Detalles del recurso

Descripción

Inversion techniques applied to GPS‐LEO radio occultation data allow the retrieval ofaccurate and worldwide‐distributed refractivity profiles, which, in the case of theionosphere, can be converted into electron densities providing information regarding theelectron content distribution in this atmospheric region. In order to guarantee the accuracyof the electron density retrievals, two key points should be taken into account: thehorizontal gradients of the electronic distribution and the topside electron content abovethe LEO orbit. The deployment in April 2006 of the satellite Constellation ObservingSystem for Meteorology Ionosphere and Climate (FORMOSAT‐3/COSMIC), carryingGPS receivers on board, provides valuable radio occultation data with global and almostuniform coverage overcoming the sparsity of data from previous LEO missions (forinstance, GPS/MET, CHAMP, and SAC‐C). This is also one of the main limitations ofother sources providing direct observations, such as ionosondes. In this study, theimproved Abel transform inversion is used to analyze derived ionospheric electron densityprofiles of the whole year 2007 in a scenario with very high electron density gradients:The neighboring area of Jicamarca (76.9°W, 12°S, dip latitude: 1°N), Perú, located at verylow latitude and close to the geomagnetic equator, and the influence of the Appleton‐Hartree equatorial anomaly (Davies, 1990). Moreover, different strategies to accountfor the topside electron content in the occultation data inversion are compared anddiscussed, taking advantage of the availability of FORMOSAT‐3/COSMIC data sets andmanually calibrated measurements from Jicamarca DPS. Statistical results show that forthe current scenario the improvements are only about 10%, evidencing that the lack ofcolocation is one important source of error for the classical Abel inversion. Implicationswith respect to the plasmaspheric contribution have been derived from this data setanalysis, in particular, the necessity to account for it specially when the Total ElectronContent (TEC) is small.

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Autor(es)

Aragón Ángel, María Ángeles -  Liou, Y. -  A. -  Lee, C. -  C. -  Reinisch, B. W. -  Hernández Pajares, Manuel -  Juan Zornoza, José Miguel -  Sanz Subirana, Jaume -