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Journal articles on the topic 'Low latitude ionosphere'

Author: Grafiati

Published: 6 September 2023

Last updated: 25 July 2025

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1

Chen, Yiding, Libo Liu, Huijun Le, Hui Zhang, and Ruilong Zhang. "Responding trends of ionospheric F₂-layer to weaker geomagnetic activities." Journal of Space Weather and Space Climate 12 (2022): 6. http://dx.doi.org/10.1051/swsc/2022005.

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Geomagnetic activities frequently occur in varying degrees. Strong geomagnetic activities, which have been widely investigated, occur occasionally; they can cause distinguishable and significant disturbances in the ionosphere. Weaker geomagnetic activities frequently appear, whereas their effects are generally difficult to be distinguished from complex ionospheric variations. Weaker geomagnetic activities play important roles in ionospheric day-to-day variability thus should deserve further attention. In this study, long-term (longer than one solar cycle) measurements of the F2-layer critical

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2

Li, Jianfeng, Yongqian Wang, Shiqi Yang, and Fang Wang. "Characteristics of Low-Latitude Ionosphere Activity and Deterioration of TEC Model during the 7–9 September 2017 Magnetic Storm." Atmosphere 13, no. 9 (2022): 1365. http://dx.doi.org/10.3390/atmos13091365.

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Under the influence of space weather, abnormal disturbances in the ionosphere will distort the ionosphere model seriously and affect the global navigation satellite system negatively. This study analyzes the ionospheric activity characteristics and the ionospheric model performance in low latitude during a strong geomagnetic storm from 7 to 9 September 2017. The research goals are to determine the abnormal behavior of the ionosphere during the geomagnetic storm and to refine the ionosphere model in the low latitude. In the experiment, the vertical total electron content (VTEC) peak value at lo

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3

Yizengaw, Endawoke. "Global Longitudinal Dependence Observation of the Neutral Wind and Ionospheric Density Distribution." International Journal of Geophysics 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/342581.

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The statistical global view of the low-latitude ionospheric density stimulates further interest in studying the strong longitudinal variability of the ionospheric density structures in low-to-equatorial latitudes. However, we are not completely certain how the electrodynamics and ion-neutral coupling proceeds at low latitudes; in particular, the longitudinal difference in the dynamics of plasma structures in the low-to-mid latitude ionosphere is not yet fully understood. Numerical studies of latent heat release in the troposphere have indicated that the lower atmosphere can indeed introduce a

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4

Liu, Tong, Zhibin Yu, Zonghua Ding, Wenfeng Nie, and Guochang Xu. "Observation of Ionospheric Gravity Waves Introduced by Thunderstorms in Low Latitudes China by GNSS." Remote Sensing 13, no. 20 (2021): 4131. http://dx.doi.org/10.3390/rs13204131.

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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

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5

Sethi, N. K., M. K. Goel, and K. K. Mahajan. "Solar Cycle variations of ƒ<i>o</i>F2 from IGY to 1990." Annales Geophysicae 20, no. 10 (2002): 1677–85. http://dx.doi.org/10.5194/angeo-20-1677-2002.

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Abstract. Noontime monthly median values of F2-layer critical frequency foF2 (m) for some ionospheric stations representing low- and mid-latitudes are examined for their dependence on solar activity for the years 1957 (IGY) to 1990. This is the period for which ionospheric data in digital form is available in two CD-ROMs at the World Data Center, Boulder. It is observed that at mid-latitudes, foF2 (m) shows nearly a linear relationship with R12 (the 12-month running average of the Zurich sunspot number), though this relation is nonlinear for low-latitudes. These results indicate some departure

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6

Farah, Ashraf. "Single-Frequency Ionospheric-Delay Correction from BeiDou & GPS Systems for Northern Hemisphere." Artificial Satellites 54, no. 1 (2019): 1–15. http://dx.doi.org/10.2478/arsa-2019-0002.

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Abstract The range delay caused by the ionosphere layer is the major current source of error for GNSS users with single-frequency receivers. GNSS advice users to correct this type of error using ionospheric models whose coefficients are sent in their navigation messages. GPS-users use the Klobuchar model to correct this type of error. GPS navigation message contains the model’s eight coefficients which vary on the basis of seasonal ionospheric variations and average solar flux. The correction accuracy of Klobuchar model is about 50% (rms) of the ionospheric range delay. Beidou system calculate

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7

Pitout, F., P. T. Newell, and S. C. Buchert. "Simultaneous high- and low-latitude reconnection: ESR and DMSP observations." Annales Geophysicae 20, no. 9 (2002): 1311–20. http://dx.doi.org/10.5194/angeo-20-1311-2002.

