Atmospheric sounding by global navigation satellite system radio occultation: An analysis of the negative refractivity bias using CHAMP observations

2004 ◽  
Vol 109 (D1) ◽  
Author(s):  
G. Beyerle
Keyword(s):  
Global Navigation Satellite System ◽  
Radio Occultation ◽  
Satellite System ◽  
Navigation Satellite ◽  
Atmospheric Sounding ◽  
Global Navigation ◽  
Global Navigation Satellite

scholarly journals Short vertical-wavelength gravity wave activities in the upper troposphere lower stratosphere observed with global navigation satellite system radio occultation under different QBO phases

2021 ◽  
Vol 893 (1) ◽  
pp. 012007
Author(s):  
Firas Rasyad ◽  
Tri Wahyu Hadi ◽  
Noersomadi
Keyword(s):  
Global Navigation Satellite System ◽  
Radio Occultation ◽  
Lower Stratosphere ◽  
Satellite System ◽  
Navigation Satellite ◽  
Vertical Wavelength ◽  
Upper Troposphere ◽  
Research Activities ◽  
Global Navigation ◽  
Global Navigation Satellite

Abstract Gravity Waves (GWs) are believed to play important role in the generation of the driving force of the stratospheric Quasi-Biennial Oscillation (QBO). Deep convection in the equatorial region can generate large amount of GW with short vertical wavelength (λz <1 km) but studies of these wave activities in the upper troposphere lower stratosphere (UTLS) region are still limited. Recent advances in Global Navigation Satellite System (GNSS) Radio Occultation (RO) retrieval techniques have made it possible to derive global temperature profile with vertical resolution of less than 1 km. In this research, activities of GW with λz from 0.5 to 3.5 km in the UTLS region of 20-27 km heights are identified by calculating the GW potential energy (E p). Correlation between GW activities and QBO phases is examined using 50 hPa zonal wind as the QBO index. The results show that during both easterly and westerly QBO phases, the GW E p value increases gradually with time and reaches its peak in the transition periods. This pattern is seen in E p with all vertical wavelengths between 0.5-3.5 km but the percentage value of E p for λz<1 km is higher during the transition from westerly to easterly QBO. The GW E p values exhibit downward propagation with the QBO phase but there are also discernible upward propagations of GW activities below 24 km height and intersect those two bring large changes in QBO phases. Additionally, higher percentage of E p with λz<1 km is also found to be associated with El Niño events.

scholarly journals Analysis of Satellite Radio Occultation Architecture and its Stakeholders

2021 ◽  
Author(s):  
Paul T. Grogan ◽  
I. Josue Tapia-Tamayo
Keyword(s):  
Global Navigation Satellite System ◽  
Radio Occultation ◽  
Weather Forecasting ◽  
Weather Prediction ◽  
Satellite System ◽  
Weather Data ◽  
Navigation Satellite ◽  
Functional Requirements ◽  
Global Navigation ◽  
Global Navigation Satellite

Global Navigation Satellite System Radio Occultation (GNSS-RO) is a technique that relies on the change of a signal transmitted from a Global Navigation Satellite System (GNSS) as it passes through the planet’s atmosphere. This technique is not only suitable to study weather forecasting or climate change, but also offers a low-cost application. This report aims to characterize and parametrize the system architecture of commercial companies pursuing the Commercial Weather Data Pilot (CWDP) contract by the National Oceanic and Atmospheric Administration (NOAA). The approach of the paper will start by explaining the Radio Occultation technique and its potential application to Numerical Weather Prediction (NWP). The paper then identifies the main stakeholders of radio occultation and NWP, and their needs. Some key functional requirements are pinpointed, and the challenges that some of these architectures must overcome is discussed.

scholarly journals OutFin, a multi-device and multi-modal dataset for outdoor localization based on the fingerprinting approach

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Fahad Alhomayani ◽  
Mohammad H. Mahoor
Keyword(s):  
Global Navigation Satellite System ◽  
Urban Areas ◽  
Satellite System ◽  
Reference Points ◽  
Navigation Satellite ◽  
Data Types ◽  
Entry Barrier ◽  
Promising Alternative ◽  
Global Navigation ◽  
Global Navigation Satellite

AbstractIn recent years, fingerprint-based positioning has gained researchers’ attention since it is a promising alternative to the Global Navigation Satellite System and cellular network-based localization in urban areas. Despite this, the lack of publicly available datasets that researchers can use to develop, evaluate, and compare fingerprint-based positioning solutions constitutes a high entry barrier for studies. As an effort to overcome this barrier and foster new research efforts, this paper presents OutFin, a novel dataset of outdoor location fingerprints that were collected using two different smartphones. OutFin is comprised of diverse data types such as WiFi, Bluetooth, and cellular signal strengths, in addition to measurements from various sensors including the magnetometer, accelerometer, gyroscope, barometer, and ambient light sensor. The collection area spanned four dispersed sites with a total of 122 reference points. Each site is different in terms of its visibility to the Global Navigation Satellite System and reference points’ number, arrangement, and spacing. Before OutFin was made available to the public, several experiments were conducted to validate its technical quality.

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