Winter Anomaly and Traveling Ionospheric Disturbances over Japan during DYANA Campaign.

Ogawa, T.; Ohtani, A.; Nagai, Seiji; Kunitake, Manabu

doi:10.5636/jgg.44.1025

Cited by 3 publications

(9 citation statements)

References 19 publications

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“…Reflecting the smaller wave amplitude, the latitudinal extent of these FMEs is narrower than that of the FMEs between January 20 and 29. Additionally, it is noted that the stratospheric temperatures at 20 hPa over Wakkanai and Akita were more largely enhanced around January 5 and 15 than between January 20 and 29 (Aerological Data of Japan, Japan Meteorological Agency; OGAWA et al, 1992). We have pointed out above that with decreasing latitude the FME began later and ended earlier.…”

Section: F -Min Variationsmentioning

confidence: 95%

“…This scenario may also be applicable to our case. In fact, when the welldeveloped anomaly appeared between January 20 and 29, planetary wave (zonal wavenumber 1) amplitude in the stratosphere (10-30 km) at 60°N was increasing to ultimately generate a minor stratospheric sudden warming in early February (HiROOKA et al, 1992;OGAWA et al, 1992). Also HIROOKA et al (1992) stratospheric planetary wave was largely amplified with three peaks (time interval of 6-7 days), which can be related to the quasi-periodic FME occurrences during January 15-29.…”

Section: F -Min Variationsmentioning

confidence: 95%

“…The generation mechanisms of winter anomaly are still controversial (e.g., OFFERMANN, 1979;SATO, 1981). OGAWA et al (1992) have reported the winter anomaly over Japan during the DYANA campaign in 1990. From a brief survey of f -min data between January 10 and February 28, 1990 at five Japanese ionosonde stations, Wakkanai (45.4°N), Akita (39.7°N), Kokubunji (35.7°N), Yamagawa (31.2°N) and Okinawa (26.3°N), they have found that the anomalous f -min enhancements (FMEs) occurred around January 15 and between January 20 and 29, and that the FMEs decreased magnitude with decreasing latitude.…”

Section: Introductionmentioning

confidence: 99%

“…The main aim of this letter is to study quantitatively and in more detail the latitudinal distribution of the f -min winter anomaly region which has been insufficiently explored by OGAWA et al (1992), and to examine a possible relationship between the D-region winter anomaly and planetary wave activity in the lower atmosphere. To do this, we use f -min data from Magadan (60.1°N) and Khabarovsk (48.5°N) in Russia, and Guangzhou (23.1°N) in China, in addition to data from five Japanese ionosonde stations.…”

Section: Introductionmentioning

confidence: 99%

“…ISHIMINE and ECHIZENYA (1986) showed that the 40 kHz signals are also useful for detecting winter anomalies. Only the data from January 1990 is examined here since no FMEs were reported in February (OGAWA et al, 1992). …”

Section: Introductionmentioning

confidence: 99%

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Latitudinal Extent of the f-min Winter Anomaly Region during the DYANA Campaign.

Ohtani

Ogawa

Igarashi

1993

J. geomagn. geoelec

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The f -min data obtained at eight ionosonde stations in the Far East during the DYANA campaign in January 1990 is analyzed to investigate the latitudinal extent of the ionospheric D-region winter anomaly region. The f -min anomaly is most intensified around the geographic latitudes of 40-45°N, becomes weaker toward higher and lower latitudes, and on occasion extends down to 26°N. Anomalous VLF and LF radio wave propagations strongly suggest the existence of D-region electron density enhancements during the winter anomaly. We hypothesize that this anomaly is triggered by planetary wave activity in the stratosphere and mesosphere.

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Section: F -Min Variationsmentioning

confidence: 95%

Section: F -Min Variationsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Latitudinal Extent of the f-min Winter Anomaly Region during the DYANA Campaign.

Ohtani

Ogawa

Igarashi

1993

J. geomagn. geoelec

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Assessing models for ionospheric weather specifications over Australia during the 2004 Climate and Weather of the Sun‐Earth‐System (CAWSES) campaign

et al. 2007

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[1] The Utah State University (USU) Global Assimilation of Ionospheric Measurements (GAIM) program is developing assimilation models to specify ionospheric weather. In this study the Gauss Markov Kalman Filter (GMKF) GAIM model was used. The period 20 March through 19 April 2004, which spanned the Climate and Weather of the SunEarth-System (CAWSES) first study period, has been extensively studied to validate the performance of the GAIM model. Although the USU-GAIM model has both regional and global capabilities and can assimilate data from a wide variety of ionospheric observations, for this study the GMKF model was run in a global mode using data only from 162 ground-based GPS slant total electron content (TEC) stations and in situ measurements from three satellites. Using measurements from the 11 ionosonde stations of the Australian Department of Defence sounder network as an independent bottomside ground-truth, the International Reference Ionosphere (IRI), Ionospheric Forecast Model (IFM), and GMKF were compared for (1) monthly mean climatology and (2) the day-to-day weather during the 31 day period. A skill score was developed for the day-to-day weather by defining the IRI as the reference model. IFM is found to be a 10% improvement, while the GMKF is 39% more capable to capture weather variability. However, the study also identifies that this global version of GMKF has difficulty around sunrise, during which time the GMKF performance can be poorer than IRI. Excluding this interval from the skill score analysis increases the GMKF ability to track weather to 48%. The use of more data and different data types should further increase the GMKF's ability to capture weather variations.

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Occurrence and Characteristics of Traveling Ionospheric Disturbances in the Antarctic Peninsula Region

et al. 2022

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A statistical picture of the occurrence and characteristics of Traveling Ionospheric Disturbances (TIDs) over the Antarctic Peninsula is established using Global Navigation Satellite System Total Electron Content and High Frequency sounding observations. The measured parameters of the majority of the disturbances allow classifying them as medium scale TIDs (MSTIDs). Overall, the observed climatology of ionospheric disturbances in the Antarctic Peninsula region varies significantly with the season and makes it possible to differentiate two major types of the disturbances: winter daytime and summer nighttime, based on their occurrence periods and characteristics. During the Antarctic summer period, the disturbances are present mainly during the nighttime and morning hours, when the background plasma density is at maximum (due to Weddell Sea Anomaly). These disturbances predominantly propagate northwestward and their occurrence probability is well correlated with the sporadic E layer observations, suggesting that these are electrified MSTIDs. During the winter, the TID events are almost exclusively observed during the daytime. The propagation direction of the disturbances during the daytime shows a strong correlation with the background neutral wind direction in the thermosphere. A possible mechanism for this effect is wind filtering of the Atmospheric Gravity Waves originating in the troposphere, which indicates that their source is in the lower atmosphere. The periods of the TIDs also significantly differ between the seasons. Wintertime TIDs have noticeably shorter periods (10–50 min) than those observed during other parts of the year (30–140 min), which also likely reflects the fact that the two types of TIDs are generated by different physical mechanisms.

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Winter Anomaly and Traveling Ionospheric Disturbances over Japan during DYANA Campaign.

Cited by 3 publications

References 19 publications

Latitudinal Extent of the f-min Winter Anomaly Region during the DYANA Campaign.

Latitudinal Extent of the f-min Winter Anomaly Region during the DYANA Campaign.

Assessing models for ionospheric weather specifications over Australia during the 2004 Climate and Weather of the Sun‐Earth‐System (CAWSES) campaign

Occurrence and Characteristics of Traveling Ionospheric Disturbances in the Antarctic Peninsula Region

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