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Record W1803290463

Radiowave propagation in the polar ionosphere

2012· dissertation· en· W1803290463 on OpenAlexaboutno aff
Mariyam Jamilah Homam

Bibliographic record

VenueFigshare · 2012
Typedissertation
Languageen
FieldPhysics and Astronomy
TopicRadio Astronomy Observations and Technology
Canadian institutionsnot available
Fundersnot available
KeywordsIonospherePolarGeophysicsPolar capGeologyMeteorologyPhysicsAstronomy
DOInot available

Abstract

fetched live from OpenAlex

A dual-frequency GPS receiver, GSV4004B, has been installed at Alert, Canada since May 2008 to study the ionospheric variability at a high-latitude location. This Ionospheric Scintillation and TEC Monitor (GISTM) receiver is able to measure amplitude and phase scintillation, and also Total Electron Content (TEC). In addition, a High Frequency (HF) link has been established from Qaanaaq to Svalbard since March 2009 to study the channel characteristics, including Doppler spreads. This study covers from end of May 2008 to February 2011 where it was mostly during the minimum state of solar activity. During the period of where both GISTM and HF data were available (i.e. March 2009-July 2010), data from both links are compared to see any relation between TEC variations and scintillation effects and also Doppler spreads. Data from the GISTM receivers at Svalbard were also utilised.
\nWinter months expectedly show lower mean vertical TEC (VTEC) than in other months. Higher mean VTEC was observed in 2010 that could be related to the increase of solar activity. In 2010, both small and large patches of moderate-high intensity were found to be more than twice as common in February and March than in other months. The difference in the occurrences of small patches between months of the same year was about 1-2% (for low intensity patches) and 1-10% (moderate-high intensity). This difference increased to 1-4% (low intensity) and 1-12% (moderate-high intensity) for large patches. UT dependence can be seen where ~80 large and ~300 small patches were identified ~1000 to 2000 UT from June to
\nOctober in both 2008 and 2009, and they doubled in 2010. Amplitude scintillations index, S4 were very low where at least ~99% were between 0 and 0.1, which is insignificant. Meanwhile, phase scintillations index, σφ were from 0 to 0.1 rad for at least 93% of the time. The relationship of TEC fluctuations/increase and phase scintillations is complex. There are few events where phase scintillations occurred simultaneously with slant TEC increases, but this is not frequent. The magnitude of the irregularities was generally independent of geomagnetic indices, Interplanetary Magnetic Field (IMF) components, and local magnetic fields at Eureka and Resolute Bay.
\nMonthly upper decile of Doppler spreads generally varied from 1 to 5.5 Hz. High upper decile normally occurred from around September/October to March, from ~0000 to 1700 UT on 6.95 and 8.01 MHz. The hourly upper decile reached up to 7-8.5 Hz (6.95 MHz) and 7-9.5 Hz (8.01 MHz). Upper decile on these frequencies was mostly 0.5-4.5 Hz larger in October 2010-February 2011 than in the same months of the previous year which possibly related to the increase in solar activity. However, Doppler spreads were generally independent of independent of geomagnetic indices, IMF components, and local magnetic fields. The relation between the irregularities observed via transionospheric link and HF link is also complex. Large TEC fluctuations/increases and/or phase scintillations observed on satellite(s) close to HF midpoint may correspond to either small or large Doppler spreads.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesInsufficient payload (model declined to judge)
Consensus categoriesInsufficient payload (model declined to judge)
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Not applicable · Consensus signal: Not applicable
GenreCandidate signal: Empirical · Consensus signal: none
Teacher disagreement score0.445
Threshold uncertainty score1.000

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.1080.001

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.018
GPT teacher head0.245
Teacher spread0.227 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; both teacher heads agree on what is shown here.

Study designNot applicable
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations0
Published2012
Admission routes1
Has abstractyes

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