Preprints
https://doi.org/10.5194/amt-2021-54
https://doi.org/10.5194/amt-2021-54

  04 Mar 2021

04 Mar 2021

Review status: a revised version of this preprint was accepted for the journal AMT and is expected to appear here in due course.

Validation of Aeolus winds using ground-based radars in Antarctica and in northern Sweden

Evgenia Belova1, Sheila Kirkwood1, Peter Voelger1, Sourav Chatterjee2, Karathazhiyath Satheesan3, Susanna Hagelin4, Magnus Lindskog4, and Heiner Körnich4 Evgenia Belova et al.
  • 1Swedish Institute of Space Physics, Kiruna, SE-98128, Sweden
  • 2National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa, 403804, India
  • 3Department of Atmospheric Sciences, School of Marine Sciences Cochin University of Science and Technology, Cochin, Kerala, 682 016, India
  • 4Swedish Meteorological and Hydrological Institute, Norrköping, SE-60176, Sweden

Abstract. Winds measured by lidar from the Aeolus satellite are compared with winds measured by two ground-based radars, MARA in Antarctica (70.77° S, 11.73° E) and ESRAD (67.88° N, 21.10° E) in Arctic Sweden. Aeolus is a demonstrator mission to test whether winds measured by Doppler lidar from space can have sufficient accuracy to contribute to improved weather forecasting. A comprehensive programme of calibration and validation has been undertaken following the satellite launch in 2018 but, so far, direct comparison with independent measurements from the Arctic or Antarctic regions have not been made. The comparison covers heights from the low troposphere to just above the tropopause. Results for each radar site are presented separately for Rayleigh (clear) winds, Mie (cloudy) winds, summer and winter, and ascending and descending satellite tracks. Horizontally-projected line-of-sight (HLOS) winds from Aeolus, for passes within 100 km from the radar sites, are compared with HLOS winds calculated from one-hour averaged radar horizontal wind components. The agreement in most data subsets is very good, with no evidence of significant biases (< 1 m s−1). Possible biases are identified for two subsets, about −2 m s−1 for MARA/Rayleigh/descending/winter winds, about 3 m s−1 for ESRAD/Mie /ascending /winter , but these are only marginally significant. A robust significant bias of about 6 m s−1 is found for MARA/Mie/ascending/summer winds. There is also some evidence for increased random error (by about 1 m s−1) for all of the Aeolus winds at MARA in summer compared to winter. This might be related to the presence of sunlight scatter over the whole of Antarctica as Aeolus transits across it during summer.

Evgenia Belova et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2021-54', Anonymous Referee #1, 22 Apr 2021
  • RC2: 'Comment on amt-2021-54', Anonymous Referee #2, 26 Apr 2021
  • RC3: 'Comment on amt-2021-54', Anonymous Referee #3, 28 Apr 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2021-54', Anonymous Referee #1, 22 Apr 2021
  • RC2: 'Comment on amt-2021-54', Anonymous Referee #2, 26 Apr 2021
  • RC3: 'Comment on amt-2021-54', Anonymous Referee #3, 28 Apr 2021

Evgenia Belova et al.

Evgenia Belova et al.

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Short summary
Wind measurements from two radars, ESRAD in Arctic Sweden and MARA at the Indian Antarctic station Maitri, are compared with lidar winds from the ESA satellite Aeolus, July–December 2019. The aim is to check if Aeolus data processing is adequate for the sunlit conditions of polar summer. Agreement is generally good with bias in Aeolus winds < 1 m s−1 in most circumstances. The exception is a large bias (6 m s−1) when the satellite has crossed a sunlit Antarctic ice-cap before passing MARA.