scholarly journals Measurement of the Characteristics of TIDs Using Small and Regional Networks of GPS Receivers during the Campaign of 17–30 July of 2008

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Cesar E. Valladares ◽  
Matthew A. Hei
Keyword(s):  
Gravity Waves ◽  
Ionospheric Disturbances ◽  
Low Latitude ◽  
Gps Receivers ◽  
Plasma Bubbles ◽  
Low Latitudes ◽  
Scientific Report ◽  
Small Array ◽  
Low Latitude Ionosphere ◽  
Regional Arrays

This scientific report presents the results of a dedicated experiment that was conducted within the framework of the Low-latitude ionospheric Sensor Network (LISN) observatory to measure the characteristics of medium-scale (hundreds of km) Traveling Ionospheric Disturbances (TIDs) as they transit through the low-latitude ionosphere. A small array of 3 GPS receivers separated by 4-5 km placed in a triangular configuration was installed near Huancayo in Peru possessing several characteristics of a radio-interferometer. During the campaign days, 17–30 July 2008, TIDs were observed daily. On July 20, 2008 between 22 and 24 UT several TIDs moved across the small array of GPS receivers with a velocity near 130 m/s, were directed northward and had wavelengths close to 450 km. Other GPS receivers that were operating hundreds of km away from Huancayo show also similar TEC traces and provide a phase velocity equal to 150 m/s. This value was measured using the GPS at Piura, Cuzco and Huancayo. Based on this positive result, we conclude that small and/or regional arrays of GPS receivers can be used at low latitudes to study the role that gravity waves may have on seeding plasma bubbles.

scholarly journals An investigation of the ionospheric F region near the EIA crest in India using OI 777.4 and 630.0 nm nightglow observations

2018 ◽  
Vol 36 (3) ◽  
pp. 809-823 ◽  
Author(s):  
Navin Parihar ◽  
Sandro Maria Radicella ◽  
Bruno Nava ◽  
Yenca Olivia Migoya-Orue ◽  
Prabhakar Tiwari ◽  
...  
Keyword(s):  
Electron Density ◽  
Gravity Waves ◽  
Satellite Mission ◽  
Low Latitude ◽  
Density Maximum ◽  
Density Profiles ◽  
F Region ◽  
Equatorial Ionization Anomaly ◽  
Low Latitude Ionosphere ◽  
Electron Density Profiles

Abstract. Simultaneous observations of OI 777.4 and OI 630.0 nm nightglow emissions were carried at a low-latitude station, Allahabad (25.5° N, 81.9° E; geomag. lat.  ∼  16.30° N), located near the crest of the Appleton anomaly in India during September–December 2009. This report attempts to study the F region of ionosphere using airglow-derived parameters. Using an empirical approach put forward by Makela et al. (2001), firstly, we propose a novel technique to calibrate OI 777.4 and 630.0 nm emission intensities using Constellation Observing System for Meteorology, Ionosphere, and Climate/Formosa Satellite Mission 3 (COSMIC/FORMOSAT-3) electron density profiles. Next, the electron density maximum (Nm) and its height (hmF2) of the F layer have been derived from the information of two calibrated intensities. Nocturnal variation of Nm showed the signatures of the retreat of the equatorial ionization anomaly (EIA) and the midnight temperature maximum (MTM) phenomenon that are usually observed in the equatorial and low-latitude ionosphere. Signatures of gravity waves with time periods in the range of 0.7–3.0 h were also seen in Nm and hmF2 variations. Sample Nm and hmF2 maps have also been generated to show the usefulness of this technique in studying ionospheric processes.

scholarly journals A review of atmospheric gravity waves and travelling ionospheric disturbances: 1982-1995

1996 ◽  
Vol 14 (9) ◽  
pp. 917-940 ◽  
Author(s):  
K. Hocke ◽  
K. Schlegel
Keyword(s):  
Gravity Waves ◽  
Ionospheric Disturbances ◽  
Atmospheric Gravity Wave ◽  
Atmospheric Gravity Waves ◽  
Travelling Ionospheric Disturbances ◽  
The Past ◽  
Low Latitudes ◽  
Subsequent Propagation ◽  
Atmospheric Gravity ◽  
Inversion Techniques

Abstract. Recent investigations of atmospheric gravity waves (AGW) and travelling ionospheric disturbances (TID) in the Earth\\'s thermosphere and ionosphere are reviewed. In the past decade, the generation of gravity waves at high latitudes and their subsequent propagation to low latitudes have been studied by several global model simulations and coordinated observation campaigns such as the Worldwide Atmospheric Gravity-wave Study (WAGS), the results are presented in the first part of the review. The second part describes the progress towards understanding the AGW/TID characteristics. It points to the AGW/TID relationship which has been recently revealed with the aid of model-data comparisons and by the application of new inversion techniques. We describe the morphology and climatology of gravity waves and their ionospheric manifestations, TIDs, from numerous new observations.

