scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Response of data-driven artificial neural network-based TEC models to neutral wind for different locations, seasons, and solar activity levels from the Indian longitude sector

01 Jul 2017-Journal of Geophysical Research (John Wiley & Sons, Ltd)-Vol. 122, Iss: 7, pp 7713-7733
TL;DR: In this article, a set of observations carried out in the Indian longitude sector have been reported in order to find the amount of improvement in performance accuracy of an ANN-based Vertical Total Electron Content (VTEC) model after incorporation of neutral wind as model input.
Abstract: The perturbations imposed on transionospheric signals by the ionosphere are a major concern for navigation. The dynamic nature of the ionosphere in the low latitude equatorial region and the Indian longitude sector has some specific characteristics such as sharp temporal and latitudinal variation of Total Electron Content (TEC). TEC in the Indian longitude sector also undergoes seasonal variations. The large magnitude and sharp variation of TEC causes large and variable range errors for satellite based navigation system such as Global Positioning System (GPS) throughout the day. For accurate navigation using Satellite Based Augmentation Systems (SBAS), proper prediction of TEC under certain geophysical conditions is necessary in the equatorial region. It has been reported in the literature that prediction accuracy of TEC has been improved using measured data driven Artificial Neural Network (ANN) based VTEC models, compared to standard ionospheric models. A set of observations carried out in the Indian longitude sector have been reported in this paper in order to find the amount of improvement in performance accuracy of an ANN-based Vertical TEC (VTEC) model after incorporation of neutral wind as model input. The variations of this improvement in prediction accuracy with respect to latitude, longitude, season and solar activity have also been reported in this paper.
Citations
More filters
Peer Review
TL;DR: In this article , a commentary about the state of Integrated, Coordinated, Open, and Networked (ICON) principles in Space Physics and Aeronomy and a discussion on several scopes and limitations to implementing them are discussed.
Abstract: This article is a commentary about the state of Integrated, Coordinated, Open, and Networked (ICON) principles (Goldman et al., 2021) in Space Physics and Aeronomy and a discussion on several scopes and limitations to implementing them. The commentary focuses on the basic introduction and brief literature survey (Section 1); possibilities of implementation of ICON in Space Physics and Aeronomy (Section 2) and limitations or challenges in this field with possible solutions using ICON principles (Section 3). The Space Physics and Aeronomy section of the American Geophysical Union (AGU) comprises the interactions between solar wind, Interplanetary Magnetic Field (IMF) and different planetary magnetospheres and ionospheres. The section also deals with solar physics, mechanisms behind existence of solar magnetic fields, and evaluations of high and low speed solar winds. This field is a collection of different interdisciplinary subtopics, making this an excellent example of integrated research. Similar and transparent methodologies are adopted to solve problems all over the world which shows a coordinated approach of research. Freely available data from different space agencies and universities are also great assets for this domain which supports open research. The scopes of possible networked research with mutual benefits are also highlighted. Examples of ICON-based international collaborations and support mechanisms towards young scientists are elaborated which are helpful to mitigate limitations in this domain. Space Physics and Aeronomy Perspectives on Integrated, Coordinated, Open, Networked (ICON) Science
References
More filters
Journal ArticleDOI
TL;DR: The MSIS-86 empirical model of thermospheric temperature, density and composition as discussed by the authors uses new temperature and composition data from the Dynamics Explorer satellite to improve the representation of polar region morphology over that in theMSIS-83 model.
Abstract: The MSIS-86 empirical model of thermospheric temperature, density and composition uses new temperature and composition data from the Dynamics Explorer satellite to improve the representation of polar region morphology over that in the MSIS-83 model. Terms were added or changed to better represent seasonal variations in the polar regions under both quiet and magnetically disturbed conditions. Local time variations in the magnetic activity effect were added. In addition a new species, atomic nitrogen, was added to the previous list of N2, O2, He, O, H, and Ar covered by the model.

