Decadal variations in atmospheric water vapor time series estimated using ground-based GNSS
Fadwa Alshawaf, Galina Dick, Stefan Heise, Tzvetan Simeonov, Sibylle Vey, Torsten Schmidt, and Jens Wickert
GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
Received: 02 May 2016 – Accepted for review: 13 May 2016 – Discussion started: 20 May 2016
Abstract. Ground-based GNSS (Global Navigation Satellite Systems) have efficiently been used since the 1990s as a meteorological observing system. Recently scientists used GNSS time series of precipitable water vapor (PWV) for climate research. In this work, we use time series from GNSS, European Center for Medium-Range Weather Forecasts Reanalysis (ERA-Interim) data, and meteorological measurements to evaluate climate evolution in Central Europe. The assessment of climate change requires monitoring of different atmospheric variables such as temperature, PWV, precipitation, and snow cover. PWV time series were obtained by three methods: 1) estimated from ground-based GNSS observations using the method of precise point positioning, 2) inferred from ERA-Interim data, and 3) determined based on daily surface measurements of temperature and relative humidity. The other variables are available from surface meteorological stations or received from ERA-Interim. The PWV trend component estimated from GNSS data strongly correlates with that estimated from the other data sets. The linear trend is estimated by straight line fitting over 30 years of seasonally-adjusted PWV time series obtained using meteorological measurements. The results show a positive trend in the PWV time series at more than 60 GNSS sites with an increase of 0.3–0.6 mm/decade. In this paper, we compare the results of three stations. The temporal increment of the PWV correlates with the temporal increase in the temperature levels.
Alshawaf, F., Dick, G., Heise, S., Simeonov, T., Vey, S., Schmidt, T., and Wickert, J.: Decadal variations in atmospheric water vapor time series estimated using ground-based GNSS, Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-151, 2016.