Diurnal changes in middle atmospheric H₂O and O₃: Observations in the Alpine region and climate models

Abstract

[1] In this paper we investigate daily variations in middle atmospheric water vapor and ozone based on data from two ground-based microwave radiometers located in the Alpine region of Europe. Temperature data are obtained from a lidar located near the two stations and from the SABER experiment on the TIMED satellite. This unique set of observations is complemented by three different three-dimensional (3-D) chemistry-climate models (Monitoring of Stratospheric Depletion of the Ozone Layer (MSDOL), Laboratoire de Météorologie Dynamique Reactive Processes Ruling the Ozone Budget in the Stratosphere (LMDz-REPROBUS), and Solar Climate Ozone Links (SOCOL)) and the 2-D atmospheric global-scale wave model (GSWM). The first part of the paper is focused on the first Climate and Weather of the Sun-Earth System (CAWSES) tidal campaign that consisted of a period of intensive measurements during September 2005. Variations in stratospheric water vapor are found to be in the order of 1% depending on altitude. Meridional advection of tidal nature is likely to be the dominant driving factor throughout the whole stratosphere, while vertical advection becomes more important in the mesosphere. Observed ozone variations in the upper stratosphere and lower mesosphere show amplitudes of several percent in accordance with photochemical models. Variations in lower stratospheric ozone are not solely governed by photochemistry but also by dynamics, with the temperature dependence of the photochemistry becoming more important. The second part presents an investigation of the seasonal dependence of daily variations. Models tend to underestimate the H 2 O diurnal amplitudes, especially during summer in the upper stratosphere. Good agreement between models and observations is found for ozone in the upper stratosphere, which reflects the fact that the O 3 daily variations are driven by the photochemistry that is well modeled.

Diurnal ozone variations in the stratosphere revealed in observations from the Superconducting Submillimeter‐Wave Limb‐Emission Sounder (SMILES) on board the International Space Station (ISS)

“…These three different regimes create a distinct altitude-latitude dependency in the amplitude and phase of the diurnal ozone variations in the stratosphere. The existence of tidal transport has been suggested previously [Huang et al, 1997;Haefele et al, 2008], but it has been confirmed and quantified for the first time here.…”

“…Haefele et al [2008] examined diurnal ozone variations in the stratosphere using data from both ground radiometer measurements at Payerne (47 N, 7 E) and two chemical climate models (CCMs). They found that in the middle stratosphere, ozone levels peak during the afternoon (approximately 3%) possibly due to photochemical factor and that this variation agrees well with the results from the CCMs.…”

Daily ozone cycle in the stratosphere: global, regional and seasonal behaviour modelled with the Whole Atmosphere Community Climate Model

“…For instance, in the upper stratosphere we assume a growing influence on ozone photochemistry from the HO x and Cl x cycles. From observations it is known that the behaviour of the daily ozone cycle is different at other altitudes (Haefele et al, 2008;Studer et al, 2014). A comprehensive understanding can be achieved by further analysis of chemistry-climate simulation data.…”

“…Connor et al (1994) presented diurnal variation in stratospheric and mesospheric ozone from 9 months of observations of a groundbased microwave radiometer at Oroville, California. Haefele et al (2008) found a daily ozone cycle in the observations of the Ground-based Millimeter-wave Ozone Spectrometer (GROMOS) which operates at Bern, Switzerland as part of Network for the Detection of Atmospheric Composition Change (NDACC). Later, Studer et al (2014) derived a monthly climatology of diurnal variation in stratospheric and mesospheric ozone from 17 years of GROMOS observations.…”

The Network for the Detection of Atmospheric Composition Change (NDACC): History, status and perspectives

“…Note that QBO and the solar cycle, indicators of natural phenomena that affect stratospheric ozone amounts, are also shown. Ground-based microwave instruments provide continuous measurements of ozone, and can thus provide 15 information on diurnal variations in ozone (Haefele et al, 2008;Parrish et al, 2014). This is of particular value for helping to interpret satellite measurements which drift in local time.…”