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Time-variable gravity fields and ocean mass change from 37 months of kinematic Swarm orbits

التفاصيل البيبلوغرافية
العنوان: Time-variable gravity fields and ocean mass change from 37 months of kinematic Swarm orbits
المؤلفون: C. Lück, J. Kusche, R. Rietbroek, A. Löcher
المصدر: Solid Earth, Vol 9, Pp 323-339 (2018)
بيانات النشر: Copernicus Publications, 2018.
سنة النشر: 2018
المجموعة: LCC:Geology
LCC:Stratigraphy
مصطلحات موضوعية: Geology, QE1-996.5, Stratigraphy, QE640-699
الوصف: Measuring the spatiotemporal variation of ocean mass allows for partitioning of volumetric sea level change, sampled by radar altimeters, into mass-driven and steric parts. The latter is related to ocean heat change and the current Earth's energy imbalance. Since 2002, the Gravity Recovery and Climate Experiment (GRACE) mission has provided monthly snapshots of the Earth's time-variable gravity field, from which one can derive ocean mass variability. However, GRACE has reached the end of its lifetime with data degradation and several gaps occurred during the last years, and there will be a prolonged gap until the launch of the follow-on mission GRACE-FO. Therefore, efforts focus on generating a long and consistent ocean mass time series by analyzing kinematic orbits from other low-flying satellites, i.e. extending the GRACE time series. Here we utilize data from the European Space Agency's (ESA) Swarm Earth Explorer satellites to derive and investigate ocean mass variations. For this aim, we use the integral equation approach with short arcs (Mayer-Gürr, 2006) to compute more than 500 time-variable gravity fields with different parameterizations from kinematic orbits. We investigate the potential to bridge the gap between the GRACE and the GRACE-FO mission and to substitute missing monthly solutions with Swarm results of significantly lower resolution. Our monthly Swarm solutions have a root mean square error (RMSE) of 4.0 mm with respect to GRACE, whereas directly estimating constant, trend, annual, and semiannual (CTAS) signal terms leads to an RMSE of only 1.7 mm. Concerning monthly gaps, our CTAS Swarm solution appears better than interpolating existing GRACE data in 13.5 % of all cases, when artificially removing one solution. In the case of an 18-month artificial gap, 80.0 % of all CTAS Swarm solutions were found closer to the observed GRACE data compared to interpolated GRACE data. Furthermore, we show that precise modeling of non-gravitational forces acting on the Swarm satellites is the key for reaching these accuracies. Our results have implications for sea level budget studies, but they may also guide further research in gravity field analysis schemes, including satellites not dedicated to gravity field studies.
نوع الوثيقة: article
وصف الملف: electronic resource
اللغة: English
تدمد: 1869-9510
1869-9529
Relation: https://www.solid-earth.net/9/323/2018/se-9-323-2018.pdf; https://doaj.org/toc/1869-9510; https://doaj.org/toc/1869-9529
DOI: 10.5194/se-9-323-2018
URL الوصول: https://doaj.org/article/3725228fac30444fa66022ad848f0204
رقم الأكسشن: edsdoj.3725228fac30444fa66022ad848f0204
قاعدة البيانات: Directory of Open Access Journals
الوصف
تدمد:18699510
18699529
DOI:10.5194/se-9-323-2018