Investigation of the ionosphere over Antarctica under quiet space weather conditions: results of vertical sounding of the ionosphere September 14–24, 2020

2020 ◽  
Vol 1 (1) ◽  
pp. 45-55
Author(s):  
Maryna Shulha ◽  
Oleksandr Bogomaz ◽  
Taras Zhivolup ◽  
Oleksander Koloskov ◽  
Andrey Zalizovski ◽  
...  
Keyword(s):  
Electron Density ◽  
Space Weather ◽  
Weather Conditions ◽  
Temporal Variations ◽  
Peak Height ◽  
International Reference Ionosphere ◽  
Antarctic Region ◽  
Model Predictions ◽  
The Antarctic ◽  
Layer Peak

We present observational results of variations in the ionospheric parameters hmF2 and NmF2 over the Ukrainian Antarctic station “Akademik Vernadsky” for magnetically quiet conditions. The results of comparative analysis of observational data and the International Reference Ionosphere-2016 model predictions are presented. The main objective of this study is to investigate the temporal variations of two key ionospheric parameters – the F2 layer peak height and electron density – during very quiet space weather conditions using data of vertical sounding of the ionosphere obtained over the Ukrainian Antarctic station “Akademik Vernadsky” and comparison the observation results with model values. Methods: The temporal variations of the F2 layer peak height and electron density were calculated from ionograms obtained with ionosonde installed at the Ukrainian Antarctic station “Akademik Vernadsky” with subsequent electron density profile inversion. Diurnal variations of hmF2 and NmF2 were calculated using a set of sub-models of the IRI-2016 model for comparison with results of observational studies. Results: We found that for the Antarctic region option of IRI-2016 model for the F2 layer peak height SHU-2015 provides a better fit for hmF2 through the investigated period compare to the AMTB-2013 model predictions. Electron density models (URSI, CCIR) generally well reproduce the observed variations of NmF2 during periods of absence non-standard manifestations of space weather, which are possible for quiet conditions too. Hypotheses regarding the possible reasons for experimental and model differences in variations of NmF2 are discussed. The analysis of effect of geomagnetic storm on September 24, 2020 on NmF2 variations was carried out. Conclusions: The obtained results demonstrate peculiarities of the state of the ionosphere-plasmasphere system over Antarctica under very quiet space weather conditions and provide evaluation of predictive capabilities of modern international reference ionosphere models. New knowledge about the features of electron density variations in the ionosphere for magnetically quiet conditions over the Antarctic region has practical value for specialists which are engaged in the study of the near-Earth space environment, in particular, at high latitudes, and also work on correction of global ionospheric models. Keywords: electron density, F2 layer peak height, ionosonde, quiet space weather, models of the ionosphere, downward plasma flux

Global Multi-layer Electron Density Modeling Based on Constraint optimization

2020 ◽  
Author(s):  
Ganesh Lalgudi Gopalakrishnan ◽  
Michael Schmidt ◽  
Eren Erdogan
Keyword(s):  
Electron Density ◽  
Space Weather ◽  
Peak Height ◽  
Optimization Approach ◽  
Iri Model ◽  
B Splines ◽  
Weather Events ◽  
The Impact ◽  
Layer Peak ◽  
Density Modeling

<p><span>Electron density is the most important key parameter to describe the </span><span>state of the ionospheric plasma </span><span>varying with latitude, longitude, altitude and time. The upper atmosphere is decomposed into the four layers D, E, F1 and F2 of the ionosphere as well as the plasmasphere. Space weather events manifest themselves with specific "signatures" in distinct ionospheric layers. Therefore, the role of each layer in characterizing the ionosphere during nominal and extreme space weather events is highly important for scientific and operational purposes. </span></p><p><span>Accordingly, we model the total electron density as the sum of the electron densities of the individual layers. The key parameters of each layer, namely peak electron density, the corresponding peak height and scale height, are modeled by series expansions in terms of polynomial B-splines for latitude and trigonometric B-splines for longitude. The Chapman profile function is chosen to define the electron density along the altitude. This way, the electron density modeling is setup as a parameter estimation problem. In the case of modelling multiple layers simultaneously, the estimation of coefficients of the key parameters becomes challenging due to the correlations between the different key parameters. </span></p><p><span>One possibility to address the above issue is by imposing constraints on the ionospheric key parameters (and by extension on the B-spline coefficients). As an example, we constrain the F2 layer peak height to be always above the F1 layer peak height. We also constrain the key parameters to be non-negative and possibly to to certain well defined bounds. This way the physical properties of the ionosphere layers are included in the modelling. We estimate the coefficients with regard to the imposition of the bounds in form of inequality constraints using a convex optimization approach. We describe the underlying mathematical procedure and validate it using </span><span>the IRI model as well as GNSS observations and electron density measurements from occultation missions. For the specific case of using IRI model data as the reference “truth”, we show the performance of the optimization algorithm using a “closed loop” validation. Such a validation allows an in-depth analysis of the impact of choosing a desired number of unknown coefficients to be estimated and the total number of constraints applied. We describe the parameterization of the different ionosphere key parameters considering the specific requirements from operational aspects (such as the need for modelling F2 layer), scientific aspects with regard to ionosphere-thermosphere studies (need for modelling the D, E or F1 layers) and also considering the aspects related to computation load. </span></p><p><span>We describe the advantages of using the optimization approach compared to the unconstrained least squares solution. While such constraints on key parameters can be fixed under nominal ionospheric conditions, but under adverse space weather effects these constraints need to be modified (constraints become stricter or more relaxed). For this purpose, we show the dynamic effect of modifying the constraints on global modelling performance and accuracy. We also provide the uncertainty of the estimated coefficients using a Monte-Carlo approach.</span></p>

