We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Variability of Water Vapor in the Tropical Middle Atmosphere Observed From Satellites and Interpreted Using SD‐WACCM Simulations.
- Authors
Yu, Wandi; Garcia, Rolando; Yue, Jia; Russell, James; Mlynczak, Martin
- Abstract
Water vapor in the middle atmosphere plays an essential role in global warming, ozone depletion, and the formation of polar stratospheric and mesospheric clouds. We show that tropical middle atmospheric water vapor simulated with the specified‐dynamics version of the Whole Atmosphere Community Climate Model (SD‐WACCM) is consistent with changes observed in a merged satellite data set, which encompasses the period 1993–2020. Consistent with previous work, we find no significant trend in the stratosphere in either the observations or the simulation; in the mesosphere, we find a long‐term trend of 0.1 ppmv per decade, but only in the observations. We also analyze an SD‐WACCM simulation for the longer period 1980–2019 to quantify the contribution of various factors to the decadal variation of middle atmospheric water vapor. Over 1980–1995, the simulated water vapor in the upper stratosphere and mesosphere, averaged zonally and over ±30° latitude, increases by 0.30 ppmv per decade due to increasing methane emissions. After 1995, a significant abrupt decrease of water vapor of 0.37 ppmv per decade and then a gradual increase of 0.33 ppmv per decade result from changes in stratospheric cold point temperature. The cold‐point temperature is strongly influenced by the strength of the Brewer‐Dobson circulation. The acceleration of the Brewer‐Dobson circulation before about 2003 leads to a cooler tropical tropopause and a decrease of water vapor, and the deceleration thereafter leads to corresponding warming of the tropopause and an increase in water vapor. Plain Language Summary: Water vapor in the middle atmosphere is important to global warming and ozone depletion. We analyze both satellite data and climate model output to understand its variation in the past four decades. We conclude that there is a slight increasing trend in observed mesospheric water vapor, but no significant trend in stratospheric water vapor. Model simulation results indicate that methane oxidation explains most of the increase of water vapor in the upper stratosphere and mesosphere over 1980–1995. Changes in the meridional circulation of the middle atmosphere lead to changes in the tropical tropopause temperature, which is the main factor that influences middle atmospheric water vapor over 1995–2020. Key Points: Our paper focuses on the long‐term trend and decadal variation of water vapor in the tropical middle atmosphereMethane oxidation explains most of the water vapor increases in the upper stratosphere and mesosphere over 1980–1995Changes in residual circulation lead to changes in the tropical tropopause temperature, and middle atmospheric water vapor over 1995–2020
- Subjects
MIDDLE atmosphere; WATER vapor; ATMOSPHERIC water vapor; NOCTILUCENT clouds; OZONE layer; QUASI-biennial oscillation (Meteorology); OZONE layer depletion
- Publication
Journal of Geophysical Research. Atmospheres, 2022, Vol 127, Issue 13, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2022JD036714