Comparison of the CMAM30 data set with ACE-FTS and OSIRIS: polar regions

摘要

CMAM30 is a 30-year data set extending from 1979 to 2010that is generated using a version of the Canadian Middle Atmosphere Model(CMAM) in which the winds and temperatures are relaxed to the InterimReanalysis product from the European Centre for Medium-Range WeatherForecasts (ERA-Interim). The data set has dynamical fields that are veryclose to the reanalysis below 1 hPa and chemical tracers that areself-consistent with respect to the model winds and temperature. The chemicaltracers are expected to be close to actual observations. The data set is herecompared to two satellite records – the Atmospheric Chemistry ExperimentFourier transform spectrometer and the Odin Optical Spectrograph and InfraredImaging System – for the purpose of validating the temperature, ozone, watervapour and methane fields. Data from the Aura microwave limb sounder are alsoused for validation of the chemical processing in the polar vortex. It isfound that the CMAM30 temperature is warmer by up to 5 K in thestratosphere, with a low bias in the mesosphere of ~ 5–15 K. Ozone isreasonable (±15 %), except near the tropopause globally and in theSouthern Hemisphere winter polar vortex. Water vapour is consistently low by10–20 %, with corresponding high methane of 10–20 %, except in theSouthern Hemisphere polar vortex. Discrepancies in this region are shown tostem from the treatment of polar stratospheric cloud formation in the model.