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
Author
S. Lossow
Karlsruhe Institute of Technology, Campus North
F. Khosrawi
Karlsruhe Institute of Technology, Campus North
G.E. Nedoluha
Naval Research Laboratory
F. Azam
University of Bremen
K. Bramstedt
University of Bremen
J. P. Burrows
University of 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
Norges Teknisk-Naturvitenskapelige Universitet
M. Garcia-Comas
CSIC - Instituto de Astrofísica de Andalucía (IAA)
J. C. Gille
National Center for Atmospheric Research
University of Colorado at Boulder
M. Kiefer
Karlsruhe Institute of Technology, Campus North
S. Noël
University of Bremen
P. Raspollini
Consiglio Nazionale delle Ricerche
W.G. Read
Jet Propulsion Laboratory, California Institute of Technology
K. H. Rosenlof
National Oceanic and Atmospheric Administration
A. Rozanov
University of Bremen
C. E. Sioris
York University
G. P. Stiller
Karlsruhe Institute of Technology, Campus North
K. A. Walker
University of Toronto
K. Weigel
University of Bremen
Atmospheric Measurement Techniques
1867-1381 (ISSN) 1867-8548 (eISSN)
Vol. 10 3 1111-1137Subject Categories (SSIF 2011)
Earth and Related Environmental Sciences
DOI
10.5194/amt-10-1111-2017