A statistical study of occurrence probability of spread<i>F</i>at high latitudes

Shimazaki, Tatsuo

doi:10.1029/jz067i012p04617

Cited by 39 publications

(30 citation statements)

References 11 publications

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“…14 indicates a tendency of the anti-correlation with the F10.7 data; i.e., the occurrence probability decreases blobs is limited only in the period of the very low F10.7 intensity. These phenomena are similar to the results of SHIMAZAKI (1959) and SINGLETON (1968), which indicate that spread F observed by the bottomside sounder occurs more frequently during the sunspot minimum year than during the sunspot maximum year in the low latitude region. In our analyses, it has been indicated that the plasma bubbles mainly appear in the periods of the increased F10.7 value while the plasma blobs do not appear in these periods.…”

Section: Effects Of Solar Radiationssupporting

confidence: 79%

Occurrence characteristics of low latitude ionosphere irregularities observed by impedance probe on board the Hinotori satellite.

Watanabe

Oya

1986

J. geomagn. geoelec

107

119

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The statistical analyses of occurrence characteristics of the plasma bubbles and blobs are made by using more than 1000 cases of observation data from the swept frequency impedance probe aboard the Hinotori satellite. The results show that formations of the plasma bubbles have the following characteristics. 1) The spatial distribution of the occurrence of the plasma bubbles is in the equatorial region within occurrence of the plasma bubbles is limited in the nighttime; favorable periods of the plasma bubble formation depend on the type of the plasma bubbles; multiple plasma bubbles (MPB) have tendency to be generated in pre-midnight, while quasi periodic plasma bubbles (QPB) show their maximum occurrence in the post-midnight period. Solitary plasma bubbles (SPB) occur, however, rather independently to the local time in so far as in the night period, 3) the magnetic activity also controls the occurrence of the plasma bubbles; the occurrence of MPB phenomena shifts the peak period to the midnight side with increasing magnetic activity and the occurrence of QPB phenomena which covers the period from midnight to the morning side shows the expansion of their occurrence into late morning period with increasing magnetic activity, 4) correlation of the occurrence of the plasma bubbles to the solar radiation flux represented by F10.7 solar radio flux is evident for MPB and QPB while there is no relation between F10.7 and the occurrence of SPB. Occurrence of the plasma blobs has a complementary nature with that of the plasma bubbles. The occurrence region of the plasma blobs is limited in the edge parts of the plasma bubble occurrence region being limited in the nighttime. The occurrence of the plasma blobs decreases with increasing magnetic activity, while there is a strong anti-correlation of the occurrence of the plasma blobs to the solar radiation (F10.7). The relation of occurrence of the plasma bubbles and blobs to the development of the equatorial anomaly and the asymmetrical distributions of the background electron density suggests the importance of the generalized Rayleigh-Taylor instability including the effects of the electric field and the neutral wind in addition to the gravitational force for the generation of the plasma bubbles and blobs.

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Section: Effects Of Solar Radiationssupporting

confidence: 79%

Occurrence characteristics of low latitude ionosphere irregularities observed by impedance probe on board the Hinotori satellite.

Watanabe

Oya

1986

J. geomagn. geoelec

107

119

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“…Our results is supported by Shimazaki [27], who demonstrated that in mid-latitude, the spread-F occurred more frequently in summer than in winter over stations in the Far East. Seasonal variations of midlatitude spread F occurrence might be related to the changes of UA-NPD [28] (upper atmosphere neutral-particle density).…”

Section: Diurnal Seasonal and Solar Activity Variation Of Spread F Osupporting

confidence: 91%

Statistical analysis and model of spread F occurrence in China

et al. 2010

Sci. China Technol. Sci.

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The spread F data obtained over Lanzhou (36.1°N, 103.9°E), Chongqing (29.5°N, 106.4°E) and Haikou (20.0°N, 110.3°E) of China during the period from 1978 to 1997 are used to analyze the occurrence characteristics. The statistical results show that the post midnight spread F occurrence is maximum during the summer solstice months of the lower solar activity period, while post sunset spread F is dominant in equinoxes of higher solar activity period over Haikou station. Over Chongqing and Lanzhou stations, spread F mostly occurs at post midnight and relates negatively with solar activity. Using regression method and Fourier expansion, the preliminary single-station model of spread F occurrence is established and the accuracy of the model is evaluated. spread F, solar cycle variation, seasonal variation, empirical model Citation:Xu T, Wu Z S, Hu Y L, et al. Statistical analysis and model of spread

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“…Ground-based measurements of spread-F and ionospheric scintillations at equatorial latitudes reveal the existence of an intense belt of ionospheric irregularities in the nighttime F region which poses serious problems for the design of communication links operating in VHF to GHz bands [ Shimazaki, 1959;Aarons et al, 1971;Craft and Westerlund, 1972]. In an effort to probe the causative mechanisms of formation of these equatorial irregularities a variety of ground-based and in-situ techniques have been employed [Farley et al, 1970;McClure and Woodman, 1972;Mozer, 1972, 1975;Balsley et al, 1972;].…”

Section: Introductionmentioning

confidence: 99%

Model of equatorial scintillations from in‐situ measurements

Basu¹,

Khan²

1976

Radio Science

121

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In‐situ measurements of F‐region irregularity amplitude and ambient electron density made by the retarding potential analyzer on OGO‐6 near the perigee altitude of 400 km have been utilized to derive the variation of electron density deviation over the equatorial region. Based on these measured electron density deviations and other assumed model parameters including a three‐dimensional power law form of irregularity spectrum with index 4, a model of equatorial scintillations is developed in the framework of diffraction theory. The percentage occurrence contours of estimated equatorial scintillations ≥ 4.5 dB at 140 MHz during 1900–2300 LMT for the period November–December 1969 and 1970 have been derived. The model is found to depict a pronounced longitude variation with the scintillation belt width and percentage occurrence being maximum over the African sector. The latitude extent of the spatial scintillation belt narrows over the American sector without much decrease in the scintillation occurrence whereas over the Indian and Far Eastern sectors both the extent and the occurrence are found to decrease. The percentage occurrence of scintillations estimated from this model is found to be consistent with VHF scintillation measurements at Ghana, Huancayo, and Calcutta. In addition, the model was found to be in qualitative agreement with GHz observations at various longitudes made by the COMSAT group. The effects of varying model parameters on scintillation estimates at VHF, UHF, and GHz are discussed. Implications of the observed longitudinal variation of scintillations on current theories of equatorial irregularity formation are indicated.

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A statistical study of occurrence probability of spreadFat high latitudes

Cited by 39 publications

References 11 publications

Occurrence characteristics of low latitude ionosphere irregularities observed by impedance probe on board the Hinotori satellite.

Occurrence characteristics of low latitude ionosphere irregularities observed by impedance probe on board the Hinotori satellite.

Statistical analysis and model of spread F occurrence in China

Model of equatorial scintillations from in‐situ measurements

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