Loiuy

.niatrep lanruoj eht ot ylppa taht sremialcsid lagel lla dna ,tnetnoc eht tceffa dluoc hcihw derevocsid eb yam srorre ssecorp noitcudorp eht gnirud taht eton esaelP .mrof lanif sti ni dehsilbup si ti erofeb foorp gnitluser eht fo weiver dna ,gnittesepyt ,gnitideypoc ogrednu lliw tpircsunam ehT .tpircsunam eht fo noisrev ylrae siht gnidivorp era ew sremotsuc ruo ot ecivres a sA .noitacilbup rofdetpecca neeb sah taht tpircsunam detidenu na fo elif FDP a si sihT

420.80.7002 .rsa.j/6101.01 :iod ,)7002( hcraeseR ecapS ni secnavdA ,spaM erehpsonoI labolG denibmoc rof yrtemitlA etilletaS dna metsyS etilletaS noitagivaN labolG eht gnisU ,.H ,huhcS ,.T ,regiboH ,.S ,avorodoT :sa elcitra siht etic esaelP 7002 tsuguA 41 7002 yluJ 52 6002 rebotcO 13 :etaD detpeccA :etaD desiveR :etaD devieceR :niraeppa oT

hcraeseR ecapS ni secnavdA
7229 RSAJ 420.80.7002.rsa.j/6101.01
5-88800)70(7711-3720S

:ecnerefeR :IOD :IIP

huhcS .H ,regiboH .T ,avorodoT .S spaM erehpsonoI labolG denib ‐moc rof yrtemitlA etilletaS dna metsyS etilletaS noitagivaN labolG eht gnisU

Accepted Manuscript

ACCEPTED MANUSCRIPT
Using the Global Navigation Satellite System and Satellite Altimetry for combinedGlobal Ionosphere Maps S. Todorova, T. Hobiger1, H. Schuh Institute of Geodesy and Geophysics, Vienna University of Technology, Gusshausstr. 27-29, 1040 Vienna, Austria, stodo@mars.hg.tuwien.ac.at

Abstract

1. Introduction 1.1. The ionosphere

1

Present address: Space-Time Standards Group, Kashima Space Research Center, National Institute of Information and Communications Technology,893-1 Hirai, Kashima, 314-0012 Ibaraki, Japan

AC C

The ionosphere can be defined as that part of the upper atmosphere where the density of free electrons and ions is high enough to influence the propagation of electromagnetic radio frequency waves (Hargreaves, 1992). The ionisation process is primarily driven by the Sun and its activity varies strongly with time, as well as with geographicallocation. When electromagnetic waves travel through the ionosphere, the integration between the electromagnetic field and the free electrons influences both the speed and the propagation direction of the signals. This effect is known as ionospheric refraction (Hartmann and Leitinger, 1984) and has to be considered in the determination of the propagation velocity of the signals of all space geodetictechniques operating with electromagnetic waves. The ionospheric refraction can be determined in terms of STEC (Slant Total Electron Content), which is the integral of the electron density along the signal path S (Eq. (1) and Eq. (2)). STEC is measured in Total Electron Content Units (TECU), with 1 TECU equivalent to 1016

EP

TE

D

MA

For deriving global maps of the Total ElectronContent (TEC) from space geodetic techniques usually observations from the Global Navigation Satellite System (GNSS) are taken. However, the GNSS stations are inhomogeneously distributed, with large gaps particularly over the sea surface. Within this study we create Global Ionosphere Maps (GIM) from GNSS data and additionally introduce satellite altimetry observations, which help to compensate theinsufficient GNSS coverage of the oceans. The obtained global maps are in two hours intervals and daily values of Differential Code Biases (DCB) for all the GNSS satellites and receivers are also estimated. The combination of the data from around 160 GNSS stations and two satellite altimetry missions - Jason-1 and TOPEX/Poseidon - is performed on the normal equation level. The comparison between theintegrated ionosphere models and the GNSS-only maps shows a higher accuracy of the combined GIM over the seas. The study aims at improved combined global TEC maps, which should make best use of the advantages of each particular type of data and have higher accuracy and reliability than the results derived by the two methods if treated individually.

NU

SC R

IP T

ACCEPTED MANUSCRIPT...