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JGR Atmospheres - 2022 - Allan - Global Changes in Water Vapor 1979 2020.pdf (1.75 MB)

Global Changes in Water Vapor 1979–2020

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journal contribution
posted on 2023-07-07, 09:36 authored by RP Allan, KM Willett, VO John, T Trent
Global-scale changes in water vapor and responses to surface temperature variability since 1979 are evaluated across a range of satellite and ground-based observations, a reanalysis (ERA5) and coupled and atmosphere-only CMIP6 climate model simulations. Global-mean column integrated water vapor increased by 1%/decade during 1988–2014 in observations and atmosphere-only simulations. However, coupled simulations overestimate water vapor trends and this is partly explained by past studies showing that internal climate variability suppressed observed warming in this period. Decreases in low-altitude tropical water vapor in ERA5 and ground-based observations before around 1993 are considered suspect based on inconsistency with simulations and increased column integrated water vapor in microwave satellite data since 1979. Atmospheric Infra-red Sounder satellite data does not capture the increased tropospheric water vapor since 2002 shown by other satellite, reanalysis, and model products. However, global water vapor responses to interannual surface temperature variability are consistent across data sets with increases of ∼4%–5% near the surface and 10%–15% at 300 hPa for each 1°C increase in global surface temperature. Global water vapor responses are explained by thermodynamic amplification of upper tropospheric temperature changes and the Clausius Clapeyron temperature dependence of saturation vapor pressure that are dominated by the tropical ocean responses. Upper tropospheric moistening is larger in climate model simulations with greater upper tropospheric warming.

Funding

National Centre for Earth Observation (RCUK). Grant Number: NE/RO16518/1

Met Office Academic Partnership

Met Office

European Organization for the Exploitation of Meteorological Satellites

Met Office Hadley Centre Climate Programme

BEIS and Defra

History

Author affiliation

School of Physics & Astronomy, University of Leicester

Version

  • VoR (Version of Record)

Published in

Journal of Geophysical Research: Atmospheres

Volume

127

Issue

12

Publisher

American Geophysical Union (AGU)

issn

2169-897X

eissn

2169-8996

Copyright date

2023

Available date

2023-07-07

Language

en

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