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Wyświetlanie 1-2 z 2
Tytuł:
Cross-comparison of meteorological parameters and ZTD observations supplied by microwave radiometers, radiosondes, and GNSS services
Autorzy:
Trzcina, Estera
Tondaś, Damian
Rohm, Witold
Powiązania:
https://bibliotekanauki.pl/articles/24524960.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
para wodna
meteorologia
opóźnienie troposferyczne
zenith tropospheric delay
water vapour radiometers
GNSS meteorology
Opis:
Water vapour radiometers (WVR) provide information about temperature and humidity in the troposphere, with high temporal resolution when compared to the radiosonde (RS) observations. This technique can provide an additional reference data source for the zenith tropospheric delay (ZTD) estimated with the use of the Global Navigation Satellite System (GNSS). In this work, the accuracy of two newly installed radiometers was examined by comparison with RS observations, in terms of temperature (T), absolute humidity (AH), and relative humidity (RH), as well as for the ZTD. The impact of cloud covering and heavy precipitation events on the quality of WVR measurements was investigated. Also, the WVR data were compared to the GNSS ZTD estimates. The experiment was performed for 17 months during 2020 and 2021. The results show agreement between RS and WVR data at the level of 2◦C in T and 1 gm-3 in AH, whereas for RH larger discrepancies were noticed (standard deviation equal to 21%). Heavy precipitation increases WVR measurement errors of all meteorological parameters. In terms of ZTD, the comparison of WVR and RS techniques results in bias equal to –0.4 m and a standard deviation of 7.4 mm. The largest discrepancies of ZTD were noticed during the summer period. The comparison between the GNSS and WVR gives similar results as the comparison between the GNSS and RS (standard deviation 7.0–9.0 mm).
Źródło:
Geodesy and Cartography; 2021, 70, 2; art. no. e08
2080-6736
2300-2581
Pojawia się w:
Geodesy and Cartography
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The combined geodetic network adjusted on the reference ellipsoid – a comparison of three functional models for GNSS observations
Autorzy:
Kadaj, R.
Powiązania:
https://bibliotekanauki.pl/articles/145404.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sieć geodezyjna
elipsoida odniesienia
parametry geodezyjne
combined geodetic network
hybrid geodetic network
GNSS vectors on ellipsoid
network adjustment on the ellipsoid
Opis:
The adjustment problem of the so-called combined (hybrid, integrated) network created with GNSS vectors and terrestrial observations has been the subject of many theoretical and applied works. The network adjustment in various mathematical spaces was considered: in the Cartesian geocentric system on a reference ellipsoid and on a mapping plane. For practical reasons, it often takes a geodetic coordinate system associated with the reference ellipsoid. In this case, the Cartesian GNSS vectors are converted, for example, into geodesic parameters (azimuth and length) on the ellipsoid, but the simple form of converted pseudo-observations are the direct differences of the geodetic coordinates. Unfortunately, such an approach may be essentially distorted by a systematic error resulting from the position error of the GNSS vector, before its projection on the ellipsoid surface. In this paper, an analysis of the impact of this error on the determined measures of geometric ellipsoid elements, including the differences of geodetic coordinates or geodesic parameters is presented. Assuming that the adjustment of a combined network on the ellipsoid shows that the optimal functional approach in relation to the satellite observation, is to create the observational equations directly for the original GNSS Cartesian vector components, writing them directly as a function of the geodetic coordinates (in numerical applications, we use the linearized forms of observational equations with explicitly specified coefficients). While retaining the original character of the Cartesian vector, one avoids any systematic errors that may occur in the conversion of the original GNSS vectors to ellipsoid elements, for example the vector of the geodesic parameters. The problem is theoretically developed and numerically tested. An example of the adjustment of a subnet loaded from the database of reference stations of the ASG-EUPOS system was considered for the preferred functional model of the GNSS observations.
Źródło:
Geodesy and Cartography; 2016, 65, 2; 229-257
2080-6736
2300-2581
Pojawia się w:
Geodesy and Cartography
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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