Characteristics of daytime medium scale traveling ionospheric disturbances (MSTIDs) as observed by SWARM

2020 ◽  
Author(s):  
Chinmaya Nayak ◽  
Stephan Buchert
Keyword(s):  
Electron Density ◽  
Ionospheric Disturbances ◽  
Magnetic Fluctuations ◽  
Low Latitude ◽  
Plasma Irregularities ◽  
Medium Scale ◽  
Traveling Ionospheric Disturbances ◽  
Spatio Temporal ◽  
Low Latitude Ionosphere ◽  
Rule Out

<p><span>This paper studies the daytime medium scale traveling ionospheric disturbances (MSTIDs) in the mid- and low-latitude ionosphere for a period of nearly half a solar cycle (2014-2019) using SWARM observations. We specifically focus on daytime MSTIDs to rule out any contribution from nighttime plasma irregularities. Fluctuations in electron density are primarily used to identify the MSTIDs. These wave like structures are independently observed in both electron density and magnetic fluctuations, although they do not always show one to one correlation. In most cases, the structures are observed by both satellite ‘A’ and ‘C’, suggesting that their zonal extent is more than 140 km. The study makes an attempt to understand and explain the magnetic conjugate nature of the MSTIDs. To have a better understanding of the dynamics of the MSTIDs, ground based GPS-TEC and ionosonde data has been used on case to case basis, wherever available. Additionally, spatio-temporal statistics of MSTID distribution is presented. </span></p>

scholarly journals Mesospheric gravity wave characteristics and identification of their sources around spring equinox over Indian low latitudes

2016 ◽  
Vol 9 (1) ◽  
pp. 93-102 ◽  
Author(s):  
M. Sivakandan ◽  
I. Paulino ◽  
A. Taori ◽  
K. Niranjan
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Longwave Radiation ◽  
Small Scale ◽  
Low Latitude ◽  
Wave Characteristics ◽  
Spring Equinox ◽  
Low Latitudes ◽  
Charged Couple Device ◽  
Wave Properties

Abstract. We report OI557.7 nm night airglow observations with the help of a charged-couple device (CCD)-based all-sky camera from a low-latitude station, Gadanki (13.5° N; 79.2° E). Based on the data collected during March and April over 3 years, from 2012 to 2014 (except March 2013), we characterize the small-scale gravity wave properties. During this period, 50 gravity wave events were detected. The horizontal wavelengths of the gravity waves are found to ranging from 12 to 42 km with the phase velocity 20–90 m s−1. In most cases, these waves were propagating northward with only a few occurrences of southward propagation. In the present novel investigation from the Indian sector, each of the wave events was reverse-ray-traced to its source. The outgoing longwave radiation (OLR) suggested that tropospheric convection was a possible source for generation of the observed waves. It was found that approximately 66 % of the events were triggered directly by the convection.

scholarly journals A case study of the day-to-day occurrence of plasma irregularities in low-latitude ionosphere from multi-satellite observations

2019 ◽  
Author(s):  
Weihua Luo ◽  
Chao Xiong ◽  
Zhengping Zhu ◽  
Shanshan Chang ◽  
Xiao Yu
Keyword(s):  
Low Earth Orbit ◽  
Low Latitude ◽  
Plasma Irregularities ◽  
Republic Of China ◽  
Plasma Bubbles ◽  
Defense Meteorological Satellite Program ◽  
Open Issue ◽  
The Republic ◽  
Low Latitude Ionosphere ◽  
Gravity Recovery

Abstract. Day-to-day variability of the occurrence of plasma irregularities in low-latitude ionosphere is still an open issue. In this study, we report the occurrence of post-sunset plasma bubbles and blobs detected by the First satellite of the Republic of China (ROCSAT-1) in the same longitude sector (170° E) on two successive days, under geomagnetically quiet and disturbed conditions, respectively. Multi-Low Earth orbit (LEO) missions, like the Defense Meteorological Satellite Program (DMSP) F13 and F15, the Gravity Recovery and Climate Experiment (GRACE) and the Challenging Mini-satellite Payload (CHAMP) satellites are used to study the preferable conditions for the occurrence of plasma bubbles and blobs. The observations from the CHAMP and GRACE show that the Equatorial Ionization Anomaly (EIA) was enhanced significantly before the occurrence of plasma irregularities on both two successive days. We suggest that the enhancement of post-sunset eastward electric field is the most important factor for the day-to-day development of the plasma irregularity in equatorial and low-latitude ionosphere. In addition, the meridional neutral wind plays an important role in the occurrence of low-latitude plasma blobs.

scholarly journals Observation of Ionospheric Gravity Waves Introduced by Thunderstorms in Low Latitudes China by GNSS

2021 ◽  
Vol 13 (20) ◽  
pp. 4131
Author(s):  
Tong Liu ◽  
Zhibin Yu ◽  
Zonghua Ding ◽  
Wenfeng Nie ◽  
Guochang Xu
Keyword(s):  
Gravity Waves ◽  
Propagation Speed ◽  
Satellite System ◽  
Lower Atmosphere ◽  
Electron Content ◽  
Low Latitude ◽  
Total Electron ◽  
Cycle Slips ◽  
Short Period ◽  
Low Latitudes