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Abstract. We present EISCAT Svalbard Radar and DMSP observations of a double cusp during an interval of predominantly northward IMF on 26 November 2000. In the cusp region, the ESR dish, pointing northward, recorded sun-ward ionospheric flow at high latitudes (above 82° GL), indicating reconnection occuring in the magnetospheric lobe. Meanwhile, the same dish also recorded bursts of poleward flow, indicative of bursty reconnection at the subsolar magnetopause. Within this time interval, the DMSP F13 satellite passed in the close vicinity of the Svalbard archipelago. The particle measurement on

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8

Bailey, G. J., Y. Z. Su, and K. I. Oyama. "Yearly variations in the low-latitude topside ionosphere." Annales Geophysicae 18, no. 7 (2000): 789–98. http://dx.doi.org/10.1007/s00585-000-0789-0.

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Abstract. Observations made by the Hinotori satellite have been analysed to determine the yearly variations of the electron density and electron temperature in the low-latitude topside ionosphere. The observations reveal the existence of an equinoctial asymmetry in the topside electron density at low latitudes, i.e. the density is higher at one equinox than at the other. The asymmetry is hemisphere-dependent with the higher electron density occurring at the March equinox in the Northern Hemisphere and at the September equinox in the Southern Hemisphere. The asymmetry becomes stronger with incr

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9

Bittencourt, J. A., V. G. Pillat, P. R. Fagundes, Y. Sahai, and A. A. Pimenta. "LION: A dynamic computer model for the low-latitude ionosphere." Annales Geophysicae 25, no. 11 (2007): 2371–92. http://dx.doi.org/10.5194/angeo-25-2371-2007.

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Abstract. A realistic fully time-dependent computer model, denominated LION (Low-latitude Ionospheric) model, that simulates the dynamic behavior of the low-latitude ionosphere is presented. The time evolution and spatial distribution of the ionospheric particle densities and velocities are computed by numerically solving the time-dependent, coupled, nonlinear system of continuity and momentum equations for the ions O+, O2+, NO+, N2+ and N+, taking into account photoionization of the atmospheric species by the solar extreme ultraviolet radiation, chemical and ionic production and loss reaction

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10

Tiwari, Rajesh, Soumi Bhattacharya, P. K. Purohit, and A. K. Gwal. "Effect of TEC Variation on GPS Precise Point at Low Latitude." Open Atmospheric Science Journal 3, no. 1 (2009): 1–12. http://dx.doi.org/10.2174/1874282300903010001.

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The ionosphere is a dispersive medium of charged particles between the satellite and the user on Earth. These dispersive ionized media play a vital role in the various applications of GPS (Global Positioning Systems) because the ionosphere directly influences transionospheric radio waves propagating from the satellite to the receiver. Solar flares affect the ionization state of the ionosphere with their high intensity. Sometimes the intensity is so severe that it accelerates the rate of ionization, resulting in ionospheric storms; during the ionospheric storms the concentration of charged part

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11

Karpachev, Alexander. "Structure of the High-Latitude Noon Ionosphere of the Southern Hemisphere." Remote Sensing 15, no. 14 (2023): 3649. http://dx.doi.org/10.3390/rs15143649.

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The structure of the winter noon ionosphere of the southern hemisphere was studied. This structure includes the dayside cusp, associated high-latitude ionospheric trough (HLT), main ionospheric trough (MIT), electron density (Ne) peak at latitudes about 70°, mid-latitude ring ionospheric trough (RIT), and low-latitude quasi-trough. Data from the CHAMP satellite in the southern hemisphere for quiet geomagnetic conditions under high solar activity were selected for analysis. The DMSP satellite data and a model of auroral diffuse precipitation were also used. This model represents two zones of au

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12

Farah, Ashraf. "Behavior of Broadcast Ionospheric-Delay Models from GPS, Beidou, and Galileo Systems." Artificial Satellites 55, no. 2 (2020): 61–76. http://dx.doi.org/10.2478/arsa-2020-0005.

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AbstractThe GNSS observations suffer from different types of errors that could affect the achieved positioning accuracy based on the receiver type used. Single-frequency receivers are widely used worldwide because of its low cost. The ionospheric delay considers the most challenging error for single-frequency GNSS observations. All satellite navigation systems, except GLONASS, are advising their users to correct for the ionospheric delay using a certain model. Those models’ coefficients are sent to users in the system’s navigation message. These models are different in their accuracy and behav

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13

Pulinets, Sergey. "Low-Latitude Atmosphere-Ionosphere Effects Initiated by Strong Earthquakes Preparation Process." International Journal of Geophysics 2012 (2012): 1–14. http://dx.doi.org/10.1155/2012/131842.

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Ionospheric and atmospheric anomalies registered around the time of strong earthquakes in low-latitude regions are reported now regularly. Majority of these reports have the character of case studies without clear physical mechanism proposed. Here we try to present the general conception of low-latitude effects using the results of the recent author’s publications, including also rethinking the earlier results interpreted basing on recently established background physical mechanisms of anomalies generation. It should be underlined that only processes initiated by earthquake preparation are con

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14

Bhuyan, K., S. B. Singh, and P. K. Bhuyan. "Application of generalized singular value decomposition to ionospheric tomography." Annales Geophysicae 22, no. 10 (2004): 3437–44. http://dx.doi.org/10.5194/angeo-22-3437-2004.

