Trends of atmospheric water vapour in Switzerland from ground-based radiometry, FTIR and GNSS data

Bernet, Leonie; Brockmann, Elmar; von Clarmann, Thomas; Kämpfer, Niklaus; Mahieu, Emmanuel; Mätzler, Christian; Stober, Gunter; Hocke, Klemens (2020). Trends of atmospheric water vapour in Switzerland from ground-based radiometry, FTIR and GNSS data. Atmospheric Chemistry and Physics, 20(19), pp. 11223-11244. 10.5194/acp-20-11223-2020

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Vertically integrated water vapour (IWV) is expected to increase globally in a warming climate. To determine whether IWV increases as expected on a regional scale, we present IWV trends in Switzerland from ground-based remote sensing techniques and reanalysis models, considering data for the time period 1995 to 2018. We estimate IWV trends from a ground-based microwave radiometer in Bern, from a Fourier transform infrared (FTIR) spectrometer at Jungfraujoch, from reanalysis data (ERA5 and MERRA-2) and from Swiss ground-based Global Navigation Satellite System (GNSS) stations. Using a straightforward trend method, we account for jumps in the GNSS data, which are highly sensitive to instrumental changes. We found that IWV generally increased by 2 % per decade to 5 % per decade, with deviating trends at some GNSS stations. Trends were significantly positive at 17 % of all GNSS stations, which often lie at higher altitudes (between 850 and 1650 m above sea level). Our results further show that IWV in Bern scales to air temperature as expected (except in winter), but the IWV–temperature relation based on reanalysis data in the whole of Switzerland is not clear everywhere. In addition to our positive IWV trends, we found that the radiometer in Bern agrees within 5 % with GNSS and reanalyses. At the Jungfraujoch high-altitude station, we found a mean difference of 0.26 mm (15 %) between the FTIR and coincident GNSS data, improving to 4 % after an antenna update in 2016. In general, we showed that ground-based GNSS data are highly valuable for climate monitoring, given that the data have been homogeneously reprocessed and that instrumental changes are accounted for. We found a response of IWV to rising temperature in Switzerland, which is relevant for projected changes in local cloud and precipitation processes.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Applied Physics
08 Faculty of Science > Institute of Applied Physics > Microwaves

UniBE Contributor:

Bernet, Leonie Anna Luisa; Stober, Gunter and Hocke, Klemens

Subjects:

600 Technology > 620 Engineering
500 Science
500 Science > 530 Physics

ISSN:

1680-7324

Language:

English

Submitter:

Simone Corry

Date Deposited:

12 Mar 2021 09:22

Last Modified:

12 Mar 2021 10:33

Publisher DOI:

10.5194/acp-20-11223-2020

BORIS DOI:

10.48350/153015

URI:

https://boris.unibe.ch/id/eprint/153015

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