The disturbances of the ionosphere caused by thunderstorms or lightning events in the troposphere have an impact on global navigation satellite system (GNSS) signals. Gravity waves (GWs) triggered by thunderstorms are one of the main factors that drive short-period Travelling Ionospheric Disturbances (TIDs). At mid-latitudes, ionospheric GWs can be detected by GNSS signals. However, at low latitudes, the multi-variability of the ionosphere leads to difficulties in identifying GWs induced by thunderstorms through GNSS data. Though disturbances of the ionosphere during low-latitude thunderstorms have been investigated, the explicit GW observation by GNSS and its propagation pattern are still unclear. In this paper, GWs with periods from 6 to 20 min are extracted from band-pass filtered GNSS carrier phase observations without cycle-slips, and 0.2–0.8 Total Electron Content Unit (TECU) magnitude perturbations are observed when the trajectories of ionospheric pierce points fall into the perturbed region. The propagation speed of 102.6–141.3 m/s and the direction of the propagation indicate that the GWs are propagating upward from a certain thunderstorm at lower atmosphere. The composite results of disturbance magnitude, period, and propagation velocity indicate that GWs initiated by thunderstorms and propagated from the troposphere to the ionosphere are observed by GNSS for the first time in the low-latitude region.

scholarly journals Low Latitude Ionosphere Error Correction Algorithms for Global Navigation Satellite System

2020 ◽  
Vol 9 (3) ◽  
pp. 3244-3248
Keyword(s):  
Error Correction ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Single Frequency ◽  
Navigation Satellite ◽  
Low Latitude ◽  
Low Latitudes ◽  
Global Navigation ◽  
Low Latitude Ionosphere ◽  
Global Navigation Satellite

The ionospheric errors occur due to loss of data in ionospheric region. Low latitudinal regions are the most affected regions due to ionospheric errors and also causes loss of signal or data for space based augmentation system(SBAS) such as aircraft. So to reduce these ionospheric errors in low latitude regions of Global Navigation Satellite System(GNSS) Klobuchar algorithm is used which mitigates the errors occurring in low latitude regions and is used as a standard algorithm in US Global Positioning System(GPS) till now; however, this model can reduce the ionospheric error by approximately 50-60% Root Mean Square(RMS) error in low-latitudes. So in order to increase the percentage deviation of errors in low-latitude regions, Enhanced Klobuchar algorithm is proposed which enhances the correction of low-latitude ionospheric errors approximately up to 80% RMS for a single frequency GPS user. In this paper error correction algorithms are performed over International GPS Service(IGS) data was collected using Hyderabad station receiver, Telangana (latitude- 17.41728°, longitude-78.55088°) in southern part of India during year 2016.

scholarly journals Maps of <I>fo</I>F2, <I>hm</I>F2, and plasma frequency above F2-layer peak in the night-time low-latitude ionosphere derived from Intercosmos-19 satellite topside sounding data

2007 ◽  
Vol 25 (8) ◽  
pp. 1827-1835 ◽  
Author(s):  
G. F. Deminova
Keyword(s):  
Plasma Frequency ◽  
Solar Maximum ◽  
Topside Ionosphere ◽  
Iri Model ◽  
Equatorial Anomaly ◽  
Night Time ◽  
Low Latitude ◽  
Low Latitudes ◽  
Longitudinal Variations ◽  
Low Latitude Ionosphere

Abstract. Maps of foF2, hmF2, and plasma frequency, fp, in the topside ionosphere at low latitudes, derived from Intercosmos-19 satellite topside sounding data, obtained from March 1979 to January 1981 and covering all longitudes, are presented for quiet geomagnetic conditions in June and December solstices at solar maximum for several local time intervals during the night. Based on these maps, features of the equatorial anomaly (EA) at different longitudes and their change during the night are considered. The maps show that averaged foF2, hmF2, and fp longitudinal variations are rather complicated, their structure looks wave-like with quasi-periods in longitude of about 75–100°, similar to that on individual days revealed previously at low latitudes using Intercosmos-19 data. Positions of the structure extrema in certain longitude intervals are stable enough so that they are clearly seen in the maps after averaging over a large number of measurements made on different days and even in different years. Such structure seems to need at least five harmonics for its description. The maps derived from Intercosmos-19 data were compared with the maps given by the IRI model. Along with general resemblance, essential distinctions between them were found. Intercosmos-19 maps show more complicated and pronounced longitudinal structure than IRI maps. They also show that at solar maximum, in general, at night, EA is stronger and persists for a longer time (on average, until 04:00 LT) than that presented in IRI model. Besides, much stronger asymmetry between the characteristics of the EA northern and southern crests in certain longitude intervals was revealed, most evident in hmF2 maps.

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