scholarly journals New GGOS JWG3 on Improved understanding of space weather events and their monitoring

2020 ◽  
Author(s):  
Alberto Garcia-Rigo ◽  
Benedikt Soja
Keyword(s):  
Electron Density ◽  
Space Weather ◽  
International Association ◽  
Real Data ◽  
Weather Conditions ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Total Electron ◽  
Weather Events ◽  
Space Geodetic Techniques

<p>Multiple space geodetic techniques are capable of measuring effects caused by space weather events. In particular, space weather events can cause ionospheric disturbances correlated with variations in the vertical total electron content (VTEC) or the electron density (Ne) of the ionosphere.</p><p>In this regard and in the context of the new Focus Area on Geodetic Space Weather Research within IAG’s GGOS (International Association of Geodesy; Global Geodetic Observing System), the Joint Working Group 3 on Improved understanding of space weather events and their monitoring by satellite missions has been created as part of IAG Commission 4, Sub-Commission 4.3 to run for the next four years.</p><p>Within JWG3, we expect investigating different approaches to monitor space weather events using the data from different space geodetic techniques and, in particular, combinations thereof. Simulations will be beneficial to identify the contribution of different techniques and prepare for the analysis of real data. Different strategies for the combination of data will also be investigated, in particular, the weighting of estimates from different techniques in order to increase the performance and reliability of the combined estimates. Furthermore, existing algorithms for the detection and prediction of space weather events will be explored and improved to the extent possible. Furthermore, the geodetic measurement of the ionospheric electron density will be complemented by direct observations from the Sun gathered from existing spacecraft, such as SOHO, ACE, SDO, Parker Solar Probe, among others. The combination and joint evaluation of multiple datasets with the measurements of space geodetic observation techniques (e.g. geodetic VLBI) is still a great challenge. In addition, other indications for solar activity - such as the F10.7 index on solar radio flux, SOLERA as EUV proxy or rate of Global Electron Content (dGEC)-, provide additional opportunities for comparisons and validation.</p><p>Through these investigations, we will identify the key parameters useful to improve real-time/prediction of ionospheric/plasmaspheric VTEC, Ne estimates, as well as ionospheric perturbations, in case of extreme solar weather conditions. In general, we will gain a better understanding of space weather events and their effect on Earth’s atmosphere and near-Earth environment.</p>

Evaluation of E-Layer Dominated Ionosphere Events Using CHAMP, COSMIC/FORMOSAT-3 and FY3C Data

2020 ◽  
Author(s):  
Sumon Kamal ◽  
Norbert Jakowski ◽  
Mohammed M. Hoque ◽  
Jens Wickert
Keyword(s):  
Electron Density ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Weather Conditions ◽  
Polar Regions ◽  
High Latitudes ◽  
Density Profiles ◽  
Temporal Occurrence ◽  
Electron Density Profiles ◽  
Activity Dependent

<p>Under certain space weather conditions the ionization level of the ionospheric E layer can dominate over that of the F2 layer. This phenomenon is known as “E layer dominated ionosphere” (ELDI) and occurs primarily at high latitudes in the polar regions. The corresponding electron density profiles show their peak ionization at the E layer height between 80 km and 150 km above the Earth’s surface. In this work we have evaluated the influence of space weather and geophysical conditions on the occurrence of ELDI events at high latitudes in the northern and southern hemispheres. For this, we used electron density profiles derived from ionospheric radio occultation measurements aboard CHAMP, COSMIC and FY3C satellites. The used CHAMP data covers the years from 2001 to 2008, the COSMIC data the years from 2006 to 2018 and the FY3C data the years from 2014 to 2018. This provides us continuous data coverage for a long period from 2001 to 2018, containing about 4 million electron density profiles. In addition to the geospatial distribution, we have also investigated the temporal occurrence of ELDI events in the form of the diurnal, the seasonal and the solar activity dependent variation. We have further investigated the influence of geomagnetic storms on the spatial and temporal occurrence of ELDI events.</p>

scholarly journals Spatial-temporal variations in surface ozone over Ushuaia and the Antarctic region: observations from in situ measurements, satellite data, and global models

2017 ◽  
Vol 25 (3) ◽  
pp. 2194-2210 ◽  
Author(s):  
Mohd Shahrul Mohd Nadzir ◽  
Matthew J. Ashfold ◽  
Md Firoz Khan ◽  
Andrew D. Robinson ◽  
Conor Bolas ◽  
...  
Keyword(s):  
Satellite Data ◽  
Surface Ozone ◽  
Temporal Variations ◽  
In Situ Measurements ◽  
Antarctic Region ◽  
Global Models ◽  
The Antarctic

scholarly journals A new global model for the ionospheric F2 peak height for radio wave propagation

2012 ◽  
Vol 30 (5) ◽  
pp. 797-809 ◽  
Author(s):  
M. M. Hoque ◽  
N. Jakowski
Keyword(s):  
Observational Data ◽  
Electron Density ◽  
Temporal Variations ◽  
Global Scale ◽  
Peak Height ◽  
Frequency Planning ◽  
Spatial Dependencies ◽  
Planning And Operation ◽  
Height Model ◽  
Model Approach

Abstract. The F2-layer peak density height hmF2 is one of the most important ionospheric parameters characterizing HF propagation conditions. Therefore, the ability to model and predict the spatial and temporal variations of the peak electron density height is of great use for both ionospheric research and radio frequency planning and operation. For global hmF2 modelling we present a nonlinear model approach with 13 model coefficients and a few empirically fixed parameters. The model approach describes the temporal and spatial dependencies of hmF2 on global scale. For determining the 13 model coefficients, we apply this model approach to a large quantity of global hmF2 observational data obtained from GNSS radio occultation measurements onboard CHAMP, GRACE and COSMIC satellites and data from 69 worldwide ionosonde stations. We have found that the model fits to these input data with the same root mean squared (RMS) and standard deviations of 10%. In comparison with the electron density NeQuick model, the proposed Neustrelitz global hmF2 model (Neustrelitz Peak Height Model – NPHM) shows percentage RMS deviations of about 13% and 12% from the observational data during high and low solar activity conditions, respectively, whereas the corresponding deviations for the NeQuick model are found 18% and 16%, respectively.

scholarly journals Recent changes in pan-Antarctic region surface snowmelt detected by AMSR-E and AMSR2

2020 ◽  
Vol 14 (11) ◽  
pp. 3811-3827
Author(s):  
Lei Zheng ◽  
Chunxia Zhou ◽  
Tingjun Zhang ◽  
Qi Liang ◽  
Kang Wang
Keyword(s):  
Sea Ice ◽  
Remote Sensing Data ◽  
Microwave Remote Sensing ◽  
Open Water ◽  
Southern Annular Mode ◽  
Temporal Variations ◽  
Polar Regions ◽  
Antarctic Region ◽  
Marginal Sea ◽  
The Antarctic

Abstract. Surface snowmelt in the pan-Antarctic region, including the Antarctic ice sheet (AIS) and sea ice, is crucial to the mass and energy balance in polar regions and can serve as an indicator of climate change. In this study, we investigate the spatial and temporal variations in surface snowmelt over the entire pan-Antarctic region from 2002 to 2017 by using passive microwave remote sensing data. The stable orbits and appropriate acquisition times of the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) and the Advanced Microwave Scanning Radiometer 2 (AMSR2) enable us to take full advantage of daily brightness temperature (Tb) variations to detect surface snowmelt. The difference between AMSR-E/2 ascending and descending 36.5 GHz Tb values in vertical polarization (DAV36) was utilized to map the pan-Antarctic region snowmelt, as this method is unaffected by snow metamorphism. We evaluated the DAV36 algorithm against ground-based measurements and further improved the method over the marginal sea ice zone by excluding the effect of open water. Snowmelt detected by AMSR-E/2 data was more extensive and persistent than that detected by the Special Sensor Microwave/Imager (SSM/I) data. Continuous melt onset (CMO) ranged from August in the marginal sea ice zone to January in the Antarctic inland, and the early transient melt events occurred several days to more than 2 months earlier. The pan-Antarctic region CMO was significantly correlated (R=0.54, p<0.05) with the summer Southern Annular Mode (SAM). The decreased AIS melt extent was very likely linked (R=-0.82, p<0.01) with the enhanced summer SAM.

