Accession Number:



The Sparc Water Vapour Assessment II: Comparison of Stratospheric and Lower Mesospheric Water Vapour Time Series Observed from Satellites

Descriptive Note:

Journal Article - Open Access

Corporate Author:


Report Date:


Pagination or Media Count:



Time series of stratospheric and lower mesospheric water vapour using 33 data sets from 15 different satellite instruments were compared in the framework of the second SPARC Stratosphere-troposphere Processes And their Role in Climate water vapour assessment WAVAS-II. This comparison aimed to provide a comprehensive overview of the typical uncertainties in the observational database that can be considered in the future in observational and modelling studies, e.g addressing stratospheric water vapour trends. The time series comparisons are presented for the three latitude bands, the Antarctic 80 degrees-70 degrees S, the tropics 15 degrees S-15 degrees N and the Northern Hemisphere mid-latitudes 50 degrees-60 degrees N at four different altitudes 0.1, 3, 10 and 80 hPa covering the stratosphere and lower mesosphere. The combined temporal coverage of observations from the 15 satellite instruments allowed the consideration of the time period 1986-2014. In addition to the qualitative comparison of the time series, the agreement of the data sets is assessed quantitatively in the form of the spread i.e. the difference between the maximum and minimum volume mixing ratios among the data sets, the Pearson correlation coefficient and the drift i.e. linear changes of the difference between time series over time. Generally, good agreement between the time series was found in the middle stratosphere while larger differences were found in the lower mesosphere and near the tropopause. Concerning the latitude bands, the largest differences were found in the Antarctic while the best agreement was found for the tropics. From our assessment we find that most data sets can be considered in future observational and modelling studies, e.g. addressing stratospheric and lower mesospheric water vapour variability and trends, if data set specific characteristics e.g. drift and restrictions e.g. temporal and spatial coverage are taken into account

Subject Categories:

  • Atmospheric Physics

Distribution Statement: