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When inspecting Figure 7 we see that the prediction consisting of d + s does not exactly match the daily estimates because the matrix C.. is not a zero matrix but contains the variances provided by the primary ionosphere parameter estimation. By performing the least-squares collocation step for each SH coefficient using the same prediction length, merging the predicted TEC coefficients to a full set of SH parameters, and writing a corresponding GIM file, we get a procedure that allows us to predict entire CODE GIMs! A software tool solving that task has been developed. HIGH TEMPORAL RESOLUTION TEC USING SPHERICAL EXPANSIONS HARMONIC In this section we discuss a method on how to increase the temporal resolution of the TEC representation when using spherical harmonic (SH) expansion. SH expansions are well suited to model tim~independent quantities given on a spherical surface. When dealing with the ionosphere, the entire sphere is probed by GPS stations when deriving on~day TEC maps. The disadvantage is a poor temporaJ resolution because of the assumption of a “frozen” ionosphere co-rotating with the Sun, However, the general ionospheric behavior may well be described with daily TEC maps. When generating several TEC maps per day, one has to expect at times unreasonable — very high or negative — TEC estimates in regions where no stations are located. One may avoid such problems by limiting the variations between consecutive TEC maps with “relative” a priori constraints between consecutive maps by adding “relative” pseud~observations of the type Aeij =eij(t~) –eij(t~-l)=o for k=2,..., n (7) to the system of normal equations stemming from actual observations. Note that the a priori sigmas ~&ij used for the pseud~observations Aeij do not affect the “absolute” TEC determinations. Optimal values for these sigmas have to be found experimentally. Due to the fact that we deal with normalized SH coefficients, we may simplify this problem by setting U&ij = U&. A series of 12 2-hourly TEC maps (taken at 01:00, 03:00, . . . . 23:00 UT) is shown in Figure 8a. The typical doubl~peak structure co-rotating with the Sun fairly well follows the geomagnetic equator, even when referring the TEC representation to a solar-geographic coordinate system. Nevertheless, Figure 8a indicates that a solar-geomagnetic reference frame is more appropriate. The associated RMS maps shown in Figure 8b describe the formal accuracy of the TEC as a function of earth-fixed coordinates and basically reflect the station coverage. “Light” regions indicate small RMS (see, e. g., Europe or North America), “dark” regions mean large RMS (see, e. g., the region around the station 0’Higgens, Antarctica). The ratio of the largest and smallest RMS is about 11. Such RMS maps may be included in IONEX files [Schaer et al., 1998]. 315
,$ ., L r 1 (a) TEc maps Figure8. 2-hourly TECand RMSmaps forday O17,1998 316 I
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T 8 A N A L Y S I S CENTER WORKSHOP
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FOREWORD The 1998 Analysis Centre W
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TABLE OF CONTENTS Foreword . . . .
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S. Schaer, W. Gurtner, J Feltens Th
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Programme of Workshop 1
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@esa m=l, ::=mlllll lx= mj:n IGS AN
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,.,,. ,:, -.. ., ,,.Y @esa 9=II::=R
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EXECUTIVE SUMMARYl G. Beutler The 1
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activities one has the problem that
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future tasks are clearly defined. M
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ut due to the usually excellent inf
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Ionosphere The position paper “IG
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SUMMARY RECOMMENDATIONS OF THE DARM
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6. That a (super) combination of G-
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Annex IGS Fiducials for ITRF Refere
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● coordinates and velocities of t
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archiving, site and RINEX standards
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it is unlikely that a single person
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GOVERNING BOARD The Governing Board
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Topic 1: The IGS Analysis Products
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used, the consistency between all t
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Consistency between the IGS orbits
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Table 1. Median daily repeatabiliti
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Of course the inclusion of bad sate
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consistent with the IGS reference f
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GNAAC, of providing station coordin
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One large future “customer” of
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seconds. A format for station and s
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Zumberge, J. F., M. B. Heflin, D. C
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INTRODUCTION PRECISE HIGH-RATE SATE
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FIXED STATION CLOCKS APPROACH A sec
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250 -150- - -250- 3.00 3.33 3.66 4.
