Loss of lock on GNSS signals and its association with ionospheric irregularities observed over Indian low latitudes

Equatorial ionospheric irregularities is an important space weather phenomenon, which can disrupt GNSS and communication systems. COSMIC 2 GNSS RO observations are affected via scintillations in signal amplitudes and phases. At the same time, we can use these scintillations to monitor and geolocate the ionospheric irregularities, which are of great value to the space weather services. Geolocation of the irregularities based on the RO signals is difficult, as any irregularities along the line between the GNSS and RO satellite can cause scintillation. Several geolocation methods are known. A back propagation (BP) method to geolocate the irregularities originally developed in 2001 and applied for GPS/MET RO data is being modified and applied for COSMIC 2 scintillation data. Because the equatorial irregularities are often associated with plasma bubbles, which are visible to the NASA UV imager GOLD, we have been using the GOLD images to validate the BP geolocation method.&#160; &#160;&#160;In this presentation, we will show the progress of recent validation effort of the BP geolocation method by comparing the COSMIC 2 geolocated irregularities with plasma bubbles in GOLD UV observations. Though, GOLD observations are only available in the American sector, COSMIC 2 observations can be used geolocate ionospheric irregularities throughout the equatorial and low latitudes

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Simultaneous 6300 Å airglow and radar observations of ionospheric irregularities and dynamics at the geomagnetic equator

Annales Geophysicae ◽

10.5194/angeo-36-473-2018 ◽

2018 ◽

Vol 36 (2) ◽

pp. 473-487 ◽

Cited By ~ 6

Author(s):

Dustin A. Hickey ◽

Carlos R. Martinis ◽

Michael Mendillo ◽

Jeffrey Baumgardner ◽

Joei Wroten ◽

...

Keyword(s):

Plasma Temperature ◽

Radar Data ◽

Ionospheric Irregularities ◽

Group Separation ◽

Plasma Parameters ◽

Zonal Winds ◽

Fabry Perot ◽

Low Latitudes ◽

Spread F ◽

Plasma Depletions

Abstract. In March 2014 an all-sky imager (ASI) was installed at the Jicamarca Radio Observatory (11.95∘ S, 76.87∘ W; 0.3∘ S MLAT). We present results of equatorial spread F (ESF) characteristics observed at Jicamarca and at low latitudes. Optical 6300 and 7774 Å airglow observations from the Jicamarca ASI are compared with other collocated instruments and with ASIs at El Leoncito, Argentina (31.8∘ S, 69.3∘ W; 19.8∘ S MLAT), and Villa de Leyva, Colombia (5.6∘ N, 73.52∘ W; 16.4∘ N MLAT). We use Jicamarca radar data, in incoherent and coherent modes, to obtain plasma parameters and detect echoes from irregularities. We find that ESF depletions tend to appear in groups with a group-to-group separation around 400–500 km and within-group separation around 50–100 km. We combine data from the three ASIs to investigate the conditions at Jicamarca that could lead to the development of high-altitude, or topside, plumes. We compare zonal winds, obtained from a Fabry–Pérot interferometer, with plasma drifts inferred from the zonal motion of plasma depletions. In addition to the ESF studies we also investigate the midnight temperature maximum and its effects at higher latitudes, visible as a brightness wave at El Leoncito. The ASI at Jicamarca along with collocated and low-latitude instruments provide a clear two-dimensional view of spatial and temporal evolution of ionospheric phenomena at equatorial and low latitudes that helps to explain the dynamics and evolution of equatorial ionospheric/thermospheric processes. Keywords. Ionosphere (equatorial ionosphere; ionospheric irregularities; plasma temperature and density)

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Climatology of GPS signal loss observed by Swarm satellites

Annales Geophysicae ◽

10.5194/angeo-36-679-2018 ◽

2018 ◽

Vol 36 (2) ◽

pp. 679-693 ◽

Cited By ~ 10

Author(s):

Chao Xiong ◽

Claudia Stolle ◽

Jaeheung Park

Keyword(s):

High Latitude ◽

Ionospheric Plasma ◽

Ionospheric Irregularities ◽

Signal Loss ◽

Radio Science ◽

Plasma Irregularities ◽

Gps Satellites ◽

Swarm Satellites ◽

Low Latitudes ◽

December Solstice

Abstract. By using 3-year global positioning system (GPS) measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between ±5 and ±20∘ magnetic latitude (MLAT) and high latitudes above 60∘ MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the high-latitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20∘, and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL) widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5 Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0 Hz, a PLL bandwidth of 0.5 Hz is a more suitable value for the Swarm receiver. Keywords. Ionosphere (equatorial ionosphere; ionospheric irregularities) – radio science (radio wave propagation)

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Detection of Daytime Ionospheric Irregularities at Low Latitudes With a Multistatic HF Radar

IEEE Geoscience and Remote Sensing Letters ◽

10.1109/lgrs.2018.2889298 ◽

2019 ◽

Vol 16 (6) ◽

pp. 839-843

Author(s):

Jinnan Wu ◽

Guobin Yang ◽

Yuannong Zhang ◽

Chen Zhou ◽

Zhengyu Zhao

Keyword(s):

Ionospheric Irregularities ◽

Hf Radar ◽

Low Latitudes

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The next generation of IGS ROTI Maps: an extension toward global coverage

10.5194/egusphere-egu2020-17905 ◽

2020 ◽

Author(s):

Andrzej Krankowski ◽

Iurii Cherniak ◽

Irina Zakharenkova ◽

Adam Fron ◽

Kacper Kotulak

Keyword(s):

Northern Hemisphere ◽

Space Weather ◽

Ionospheric Irregularities ◽

Next Generation ◽

Dual Frequency ◽

Case Scenario ◽

Worst Case ◽

Plasma Irregularities ◽

Low Latitudes ◽

Global Coverage

The International GNSS Service (IGS) has accepted for official release a new ionospheric product for specification of ionospheric irregularities occurrence and intensity over the Northern Hemisphere as derived from multi-site ground-based GPS observations. Initially, we focused on the Northern Hemisphere auroral and midlatitude regions because of the highest concentration of the GNSS users and user supporting permanent networks located within the American, European, and Asian sectors. The IGS ROTI maps product is routinely generated by multi-step processing of carrier phase delays in dual-frequency GPS signals and transferred to the IGS CDDIS database. Now, ROTI maps allow regular monitoring of ionospheric irregularities over the Northern Hemisphere and provide information about past events when strong ionospheric irregularities developed here.Obviously, the plasma irregularities that occur at high, middle, and low latitudes have different physical mechanisms of their origin and development. For study of the climatological features of ionospheric irregularities occurrence, investigation of the ionospheric responses for Space Weather drivers, processes derived from below, this actual ROTI Map product is required to cover low latitudes and the Southern hemisphere polar and midlatitudes.During last decade, numerous ground-based permanent receivers were deployed within the global and regional networks and these observations are publicly available. These data can support our activity toward extending the current IGS ROTI maps product for a global coverage. In this paper, we present initial results of ROTI maps product performance to characterize ionospheric irregularities exited by different types of geophysical processes and space weather events. The next generation of the IGS ROTI maps product can be a valuable tool for global ionospheric irregularities monitoring and retrospective analysis of plasma irregularities impact on the GNSS positioning in the &#8220;worst case scenario&#8221; domain.The research is supported by the National Science Centre, Poland, through grants 2017/25/B/ST10/00479 and 2017/27/B/ST10/02190 and the National Centre for Research and Development, Poland, through grant DWM/PL-CHN/97/2019&#160;Keywords: GPS, ionosphere, ionospheric irregularities, ROTI, IGS

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