Preprints
https://doi.org/10.5194/amt-2024-60
https://doi.org/10.5194/amt-2024-60
02 May 2024
 | 02 May 2024
Status: this preprint is currently under review for the journal AMT.

The GRAS-2 Radio Occultation Mission

Joel Rasch, Anders Carlström, Jacob Christensen, and Thomas Liljegren

Abstract. The second generation of the Global navigation satellite system Receiver for Atmospheric Sounding (GRAS-2) is a Radio Occultation (RO) instrument which is capable of providing 2000 atmospheric profiles per day. The instrument is hosted on all satellites in the Metop Second Generation (Metop-SG) series for polar orbit operation. The GRAS-2 instruments provide occultation measurements from the Galileo, GPS and BeiDou satellites at their common frequencies centred at 1575.42 MHz (L1) and 1176.45 MHz (L5). Using high-gain antennas and an ultra-stable oscillator, neutral bending angles are measured at an unprecedented accuracy of 0.3–0.4 µrad which is better than the requirement of less than 0.5 µrad. The RO signal will be measured deep into the troposphere using a novel open loop tracking scheme utilizing multiple correlator outputs for operation with a tailored ground processing algorithm optimized for extracting signals with low amplitudes approaching the noise floor limitation. Ionosphere measurements to an altitude of 600 km are also acquired.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Joel Rasch, Anders Carlström, Jacob Christensen, and Thomas Liljegren

Status: open (until 22 Jun 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
Joel Rasch, Anders Carlström, Jacob Christensen, and Thomas Liljegren
Joel Rasch, Anders Carlström, Jacob Christensen, and Thomas Liljegren

Viewed

Total article views: 138 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
107 23 8 138 8 5
  • HTML: 107
  • PDF: 23
  • XML: 8
  • Total: 138
  • BibTeX: 8
  • EndNote: 5
Views and downloads (calculated since 02 May 2024)
Cumulative views and downloads (calculated since 02 May 2024)

Viewed (geographical distribution)

Total article views: 137 (including HTML, PDF, and XML) Thereof 137 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 29 May 2024
Download
Short summary
Soon the Metop Second Generation (Metop-SG) series of polar orbiting meteorological satellite will be launched. On these satellites the GRAS-2 instrument will be mounted. It will provide GNSS radio occultation measurements with unsurpassed accuracy. The occultation measurements are used routinely for numerical weather prognosis, i.e. predicting the weather. In this paper we describe the design of this new instrument and the novel methods developed to process the data.