1,699 citations

Journal ArticleDOI
01 May 1946-Nature
TL;DR: In this article, a study of these data has disclosed the remarkable result that although ionospheric events in the E and F1 layers are similarly reproduced at the same local time on the same day at all locations on a line of constant geographic latitude, the same is by no means the case for the F2 layer.
Abstract: DURING the War, many new ionospheric stations were instituted in different parts of the world to serve the operational requirements of the Allied Forces. As a result, there have become available, for the first time, sufficient data to provide a rough general morphological picture of the F2 layer of the ionosphere. A study of these data has disclosed the remarkable result that, although ionospheric events in the E and F1 layers are similarly reproduced at the same local time on the same day at all locations on a line of constant geographic latitude, the same is by no means the case for the F2 layer. It has also been confirmed, as was suspected earlier, that under conditions of symmetrical solar illumination, an asymmetry of ionization exists for certain station on the same longitude and situated at equal latitudes north and south of the equator.

618 citations

Journal ArticleDOI
TL;DR: Immel et al. as discussed by the authors showed that ionospheric densities vary with the strength of nonmigrating, diurnal atmospheric tides that are, in turn, driven mainly by weather in the tropics.
Abstract: [1] A newly discovered 1000-km scale longitudinal variation in ionospheric densities is an unexpected and heretofore unexplained phenomenon. Here we show that ionospheric densities vary with the strength of nonmigrating, diurnal atmospheric tides that are, in turn, driven mainly by weather in the tropics. A strong connection between tropospheric and ionospheric conditions is unexpected, as these upward propagating tides are damped far below the peak in ionospheric density. The observations can be explained by consideration of the dynamo interaction of the tides with the lower ionosphere (E-layer) in daytime. The influence of persistent tropical rainstorms is therefore an important new consideration for space weather. Citation: Immel, T. J., E. Sagawa, S. L. England, S. B. Henderson, M. E. Hagan, S. B. Mende, H. U. Frey, C. M. Swenson, and L. J. Paxton (2006), Control of equatorial ionospheric morphology by atmospheric tides, Geophys. Res. Lett., 33, L15108, doi:10.1029/2006GL026161. [2] The ionosphere is the region of highest plasma density in Earth’s space environment. It is a dynamic environment supporting a host of plasma instability processes, with important implications for global communications and geo-location applications. Produced by the ionization of the neutral atmosphere by solar x-ray and UV radiation, the uppermost ionospheric layer has the highest plasma density with a peak around 350–400 km altitude and primarily consists of O + ions. This is called the F-layer and it is considered to be a collisionless environment such that the charged particles interact only weakly with the neutral atmosphere, lingering long after sunset. The E-layer is composed of molecular ions and is located between 100–150 km where collisions between ions and neutrals are much more frequent, with the result that the layer recombines and is reduced in density a hundredfold soon after sunset [Rees ,1 989;Heelis, 2004]. The respective altitude regimes of these two layers are commonly called the E- and F-regions. [3] The ionosphere glows as O + ions recombine to an excited state of atomic oxygen (O I) at a rate proportional to

597 citations

Journal ArticleDOI
TL;DR: The Horizontal Wind Model (HWM07) as mentioned in this paper provides a statistical representation of the horizontal wind fields of the Earth's atmosphere from the ground to the exosphere (0-500 km).
Abstract: [1] The new Horizontal Wind Model (HWM07) provides a statistical representation of the horizontal wind fields of the Earth's atmosphere from the ground to the exosphere (0–500 km). It represents over 50 years of satellite, rocket, and ground-based wind measurements via a compact Fortran 90 subroutine. The computer model is a function of geographic location, altitude, day of the year, solar local time, and geomagnetic activity. It includes representations of the zonal mean circulation, stationary planetary waves, migrating tides, and the seasonal modulation thereof. HWM07 is composed of two components, a quiet time component for the background state described in this paper and a geomagnetic storm time component (DWM07) described in a companion paper.

490 citations

Journal ArticleDOI
TL;DR: In this article, the continuity equation for electrons in F-2 layer obtained for region near geomagnetic equator at noon including photoionization, recombination, drift, etc.
Abstract: Continuity equation for electrons in F-2 layer obtained for region near geomagnetic equator at noon including photoionization, recombination, drift, etc

483 citations