Impact of GPS antenna phase center and code residual variation maps on orbit and baseline determination of GRACE

Mao, Xinyuan; Visser, Pieter; IJssel, José van den

doi:10.1016/j.asr.2017.03.019

Cited by 23 publications

(19 citation statements)

References 21 publications

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“…The SLR validation statistics confirm that MODK provides high-precision orbit solutions. However, for the PBD solutions the RMS of SLR fit deteriorates by only 1 mm for both Swarm-A and -C. Similar result is reported by [23,15] that the wrongly fixed integer ambiguities reduce the orbit precision. The fixing process can also be easily influenced by the ionospheric activity level between two receivers.…”

Section: Accepted Manuscriptsupporting

confidence: 80%

“…Much research has proved the significance of using in-flight data derived antenna Phase Center Variation (PCV) and Code Residual Variation (CRV) patterns. Using these patterns for correcting the GPS observations enhances the POD and PBD performance [9,10,11,12,13,14,15,16]. At present 2 cm precision level is achievable for Swarm POD solutions [12], and 1-2 cm consistency level is obtained between Swarm-A/-C kinematic and reduced-dynamic PBD solutions [17].…”

Section: Accepted Manuscriptmentioning

confidence: 95%

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The impact of GPS receiver modifications and ionospheric activity on Swarm baseline determination

2018

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The European Space Agency (ESA) Swarm mission is a satellite constellation launched on 22 November 2013 aiming at observing the Earth geomagnetic field and its temporal variations. The three identical satellites are equipped with high-precision dual-frequency Global Positioning System (GPS) receivers, which make the constellation an ideal test bed for baseline determination. From October 2014 to August 2016, a number of GPS receiver modifications and a new GPS Receiver Independent Exchange Format (RINEX) converter were implemented. Moreover, the on-board GPS receiver performance has been influenced

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Section: Accepted Manuscriptsupporting

confidence: 80%

Section: Accepted Manuscriptmentioning

confidence: 95%

The impact of GPS receiver modifications and ionospheric activity on Swarm baseline determination

2018

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“…Kinematic baselines (KBs) between two LEO formation-flying spacecraft can typically be derived with much better precision than the absolute positions by making use of ambiguity-fixing schemes and due to cancellation of common errors (Kroes, 2006;Allende-Alba et al, 2017). The possible added value of KBs for the observation of temporal gravity field variations will be assessed making use of two different KB solutions by TUD (Mao et al, 2017) and the AIUB (Jäggi et al, 2007(Jäggi et al, , 2009.…”

Section: Introductionmentioning

confidence: 99%

Description of the multi-approach gravity field models from Swarm GPS data

Encarnação¹,

Visser

Arnold

et al. 2020

Earth Syst. Sci. Data

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Abstract. Although the knowledge of the gravity of the Earth has improved considerably with CHAMP, GRACE, and GOCE (see appendices for a list of abbreviations) satellite missions, the geophysical community has identified the need for the continued monitoring of the time-variable component with the purpose of estimating the hydrological and glaciological yearly cycles and long-term trends. Currently, the GRACE-FO satellites are the sole dedicated provider of these data, while previously the GRACE mission fulfilled that role for 15 years. There is a data gap spanning from July 2017 to May 2018 between the end of the GRACE mission and start the of GRACE-FO, while the Swarm satellites have collected gravimetric data with their GPS receivers since December 2013. We present high-quality gravity field models (GFMs) from Swarm data that constitute an alternative and independent source of gravimetric data, which could help alleviate the consequences of the 10-month gap between GRACE and GRACE-FO, as well as the short gaps in the existing GRACE and GRACE-FO monthly time series. The geodetic community has realized that the combination of different gravity field solutions is superior to any individual model and set up the Combination Service of Time-variable Gravity Fields (COST-G) under the umbrella of the International Gravity Field Service (IGFS), part of the International Association of Geodesy (IAG). We exploit this fact and deliver the highest-quality monthly GFMs, resulting from the combination of four different gravity field estimation approaches. All solutions are unconstrained and estimated independently from month to month. We tested the added value of including kinematic baselines (KBs) in our estimation of GFMs and conclude that there is no significant improvement. The non-gravitational accelerations measured by the accelerometer on board Swarm C were also included in our processing to determine if this would improve the quality of the GFMs, but we observed that is only the case when the amplitude of the non-gravitational accelerations is higher than during the current quiet period in solar activity. Using GRACE data for comparison, we demonstrate that the geophysical signal in the Swarm GFMs is largely restricted to spherical harmonic degrees below 12. A 750 km smoothing radius is suitable to retrieve the temporal variations in Earth's gravity field over land areas since mid-2015 with roughly 4 cm equivalent water height (EWH) agreement with respect to GRACE. Over ocean areas, we illustrate that a more intense smoothing with 3000 km radius is necessary to resolve large-scale gravity variations, which agree with GRACE roughly at the level of 1 cm EWH, while at these spatial scales the GRACE observes variations with amplitudes between 0.3 and 1 cm EWH. The agreement with GRACE and GRACE-FO over nine selected large basins under analysis is 0.91 cm, 0.76 cm yr−1, and 0.79 in terms of temporal mean, trend, and correlation coefficient, respectively. The Swarm monthly models are distributed on a quarterly basis at ESA's Earth Swarm Data Access (at https://swarm-diss.eo.esa.int/, last access: 5 June 2020, follow Level2longterm and then EGF) and at the International Centre for Global Earth Models (http://icgem.gfz-potsdam.de/series/02_COST-G/Swarm, last access: 5 June 2020), as well as identified with the DOI https://doi.org/10.5880/ICGEM.2019.006 (Encarnacao et al., 2019).

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“…Multipath errors will therefore show up in much the same way as phase center offsets and phase variations. Even though the exact magnitude and variation of these errors cannot reliably be predicted, experience in other space missions shows that they can well be calibrated from inflight data using, for example, a residuals stacking approach. This applies even in the case of pronounced multipath errors as present on the trailing GRACE satellite due to crosstalk between the navigation and radio‐occultation antennas.…”

Section: Impact Of Non‐common Spacecraftmentioning

confidence: 99%

Precise Orbit and Baseline Determination for the SAOCOM-CS Bistatic Radar Mission

et al. 2018

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This paper presents an overview of the SAOCOM-CS synthetic aperture radar (SAR) interferometry mission and the use of GPS/GNSS for precise orbit and baseline determination. Compared to X-band SAR interferometry missions, the use of L-band SAR in SAOCOM-CS poses less stringent (sub-centimeter rather than mm-level) requirements on the baseline accuracy. At the same time, however, the use of dissimilar spacecraft and GNSS receivers implies a less than optimal precondition for carrier phase differential GPS (CDGPS) navigation and is likely to degrade the baseline determination accuracy compared to ideal conditions. Based on GPS data collected in previous formation flying missions, the achievable baseline performance in SAOCOM-CS is assessed and recommendations for the most suitable processing scheme are given.

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Impact of GPS antenna phase center and code residual variation maps on orbit and baseline determination of GRACE

Cited by 23 publications

References 21 publications

The impact of GPS receiver modifications and ionospheric activity on Swarm baseline determination

The impact of GPS receiver modifications and ionospheric activity on Swarm baseline determination

Description of the multi-approach gravity field models from Swarm GPS data

Precise Orbit and Baseline Determination for the SAOCOM-CS Bistatic Radar Mission

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