Vertical structure of stratospheric water vapour trends derived from merged satellite data
Artikel i vetenskaplig tidskrift, 2014

Stratospheric water vapour is a powerful greenhouse gas. The longest available record from balloon observations over Boulder, Colorado, USA shows increases in stratospheric water vapour concentrations that cannot be fully explained by observed changes in the main drivers, tropical tropopause temperatures and methane. Satellite observations could help resolve the issue, but constructing a reliable long-term data record from individual short satellite records is challenging. Here we present an approach to merge satellite data sets with the help of a chemistry-climate model nudged to observed meteorology. We use the models' water vapour as a transfer function between data sets that overcomes issues arising from instrument drift and short overlap periods. In the lower stratosphere, our water vapour record extends back to 1988 and water vapour concentrations largely follow tropical tropopause temperatures. Lower and mid-stratospheric long-term trends are negative, and the trends from Boulder are shown not to be globally representative. In the upper stratosphere, our record extends back to 1986 and shows positive long-term trends. The altitudinal differences in the trends are explained by methane oxidation together with a strengthened lower-stratospheric and a weakened upper-stratospheric circulation inferred by this analysis. Our results call into question previous estimates of surface radiative forcing based on presumed global long-term increases in water vapour concentrations in the lower stratosphere.

Författare

M. I. Hegglin

University of Reading

D. A. Plummer

Environment Canada

T. G. Shepherd

University of Reading

J. F. Scinocca

Environment Canada

J. Anderson

Hampton University

L. Froidevaux

Jet Propulsion Laboratory, California Institute of Technology

B. Funke

CSIC - Instituto de Astrofísica de Andalucía (IAA)

D. Hurst

National Oceanic and Atmospheric Administration

A. Rozanov

University of Bremen

Joachim Urban

Chalmers, Rymd- och geovetenskap, Global miljömätteknik och modellering

T. von Clarmann

Karlsruher Institut für Technologie (KIT)

K. A. Walker

University of Toronto

H. J. Wang

Georgia Institute of Technology

S. Tegtmeier

GEOMAR - Helmholtz Zentrum für Ozeanforschung Kiel

K. Weigel

University of Bremen

Nature Geoscience

1752-0894 (ISSN) 1752-0908 (eISSN)

Vol. 7 768-776

Ämneskategorier

Meteorologi och atmosfärforskning

DOI

10.1038/ngeo2236