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Abstract. The electron density distribution of the low- and mid-latitude ionosphere has been investigated by the computerized tomography technique using a Generalized Singular Value Decomposition (GSVD) based algorithm. Model ionospheric total electron content (TEC) data obtained from the International Reference Ionosphere 2001 and slant relative TEC data measured at a chain of three stations receiving transit satellite transmissions in Alaska, USA are used in this analysis. The issue of optimum efficiency of the GSVD algorithm in the reconstruction of ionospheric structures is being addressed

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15

Kim, Mingyu, and Jeongrae Kim. "SBAS-Aided GPS Positioning with an Extended Ionosphere Map at the Boundaries of WAAS Service Area." Remote Sensing 13, no. 1 (2021): 151. http://dx.doi.org/10.3390/rs13010151.

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Space-based augmentation system (SBAS) provides correction information for improving the global navigation satellite system (GNSS) positioning accuracy in real-time, which includes satellite orbit/clock and ionospheric delay corrections. At SBAS service area boundaries, the correction is not fully available to GNSS users and only a partial correction is available, mostly satellite orbit/clock information. By using the geospatial correlation property of the ionosphere delay information, the ionosphere correction coverage can be extended by a spatial extrapolation algorithm. This paper proposes

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16

Xiong, Chao, Claudia Stolle, and Jaeheung Park. "Climatology of GPS signal loss observed by Swarm satellites." Annales Geophysicae 36, no. 2 (2018): 679–93. http://dx.doi.org/10.5194/angeo-36-679-2018.

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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

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17

Suvorova, Alla, and Alexei Dmitriev. "The impact of intense fluxes of energetic protons on the low-latitude ionosphere." E3S Web of Conferences 196 (2020): 01011. http://dx.doi.org/10.1051/e3sconf/202019601011.

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Experiments on board low-Earth orbit satellites show that energetic particles (tens of keV) of the Earth’s radiation belt can penetrate to the equatorial ionosphere. Impact of the energetic particles on the upper atmosphere and ionosphere was studied for the case of the geomagnetic storm on 22 July 2009. We present changes of local ion concentration in the low-latitude ionosphere at night measured by the C/NOFS satellite at heights 400-800 km during the magnetic storm and quiet days. The ionospheric density during the storm was compared with a simultaneous observation of enhancements of 30-80

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18

G. Chandra Shekar. "Estimation and Evaluation of Ionospheric Scintillations at Various NavIC Signal Frequencies using Real Time Data." Journal of Electrical Systems 20, no. 7s (2024): 1169–78. http://dx.doi.org/10.52783/jes.3614.

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The ionospheric scintillations affect radio waves from the NavIC satellites through the ionosphere. The ionospheric scintillations lower receiver tracking accuracy, integrity, and continuity. This paper presents the computation of ionosphere parameters such as TEC, ROTI and scintillation index (S) using pseudo range and Carrier to Noise density ratio (C/No) measurements of NavIC L5 and S-band signals. Also, investigates the ionospheric scintillations, which are common in the equatorial and low latitude region. The correlation between the amplitude scintillation index S4 and ROTI is investigate

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19

Zhang, D. H., W. Zhang, Q. Li, L. Q. Shi, Y. Q. Hao, and Z. Xiao. "Accuracy analysis of the GPS instrumental bias estimated from observations in middle and low latitudes." Annales Geophysicae 28, no. 8 (2010): 1571–80. http://dx.doi.org/10.5194/angeo-28-1571-2010.

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Abstract. With one bias estimation method, the latitude-related error distribution of instrumental biases estimated from the GPS observations in Chinese middle and low latitude region in 2004 is analyzed statistically. It is found that the error of GPS instrumental biases estimated under the assumption of a quiet ionosphere has an increasing tendency with the latitude decreasing. Besides the asymmetrical distribution of the plasmaspheric electron content, the obvious spatial gradient of the ionospheric total electron content (TEC) along the meridional line that related to the Equatorial Ionosp

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20

Mustapha, Abbas, Joshua Wisdom, Mukhtar Furfuri, and Mohammad Kaoje. "Longitudinal Response of the Low-latitude Ionosphere to 2017 Sudden Stratospheric Warming Event." International Journal of Atmospheric and Oceanic Sciences 9, no. 1 (2025): 1–8. https://doi.org/10.11648/j.ijaos.20250901.11.

