Water Vapour Assessment Using GNSS and Radiosondes over Polar Regions and Estimation of Climatological Trends from Long-Term Time Series Analysis

• Published in: Remote Sensing
• Main Authors: Monia Negusini, Boyan H. Petkov, Vincenza Tornatore, Stefano Barindelli, Leonardo Martelli, Pierguido Sarti, Claudio Tomasi
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2021
• Subjects: GNSS; radiosonde; ERA; precipitable water vapour; climate trends; Arctic; Science; Q; Antarctic; East Antarctica; Greenland; Hector; Antarc*; Antarctica
• Online Access: https://doi.org/10.3390/rs13234871; https://doaj.org/article/4f83e93a36e64c06a40e47dabc4d78b4

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). The PW values retrieved from Global Positioning System (GPS), hereafter PW GPS , refer to 20-year observations acquired by more than 40 GNSS geodetic stations located in the polar regions. For GNSS stations co-located with radio-sounding stations (RS), which operate Vaisala radiosondes, we estimated the PW from RS observations (PW RS ). The PW values from the ERA-Interim global atmospheric reanalysis were used for validation and comparison of the results for all the selected GPS and RS stations. The correlation coefficients between times series are very high: 0.96 for RS and GPS, 0.98 for RS and ERA in the Arctic; 0.89 for RS and GPS, 0.97 for RS and ERA in Antarctica. The Root-Mean-Square of the Error (RMSE) is 0.9 mm on average for both RS vs. GPS and RS vs. ERA in the Arctic, and 0.6 mm for RS vs. GPS and 0.4 mm for RS vs. ERA in Antarctica. After validation, long-term trends, both for Arctic and Antarctic regions, were estimated using Hector scientific software. Positive PW GPS trends dominate at Arctic sites near the borders of the Atlantic Ocean. Sites located at higher latitudes show no significant values (at 1σ level). Negative PW GPS trends were observed in the Arctic region of Greenland and North America. A similar behaviour was found in the Arctic for PW RS trends. The stations in the West Antarctic sector show a general positive PW GPS trend, while the sites on the coastal area of East Antarctica exhibit some significant negative PW GPS trends, but in most cases, no significant PW RS trends were found. The present work confirms that GPS is able to provide reliable estimates of water vapour content in Arctic and Antarctic regions too, where data are sparse and not easy to ...