scholarly journals Observing the north polar ionosphere on 30 October 2003 by GPS imaging and IS radars

2006 ◽  
Vol 24 (1) ◽  
pp. 107-113 ◽  
Author(s):  
C. Stolle ◽  
J. Lilensten ◽  
S. Schlüter ◽  
Ch. Jacobi ◽  
M. Rietveld ◽  
...  
Keyword(s):  
Time Series ◽  
Electron Density ◽  
Large Scale ◽  
Electron Content ◽  
Polar Ionosphere ◽  
Storm Main Phase ◽  
The North ◽  
F Region ◽  
Longitudinal Band ◽  
North Polar

Abstract. The evening of 30 October 2003 was subject to a major storm main phase. For this time, we combine large-scale electron content maps from GPS imaging with time series of electron density and temperature of two EISCAT radars in Tromsø and Svalbard and the Sondrestrom radar, for observing the north polar ionosphere. The GPS assimilations resulted in the image of the electron content trace of an anti-sunward polar Tongue Of Ionisation (TOI) consecutively to 20:00 UT. In combination with the radar observations we concluded that the TOI persisted during the whole period of continuous southward IMF Bz until about 22:40 UT while its largest extension toward the nightside auroral region was found between 21:00-22:00 UT. A typical F region electron temperature of ~2000 K and the plasma velocity of ~800 ms-1 support its convective origin from the dayside mid-latitudes. Due to the structured appearance of the electron content distribution and the radar electron density time series we believe that discrete plasma patches formed inside the anti-sunward drift pattern. After two large oscillations of the IMF Bz the nightside plasma density was observed to re-enhance after 23:00 UT along a longitudinal band below 70 N. Coinciding electron temperatures of ~2000 K suggest again the convective nature of the plasma, while a modified convection pattern is expected.

scholarly journals Observations of AGW/TID propagation across the polar cap: a case study

2011 ◽  
Vol 29 (8) ◽  
pp. 1355-1363 ◽  
Author(s):  
H. T. Cai ◽  
F. Yin ◽  
S. Y. Ma ◽  
I. W. McCrea
Keyword(s):  
Large Scale ◽  
Source Region ◽  
Polar Cap ◽  
Night Time ◽  
F Region ◽  
Atmospheric Disturbances ◽  
Geomagnetic Pole ◽  
Ionization Waves ◽  
North Polar ◽  
Propagation Properties

Abstract. In this paper, we present observational evidence for the trans-polar propagation of large-scale Traveling Ionospheric Disturbances (TIDs) from their nightside source region to the dayside. On 13 February 2001, the 32 m dish of EISCAT Svalbard Radar (ESR) was directing toward the geomagnetic pole at low elevation (30°) during the interval 06:00–12:00 UT (MLT ≈ UT + 3 h), providing an excellent opportunity to monitor the ionosphere F-region over the polar cap. The TIDs were first detected by the ESR over the dayside north polar cap, propagating equatorward, and were subsequently seen by the mainland UHF radar at auroral latitudes around geomagnetic local noon. The propagation properties of the observed ionization waves suggest the presence of a moderately large-scale TIDs, propagating across the northern polar cap from the night-time auroral source during substorm conditions. Our results agree with the theoretical simulations by Balthazor and Moffett (1999) in which poleward-propagating large-scale traveling atmospheric disturbances were found to be self-consistently driven by enhancements in auroral heating.

scholarly journals Localized electron density enhancements in the high-altitude polar ionosphere and their relationships with storm-enhanced density (SED) plumes and polar tongues of ionization (TOI)

2011 ◽  
Vol 29 (2) ◽  
pp. 367-375 ◽  
Author(s):  
Y. Kitanoya ◽  
T. Abe ◽  
A. W. Yau ◽  
T. Hori ◽  
N. Nishitani
Keyword(s):  
High Altitude ◽  
Electron Density ◽  
Plasma Density ◽  
High Plasma ◽  
Density Increase ◽  
Statistical Characteristics ◽  
Electron Content ◽  
Polar Ionosphere ◽  
Plasma Convection ◽  
Total Electron