scholarly journals An evaluation of International Reference Ionosphere electron density in the polar cap and cusp using EISCAT Svalbard radar measurements

2016 ◽  
Vol 34 (9) ◽  
pp. 751-758 ◽  
Author(s):  
Lindis Merete Bjoland ◽  
Vasyl Belyey ◽  
Unni Pia Løvhaug ◽  
Cesar La Hoz
Keyword(s):  
Electron Density ◽  
Peak Height ◽  
International Reference Ionosphere ◽  
Ion Temperature ◽  
Polar Cap ◽  
Iri Model ◽  
Plasma Parameters ◽  
International Reference ◽  
Radar Measurements

Abstract. Incoherent scatter radar measurements are an important source for studies of ionospheric plasma parameters. In this paper the EISCAT Svalbard radar (ESR) long-term database is used to evaluate the International Reference Ionosphere (IRI) model. The ESR started operations in 1996, and the accumulated database up to 2012 thus covers 16 years, giving an overview of the ionosphere in the polar cap and cusp during more than one solar cycle. Data from ESR can be used to obtain information about primary plasma parameters: electron density, electron and ion temperature, and line-of-sight plasma velocity from an altitude of about 50 and up to 1600 km. Monthly averages of electron density and temperature and ion temperature and composition are also provided by the IRI model from an altitude of 50 to 2000 km. We have compared electron density data obtained from the ESR with the predicted electron density from the IRI-2016 model. Our results show that the IRI model in general fits the ESR data well around the F2 peak height. However, the model seems to underestimate the electron density at lower altitudes, particularly during winter months. During solar minimum the model is also less accurate at higher altitudes. The purpose of this study is to validate the IRI model at polar latitudes.

scholarly journals Surface radiation balance and weather conditions on a non-glaciated coastal area in the Antarctic region

Polar Science ◽  
2019 ◽  
Vol 20 ◽  
pp. 117-128 ◽  
Author(s):  
Jacyra Soares ◽  
Marco Alves ◽  
Flávia Noronha Dutra Ribeiro ◽  
Georgia Codato
Keyword(s):  
Coastal Area ◽  
Weather Conditions ◽  
Surface Radiation ◽  
Radiation Balance ◽  
Antarctic Region ◽  
The Antarctic

scholarly journals Coupled investigations of ionosphere variations over European and Japanese regions: observations, comparative analysis, and validation of models and facilities

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Sergii V. Panasenko ◽  
Dmytro V. Kotov ◽  
Yuichi Otsuka ◽  
Mamoru Yamamoto ◽  
Hiroyuki Hashiguchi ◽  
...  
Keyword(s):  
Physical Model ◽  
Electron Density ◽  
Neutral Hydrogen ◽  
Peak Height ◽  
Topside Ionosphere ◽  
Plasma Parameters ◽  
Incoherent Scatter ◽  
Longitudinal Sector ◽  
Japanese Regions ◽  
Layer Peak

AbstractThis paper presents the results of a coordinated measurement campaign with ground based and satellite observations over European and Japanese regions during September 5–6, 2017. Two incoherent scatter radars, two satellite missions, International Reference Ionosphere (IRI-2016) empirical model, and Field Line Interhemispheric Plasma (FLIP) physical model were employed to examine the regular behavior of the F2-layer peak height and density and the topside ionosphere electron density, electron, and ion temperatures as well as traveling ionospheric disturbances (TIDs). The daily ionospheric variations over Kharkiv and Shigaraki exhibited similar behavior qualitatively and quantitatively. The results show that none of the empirical IRI-2016 models of F2-layer peak height, topside electron density, and temperature can be preferred for predicting the key qualitative features of variations in ionospheric plasma parameters over Kharkiv and Shigaraki. The likely reason is rapid day to day changes in solar activity and series of moderate enhancements of magnetic activity occurring in the observation period and preceding days. Compared with IRI-2016 model, the FLIP physical model was shown to provide the best agreement with the observations when constrained to follow the observed diurnal variations of F2-layer peak height both over Europe and Japan. This paper presents the first direct comparison of the mid-latitude electron density measured by the Swarm satellite with incoherent scatter radar data and it confirms the high quality of the space-borne data. For the first time, evidence of the possible need to increase the neutral hydrogen density in NRLMSISE-00 model by at least a factor of 2 was obtained for the Asian longitudinal sector. The TIDs, which have predominant periods of about 50 min over Europe and 80 min over Japan, were detected, likely caused by passage of the solar terminator. Such a difference in the periods could indicate regional features and is the topic for further research.

Sign in / Sign up

Export Citation Format

Share Document