ESA TND

Background:

Satellite geodetic missions such as CHAMP (2000-2010), GRACE (2002-2017), GOCE (2009-2013), GRACE Follow-On (GRACE-FO, launched in 2018), and Swarm (launched in 2013) are equipped with accelerometer to measure non-gravitational forces acting on their surface. The dominant portion of these forces is due to the atmospheric drag, which are used to estimate Thermosphere Neutral Density (TND) along-track of satellites with very high temporal rates.

Great attempts have already been taken to produce along-track TND products from these missions, using accelerometer measurements or Precise Orbit Determination (POD) data, from which those of along Swarm and GRACE(-FO) track TNDs are the official products of Swarm DISC. Accelerometer-derived TNDs are typically delivered very ~3 months, and TUDelft routinely produces the POD-derived Swarm TNDs, currently, on monthly basis with a latency of about three weeks. Extending these along-track data to produce a new multi-(altitude)-level global thermospheric neutral density products is desirable for many geodetic applications and for re-processing space weather events.

Main aim of the project:

In this work, we propose to leverage the publicly available along-track Swarm and GRACE(-FO) along-track TND data, and producing the following L3 data and modelling tools: 1- Global TND data, e.g., with 1 ͦ spatial resolution covering the altitudes of 150 – 450 km; 2- Calibration parameters to adjust the TND outputs of common empirical models such as NRLMSISE00 and NRLMSIS2 to simulate 3D TNDs that are consistent with those of Swarm and GRACE(-FO); or alternatively, a new model that incorporates the calibrated parameters providing TNDs on any satellite tracks or globally on user-defined grids and altitudes. Therefore, unlike other available global (assimilative) products, our proposed product (in 1) or model (in 2) is based purely on openly available data, which makes it reproducible. Besides, the Swarm and GRACE(-FO) data provides high temporal resolution, as well as dense spatial resolution in the latitudinal (North/South) direction, which likely results in producing more accurate global TND estimates (Forootan et al., 2019, 2021).

An overview of the implementation steps of the ESA TND (2022) by the ESA Swarm DISC (ESA Contract No. 4000109587/13/I-NB), see details here.

An overview of the Thermosphere Neutral Density (TND) changes during the famous geomagnetic storm of March 2015 (around 18th). The results are shown for the altitude of 250 km. Swarm-C is applied to tune the NRLMSISE00 and bring it closer to the reality. This is a part of a Technical Report, where more details can be found here.

Project members:

  • External Team Members:
    • Claudia Borries (German Aerospace Center, DLR, Neustrelitz, Germany)
    • Timothy Kodikara (German Aerospace Center, DLR, Neustrelitz, Germany)
    • Eelco Doornbos (KNMI: De Bilt, Utrecht, Netherlands)
    • Christian Siemes (Delft University of Technology, Netherlands)
    • Saeed Farzaneh (University of Tehran)
    • Mona Kosary (University of Tehran)

Publications:

Dataset:

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