Bibliography

The investigation on daytime conjugate hemispheric asymmetry along 100°E longitude using observations and model simulations: New insights

The hemispherical asymmetry of the low latitude region along 100°E ± 5°E is scrutinized for the year 2015 at magnetically conjugate points on seasonal and intra-seasonal time scales. Two conjugate Ionosonde station pairs are selected- one pair in the inner valley (from SEALION) and the other in the outer edges of the EIA region. The anomaly in the stations is estimated using the difference of low latitude NmF2 from the dip equatorial NmF2 in the same meridian. A monthly average scheme is used instead of a seasonal mean, as the month-to-month variations are found to provide intricate details. The anomaly at the conjugate stations is highly asymmetric even during the equinoctial months of March and October, whereas it is nearly symmetric during April. During June/July, the morning time hemispheric asymmetry (larger on the winter side) temporarily reduces in the midday period and then reverses sign (larger in summer) in the afternoon. The NmF2 observations suggest a close relation of hemispheric symmetry to the position of the subsolar point with respect to the dip equator and a shift/expansion of the trough region of the EIA towards the summer hemisphere. The inter-hemispheric comparison of the hmF2 suggests a strong modulating influence of meridional winds at both the inner and outer stations which depend strongly on the relative position of the subsolar point with respect to the field line geometry. Theoretical (SAMI3/SAMI2) and empirical model (IRI) simulations show a meridional movement of the EIA region with the subsolar point. The winter to summer hemisphere movement of the EIA trough and crest region is also reproduced in the GIM-TEC along 100°E for 2015. This shifting or tailoring of the trough and the crest region is attributed primarily to the meridional wind field, which varies with the shifting position of subsolar point relative to the field line geometry. The seasonal and intra-seasonal difference in the NmF2 hemispheric asymmetry is attributed to the misalignment of the two centers of power viz., the thermospheric/neutral processes and the electromagnetic forces, due to the geographic-geomagnetic offset in this longitude.

Kalita, B.; Bhuyan, P.; Nath, S.; Choudhury, M.; Chakrabarty, D.; Wang, K.; Hozumi, K.; Supnithi, P.; Komolmis, T.; . Y. Yatini, C; Le Huy, M.;

Published by: Advances in Space Research      Published on: may

YEAR: 2022     DOI: 10.1016/j.asr.2022.02.058

NmF2; asymmetry; Conjugate; EIA; model; Hemisphere; hmF2; Subsolar

Conjugate hemisphere ionospheric response to the St. Patrick\textquoterights Day storms of 2013 and 2015 in the 100\textdegreeE longitude sector

The effects of the St. Patrick\textquoterights Day geomagnetic storms of 2013 and 2015 in the equatorial and low-latitude regions of both hemispheres in the 100\textdegreeE longitude sector is investigated and compared with the response in the Indian sector at 77\textdegreeE. The data from a chain of ionosondes and GPS/Global Navigation Satellite Systems receivers at magnetic conjugate locations in the 100\textdegreeE sector have been used. The perturbation in the equatorial zonal electric field due to the prompt penetration of the magnetospheric convective under shielded electric field and the over shielding electric field gives rise to rapid fluctuations in the F₂ layer parameters. The direction of IMF B_z and disturbance electric field perturbations in the sunset/sunrise period is found to play a crucial role in deciding the extent of prereversal enhancement which in turn affect the irregularity formation (equatorial spread F) in the equatorial region. The northward (southward) IMF B_z in the sunset period inhibited (supported) the irregularity formation in 2015 (2013) in the 100\textdegreeE sector. Large height increase (h_mF₂) during sunrise produced short-duration irregularities during both the storms. The westward disturbance electric field on 18 March inhibited the equatorial ionization anomaly causing negative (positive) storm effect in low latitude (equatorial) region. The negative effect was amplified in low midlatitude by disturbed thermospheric composition which produced severe density/total electron content depletion. The longitudinal and hemispheric asymmetry of storm response is observed and attributed to electrodynamic and thermospheric differences.

Kalita, Bitap; Hazarika, Rumajyoti; Kakoti, Geetashree; Bhuyan, P.; Chakrabarty, D.; Seemala, G.; Wang, K.; Sharma, S.; Yokoyama, T.; Supnithi, P.; Komolmis, T.; Yatini, C; Le Huy, M.; Roy, P.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2016

YEAR: 2016     DOI: 10.1002/2016JA023119

Conjugate hemisphere ionospheric response to the St. Patrick s Day storms of 2013 and 2015 in the 100° E longitude sector

The GUVI data used here are provided through support from the NASA MO&DA program. The GUVI instrument was designed and built by The Aerospace Corporation and The John

Kalita, Bitap; Hazarika, Rumajyoti; Kakoti, Geetashree; Bhuyan, PK; Chakrabarty, D; Seemala, Gopi; Wang, K; Sharma, S; Yokoyama, T; Supnithi, P; , others;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2016     DOI: 10.1002/2016JA023119

Conjugate hemisphere ionospheric response to the St. Patrick s Day storms of 2013 and 2015 in the 100° E longitude sector

Kalita, Bitap; Hazarika, Rumajyoti; Kakoti, Geetashree; Bhuyan, PK; Chakrabarty, D; Seemala, Gopi; Wang, K; Sharma, S; Yokoyama, T; Supnithi, P; , others;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2016     DOI:

Ionospheric response to the 17-18 March 2015 geomagnetic storm as seen from multiple TEC and NmF2 measurements along 100° E

Bhuyan, Pradip; Yokoyama, Tatsuhiro; Kalita, Bitap; Seemala, GK; Hazarika, Rumajyoti; Komolmis, Tharadol; Yatini, Clara; Chakrabarty, Dibyendu; Supnithi, Pornchai;

Published by: 41st COSPAR Scientific Assembly      Published on:

YEAR: 2016     DOI: