Preprints
https://doi.org/10.5194/amt-2022-40
https://doi.org/10.5194/amt-2022-40
 
21 Apr 2022
21 Apr 2022
Status: a revised version of this preprint was accepted for the journal AMT and is expected to appear here in due course.

An improved vertical correction method for the inter-comparison and inter-validation of Integrated Water Vapour measurements

Olivier Bock1,2, Pierre Bosser3, and Carl Mears4 Olivier Bock et al.
  • 1Université de Paris, Institut de physique du globe de Paris, CNRS, IGN, F-75005 Paris, France
  • 2ENSG-Géomatique, IGN, F-77455 Marne-la-Vallée, France
  • 3Lab-STICC UMR 6285 CNRS / PRASYS, ENSTA Bretagne / HOP, F-29200 Brest, France
  • 4Remote Sensing Systems, Santa Rosa, California, USA

Abstract. Integrated Water Vapour (IWV) measurements from similar or different techniques are often inter-compared for calibration and validation purposes. Results are usually assessed in terms of bias (difference of the means), standard deviation of the differences, and linear fit slope and offset (intercept) estimates. When the instruments are located at different elevations, a correction must be applied to account for the vertical displacement between the sites. Empirical formulations are traditionally used for this correction. In this paper we show that the widely-used correction model based on a standard, exponential, profile for water vapour cannot properly correct the bias, slope, and offset parameters simultaneously. Correcting the bias with this model degrades the slope and offset estimates, and vice-versa. This paper proposes an improved correction model which overcomes these limitations. The model uses a multi-linear regression of slope and offset parameters from a radiosonde climatology. It is able to predict monthly parameters with a root-mean-square error smaller than 0.5 kg m-2 for height differences up to 500 m. The method is applied to the inter-comparison of GPS IWV data in a tropical mountainous area and to the inter-validation of GPS and satellite microwave radiometer data. This paper also emphasizes the need for using a slope and offset regression method that accounts for errors in both variables and for correctly specifying these errors.

Olivier Bock et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-40', Anonymous Referee #2, 10 Jun 2022
    • AC1: 'Reply on RC1', Olivier Bock, 22 Jul 2022
  • RC2: 'Comment on amt-2022-40', Anonymous Referee #3, 14 Jun 2022
    • AC2: 'Reply on RC2', Olivier Bock, 22 Jul 2022

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-40', Anonymous Referee #2, 10 Jun 2022
    • AC1: 'Reply on RC1', Olivier Bock, 22 Jul 2022
  • RC2: 'Comment on amt-2022-40', Anonymous Referee #3, 14 Jun 2022
    • AC2: 'Reply on RC2', Olivier Bock, 22 Jul 2022

Olivier Bock et al.

Data sets

Reprocessed IWV data from ground-based GNSS network during EUREC4A campaign Bock, O. https://doi.org/10.25326/79

Olivier Bock et al.

Viewed

Total article views: 492 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
359 120 13 492 4 8
  • HTML: 359
  • PDF: 120
  • XML: 13
  • Total: 492
  • BibTeX: 4
  • EndNote: 8
Views and downloads (calculated since 21 Apr 2022)
Cumulative views and downloads (calculated since 21 Apr 2022)

Viewed (geographical distribution)

Total article views: 485 (including HTML, PDF, and XML) Thereof 485 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 14 Sep 2022
Download
Short summary
Integrated Water Vapour measurements are often compared for the calibration/validation of different instruments or techniques. Measurements made from different altitudes must be corrected to account for the vertical variation of water vapour. This paper shows that the widely-used empirical correction model has severe limitations which are overcome with the proposed model. The method is applied to the inter-comparison of GPS and satellite microwave radiometer data in a tropical mountainous area.