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HIGH-RATE STATION CLOCKS One advant
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INTRODUCTION THE IGS/BIPM TIME TRAN
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A type of point positioning likely
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differences. This is probably suffi
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Topic 2: Orbit Prediction and Rapid
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The factors that limit the accuracy
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Table 1. Number of stations availab
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Table 3. Effect of different pertur
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Table 4. Orbit fit (7-day) and orbi
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A more than twofold improvement in
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60 40 Ii . . . ..- ● E WC.W 2 heu
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10 5 t t + IV (cm) ☞ ☞ IGS rapi
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Broc~dcast orbits for non—eclipsi
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Table 1. Effect of different Pertur
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where aD~, aDC, aDS, aye, aye, ays,
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: : m . > > : ~ ~ g z 2 CPS WEK (a)
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Table 2. Selected “optimal” orb
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lines in both plots showing the Do
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The RPR model is based on the time
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likely caused by the eclipsing sate
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Appendix This Appendix gives some s
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NEW SOLAR RADIATION PRESSURE MODELS
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120 100 20 \ lm 10m J-IA c Ic predi
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Using the current GNSS systems, use
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meter, this will be sufficient to p
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Standards and meteorological loggin
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decades, This package has been exte
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mainly due to the bad geometrical c
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corrections can be compensated by c
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These results can be compared with
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BACKGROUND POTENTIAL USE OF ORBIT P
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were used to validate the basic des
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METOP a.m. GRAS data as parl 0( the
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parameters of both the ‘model wor
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A critical aspect is given by the d
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Topic 3: IGS Reference Frame Realis
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“A global IGS reference system”
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determinations (largely free of the
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Fig. 2. of IGS he Proposed set of 5
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software. As seen from Table 2 and
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of about 0.2 mas are expected, it i
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. All the A-SINEX files (with stati
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choose (unconstrained, minimum) to
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and semiannual effects for some sta
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Zumberge, J. F, M.B. Heflin, D.C. J
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Africa/Arabia : BAHR r,e,n,s Z12 0.
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However there will be something lik
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TROM TSKB VILL WES2 WTZR YAR1 YELL
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Sigma CAS1 DAV1 MCM4 OHIG KERG Mean
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Example #1: Minimum datum (rotation
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APPENDIX VI SUGGESTIONS AND DISCUSS
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Table 1: 7 parameter orbit and stat
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ITRF96 AND FOLLOW ON FOR 1998 Claud
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Table 1. Global ITRF96 residuals pe
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INTRODUCTION IGS REFERENCE STATIONS
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Class D: Velocity residuals larger
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(MCM466001MO03). These stations sho
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ABSTRACT ESTIMATION OF NUTATION TER
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that the VLEII formal errors will o
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with oj denoting a combination of t
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Figure 5. 0.20 0.15 0.10 0.05 0.00
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GLOBALLY CONSISTENT RIGID PLATE MOT
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I The velocity of a point that is f
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mass (which we assume to be Euler
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otated into ITRF using a 14-paramet
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can arise because the station actua
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. In northern Algeria, convergence
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Topic 4: IGS Products for Troposphe
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that all coordinates refer to the s
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GFZ are extracted for 90 days at th
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15. ~2. CODE 9. 6. 3, 00 15. 12, 9.
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10 4 8. 2. I 890. 893. 8%. 899. 902
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18. 12. n 6. 2 ~ ‘“ N -6. -12.
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L 10. I 5. r o. L-- 97250. 40. 35.