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The Earth&apos;s ionosphere, a crucial region for communication and navigation systems, is susceptible to disturbances driven by both external (solar and geomagnetic activity) and internal (atmospheric waves) forces. These internal forces are known to be amplified during SSW events, creating significant ionospheric perturbations. This study investigates the longitudinal response of the low-latitude ionosphere, specifically focusing on the EIA, to the 2017 SSW event. Addressing a gap in current understanding, this research analyzes the longitudinal variations in TEC within the African and A

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21

Wei, Lehui, Chunhua Jiang, Yaogai Hu, et al. "Ionosonde Observations of Spread F and Spread Es at Low and Middle Latitudes during the Recovery Phase of the 7–9 September 2017 Geomagnetic Storm." Remote Sensing 13, no. 5 (2021): 1010. http://dx.doi.org/10.3390/rs13051010.

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This study presents observations of nighttime spread F/ionospheric irregularities and spread Es at low and middle latitudes in the South East Asia longitude of China sectors during the recovery phase of the 7–9 September 2017 geomagnetic storm. In this study, multiple observations, including a chain of three ionosondes located about the longitude of 100°E, Swarm satellites, and Global Navigation Satellite System (GNSS) ROTI maps, were used to study the development process and evolution characteristics of the nighttime spread F/ionospheric irregularities at low and middle latitudes. Interesting

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22

Marshall, R. A., and F. W. Menk. "Observations of Pc 3-4 and Pi 2 geomagnetic pulsations in the low-latitude ionosphere." Annales Geophysicae 17, no. 11 (1999): 1397–410. http://dx.doi.org/10.1007/s00585-999-1397-2.

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Abstract. Day-time Pc 3–4 (~5–60 mHz) and night-time Pi 2 (~5–20 mHz) ULF waves propagating down through the ionosphere can cause oscillations in the Doppler shift of HF radio transmissions that are correlated with the magnetic pulsations recorded on the ground. In order to examine properties of these correlated signals, we conducted a joint HF Doppler/magnetometer experiment for two six-month intervals at a location near L = 1.8. The magnetic pulsations were best correlated with ionospheric oscillations from near the F region peak. The Doppler oscillations were in phase at two different altit

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Wang, Qisheng, Jiaru Zhu, and Genxin Yang. "Characteristic analysis of the differences between total electron content (TEC) values in global ionosphere map (GIM) grids." Annales Geophysicae 42, no. 1 (2024): 45–53. http://dx.doi.org/10.5194/angeo-42-45-2024.

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Abstract. Using total electron content (TEC) from a global ionosphere map (GIM) for ionospheric delay correction is a common method of eliminating ionospheric errors in satellite navigation and positioning. On this basis, the TEC of a puncture point can be obtained by GIM grid TEC interpolation. However, in terms of grid, only few studies have analyzed the TEC value size characteristics of its four grid points, that is, the TEC difference characteristics among them. In view of this, by utilizing the GIM data from high solar-activity years (2014) and low solar-activity years (2021) provided by

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24

Tatsuta, K., Y. Hobara, S. Pal, and M. Balikhin. "Sub-ionospheric VLF signal anomaly due to geomagnetic storms: a statistical study." Annales Geophysicae 33, no. 11 (2015): 1457–67. http://dx.doi.org/10.5194/angeo-33-1457-2015.

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Abstract. We investigate quantitatively the effect of geomagnetic storms on the sub-ionospheric VLF/LF (Very Low Frequency/Low Frequency) propagations for different latitudes based on 2-year nighttime data from Japanese VLF/LF observation network. Three statistical parameters such as average signal amplitude, variability of the signal amplitude, and nighttime fluctuation were calculated daily for 2 years for 16–21 independent VLF/LF transmitter–receiver propagation paths consisting of three transmitters and seven receiving stations. These propagation paths are suitable to simultaneously study

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Ridley, A. J., T. I. Gombosi, and D. L. DeZeeuw. "Ionospheric control of the magnetosphere: conductance." Annales Geophysicae 22, no. 2 (2004): 567–84. http://dx.doi.org/10.5194/angeo-22-567-2004.

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Abstract. It is well known that the ionosphere plays a role in determining the global state of the magnetosphere. The ionosphere allows magnetospheric currents to close, thereby allowing magnetospheric convection to occur. The amount of current which can be carried through the ionosphere is mainly determined by the ionospheric conductivity. This paper starts to quantify the nonlinear relationship between the ionospheric conductivity and the global state of the magnetosphere. It is found that the steady-state magnetosphere acts neither as a current nor as a voltage generator; a uniform Hall con

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Chernogor, L., Yu Mylovanov, and Y. Luo. "EFFECTS FROM THE JUNE 10, 2021 SOLAR ECLIPSE IN THE HIGH-LATITUDE IONOSPHERE: RESULTS OF GPS OBSERVATIONS." RADIO PHYSICS AND RADIO ASTRONOMY 27, no. 2 (2022): 093–109. http://dx.doi.org/10.15407/rpra27.02.093.

