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Using FORMOSAT-3/COSMIC GPS data to improve the La Plata Ionospheric Model

Using FORMOSAT-3/COSMIC GPS data to improve the La Plata Ionospheric Model. J. Federico Conte , Francisco Azpilicueta , Claudio Brunini , Diego Janches GESA, Facultad de Ciencias Astronómicas y Geofísicas, UNLP NASA. Second LISN Workshop São José dos Campos, Brasil

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Using FORMOSAT-3/COSMIC GPS data to improve the La Plata Ionospheric Model

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  1. Using FORMOSAT-3/COSMIC GPS data to improve the La Plata Ionospheric Model J. Federico Conte, Francisco Azpilicueta, Claudio Brunini, Diego Janches GESA, Facultad de Ciencias Astronómicas y Geofísicas, UNLP NASA Second LISN Workshop São José dos Campos, Brasil November 7 – 11, 2011

  2. Abstract In the framework of the AIRES (Argentine Ionospheric Radar Experiment Station) Project, we are currently upgrading the La Plata Ionospheric Model (Brunini et al., 2011b). Inspired by the IRI model (Bilitza, 2002) and based on the Jones & Gallet (1962) mapping technique, after a process of data assimilation is applied, this semi-empirical model is capable of reproducing electron density profiles dependent on the Universal Time, the geographical location and the solar activity level. At the moment, the data assimilation technique only processes the raw-data obtained from ground-based dual-frequency GPS measurements. Nevertheless, the model is also capable to incorporate FORMOSAT-3/COSMIC electron density profiles externally calculated which, combined with the ionospheric information obtained from the ground-based GPS measurements are used to correct the coefficients of the Jones & Gallet formulation. Consequently, we are currently analyzing and pre-processing GPS raw-data from the FORMOSAT-3/COSMIC mission and appropriately modifying our model in order to incorporate this data to our formulation to have a better description of the electron density profile, especially for the top-side region of the ionosphere. Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 2

  3. La Plata IonosphericModel (LPIM) • Semi-empiricalmodeldevelopedby Prof. Brunini (Brunini, 1998) • Continuouslyupdated and upgradedbyBrunini’sgroup(e.g., Azpilicuetaet al., 2006) • Originally, LPIM wascapable of reproducing global (local) TEC mapsusingground-based dual-frequency GPS raw data fromapprox. 300 (a particular) IGS stations. Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 3

  4. Currentversion of La Plata IonosphericModel • Now, besidescomputing global or local TEC maps, themodelisalsocapable of reproducingelectrondensity (ED) profilesforthewholeionosphere (Brunini et al., 2011a). • Following a similar proceduretothatimplementedby IRI (Bilitza, 2002), the LPIM implementsthe Jones & Galletformulationtorepresentthegeographical (latitude and longitude) and daily (UT) variations of the F2 peakparameters, HmF2 (M3000F2) and NmF2 (f0F2). • Theelectrondensities (criticalfrequencies) and heights of the E and F1 ionosphericlayers are estimatedfollowingthe CCIR recommendations (CCIR, 1991). Also, thescaleheights of the E, F1 and F2 layers are computedaccordingtothe CCIR recommendations. • FourChapmanlayers are adjustedusing actual ground-based dual-frequency GPS raw data and externallycalculated ED profiles. Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 4

  5. Currentversion of La Plata IonosphericModel • Depending on the description of the electron loss process, the factor k can be 0.5 or 1. • According to Bilitza (2002), most modelers have found that 0.5 provides a better match with observations; and according to that experience, LPIM’s formulation uses that value. • The top-side profile of the LPIM is represented with an α-Chapman (k=0,5) function with height-varying scale height (Reinisch and Huang, 2001). Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 5

  6. Currentversion of La Plata IonosphericModel • In summary, the LPIM ED profile is given by a function that depends on two sets of constants but unknown parameters: • Finally, LPIM uses the Least Square method to daily estimate the parameters aforementioned together with the satellite and receivers DCBs: Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 6

  7. Currentversion of La Plata IonosphericModel Brunini et al., 2011a Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 7

  8. FORMOSAT-3/COSMIC • ConstellationObservingSystemforMeteorology, Ionosphere, and Climate. • JointTaiwan-US constellation of sixsatellitesorbiting at around 800 km of altitude. • Payloadconsisting of threeinstruments: • GPS occultationexperiment (GOX). • Ionosphericphotometertostudynighttimeairglowemission. • Tri-band beacon (TBB) totomographicallyestimateionospheric fine structures. • GPS occultationexperiment: two POD antennas, and twoOccultationantennasdistributed in a diamondconfiguration. Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 8

  9. Work in progress At present, we are adapting our model so it can process, together with ground-based GPS measurements, the dual-frequency raw data obtained from the GPS receivers onboard the FORMOSAT-3/COSMIC mission. Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 9

  10. References • -Azpilicueta F, Brunini C, Radicella SM (2006) Global ionospheric maps from GPS observations using modip latitude. Adv Space Res, 38(11): 2324-2331. doi:10.1016/j.asr.2005.07.069. • Bilitza D, Sheik NM, Eyfrig R (1979) A global model for the height of the F2-peak using M3000 values from CCIR. Telecommunication Journal, 46: 549-553. • Bilitza D (2002) Ionospheric Models for Radio Propagation Studies. In: Review of Radio Science 1999-2002, 625-679, Oxford University Press. • Brunini, Claudio: Global Ionospheric Model from GPS measurements. Tesis Doctoral. Facultad de Ciencias Astronómicas y Geofísicas de La Plata, 1998. • Brunini C, Azpilicueta F, Gende M, Aragón-Ángel A, Hernández-Pajares M, Juan JM, Sanz J (2011a) Toward a SIRGAS service for mapping the ionosphere’s electron density distribution. In Pacino et al. (eds): Geodesy for Planet Earth, IAG Symposia, 135:575-580. • Brunini C, Azpilicueta F, Gende M, Camilión E, Aragón-Ángel A, Hernández-Pajares M, Juan M, Sanz J, Salazar D (2011b) Ground- and space-based GPS data ingestion into the NeQuick model. J Geod (in press). • CCIR (1991) Report 340-6. ComitéConsultatif International des Radio communications, Genève, Switzerland. • Chapman S (1931) The absorption and dissociative or ionizing effect of monochromatic radiation in an atmosphere on a rotating Earth. Proceedings of the Physical Society, 43: 483-501. • Dudeney JR (1974) A simple empirical method for estimating the height of the F2-layer at the Argentine Islands Graham Land. Science Report Nº 88, London, UK, British Antarctic Survey. • Jones WB, Gallet RM (1962) Representation of diurnal and geographical variations of Ionospheric data by numerical methods. Telecommunication Journal, 29: 129-149. • Reinisch BW, Huang X (2001) Deducing top-side profiles and total electron content from bottom-side ionograms. Adv Space Res, 27(1): 23-30. Second LISN Workshop, São José dos Campos, Brasil, November 7-11, 2011 Conte et al. 10

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