Abstract. Events of localized electron density increase in the high-altitude (>3000 km) polar ionosphere are occasionally identified by the thermal plasma instruments on the Akebono satellite. In this paper, we investigate the vertical density structure in one of such events in detail using simultaneous observations by the Akebono and DMSP F15 satellites, the SuperDARN radars, and a network of ground Global Positioning System (GPS) receivers, and the statistical characteristics of a large number (>10 000) of such events using Akebono data over half of an 11-year solar cycle. At Akebono altitude, the parallel drift velocity is remarkably low and the O+ ion composition ratio remarkably high, inside the high plasma-density regions at high altitude. Detailed comparisons between Akebono, DMSP ion velocity and density, and GPS total electron content (TEC) data suggest that the localized plasma density increase observed at high altitude on Akebono was likely connected with the polar tongue of ionization (TOI) and/or storm enhanced density (SED) plume observed in the F-region ionosphere. Together with the SuperDARN plasma convection map these data suggest that the TOI/SED plume penetrated into the polar cap due to anti-sunward convection and the plume existed in the same convection channel as the dense plasma at high altitude; in other words, the two were probably connected to each other by the convecting magnetic field lines. The observed features are consistent with the observed high-density plasma being transported from the mid-latitude ionosphere or plasmasphere and unlikely a part of the polar wind population.

scholarly journals Study of mid-latitude nighttime enhancement in F-region electron density using tomographic images over the UK

2003 ◽  
Vol 21 (12) ◽  
pp. 2323-2328 ◽  
Author(s):  
R. S. Dabas ◽  
L. Kersley
Keyword(s):  
Electron Density ◽  
Magnetic Activity ◽  
Electron Content ◽  
Equatorial Anomaly ◽  
Tomographic Images ◽  
F Region ◽  
Electron Density Gradient ◽  
Modeling And Forecasting ◽  
Ionospheric Electron Content ◽  
The Uk

Abstract. Nighttime enhancements in ionospheric electron content (IEC)/peak electron density (NmF2) have been studied by various workers in the equatorial anomaly and mid-latitude regions. Such studies give an idea about their enhancement over that location only. In the present study tomographic images over the UK, which give a latitudinal versus height distributions of ionospheric electron density in a much wider area, have been used to study the anomalous increases in nighttime F-region electron density at mid-latitudes. From the analysis of four seasonal representative months (November 1997, March, June and October 1998) data it was noted that the majority of the cases of nighttime enhancements were observed after local midnight, with a maximum between 03:00–04:00 LT in the month of November 1997. Enhancements were observed mostly between 45–50° N latitudes, and their positions are not affected by magnetic activity (Kp ) variations, whereas the separation between the mid-latitude trough and enhancement decreases with increases in magnetic activity. This finding shows that only the trough moves equatorward with the increase in magnetic activity. It is also noted that the electron density gradient from the trough to the enhancement increases with an increase in Kp. Results are discussed in terms of downward plasma transport from the protonosphere to the ionosphere and the nighttime neutral winds.Key words. Ionosphere (mid-latitude ionosphere; modeling and forecasting; instruments and techniques)

scholarly journals Dynamic wavelet correlation analysis for multivariate climate time series

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Josué M. Polanco-Martínez ◽  
Javier Fernández-Macho ◽  
Martín Medina-Elizalde
Keyword(s):  
Time Series ◽  
Tropical Cyclone ◽  
North Atlantic ◽  
Large Scale ◽  
Southern Oscillation ◽  
Atlantic Multidecadal Oscillation ◽  
Last Millennium ◽  
Climate Data ◽  
The North ◽  
Climate Time Series

AbstractThe wavelet local multiple correlation (WLMC) is introduced for the first time in the study of climate dynamics inferred from multivariate climate time series. To exemplify the use of WLMC with real climate data, we analyse Last Millennium (LM) relationships among several large-scale reconstructed climate variables characterizing North Atlantic: i.e. sea surface temperatures (SST) from the tropical cyclone main developmental region (MDR), the El Niño-Southern Oscillation (ENSO), the North Atlantic Multidecadal Oscillation (AMO), and tropical cyclone counts (TC). We examine the former three large-scale variables because they are known to influence North Atlantic tropical cyclone activity and because their underlying drivers are still under investigation. WLMC results obtained for these multivariate climate time series suggest that: (1) MDRSST and AMO show the highest correlation with each other and with respect to the TC record over the last millennium, and: (2) MDRSST is the dominant climate variable that explains TC temporal variability. WLMC results confirm that this method is able to capture the most fundamental information contained in multivariate climate time series and is suitable to investigate correlation among climate time series in a multivariate context.

scholarly journals Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

2018 ◽  
Vol 36 (1) ◽  
pp. 125-138 ◽  
Author(s):  
James A. D. Parker ◽  
S. Eleri Pryse ◽  
Natasha Jackson-Booth ◽  
Rachel A. Buckland
Keyword(s):  
Electron Density ◽  
Large Scale ◽  
Western Europe ◽  
Global Scale ◽  
Electron Content ◽  
Total Electron ◽  
Radio Science ◽  
Ionospheric Physics ◽  
Main Ionospheric Trough ◽  
Plasma Distribution

Abstract. The main ionospheric trough is a large-scale spatial depletion in the electron density distribution at the interface between the high- and mid-latitude ionosphere. In western Europe it appears in early evening, progresses equatorward during the night, and retreats rapidly poleward at dawn. It exhibits substantial day-to-day variability and under conditions of increased geomagnetic activity it moves progressively to lower latitudes. Steep gradients on the trough-walls on either side of the trough minimum, and their variability, can cause problems for radio applications. Numerous studies have sought to characterize and quantify the trough behaviour. The Electron Density Assimilative Model (EDAM) models the ionosphere on a global scale. It assimilates observations into a background ionosphere, the International Reference Ionosphere 2007 (IRI2007), to provide a full 3-D representation of the ionospheric plasma distribution at specified times and days. This current investigation studied the capability of EDAM to model the ionosphere in the region of the main trough. Total electron content (TEC) measurements from 46 GPS stations in western Europe from September to December 2002 were assimilated into EDAM to provide a model of the ionosphere in the trough region. Vertical electron content profiles through the model revealed the trough and the detail of its structure. Statistical results are presented of the latitude of the trough minimum, TEC at the minimum and of other defined parameters that characterize the trough structure. The results are compared with previous observations made with the Navy Ionospheric Monitoring System (NIMS), and reveal the potential of EDAM to model the large-scale structure of the ionosphere. Keywords. Ionosphere (midlatitude ionosphere; modelling and forecasting) – radio science (ionospheric physics)

GPS ionospheric imaging of the north polar ionosphere on 30 October 2003

2005 ◽  
Vol 36 (11) ◽  
pp. 2201-2206 ◽  
Author(s):  
C. Stolle ◽  
S. Schlüter ◽  
S. Heise ◽  
Ch. Jacobi ◽  
N. Jakowski ◽  
...  
Keyword(s):  
Polar Ionosphere ◽  
The North ◽  
North Polar ◽  
Ionospheric Imaging

Vibrational nitrogen concentration in the ionosphere and its dependence on season and solar cycle

1995 ◽  
Vol 13 (11) ◽  
pp. 1164-1171 ◽  
Author(s):  
A. E. Ennis ◽  
G. J. Bailey ◽  
R. J. Moffett
Keyword(s):  
Mathematical Model ◽  
Solar Cycle ◽  
Electron Density ◽  
Geomagnetic Field ◽  
Nitrogen Concentration ◽  
Time Dependent ◽  
Electron Content ◽  
Vibrationally Excited ◽  
F Region ◽  
Excited Nitrogen

Abstract. A fully time-dependent mathematical model, SUPIM, of the Earth's plasmasphere is used in this investigation. The model solves coupled time-dependent equations of continuity, momentum and energy balance for the O+, H+, He+, N+2, O+2, NO+ ions and electrons; in the present study, the geomagnetic field is represented by an axial-centred dipole. Calculation of vibrationally excited nitrogen molecules, which has been incorporated into the model, is presented here. The enhanced model is then used to investigate the behaviour of vibrationally excited nitrogen molecules with F10.7 and solar EUV flux, during summer, winter and equinox conditions. The presence of vibrational nitrogen causes a reduction in the electron content. The diurnal peak in electron content increases linearly up to a certain value of F10.7, and above this value increases at a lesser rate, in agreement with previous observations and modelling work. The value of F10.7 at which this change in gradient occurs is reduced by the presence of vibrational nitrogen. Vibrational nitrogen is most effective at F-region altitudes during summer daytime conditions when a reduction in the electron density is seen. A lesser effect is seen at equinox, and in winter the effect is negligible. The summer reduction in electron density due to vibrational nitrogen therefore reinforces the seasonal anomaly.