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Subject and Purpose. The unique natural phenomena which solar eclipses are can activate coupling between the subsystems of the Earth–atmosphere–ionosphere–magnetosphere system. Following an eclipse, disturbances may get induced in all the subsystems and their associated geophysical fields. It is important that a subsystem’s response does not depend on the phase of the eclipse alone, but also on the state of space weather and the observation site coordinates. The majority of solar eclipses occur at middle and low latitudes. The maximum phase of the June 10, 2021 annular eclipse was observed at

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Yizengaw, E., E. A. Essex, and R. Birsa. "The Southern Hemisphere and equatorial region ionization response for a 22 September 1999 severe magnetic storm." Annales Geophysicae 22, no. 8 (2004): 2765–73. http://dx.doi.org/10.5194/angeo-22-2765-2004.

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Abstract. The ionospheric storm evolution process was monitored during the 22 September 1999 magnetic storm over the Australian eastern region, through measurements of the ionospheric Total Electron Content (TEC) from seven Global Positioning Systems (GPS) stations. The spatial and temporal variations of the ionosphere were analysed as a time series of TEC maps. Results of our analysis show that the main ionospheric effect of the storm under consideration are: the long lasting negative storm effect during a magnetic storm at mid-latitude regions; the strong, positive disturbances during the st

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Le, H., L. Liu, X. Yue, and W. Wan. "The ionospheric responses to the 11 August 1999 solar eclipse: observations and modeling." Annales Geophysicae 26, no. 1 (2008): 107–16. http://dx.doi.org/10.5194/angeo-26-107-2008.

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Abstract. A total eclipse occurred on 11 August 1999 with its path of totality passing over central Europe in the latitude range 40°–50° N. The ionospheric responses to this eclipse were measured by a wide ionosonde network. On the basis of the measurements of foE, foF1, and foF2 at sixteen ionosonde stations in Europe, we statistically analyze the variations of these parameters with a function of eclipse magnitude. To model the eclipse effects more accurately, a revised eclipse factor, FR, is constructed to describe the variations of solar radiation during the solar eclipse. Then we simulate

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Sahai, Y., R. S. Dabas, Y. Otsuka, and M. Klimenko. "Low-Latitude Mesosphere, Thermosphere, and Ionosphere." International Journal of Geophysics 2012 (2012): 1–2. http://dx.doi.org/10.1155/2012/671240.

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Giannattasio, Fabio, Alessio Pignalberi, Roberta Tozzi, et al. "Perpendicular Electrical Conductivity in the Topside Ionosphere Derived from Swarm Measurements." Remote Sensing 16, no. 17 (2024): 3129. http://dx.doi.org/10.3390/rs16173129.

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The study of the physical properties of the topside ionosphere is fundamental to investigating the energy balance of the ionosphere and developing accurate models to predict relevant phenomena, which are often at the root of Space Weather effects in the near-Earth environment. One of the most important physical parameters characterising the ionospheric medium is electrical conductivity, which is crucial for the onset and amplification of ionospheric currents and for calculating the power density dissipated by such currents. We characterise, for the first time, electrical conductivity in the di

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Onohara, Amelia Naomi, Inez Staciarini Batista, and Paulo Prado Batista. "Wavenumber-4 structures observed in the low-latitude ionosphere during low and high solar activity periods using FORMOSAT/COSMIC observations." Annales Geophysicae 36, no. 2 (2018): 459–71. http://dx.doi.org/10.5194/angeo-36-459-2018.

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Abstract. The main purpose of this study is to investigate the four-peak structure observed in the low-latitude equatorial ionosphere by the FORMOSAT/COSMIC satellites. Longitudinal distributions of NmF2 (the density of the F layer peak) and hmF2 (ionospheric F2-layer peak height) averages, obtained around September equinox periods from 2007 to 2015, were submitted to a bi-spectral Fourier analysis in order to obtain the amplitudes and phases of the main waves. The four-peak structure in the equatorial and low-latitude ionosphere was present in both low and high solar activity periods. This ki

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Karpachev, A. T. "Features of the Structure of the Winter Morning High- and Mid-Latitude Ionosphere." Геомагнетизм и аэрономия 63, no. 6 (2023): 788–97. http://dx.doi.org/10.31857/s0016794023600370.

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The structure of the winter morning (0500–0900 LT) ionosphere in the Northern and Southern hemispheres is studied in detail. For this, CHAMP satellite data for quiet conditions during the period of high solar activity of 2000–2002 are used. Careful analysis is used to identify electron concentration troughs: the high-latitude ionospheric trough; subauroral, or main, ionospheric trough; and mid-latitude ring ionospheric trough. In order to identify and separate the high-latitude and main ionospheric troughs, the model of auroral diffuse precipitation of the Polar Geophysical Institute is used,

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Imtiaz, Nadia, Waqar Younas, and Majid Khan. "Response of the low- to mid-latitude ionosphere to the geomagnetic storm of September 2017." Annales Geophysicae 38, no. 2 (2020): 359–72. http://dx.doi.org/10.5194/angeo-38-359-2020.

