Details

Autor(en) / Beteiligte

• Panda, Sampad Kumar
• Haralambous, Haris
• Kavutarapu, Venkatesh

Titel

Global Longitudinal Behavior of IRI Bottomside Profile Parameters From FORMOSAT‐3/COSMIC Ionospheric Occultations

Ist Teil von

• Journal of geophysical research. Space physics, 2018-08, Vol.123 (8), p.7011-7028

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2018

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• The bottomside thickness and shape (B0 and B1) are the critical key elements for depicting a realistic electron density profile in the International Reference Ionosphere (IRI) model. We investigated their longitudinal variability using a large database of FORMOSAT‐3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) electron density profiles covering the period 2006–2015 from which these parameters are derived using a simple analytic Chapman least squares fitting. The parameters are then compared with the IRI‐2012 submodels, that is, Bil‐2000, Gul‐1987, and ABT‐2009 during different seasons and solar activity. Besides apparent adherence of B0 to the equatorial region, the opposite occurrence pattern of maximum B0 to that of NmF2 is realized, manifesting semiannual distribution and hemispheric asymmetry. Unlike NmF2, the presence of single anomaly crest in B0 in all seasons except March equinox and their leading local time stamps are among the key observations. In spite of regular representation of IRI submodels during equinox, the performance of Gul‐1987 seems to be inferior during solstice with respect to geomagnetic field and equatorial electrodynamics, thereby depicting an erroneous distribution of B0. The striking wave‐like feature in B0 longitudinal variability is also revealed indicating its possible connection with the nonmigrating diurnal/semidiurnal tides. Moreover, the solar activity effect on B0 appears to be relatively higher over the Asian and Pacific longitudes (60–150°E). Although speculations are made over B1 variability, its complete longitudinal characteristics are indistinguishable in our results, except the subordinate magnitude as compared to IRI estimations. The important findings from this study may reinforce the understanding of bottomside variability and future improvements in IRI. Key Points Longitudinal variability of B0 and B1 is investigated from FORMOSAT‐3/COSMIC occultation profiles Longitudinal wave‐like feature in B0 indicates nonmigrating tidal influences with latitudinal anticorrelation connection with NmF2 Discrepancy among the bottomside submodels in IRI is noticed with the relatively improved performance in ABT‐2009