EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Water Vapour assessment using GNSS and Radiosondes and long-term trends estimation over Polar Regions

Monia Negusini1, Boyan Petkov2,3, Vincenza Tornatore4, Stefano Barindelli4, Leonardo Martelli5, Pierguido Sarti1, and Claudio Tomasi6
Monia Negusini et al.
  • 1Istituto di Radioastronomia, Istituto Nazionale di Astrofisica, 40129 Bologna, Italy
  • 2Dipartimento di Tecnologie Innovative in Medicina e Odontoiatria, Università degli Studi “G. D’Annunzio”, 66100 Chieti, Italy
  • 3Istituto di Scienze Polari, Consiglio Nazionale delle Ricerche, 40129 Bologna
  • 4Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Milano, 20133 Milano, Italy
  • 5Istituto Nazionale di Geofisica e Vulcanologia, 40128 Bologna, Italy
  • 6Istituto di Scienze dell’Atmosfera e del Clima, Consiglio Nazionale delle Ricerche, 40129 Bologna, Italy

The atmospheric humidity in the Polar Regions is an important factor for the global budget of water vapour, which is a significant indicator of Earth’s climate state and evolution. The Global Navigation Satellite System (GNSS) can make a valuable contribution in the calculation of the amount of Precipitable Water Vapour (PW). We focus on Polar Regions, especially Antarctica. 20-year GPS observations, acquired by more than 40 GNSS geodetic stations, were processed with the purpose of ensuring the utmost accuracy of the PW retrieval, adopting homogeneous, consistent, and up-to-date processing strategies. We also estimated PW from radio-sounding stations (RS), which operate Vaisala radiosondes, co-located with GNSS stations. The PW values from global atmospheric reanalysis model were used for validation and comparison, very high correlation coefficients between times series, have been highlighted both in the Arctic and Antarctica. A small dry bias of RS vs. GPS values was found in the Arctic, while no clear behaviour is present in Antarctica. The PWGPS and PWRS seasonal variations are consistent, as also confirmed by scatter plots.

After validation, long-term trends, both for Arctic and Antarctic regions, were estimated using Hector scientific software, which allows the estimation of trends from time series with temporal correlated noise. We applied a function to estimate the linear trend plus the annual/semiannual signals, and autoregressive noise model AR(1) which best fits the residuals of all investigated PW time series. We investigated also on the choice of the most suitable noise model, this study was useful in determining the residuals of the time series, once the trend and seasonal signals were subtracted. Positive PWGPS trends dominate at Arctic sites near the borders of the Atlantic Ocean. Sites located at higher latitudes show no significant values. Negative PWGPS trends were observed in the Arctic region of Greenland and North America. A similar behaviour was found in the Arctic for PWRS trends. The stations in the West Antarctic sector show a general positive PWGPS trend, while the sites on the coastal area of East Antarctica exhibit some significant negative PWGPS trends, while in most cases, no significant PWRS trends were found. The present work confirms also that GPS is also able to provide reliable estimates of water vapour content in regions where data are sparse and not easy to collect as the Arctic and Antarctic regions are.

How to cite: Negusini, M., Petkov, B., Tornatore, V., Barindelli, S., Martelli, L., Sarti, P., and Tomasi, C.: Water Vapour assessment using GNSS and Radiosondes and long-term trends estimation over Polar Regions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13470,, 2022.


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