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Abstract. We study the impact of the geomagnetic storm of 7–9 September 2017 on the low- to mid-latitude ionosphere. The prominent feature of this solar event is the sequential occurrence of two SYM-H minima with values of −146 and −115 nT on 8 September at 01:08 and 13:56 UT, respectively. The study is based on the analysis of data from the Global Positioning System (GPS) stations and magnetic observatories located at different longitudinal sectors corresponding to the Pacific, Asia, Africa and the Americas during the period 4–14 September 2017. The GPS data are used to derive the global, reg

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Agiwal, Omakshi, Luke Moore, Carlos Martinis, Ingo Mueller-Wodarg, and J. D. Huba. "A New Saturn Model of Ionospheric Transport and Electrodynamics (SMITE)." Planetary Science Journal 6, no. 6 (2025): 136. https://doi.org/10.3847/psj/add108.

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Abstract We introduce the Saturn Model of Ionospheric Transport and Electrodynamics (SMITE), a new model that incorporates interhemispheric plasma transport using a dipole magnetic field aligned grid, and a range of dynamic processes that influence Saturn’s ionosphere. SMITE includes tunable parameters for the inflow of exogenous material, seasonal and local time atmospheric variations, the ring shadow, and plasma transport driven by neutral winds and low-latitude electrodynamics. SMITE is an adaptation of the terrestrial SAMI2 model, which has successfully reproduced numerous ionospheric phen

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Chatterjee, S., and P. K. Purohit. "Effect of Ionospheric Perturbation on GPS Observation over Low Latitude Region, Bhopal." Journal of Scientific Research 4, no. 3 (2012): 577–87. http://dx.doi.org/10.3329/jsr.v4i3.10146.

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Increased knowledge on the ionospheric structure is of important interest for precise positioning, since the ionosphere has an impact on global positioning system (GPS) L-band radio waves by its free electrons. Especially during perturbed geomagnetic conditions when the ionosphere differs from its undisturbed state, quasi real time data assimilation would be useful. On the other hand, these perturbations of the GPS signals are taken as scientific information to investigate ionospheric scenarios. In this paper we describe the occurrence of GPS phase fluctuations during January to December 2005

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Ma, Zheng, Yun Gong, Shaodong Zhang, Jiaxin Bao, Song Yin, and Qihou Zhou. "Seasonal Variations in Ion Density, Ion Temperature, and Migrating Tides in the Topside Ionosphere Revealed by ICON/IVM." Remote Sensing 15, no. 21 (2023): 5205. http://dx.doi.org/10.3390/rs15215205.

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Based on the plasma parameters measured by the Ion Velocity Meter (IVM) instrument on the Ionospheric Connection Explorer (ICON) satellite from 2020 to 2021, we present an analysis of seasonal variations in ion density, ion temperature, and migrating tides in the low-latitude topside ionosphere. The interannual variations in total ion density and O+ density are directly impacted by solar radiation. However, the concentration of H+ is not highly related to solar activity. The measurements show that the hemispheric dividing latitude for the seasonal variation in Ti is at about 9°N. We suggest th

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Elias, Ana G., Blas F. de Haro Barbas, Bruno S. Zossi, Franco D. Medina, Mariano Fagre, and Jose V. Venchiarutti. "Review of Long-Term Trends in the Equatorial Ionosphere Due the Geomagnetic Field Secular Variations and Its Relevance to Space Weather." Atmosphere 13, no. 1 (2021): 40. http://dx.doi.org/10.3390/atmos13010040.

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The Earth’s ionosphere presents long-term trends that have been of interest since a pioneering study in 1989 suggesting that greenhouse gases increasing due to anthropogenic activity will produce not only a troposphere global warming, but a cooling in the upper atmosphere as well. Since then, long-term changes in the upper atmosphere, and particularly in the ionosphere, have become a significant topic in global change studies with many results already published. There are also other ionospheric long-term change forcings of natural origin, such as the Earth’s magnetic field secular variation wi

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Dashora, N., S. Sharma, R. S. Dabas, S. Alex, and R. Pandey. "Large enhancements in low latitude total electron content during 15 May 2005 geomagnetic storm in Indian zone." Annales Geophysicae 27, no. 5 (2009): 1803–20. http://dx.doi.org/10.5194/angeo-27-1803-2009.

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Abstract. Results pertaining to the response of the equatorial and low latitude ionosphere to a major geomagnetic storm that occurred on 15 May 2005 are presented. These results are also the first from the Indian zone in terms of (i) GPS derived total electron content (TEC) variations following the storm (ii) Local low latitude electrodynamics response to penetration of high latitude convection electric field (iii) effect of storm induced traveling atmospheric disturbances (TAD's) on GPS-TEC in equatorial ionization anomaly (EIA) zone. Data set comprising of ionospheric TEC obtained from GPS m

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Hajkowicz, L. A., and H. Minakoshi. "Mid-latitude ionospheric scintillation anomaly in the Far East." Annales Geophysicae 21, no. 2 (2003): 577–81. http://dx.doi.org/10.5194/angeo-21-577-2003.

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Abstract. A long-term (over 3 years) study has been undertaken to obtain a comprehensive evaluation of VHF ionospheric scintillation morphology in East Asia (at Kokobunji in Japan), using amplitude records from Transit satellites. It is now evident that summer day and night scintillation enhancement in this mid-latitude region is a long-term evidence of a well-known Asian ionospheric disturbance anomaly. The scintillation activity is particularly strong during summer nights (21:00–24:00 LT) and on occasion, all satellite passes recorded on consecutive days are associated with pronounced scinti

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Wang, H., H. Lühr, S. Y. Ma, and P. Ritter. "Statistical study of the substorm onset: its dependence on solar wind parameters and solar illumination." Annales Geophysicae 23, no. 6 (2005): 2069–79. http://dx.doi.org/10.5194/angeo-23-2069-2005.

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Abstract. Based on 1829 well-defined substorm onsets in the Northern Hemisphere, observed during a 2-year period by the FUV Imager on board the IMAGE spacecraft, a statistical study is performed. From the combination of solar wind parameter observations by ACE and magnetic field observations by the low altitude satellite CHAMP, the location of auroral breakups in response to solar illumination and solar coupling parameters are studied. Furthermore, the correspondence of the onset location with prominent large-scale field-aligned currents and electrojets are investigated. Solar illumination and

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Olatunbosun, LG, AO Olabode, AB Babinisi, and EA Ariyibi. "HF Propagation during geomagnetic storms at a low latitude station." Physics & Astronomy International Journal 4, no. 1 (2020): 11–16. http://dx.doi.org/10.15406/paij.2020.04.00197.

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The variations in the ionosphere affect the radio wave propagation. These variations become more pronounced as a result of geomagnetic storms. The data from a Digitonide installed at Guam station (Lat. 13.62oN and Long. 144.86oE) during geomagnetic events was scaled for an ionogram, which shows the heights of different layers in the ionosphere at different frequencies. The ionogram was then analysed and interpreted. Results showed that virtual heights steadily increased as frequency increased. The splitting of waves into ordinary and extraordinary waves as they enter the ionosphere was an indi

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Mingaleva, G. I., and V. S. Mingalev. "Response of the convecting high-latitude F layer to a powerful HF wave." Annales Geophysicae 15, no. 10 (1997): 1291–300. http://dx.doi.org/10.1007/s00585-997-1291-8.

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Abstract. A numerical model of the high-latitude ionosphere, which takes into account the convection of the ionospheric plasma, has been developed and utilized to simulate the F-layer response at auroral latitudes to high-power radio waves. The model produces the time variations of the electron density, positive ion velocity, and ion and electron temperature profiles within a magnetic field tube carried over an ionospheric heater by the convection electric field. The simulations have been performed for the point with the geographic coordinates of the ionospheric HF heating facility near Tromso

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Wright, D. M., T. K. Yeoman, and T. B. Jones. "ULF wave occurrence statistics in a high-latitude HF Doppler sounder." Annales Geophysicae 17, no. 6 (1999): 749–58. http://dx.doi.org/10.1007/s00585-999-0749-2.

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Abstract. Ultra low frequency (ULF) wave activity in the high-latitude ionosphere has been observed by a high frequency (HF) Doppler sounder located at Tromsø, Norway (69.7°N, 19.2°E geographic coordinates). A statistical study of the occurrence of these waves has been undertaken from data collected between 1979 and 1984. The diurnal, seasonal, solar cycle and geomagnetic activity variations in occurrence have been investigated. The findings demonstrate that the ability of the sounder to detect ULF wave signatures maximises at the equinoxes and that there is a peak in occurrence in the morning

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Jenkins, B., G. J. Bailey, A. E. Ennis, and R. J. Moffett. "The effect of vibrationally excited nitrogen on the low-latitude ionosphere." Annales Geophysicae 15, no. 11 (1997): 1422–28. http://dx.doi.org/10.1007/s00585-997-1422-2.

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Abstract. The first five vibrationally excited states of molecular nitrogen have been included in the Sheffield University plasmasphere ionosphere model. Vibrationally excited molecular nitrogen reacts much more strongly with atomic oxygen ions than ground-state nitrogen; this means that more O+ ions are converted to NO+ ions, which in turn combine with the electrons to give reduced electron densities. Model calculations have been carried out to investigate the effect of including vibrationally excited molecular nitrogen on the low-latitude ionosphere. In contrast to mid-latitudes, a reduction

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Dashora, N., and R. Pandey. "Observations in equatorial anomaly region of total electron content enhancements and depletions." Annales Geophysicae 23, no. 7 (2005): 2449–56. http://dx.doi.org/10.5194/angeo-23-2449-2005.

