The SPARC water vapour assessment II: comparison of annual, semi-annual and quasi-biennial variations in stratospheric and lower mesospheric water vapour observed from satellites
Journal article, 2017

In the framework of the second SPARC (Stratosphere-troposphere Processes And their Role in Climate) water vapour assessment (WAVAS-II), the amplitudes and phases of the annual, semi-annual and quasi-biennial variation in stratospheric and lower mesospheric water were compared using 30 data sets from 13 different satellite instruments. These comparisons aimed to provide a comprehensive overview of the typical uncertainties in the observational database which can be considered in subsequent observational and modelling studies. For the amplitudes, a good agreement of their latitude and altitude distribution was found. Quantitatively there were differences in particular at high latitudes, close to the tropopause and in the lower mesosphere. In these regions, the standard deviation over all data sets typically exceeded 0.2 ppmv for the annual variation and 0.1 ppmv for the semi-annual and quasi-biennial variation. For the phase, larger differences between the data sets were found in the lower mesosphere. Generally the smallest phase uncertainties can be observed in regions where the amplitude of the variability is large. The standard deviations of the phases for all data sets were typically smaller than a month for the annual and semi-annual variation and smaller than 5 months for the quasi-biennial variation. The amplitude and phase differences among the data sets are caused by a combination of factors. In general, differences in the temporal variation of systematic errors and in the observational sampling play a dominant role. In addition, differences in the vertical resolution of the data, the considered time periods and influences of clouds, aerosols as well as non-local thermodynamic equilibrium (NLTE) effects cause differences between the individual data sets. .1 Symposia of COSPAR Scientific Commission A, held during the Thirty-first COSPAR Scientific Assembly


S. Lossow

Karlsruhe Institute of Technology (KIT)

F. Khosrawi

Karlsruhe Institute of Technology (KIT)

G.E. Nedoluha

Naval Research Laboratory

F. Azam

Universität Bremen

K. Bramstedt

Universität Bremen

J. P. Burrows

Universität Bremen

B. M. Dinelli

Institute of Atmospheric Sciences and Climate, Bologna

Patrick Eriksson

Chalmers, Earth and Space Sciences, Global Environmental Measurements and Modelling

P. J. Espy

Norwegian University of Science and Technology (NTNU)

M. Garcia-Comas

Institute of Astrophysics of Andalusia (IAA)

J. C. Gille

University of Colorado at Boulder

National Center for Atmospheric Research

M. Kiefer

Karlsruhe Institute of Technology (KIT)

S. Noël

Universität Bremen

P. Raspollini

Consiglo Nazionale Delle Richerche

W.G. Read

Jet Propulsion Laboratory, California Institute of Technology

K. H. Rosenlof

National Oceanic and Atmospheric Administration

A. Rozanov

Universität Bremen

C. E. Sioris

York University

G. P. Stiller

Karlsruhe Institute of Technology (KIT)

K. A. Walker

University of Toronto

K. Weigel

Universität Bremen

Atmospheric Measurement Techniques

1867-1381 (ISSN) 1867-8548 (eISSN)

Vol. 10 3 1111-1137

Subject Categories

Earth and Related Environmental Sciences



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