Geodesy using the Swedish permanent GPS network: Effects of signal scattering on estimates of relative site positions

Jaldehag, R. T. Kenneth; Johansson, Jan M.; Ronnang, B. O.; Elósegui, P.; Davis, J. L.; Shapiro, I. I.; Niell, A. E.

doi:10.1029/96jb01183

Cited by 31 publications

(15 citation statements)

References 15 publications

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“…We selected GPS stations that are close to the radiosonde stations deployed by the Japan Meteorological Agency (JMA), taking account of (1) the distance between GPS and radiosonde stations is as far as 40 km and (2) the height difference between them is below 100 m. Also, to avoid antenna mixing problems and signal scattering associated with the antenna mount [Jaldehag et al, 1996], we selected stations belonging to the same cluster so that the antenna type and mounting system are identical.…”

Section: Comparisons Of Pwv Derived From Routine Gps Analysis With Rasupporting

confidence: 88%

Comparisons of GPS‐derived precipitable water vapors with radiosonde observations in Japan

Ohtani¹,

Naito²

2000

J. Geophys. Res.

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Abstract. We investigated the accuracy and features of precipitable water vapor (PWV) obtained from the Japanese Global Positioning System (GPS) network. We compared PWVs estimated from the Geographical Survey Institute (GSI) routine geodetic analysis using the Bernese software with those derived from the nearest 10 radiosonde stations over the Japanese islands. The comparisons for a half year showed that the agreement of the GPS-derived PWV was 3.7 mm in terms of rms difference, with a standard deviation of 2.6 mm and a mean bias of -2.7 mm, which is less precise than those obtained in central North America. This may reflect the high temporal and spatial variability of water vapor over the Japanese islands, causing differences between PWVs if GPS and radiosonde launch stations are not colocated. We also found systematic biases in the GPSderived PWV. The absolute value of the mean bias at 1200 UT was systematically larger than that at 0000 UT. Their difference reached as much as 2 mm. Moreover, the mean biases tended to increase as PWV increased. We also confirmed that there were similar systematic biases in the PWV obtained from our GPS analysis using the GIPSY software with high temporal resolution. This fact indicates that the systematic biases depend neither on analysis software nor on temporal resolution of PWV estimation. We analyzed GPS data collected at the Tsukuba station using GIPSY for 2 years and showed a possibility that the systematic biases also found at the Tsukuba station were attributed to ocean tidal loading and seasonal variation of the mapping function both of which were not taken into account in the GPS analysis with the routine analysis using Bernese and our analysis using GIPSY. These results suggest the importance of implementing them in the analysis for accurate estimates of absolute value of PWV from the Japanese GPS network. IntroductionWater vapor plays a crucial role in various atmospheric processes. Accurate estimates of spatial distribution and temporal variation of water vapor are needed in forecasting regional precipitation, understanding global climate, and studying the hydrologic cycle. Especially, to study short-term severe weather phenomena, such as localized torrential rainfalls that often cause serious damages in the southwestern parts of Japan, observations of water vapor both with high temporal and spatial resolution are urgently required. However, since water vapor is highly variable in time and space, it is difficult to acquire such information with high resolution using conventional meteorological techniques such as radiosonde, water vapor radiometer, and so forth.In this decade it has been demonstrated through much re-

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Section: Comparisons Of Pwv Derived From Routine Gps Analysis With Rasupporting

confidence: 88%

Comparisons of GPS‐derived precipitable water vapors with radiosonde observations in Japan

Ohtani¹,

Naito²

2000

J. Geophys. Res.

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“…In addition to the error introduced by the radome itself, additional error may be incurred as matter accumulates on the radome. For example, the effect on height measurements of the accumulation of snow on the radome is documented by Jaldehag et al (1996a). The equivalent change in ZWD for the errors observed during one month in January 1994 (50 mm in height) amounts to 20 mm.…”

Section: ) Effect Of Radomementioning

confidence: 99%

Comparison of Measurements of Atmospheric Wet Delay by Radiosonde, Water Vapor Radiometer, GPS, and VLBI