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1. Verification of DWD Weather Fore
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5. DAILY BKG SOLUTION, GREF PART, D
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ESTIMATING HORIZONTAL GRADIENTS OF
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ABSTRACT IGS PRODUCTS FOR THE IONOS
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POTENTIAL PARTICIPANTS IN A ROUTINE
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TOWARDS A COMBINED IGS IONOSPHERE P
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GOALS AND NEXT STEPS For the near f
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IONEX: The ionosphere Map EXchange
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From method (1) to method (3), one
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Reading and Writing IONEX Modules F
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I I I I I I I I I contained in curr
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Table 2: Ionosphere map file — da
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1000 1000 1000 1000 1000 1000 1000
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1000 1000 1000 1000 1000 1000 1000
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Table 2: Differential code biases
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This equation can be rewritten in f
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In practice, the combined biases (r
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w o z w & LLl IL LL E DENT -BRUS (D
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10.00 ‘ - — 5.00 ‘- -- 0.00
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In a similar way as Wanninger (1994
Page 253 and 254: anging fi-om a few minutes to sever
Page 255 and 256: CONCLUSIONS The paper has outlined
Page 257 and 258: ABSTRACT MONITORING THE IONOSPHERE
Page 259 and 260: check and/or improve well-known ion
Page 261 and 262: 1990). Collecting more and more TEC
Page 263 and 264: References Davies K., W. Degenhardt
Page 265 and 266: The main part of the paper will the
Page 267 and 268: One indicator of accuracy is the da
Page 269 and 270: Figure 3: Global TEC map from GE fi
Page 271 and 272: 90 45 0 -45 -90 -100 -90 0 90 10< F
Page 273 and 274: When comparing the TEC maps in Figu
Page 275 and 276: Chapman Profile approach, thus prov
Page 277 and 278: points, but represent the integral
Page 279 and 280: Cosz cosine of slant range zenith d
Page 281 and 282: if not linear - the unknown paramet
Page 283 and 284: geometrical conditions can arise, a
Page 285 and 286: Establishment of Linearized Observa
Page 287 and 288: spending tracking data, the SST opt
Page 289 and 290: THE ROLE OF GPS DATA IN IONOSPHERIC
Page 291 and 292: (e.g., using the 40 and 360 MHz sig
Page 293 and 294: Retrospective nowcasting Retrospect
Page 295 and 296: (chairman: R. Leitinger, Austria, c
Page 297 and 298: ● ● ● ● 24-hour global iono
Page 299 and 300: G .- 0 y 180 -150 -120 -90 -60 -30
Page 301 and 302: E 9 .2 ?: j ~ ?4 ?30 ~“ ~z % :’
Page 303: c c E c .- E! !2 %0 . m t 1 1 0 200
Page 307 and 308: Rothacher, M., G. Beutler, E. Brock
Page 309 and 310: Experiences of the BKG in Processin
Page 311 and 312: RINEX N-l?ite for GPS modified Kepl
Page 313 and 314: The combined SP3-fde includes also
Page 315 and 316: 1) Set up n single difference ambig
Page 317 and 318: 0.10 a) z g 0.06 0.02 Figure 5: Fra
Page 319 and 320: [ 1) Compute triple difference resi
Page 321 and 322: PRECISE AUTONOMOUS EPHEMERIS DETERM
Page 323 and 324: ephemeris message will be computed
Page 325 and 326: The solution to the problem can be
Page 327 and 328: integration period, e.g. 5 minutes
Page 329 and 330: LATITUDE (DEG) 9L . . 6& - ;+5 ,- o
Page 331 and 332: First from the generation of the si
Page 333 and 334: it is believed that, with dedicated
Page 335 and 336: needed in order to use them as yard
Page 337 and 338: close to the maximum. It was decide
Page 339 and 340: Summary IGS Related Activities at t
Page 341 and 342: Table 1. Point positioning using NR
Page 343 and 344: ESA/ESOC IGS ANALYSIS CENTRE POSTER
Page 345 and 346: ESTIMATION OF MANOEUVRES Manoeuvres
Page 347 and 348: TROPOSPHERIC ESTIMATES Tropospheric
Page 349 and 350: Sever (JPL) and Gerd Gendt (GFZ). S
Page 351 and 352: A REVIEW OF GPS RELATED ACTIVITIES
Page 353 and 354: 2.5 2.0 1.5 ~ 1.0 % E 0.5 x 0.0 -0.
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TEC from the CORS Network Figure 4
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REFERENCES Cartwright, D.E., and R.
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In recent years, the Bulletin A pol
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frequency reference. A second recei
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THE IGS REGIONAL NETWORK ASSOCIATE
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IJJcl UKJ 4“’’’’’’’
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W.-,-,- ,,, IJJ3 d , , , ,. . . . !
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Variations of weekly SIR R solution
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w’ —— L .sT41w.!l. c8Q#_. .J
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T HE N EWCASTLE G LOBAL N ETWORK A
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6 5 4 23 2 1 0 S TRATEGY Figure 2:
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IGS Workshop Dinner, Jagschloss Kra
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