Water vapour (\(H_2 O\)) is one of the key species that is measured by both ACE-FTS and ACE-MAESTRO and has a significant role in atmospheric chemistry. Water vapour volume mixing ratio profiles are compared with space-borne as well as ground based and balloon-borne instruments. Comparisons are also made between ACE-FTS and ACE-MAESTRO.

A two-part paper published in 2016 (Sioris et al., 2016) discusses the upper tropospheric water vapour variability (UTWV) at high latitudes. In part I the influence of the Arctic Oscillation (AO) or Northern Annular Mode (NAM) and the Antarctic Oscillation (AAO) or Southern Annular Mode (SAM) on the monthly variability of water vapour in the northern and southern high latitudes is explained. Dynamical variability via the annular modes has been shown here to strongly affect UTWV at high latitudes. Apart from the seasonal cycle, the Antarctic oscillation is a dominant mode of variability in upper tropospheric (∼ 8 km) water vapour at southern high latitudes on a seasonal timescale, and the Arctic oscillation explains most of the variability in wintertime UTWV at northern high latitudes.

In part II the impact of volcanic eruptions on the UTWV is discussed. The Puyehue– Cordón Caulle volcanic eruption in June 2011 was the most explosive in the past 24 years and is shown to be able to account for the observed (50 ± 12) % increase in water vapour in the southern high-latitude upper troposphere in July 2011 after a minor adjustment for the simultaneous influence of the Antarctic oscillation. Eyjafjallajökull erupted in the spring of 2010, increasing water vapour in the upper troposphere at northern high latitudes significantly for a period of ∼ 1 month. These findings imply that extratropical volcanic eruptions in windy environments can lead to significant perturbations to high-latitude UTWV mostly due to entrainment of lower tropospheric moisture by windblown plumes.

References

Sioris, C. E., et al. (2016), Upper tropospheric water vapour variability at high latitudes – Part 1: Influence of the annular modes, Atmos. Chem. Phys., Vol. 16, pp. 3265-3278

Sioris, C. E., et al. (2016), Water vapour variability in the high-latitude upper troposphere – Part 2: Impact of volcanic eruptions, Atmos. Chem. Phys., Vol. 16, pp. 2207-2219