56-day shipborne GNSS observations over the Indian Ocean. The processing strategy for GNSS data and CMR data is discussed in detail. Special efforts were made to the quality control and reconstruction of contaminated CMR data. The validation result shows that HY-2A CMR PWV agrees well with ground-based GNSS PWV with 2.67 mm in RMS within 100 km. Geographically, the RMS is 1.12 mm in the polar region and 2.78 mm elsewhere. The PWV agreement between HY-2A and shipborne GNSS shows a significant correlation with the distance between the ship and the satellite footprint, with an RMS of 1.57 mm for the distance threshold of 100 km. Ground-based GNSS and shipborne GNSS agree with HY-2A CMR well with no obvious system error.

scholarly journals GNSS-based Orbital Filter for Earth Moon Transfer Orbits

2015 ◽  
Vol 69 (4) ◽  
pp. 745-764 ◽  
Author(s):  
Vincenzo Capuano ◽  
Francesco Basile ◽  
Cyril Botteron ◽  
Pierre- André Farine
Keyword(s):  
Model Simulation ◽  
Global Navigation Satellite Systems ◽  
Navigation Systems ◽  
Satellite Systems ◽  
Transfer Orbits ◽  
Low Earth Orbits ◽  
Global Navigation Satellite ◽  
Navigation Accuracy ◽  
Earth Orbits ◽  
Gnss Observations

Numerous applications, not only Earth-based, but also space-based, have strengthened the interest of the international scientific community in using Global Navigation Satellite Systems (GNSSs) as navigation systems for space missions that require good accuracy and low operating costs. Indeed, already successfully used in Low Earth Orbits (LEOs), GNSS-based navigation systems can maximise the autonomy of a spacecraft while reducing the burden and the costs of ground operations. That is why GNSS is also attractive for applications in higher Earth orbits up to the Moon, such as in Moon Transfer Orbits (MTOs). However, the higher the altitude the receiver is above the GNSS constellations, the poorer and the weaker are the relative geometry and the received signal powers, respectively, leading to a significant navigation accuracy reduction. In order to improve the achievable GNSS performance in MTOs, we consider in this paper an adaptive orbital filter that fuses the GNSS observations with an orbital forces model. Simulation results show a navigation accuracy significantly higher than that attainable individually by a standalone GNSS receiver or by means of a pure orbital propagation.

scholarly journals New GNSS tomography of the atmosphere method – proposal and testing

2012 ◽  
Vol 9 ◽  
pp. 63-76 ◽  
Author(s):  
Michal Kačmařík ◽  
Lukáš Rapant
Keyword(s):  
Water Vapour ◽  
Theoretical Concept ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Gnss Meteorology ◽  
Gnss Receivers ◽  
Tomography Method ◽  
Gnss Measurements ◽  
Global Navigation Satellite

Paper is focused on GNSS meteorology which is generally used for the determination of water vapour distribution in the atmosphere from GNSS measurements. Water vapour in the atmosphere is an important parameter which influences the state and development of the weather. At first, the paper presents basics of the GNSS meteorology and tomography of the atmosphere and subsequently introduces a new GNSS tomography method which doesn't require an extensive network of GNSS receivers, but uses only a few receivers situated in a line. After a theoretical concept describing this method and used mathematical background, the results from a real experiment are shown and discussed. Unfortunately the results indicate that presented method is not able to provide credible outputs. Possibly the main problem lies in an insufficient number of available signals from current global navigation satellite systems (GPS and GLONASS) where the improvement could be expected after the start of Galileo and Compass. Potential ways how to improve the results without increasing the number of satellites are outlined in the last section.

scholarly journals GNSS-R with Low-Cost Receivers for Retrieval of Antenna Height from Snow Surfaces Using Single-Frequency Observations

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5536 ◽  
Author(s):  
Simone Rover ◽  
Alfonso Vitti
Keyword(s):  
Low Cost ◽  
Test Site ◽  
Global Navigation Satellite Systems ◽  
Single Frequency ◽  
Satellite Systems ◽  
Management Plans ◽  
Gnss Reflectometry ◽  
Application Fields ◽  
Global Navigation Satellite ◽  
Gnss Observations

Snowpack is an important fresh water storage; the retrieval of snow water equivalents from satellite data permits to estimate potentially available water amounts which is an essential parameter in water management plans running in several application fields (e.g., basic needs, hydroelectric, agriculture, hazard and risk monitoring, climate change studies). The possibility to assess snowpack height from Global Navigation Satellite Systems (GNSS) observations by means of the GNSS reflectometry technique (GNSS-R) has been shown by several studies. However, in general, studies are being conducted using observations collected by continuously operating reference stations (CORS) built for geodetic purposes and equipped with geodetic-grade instruments. Moreover, CORS are located on sites selected according to criteria different from those more suitable for snowpack studies. In this work, beside an overview of key elements of GNSS reflectometry, single-frequency GNSS observations collected by u-blox M8T GNSS receivers and patch antennas from u-blox and Tallysman have been considered for the determination of antenna height from the snowpack surface on a selected test site. Results demonstrate the feasibility of GNSS-R even with non-geodetic-grade instruments, opening the way towards diffuse GNSS-R targeted applications.

scholarly journals Estimation of Ionospheric Delay Influence on the Efficiency of Precise Positioning of Multi-GNSS Observations

2020 ◽  
Vol 12 ◽  
pp. 14-18
Author(s):  
Alina Khoptar ◽  
Stepan Savchuk
Keyword(s):  
Ionospheric Delay ◽  
Global Navigation Satellite Systems ◽  
Dual Frequency ◽  
Error Sources ◽  
Satellite Systems ◽  
3 Dimensional ◽  
Rapid Pace ◽  
Global Navigation Satellite ◽  
Gnss Processing ◽  
Gnss Observations

Currently, Global Navigation Satellite Systems (GNSS) are developing at a fairly rapid pace. Over the last years US GPS and Russian GLONASS were modernizing, whilst new systems like European Galileo and Chinese BDS are launched. The modernizations of the existing and the deployment of new GNSS made a whole range of new signals available to the users, and create a new concept  multi-GNSS. Ionospheric delay is one of the major error sources in multi-GNSS observations. At present, GNSS users usually eliminate the influence of ionospheric delay of the first order items by dual-frequency ionosphere-free combinations. But there is still residual ionospheric delay error of higher orders. In this paper we present four different processing scenarios to exclude the higher orders ionospheric delay effects on multi-GNSS Precise Point Positioning (PPP) performance, including: “only GPS” and “GPS+GLONASS+Galileo+BDS” – without/with eliminating ionospheric delay error of higher orders. Dataset collected from one GNSS station BOR1 (Borowiec, Poland) over almost two years provided by multi-GNSS experiment (MGEX) were used for dual-frequency PPP tests with one- and quadconstellation signals. For the second pair of scenarios were used a IONosphere map EXchange format (IONEX) that supports the exchange of 2- and 3-dimensional TEC maps given in a geographic grid. Numeric experiments show that, the results of different pairs of scenarios differ at the submillimeter level. The results also show that the multi-GNSS processing are better than those based on “only GPS”.

Sign in / Sign up

Export Citation Format

Share Document