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Session Overview
P13: The future: extended mission, future missions - posters
Monday, 20/Mar/2017:
6:00pm - 7:00pm

Session Chair: Nils Olsen
Session Chair: Giuseppe Ottavianelli

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Improvements in Crustal Field Modeling with Swarm at Lower Altitudes

Patrick Alken1, Arnaud Chulliat1, Stavros Kotsiaros2

1University of Colorado at Boulder, Boulder, CO, USA; 2NASA Goddard Space Flight Center, Greenbelt, MD, USA

Lowering the Swarm pair A and C is assumed to be necessary for new advances in crustal field modeling. To our knowledge, no one has yet quantified how much improvement can be gained from lower altitudes. In this work, we will construct a realistic Swarm dataset at a lower altitude using several years of actual Swarm ephemeris, and reducing the altitudes by about 100km. The data will be corrected for main and ionospheric field effects at the lower altitude. MF7 will be subtracted from the nominal Swarm data, and a high-degree synthetic crustal field model will be added to the lower altitude data. The resulting dataset will contain a known synthetic high-degree crustal field, as well as realistic external fields. The lower altitude dataset will be inverted using east-west gradients between Swarm A and C to determine how much of the known crustal field can be recovered at the lower altitude.

Lowering SWARM’s AC Satellites and Implications for Studying Ocean Circulation

Neesha Regmi Schnepf1, Manoj Nair1, Patrick Alken1, Arnaud Chulliat1, Alexey Kuvshinov2

1University of Colorado Boulder, United States of America; 2Institute of Geophysics, ETH Zürich, Switzerland

Decreasing the altitude of the Swarm pair A and C for the upcoming solar minimum may be very beneficial for magnetic detection of ocean circulation. Simulations of magnetic induction due to ocean circulation predict most oceanic areas would have an increase in signal strength of 10-20% should A and C lower to a 350 altitude orbit. Regions along the Antarctic Circumpolar Current, North Pacific Gyre and North Atlantic Gyre may see a 100+% improvement in signal strength should the satellites decrease to a 350 altitude orbit.

Besides discussing the predicted field strength at different orbital altitudes, we will attempt to determine the minimum threshold circulation signal strength needed for recovery from gradient data. We will process the current altitude SWARM data to concentrate on signals of ocean variability by applying the following corrections: 1) Subtracting a model of the Earth’s internal magnetic field and removing time-varying contributions from the core, as well as a significant portion of the static crustal field; 2) subtracting time-varying models of the ionospheric and magnetospheric contributions; 3) subtracting the oceanic tidal signal.

To this dataset, we will add the signal produced from the forward model to strengthen the circulation signal. Pairs of fully processed repeated tracks will then be subtracted from each other in order to remove any remaining static contributions. By altering the strength of the forward model results added to the data, we can evaluate the minimum threshold circulation signal strength needed for recovery from this gradient data and recommend the orbit altitude to achieve that.

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Conference: Swarm 2017
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