The SPARC water vapor assessment II: intercomparison of satellite and ground-based microwave measurements
Artikel i vetenskaplig tidskrift, 2017

As part of the second SPARC (Stratosphere-troposphere Processes And their Role in Climate) water vapor assessment (WAVAS-II), we present measurements taken from or coincident with seven sites from which ground-based microwave instruments measure water vapor in the middle atmosphere. Six of the ground-based instruments are part of the Network for the Detection of Atmospheric Composition Change (NDACC) and provide datasets that can be used for drift and trend assessment. We compare measurements from these ground-based instruments with satellite datasets that have provided retrievals of water vapor in the lower mesosphere over extended periods since 1996. We first compare biases between the satellite and ground-based instruments from the upper stratosphere to the upper mesosphere. We then show a number of time series comparisons at 0.46 hPa, a level that is sensitive to changes in H2O and CH4 entering the stratosphere but, because almost all CH4 has been oxidized, is relatively insensitive to dynamical variations. Interannual variations and drifts are investigated with respect to both the Aura Microwave Limb Sounder (MLS; from 2004 onwards) and each instrument's climatological mean. We find that the variation in the interannual difference in the mean H2O measured by any two instruments is typically similar to 1%. Most of the datasets start in or after 2004 and show annual increases in H2O of 0-1% yr(-1). In particular, MLS shows a trend of between 0.5% yr(-1) and 0.7% yr(-1) at the comparison sites. However, the two longest measurement datasets used here, with measurements back to 1996, show much smaller trends of +0.1% yr(-1) (at Mauna Loa, Hawaii) and -0.1% yr(-1) (at Lauder, New Zealand).

millimeter-wave spectrometer






middle atmosphere





G.E. Nedoluha

Naval Research Laboratory

M. Kiefer

Karlsruhe Institute of Technology

Stefan Lossow

Karlsruhe Institute of Technology

R. Michael Gomez

Naval Research Laboratory

N. Kämpfer

Universitat Bern

Martin Lainer

Universitat Bern

Peter Forkman

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

Ole Martin Christensen

Rymd-, geo- och miljövetenskap

Jung Jin Oh

Sookmyung Women's University

P. Hartogh

Max Planck Institut fur Sonnensystemforschung

John Anderson

Hampton University

K. Bramstedt

University of Bremen

B. M. Dinelli

Institute of Atmospheric Sciences and Climate, Bologna

M. Garcia-Comas

CSIC - Instituto de Astrofísica de Andalucía (IAA)

M.E. Hervig

GATS, Inc.

Donal Murtagh

Mikrovågs- och optisk fjärranalys

P. Raspollini

Istituto Di Fisica Applicata Nello Carrara

W.G. Read

Jet Propulsion Laboratory, California Institute of Technology

K. H. Rosenlof

University of Colorado at Boulder

G.P. Stiller

Karlsruhe Institute of Technology

K. A. Walker

University of Toronto

Atmospheric Chemistry and Physics

1680-7316 (ISSN) 1680-7324 (eISSN)

Vol. 17 14543-14558


Meteorologi och atmosfärforskning