Preprints
https://doi.org/10.5194/egusphere-2023-1246
https://doi.org/10.5194/egusphere-2023-1246
18 Jul 2023
 | 18 Jul 2023

Estimating the refractivity bias of Formosat-7/COSMIC-II GNSS Radio Occultation in the planetary boundary layer

Gia Huan Pham, Shu-Chih Yang, Chih-Chien Chang, Shu-Ya Chen, and Cheng-Yung Huang

Abstract. FORMOSAT-7/COSMIC-2 radio occultation (RO) measurements are promising for observing the deep troposphere and providing critical information on the Earth's planetary boundary layer (PBL). However, refractivity retrieved in the low troposphere can have severe bias under certain thermodynamic conditions. This research examines the characteristics of bias in the low troposphere and presents methods for estimating the region-dependent bias using regression models. The results show that the bias has characteristics that vary with land and oceans. With substantial correlation between local spectral width (LSW) and bias, the LSW-based bias estimation model can explain the general pattern of the refractivity bias but with deficiencies in measuring the bias in the ducting regions and certain areas over land. The estimation model involving the relationship with temperature and specific humidity can capture the bias of large amplitude associated with ducting. Finally, a minimum variance estimation that combines the benefits of the individual estimation provides the most accurate estimation of the refractivity bias.

Gia Huan Pham, Shu-Chih Yang, Chih-Chien Chang, Shu-Ya Chen, and Cheng-Yung Huang

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1246', Richard Anthes, 04 Oct 2023
  • RC2: 'Comment on egusphere-2023-1246', Anonymous Referee #2, 06 Dec 2023
    • AC2: 'Reply on RC2', Shu-Chih Yang, 13 Feb 2024
Gia Huan Pham, Shu-Chih Yang, Chih-Chien Chang, Shu-Ya Chen, and Cheng-Yung Huang
Gia Huan Pham, Shu-Chih Yang, Chih-Chien Chang, Shu-Ya Chen, and Cheng-Yung Huang

Viewed

Total article views: 410 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
284 112 14 410 11 9
  • HTML: 284
  • PDF: 112
  • XML: 14
  • Total: 410
  • BibTeX: 11
  • EndNote: 9
Views and downloads (calculated since 18 Jul 2023)
Cumulative views and downloads (calculated since 18 Jul 2023)

Viewed (geographical distribution)

Total article views: 403 (including HTML, PDF, and XML) Thereof 403 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 01 Mar 2024
Download
Short summary
This research examines the characteristics of low-level GNSS radio occultation (RO) refractivity bias over ocean and land and their dependency on the RO retrieval uncertainty, atmospheric temperature, and moisture. We proposed methods for estimating the region-dependent refractivity bias. Our methods can be applied to calibrate the bias under different atmospheric conditions and thus improves the applications of the GNSS RO data in the planetary boundary layer.