scholarly journals MARCI observations of a wavenumber-2 large-scale feature in the north polar hood of Mars: Interpretation with the NASA/Ames Legacy Global Climate Model

Icarus ◽  
2020 ◽  
Vol 335 ◽  
pp. 113367
Author(s):  
Robert M. Haberle ◽  
Melinda A. Kahre ◽  
Jeffrey R. Barnes ◽  
Jeffery L. Hollingsworth ◽  
Michael J. Wolff
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Scale Feature ◽  
The North ◽  
North Polar

scholarly journals Error analysis of Abel retrieved electron density profiles from radio occultation measurements

2010 ◽  
Vol 28 (1) ◽  
pp. 217-222 ◽  
Author(s):  
X. Yue ◽  
W. S. Schreiner ◽  
J. Lei ◽  
S. V. Sokolovskiy ◽  
C. Rocken ◽  
...  
Keyword(s):  
Electron Density ◽  
Radio Occultation ◽  
Electron Content ◽  
Electron Densities ◽  
Density Profiles ◽  
Total Electron ◽  
The North ◽  
Spring Equinox ◽  
Electron Density Profiles ◽  
Artificial Plasma

Abstract. This letter reports for the first time the simulated error distribution of radio occultation (RO) electron density profiles (EDPs) from the Abel inversion in a systematic way. Occultation events observed by the COSMIC satellites are simulated during the spring equinox of 2008 by calculating the integrated total electron content (TEC) along the COSMIC occultation paths with the "true" electron density from an empirical model. The retrieval errors are computed by comparing the retrieved EDPs with the "true" EDPs. The results show that the retrieved NmF2 and hmF2 are generally in good agreement with the true values, but the reliability of the retrieved electron density degrades in low latitude regions and at low altitudes. Specifically, the Abel retrieval method overestimates electron density to the north and south of the crests of the equatorial ionization anomaly (EIA), and introduces artificial plasma caves underneath the EIA crests. At lower altitudes (E- and F1-regions), it results in three pseudo peaks in daytime electron densities along the magnetic latitude and a pseudo trough in nighttime equatorial electron densities.

scholarly journals Decadal changes in hydrographic and ecological time-series in the Balearic Sea (western Mediterranean), identifying links between climate and zooplankton

2008 ◽  
Vol 65 (3) ◽  
pp. 311-317 ◽  
Author(s):  
Maria Luz Fernández de Puelles ◽  
Juan Carlos Molinero
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Western Mediterranean ◽  
Zooplankton Abundance ◽  
Atmospheric Variability ◽  
Survey Period ◽  
Climate Effect ◽  
The North ◽  
Western Mediterranean Sea ◽  
Balearic Sea

Abstract Fernández de Puelles, M. L., and Molinero, J. C. 2008. Decadal changes in hydrographic and ecological time-series in the Balearic Sea (western Mediterranean), identifying links between climate and zooplankton. – ICES Journal of Marine Science, 65: 311–317. We investigated possible relationships between climate, hydrography, and zooplankton abundance in the Balearic Sea (BS), during a 10-year survey period spanning January 1994 to December 2003. It was demonstrated that large-scale atmospheric variability in the North Atlantic (NA) Ocean acts as a driver of regional meteorological variations and hydrographic patterns in the BS. The results also revealed that the variability of copepods, appendicularians, cladocerans, siphonophores, doliolids, and ostracods is closely related to variations in water temperature recorded during strong anomalies of the NA climate (>1 s.d.). Although the time-series that we analysed cover a period that is relatively short for investigating climate effects on marine ecosystems, the statistical results reported were consistent enough to emphasize the NA’s climate effect on the BS. The cascade of links identified by these results should be considered and integrated into the assessment and modelling studies of pelagic ecosystem and biogeochemical fluxes in the western Mediterranean Sea.

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