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Abstract. A GSV 4004A GPS receiver has been operational near the crest of the equatorial anomaly at Udaipur, India for some time now. The receiver provides the line-of-sight total electron content (TEC), the phase and amplitude scintillation index, σφ and S4, respectively. This paper presents the first results on the nighttime TEC depletions associated with the equatorial spread F in the Indian zone. The TEC depletions are found to be very well correlated with the increased S4 index. A new feature of low-latitude TEC is also reported, concerning the observation of isolated and localized TEC en

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DABBAKUTI, J. R. K. Kumar, D. Venkata RATNAM, and Surendra SUNDA. "MODELLING OF IONOSPHERIC TIME DELAYS BASED ON ADJUSTED SPHERICAL HARMONIC ANALYSIS." Aviation 20, no. 1 (2016): 1–7. http://dx.doi.org/10.3846/16487788.2016.1162197.

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The ionosphere is the region of the upper atmosphere and the study of the upper atmosphere has a significant role in monitoring, modeling and forecasting for satellite based navigation services. As India lies in a low latitude region, a more careful approach has to be taken to characterize the ionosphere due to the irregularities and equatorial anomaly conditions. In order to study the ionospheric temporal variations, a regional ionospheric model based on the Adjusted Spherical Harmonic Analysis (ASHA) is implemented. The results indicate that the ASHA model is one of the contenders for estima

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Singh, D. K., Ashok K. Singh, R. P. Patel, R. P. Singh, and A. K. Singh. "Two types of ELF hiss observed at Varanasi, India." Annales Geophysicae 17, no. 10 (1999): 1260–67. http://dx.doi.org/10.1007/s00585-999-1260-5.

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Abstract. The morphology of ELF hiss events observed at low-latitude ground station Varanasi (L = 1.07, geomagnetic latitude 14°55'N) are reported, which consist of two types: (1) events which propagated in ducted mode along the geomagnetic field line corresponding to observing station Varanasi and (2) events which propagated in ducted mode along higher L-values (L = 4–6), after reaching the lower edge of ionosphere excite the Earth-ionosphere wave guide and propagate towards equator to be received at Varanasi. To understand the generation mechanism of ELF hiss, incoherent Cerenkov radiated po

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Ma, Guanyi, and Klemens Hocke. "Effects of sudden stratospheric warmings on the global ionospheric total electron content using a machine learning analysis." Atmospheric Chemistry and Physics 25, no. 9 (2025): 5009–20. https://doi.org/10.5194/acp-25-5009-2025.

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Abstract. A sudden stratospheric warming (SSW) is a breakdown of the winter stratospheric polar vortex. It has atmospheric effects in both the Northern Hemisphere and Southern Hemisphere, leading to disturbances in the whole ionosphere. Previous case studies have shown that SSW effects are observed mainly in the low-latitude ionosphere, and each SSW event may have a different effect on the ionosphere due to complex dynamics from solar and geomagnetic activities and seasonal changes. However, the SSW-induced tidal variability in the mid- to high-latitude ionosphere is only identified for severa

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Horvath, I., and E. A. Essex. "Vertical <i>E</i> × <i>B</i> drift velocity variations and associated low-latitude ionospheric irregularities investigated with the TOPEX and GPS satellite data." Annales Geophysicae 21, no. 4 (2003): 1017–30. http://dx.doi.org/10.5194/angeo-21-1017-2003.

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Abstract. With a well-selected data set, the various events of the vertical E × B drift velocity variations at magnetic-equator-latitudes, the resultant ionospheric features at low-and mid-latitudes, and the practical consequences of these E × B events on the equatorial radio signal propagation are demonstrated. On a global scale, the development of a equatorial anomaly is illustrated with a series of 1995 global TOPEX TEC (total electron content) maps. Locally, in the Australian longitude region, some field-aligned TOPEX TEC cross sections are combined with the matching Guam (144.86° E; 13.59

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Yizengaw, E., P. L. Dyson, E. A. Essex, and M. B. Moldwin. "Ionosphere dynamics over the Southern Hemisphere during the 31 March 2001 severe magnetic storm using multi-instrument measurement data." Annales Geophysicae 23, no. 3 (2005): 707–21. http://dx.doi.org/10.5194/angeo-23-707-2005.

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Abstract. The effects of the 31 March 2001 severe magnetic storm on the Southern Hemisphere ionosphere have been studied using ground-based and satellite measurements. The prime goal of this comprehensive study is to track the ionospheric response from high-to-low latitude to obtain a clear understanding of storm-time ionospheric change. The study uses a combination of ionospheric Total Electron Content (TEC) obtained from GPS signal group delay and phase advance measurements, ionosonde data, and data from satellite in-situ measurements, such as the Defense Metrological Satellite Program (DMSP

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