A Global Assessment of Diurnal Discontinuities in ERA5 Tropospheric Zenith Total Delays Using 10 Years of GNSS Data

authored by: Peng Yuan, Geoffrey Blewitt, Corné Kreemer, Weiping Jiang, Tianjun Liu, Linyu He, Qiang Shan, Kyriakos Balidakis, Harald Schuh, Jens Wickert, Zhiguo Deng
Abstract: The diurnal cycle of tropospheric Zenith Total Delays (ZTD) is critical for refining tropospheric models and understanding key geophysical and atmospheric processes. The fifth European Centre for Medium-Range Weather Forecasts reanalysis ERA5, with its unique 1-hr temporal resolution, provides valuable data for these purposes. However, we identified obvious discontinuities in ERA5-derived ZTD at 09:00 and 21:00 UTC. A comparison with 10-year GNSS data from 6,437 stations showed that 32.8% of the stations experienced discontinuities in mean diurnal anomalies of ERA5 ZTD, with an average magnitude of 2.2 mm, far exceeding the 0.3 mm hour-to-hour variations observed by GNSS. The discontinuities are more pronounced in summer and are primarily due to errors in ERA5's humidity modeling, with a few pressure-related issues limited to Antarctica. The discontinuity is attributed to the transition between ERA5's 12-hr assimilation windows and suggest that other ERA5 variables may also be impacted, warranting caution in ERA5-based diurnal cycle studies.
External Organisation(s): Section 1.1: Space Geodetic Techniques GFZ Helmholtz Centre for Geosciences Potsdam Germany
Nevada Bureau of Mines and Geology University of Nevada, Reno Reno NV USA
GNSS Research Center Wuhan University Wuhan China
Department G1: General Aspects of Geodesy and Combination of Space Techniques Federal Agency for Cartography and Geodesy Frankfurt am Main Germany
Institut für Geodäsie und Geoinformationstechnik Technische Universität Berlin Berlin Germany
Type: Article
Journal: Geophysical research letters
Volume: 52
ISSN: 0094-8276
Publication date: 08.03.2025
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Geophysics, General Earth and Planetary Sciences
Electronic version(s): https://doi.org/10.1029/2024GL113140 (Access: Unknown)
https://doi.org/10.1029/grl.v52.5 (Access: Unknown)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL113140 (Access: Unknown)

BibTeX

@article{872cf452556b4eeaa6039d532314bf5d,
title = "A Global Assessment of Diurnal Discontinuities in ERA5 Tropospheric Zenith Total Delays Using 10 Years of GNSS Data",
abstract = "The diurnal cycle of tropospheric Zenith Total Delays (ZTD) is critical for refining tropospheric models and understanding key geophysical and atmospheric processes. The fifth European Centre for Medium-Range Weather Forecasts reanalysis ERA5, with its unique 1-hr temporal resolution, provides valuable data for these purposes. However, we identified obvious discontinuities in ERA5-derived ZTD at 09:00 and 21:00 UTC. A comparison with 10-year GNSS data from 6,437 stations showed that 32.8% of the stations experienced discontinuities in mean diurnal anomalies of ERA5 ZTD, with an average magnitude of 2.2 mm, far exceeding the 0.3 mm hour-to-hour variations observed by GNSS. The discontinuities are more pronounced in summer and are primarily due to errors in ERA5's humidity modeling, with a few pressure-related issues limited to Antarctica. The discontinuity is attributed to the transition between ERA5's 12-hr assimilation windows and suggest that other ERA5 variables may also be impacted, warranting caution in ERA5-based diurnal cycle studies.",
keywords = "discontinuity, diurnal cycle, ERA5, GNSS, tropospheric delay, water vapor",
author = "Peng Yuan and Geoffrey Blewitt and Corn{\'e} Kreemer and Weiping Jiang and Tianjun Liu and Linyu He and Qiang Shan and Kyriakos Balidakis and Harald Schuh and Jens Wickert and Zhiguo Deng",
note = "Publisher Copyright: {\textcopyright} 2025. The Author(s).",
year = "2025",
month = mar,
day = "8",
doi = "10.1029/2024GL113140",
language = "English",
volume = "52",
journal = "Geophysical research letters",
issn = "0094-8276",
publisher = "Wiley-Blackwell",
number = "5",
}