Niell¹,

Coster²,

Solheim³

et al. 2001

J. Atmos. Oceanic Technol.

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255

185

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The accuracy of the Global Positioning System (GPS) as an instrument for measuring the integrated water vapor content of the atmosphere has been evaluated by comparison with concurrent observations made over a 14-day period by radiosonde, microwave water vapor radiometer (WVR), and Very Long Baseline Interferometry (VLBI). The Vaisala RS-80 A-HUMICAP radiosondes required a correction to the relative humidity readings (provided by Vaisala) to account for packaging contamination; the WVR data required a correction in order to be consistent with the wet refractivity formulation of the VLBI, GPS, and radiosondes. The best agreement of zenith wet delay (ZWD) among the collocated WVR, radiosondes, VLBI, and GPS was for minimum elevations of the GPS measurements below 10Њ. After corrections were applied to the WVR and radiosonde measurements, WVR, GPS, and VLBI (with 5Њ minimum elevation angle cutoff ) agreed within ϳ6 mm of ZWD [1 mm of precipitable water vapor (PWV)] when the differences were averaged, while the radiosondes averaged ϳ6 mm of ZWD lower than the WVR. After the removal of biases between the techniques, the VLBI and GPS scales differ by less than 3%, while the WVR scale was ϳ5% higher and the radiosonde scale was ϳ5% lower. Estimates of zenith wet delay by GPS receivers equipped with Dorne-Margolin choke ring antennas were found to have a strong dependence on the minimum elevation angle of the data. Elevation angle dependent phase errors for the GPS antenna/mount combination can produce ZWD errors of greater than 30 mm over a few hour interval for typical GPS satellite coverage. The VLBI measurements of ZWD are independent of minimum elevation angle and, based on known error sources, appear to be the most accurate of the four techniques.

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“…Elósegui et al (1995) and Jaldehag et al (1996a) showed that the signal scattering from the top of the antenna pillar affects the phase observable and the estimate of vertical component of site position, and that putting electrical wave absorbing materials on the pillar is effective in reducing this problem. Carrier phase of GPS signals is also affected by radomes used for protecting GPS antennas, and thus affects the results of the analysis (Meertens et al, 1996;Johansson et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Calibration of antenna-radome and monument-multipath effect of GEONET—Part 1: Measurement of phase characteristics

et al. 2014

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Severe, 10-cm level, elevation angle cutoff dependence of the height solution is detected in the analysis of sample baselines from GSI/GEONET (Geographical Survey Institute/GPS Earth Observation NETwork). It is inferred that station and monument specific differences in the radome and/or multipath environment are responsible for this effect, because it can be observed over short sample baselines for identical antennas mounted atop different monument types. Our test results show that both the radome and multipath from the metal plate at the top of the pillar affect the baseline solutions. A calibration experiment was carried out by observing short (<10 m) known baselines to obtain phase correction maps for the typical GEONET monuments. The antenna/monument phase centers of GEONET monument replicas with the same attachment and radomes but shortened in height, were determined relative to a tripod-mounted TRM29659.00 antenna. Phase maps were obtained with the BERNESE software for 6 typical combinations of 3 antenna types, 3 monument types, and 3 radome types commonly used in GEONET. We find monument/antenna specific phase differences up to 1 cm. These phase differences can result in more than 10-cm station height biases when tropospheric delay parameters are estimated, which is consistent with the height errors observed for GEONET.

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Geodesy using the Swedish permanent GPS network: Effects of signal scattering on estimates of relative site positions

Cited by 31 publications

References 15 publications

Comparisons of GPS‐derived precipitable water vapors with radiosonde observations in Japan

Comparisons of GPS‐derived precipitable water vapors with radiosonde observations in Japan

Comparison of Measurements of Atmospheric Wet Delay by Radiosonde, Water Vapor Radiometer, GPS, and VLBI

Calibration of antenna-radome and monument-multipath effect of GEONET—Part 1: Measurement of phase characteristics

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