Impacts of a sudden stratospheric warming on the mesospheric metal layers. (September 2017)

• Record Type: Journal Article
• Authors: Feng, Wuhu; Kaifler, Bernd; Marsh, Daniel R.; Höffner, Josef; Hoppe, Ulf-Peter; Williams, Bifford P.; Plane, John M.C.
• Is Part Of: Journal of atmospheric and solar-terrestrial physics. Volume 162(2017)
• Page Start: 162
• Page End: 171
• Publication Date: 2017-09
• Subjects: Sudden stratospheric warming -- Mesospheric metal layers -- Lidar observations -- Whole atmosphere model; Geophysics -- Periodicals; Atmospheric physics -- Periodicals; Géophysique -- Périodiques; Météorologie physique -- Périodiques; Electronic journals; 551.51
• DOI: 10.1016/j.jastp.2017.02.004
• Languages: English
• ISSNs: 1364-6826

Abstract

Abstract: We report measurements of atomic sodium, iron and temperature in the mesosphere and lower thermosphere (MLT) made by ground-based lidars at the ALOMAR observatory (69°N, 16°E) during a major sudden stratospheric warming (SSW) event that occurred in January 2009. The high resolution temporal observations allow the responses of the Na and Fe layers to the SSW at high northern latitudes to be investigated. A significant cooling with temperatures as low as 136 K around 90 km was observed on 22–23 January 2009, along with substantial depletions of the Na and Fe layers (an ~80% decrease in the column abundance with respect to the mean over the observation period). The Whole Atmosphere Community Climate Model (WACCM) incorporating the chemistry of Na, Fe, Mg and K, and nudged with reanalysis data below 60 km, captures well the timing of the SSW, although the extent of the cooling and consequently the depletion in the Na and Fe layers is slightly underestimated. The model also predicts that the perturbations to the metal layers would have been observable even at equatorial latitudes. The modelled Mg layer responds in a very similar way to Na and Fe, whereas the K layer is barely affected by the SSW because of the enhanced conversion of K + ions to K atoms at the very low temperatures. Highlights: Substantial depletion of the Na and Fe mesospheric layers is observed during a major SSW event. A whole atmosphere model shows that this is caused by SSW-driven cooling in the MLT, and the impact extends to the tropics. The response of the K layer is predicted to be much smaller than Na, Fe and Mg.