Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.509 IF 5.509
  • IF 5-year value: 5.689 IF 5-year
    5.689
  • CiteScore value: 5.44 CiteScore
    5.44
  • SNIP value: 1.519 SNIP 1.519
  • SJR value: 3.032 SJR 3.032
  • IPP value: 5.37 IPP 5.37
  • h5-index value: 86 h5-index 86
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 161 Scimago H
    index 161
Discussion papers
https://doi.org/10.5194/acp-2019-28
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-2019-28
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 22 Jan 2019

Research article | 22 Jan 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).

Consistency and representativeness of integrated water vapour from ground-based GPS observations and ERA-Interim reanalysis

Olivier Bock1 and Ana C. Parracho2 Olivier Bock and Ana C. Parracho
  • 1IPGP, IGN, ENSG, Universite Paris Diderot, Sorbonne Paris Cite, UMR 7154 CNRS, Paris, France
  • 2LATMOS-IPSL, CNRS UMR8190, Sorbonne Université, Paris, France

Abstract. This study examines the consistency and representativeness differences of daily IWV data from ERA-Interim reanalysis and GPS observations at 120 global sites over a 16-year period (1995–2010). Various comparison statistics are analysed as a function of geographic, topographic, and climatic features. A small (±1 kg m−2) bias is found in the reanalysis across latitudes (moist in northern and southern mid-latitudes and dry in the tropics). The standard deviation of daily IWV differences is generally below 2 kg m−2 but peaks in the northern and southern storm-tracks regions. In general, the larger IWV differences are explained by increased representativeness errors, when GPS observations capture some small-scale variability that is not resolved by the reanalysis. A representativeness error statistic is proposed which measures the spatiotemporal variability in the vicinity of the GPS sites, based on reanalysis data at the four surrounding grid points. It allows to predict the standard deviation of daily IWV differences with a correlation of 0.73. In general, representativeness differences can be reduced by temporal averaging and spatial interpolation from the four surrounding grid points. A small number of outlying cases (15 sites) which don’t follow the general tendencies are further examined. It is found that their special topographic and climatic features strongly enhance the representativeness errors (e.g. steep topography and coast-lines, strong seasonal cycle in monsoon regions). Discarding these sites significantly improves the global ERA-Interim and GPS comparison results. The selection of site a priori, based on the representativeness error statistic, is able to detect 11 out of the 15 sites and improve the comparison results by 20 to 30 %.

Olivier Bock and Ana C. Parracho
Interactive discussion
Status: open (extended)
Status: open (extended)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement
Olivier Bock and Ana C. Parracho
Data sets

Global GPS IWV data at 120 stations of IGS permanent network O. Bock https://doi.org/10.14768/06337394-73a9-407c-9997-0e380dac5591

Olivier Bock and Ana C. Parracho
Viewed  
Total article views: 222 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
180 42 0 222 10 0 1
  • HTML: 180
  • PDF: 42
  • XML: 0
  • Total: 222
  • Supplement: 10
  • BibTeX: 0
  • EndNote: 1
Views and downloads (calculated since 22 Jan 2019)
Cumulative views and downloads (calculated since 22 Jan 2019)
Viewed (geographical distribution)  
Total article views: 183 (including HTML, PDF, and XML) Thereof 182 with geography defined and 1 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
No discussed metrics found.
Latest update: 20 Apr 2019
Publications Copernicus
Download
Short summary
We examine the consistency of global IWV data from ERA-Interim reanalysis and 16 years of GPS observations. Representativeness differences are found to be a dominant error source, with a strong dependence on geographic, topographic, and climatic features, which explain both average and extreme differences. A methodology for reducing the representativeness errors and detecting the extreme, outlying, cases is discussed.
We examine the consistency of global IWV data from ERA-Interim reanalysis and 16 years of GPS...
Citation