Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 13983-13998, 2017
https://doi.org/10.5194/acp-17-13983-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
24 Nov 2017
Data assimilation of GNSS zenith total delays from a Nordic processing centre
Magnus Lindskog1, Martin Ridal1, Sigurdur Thorsteinsson2, and Tong Ning3 1Swedish Meteorological and Hydrological Institute, Norrköping, Sweden
2Icelandic Meteorological Office, Reykjavík, Iceland
3Lantmäteriet, Gävle, Sweden
Abstract. Atmospheric moisture-related information estimated from Global Navigation Satellite System (GNSS) ground-based receiver stations by the Nordic GNSS Analysis Centre (NGAA) have been used within a state-of-the-art kilometre-scale numerical weather prediction system. Different processing techniques have been implemented to derive the moisture-related GNSS information in the form of zenith total delays (ZTDs) and these are described and compared. In addition full-scale data assimilation and modelling experiments have been carried out to investigate the impact of utilizing moisture-related GNSS data from the NGAA processing centre on a numerical weather prediction (NWP) model initial state and on the ensuing forecast quality. The sensitivity of results to aspects of the data processing, station density, bias-correction and data assimilation have been investigated. Results show benefits to forecast quality when using GNSS ZTD as an additional observation type. The results also show a sensitivity to thinning distance applied for GNSS ZTD observations but not to modifications to the number of predictors used in the variational bias correction applied. In addition, it is demonstrated that the assimilation of GNSS ZTD can benefit from more general data assimilation enhancements and that there is an interaction of GNSS ZTD with other types of observations used in the data assimilation. Future plans include further investigation of optimal thinning distances and application of more advanced data assimilation techniques.

Citation: Lindskog, M., Ridal, M., Thorsteinsson, S., and Ning, T.: Data assimilation of GNSS zenith total delays from a Nordic processing centre, Atmos. Chem. Phys., 17, 13983-13998, https://doi.org/10.5194/acp-17-13983-2017, 2017.
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Short summary
Atmospheric moisture-related information obtained from Global Navigation Satellite System (GNSS) observations from ground-based receiver stations of the Nordic GNSS Analysis Centre (NGAA) has been used within a state-of-the-art kilometre-scale numerical weather prediction system. The sensitivity of results to aspects of the data processing, observation density, bias-correction and data assimilation has been investigated. Results show a benefit on forecast quality of using GNSS ZTD.
Atmospheric moisture-related information obtained from Global Navigation Satellite System (GNSS)...
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