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): Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ)
University of Nevada, Reno
Wuhan University
Federal Agency for Cartography and Geodesy (BKG)
Technische Universität Berlin
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",
}