The eruption of the submarine Hunga volcano in January 2022 was associated with a powerful blast that injected volcanic material to altitudes up to 58 km. From a combination of various types of satellite and ground-based observations supported by transport modeling, we show evidence for an unprecedented increase in the global stratospheric water mass by 13% relative to climatological levels, and a 5-fold increase of stratospheric aerosol load, the highest in the last three decades. Owing to the extreme injection altitude, the volcanic plume circumnavigated the Earth in only 1 week and dispersed nearly pole-to-pole in three months. The unique nature and magnitude of the global stratospheric perturbation by the Hunga eruption ranks it among the most remarkable climatic events in the modern observation era, with a range of potential long-lasting repercussions for stratospheric composition and climate.
[1] We report on observations of noctilucent clouds (NLCs) by a ground-based lidar located in northern Norway at 69°N, 16°E. The ALOMAR Rayleigh/Mie/Raman (RMR) lidar conducted measurements of the Arctic middle atmosphere from 1 June to 15 August during each year from 1997 to 2001. This data set contains 1122 hours of lidar observations whereof 408 hours include NLC signatures. The interannual variation of the NLC occurrence frequency shows a decrease of strong NLCs, while weak NLCs occur more frequent. The seasonal variation of the NLC occurrence shows a well pronounced core period where NLCs appeared during 43% of the time. The basic properties of NLCs are characterized by three parameters: maximum value of the volume backscatter coefficient b max (brightness), centroid altitude z c , and half width dz (thickness). A typical NLC above ALOMAR during the 5-year period reported here owns a brightness of b max = 9.6 Â 10 À10 m À1 sr À1 , an altitude of z c = 83.3 km, and a thickness of dz = 1.2 km. The interannual variation of the parameters shows a decrease of the brightness, an increase of the altitude, and a nearly constant thickness, while seasonal variability is higher than these interannual changes. During the core period, the NLCs are noticeably brighter than at the beginning as well as the end of the season. Altitude and thickness of NLCs decrease during the season.
26New capabilities for imaging small-scale instabilities and turbulence and for modeling 27 gravity wave (GW), instability, and turbulence dynamics at high Reynolds numbers are 28 employed to identify the major instabilities and quantify turbulence intensities near the summer 29 mesopause. High-resolution imaging of polar mesospheric clouds (PMCs) reveal a range of 30 instability dynamics and turbulence sources that have their roots in multi-scale GW dynamics at 31 larger spatial scales. Direct numerical simulations (DNS) of these dynamics exhibit a range of 32 instability types that closely resemble instabilities and turbulence seen in PMC imaging and by 33 ground-based and in-situ instruments at all times and altitudes. The DNS also exhibit the 34 development of "sheet-and-layer" (S&L) structures in the horizontal wind and thermal stability 35 fields that resemble observed flows near the mesopause and at lower altitudes. 36Both observations and modeling suggest major roles for GW breaking, Kelvin-Helmholtz 37 instabilities (KHI), and intrusions in turbulence generation and energy dissipation. Of these, 38 larger-scale GW breaking and KHI play the major roles in energetic flows leading to strong 39 turbulence. GW propagation and breaking can span several S&L features and induce KHI 40 ranging from GW to turbulence scales. Intrusions make comparable contributions to turbulence 41 generation as instabilities become weaker and more intermittent. Turbulence intensities are 42 highly variable in the vertical and typically span 3 or more decades. DNS results that closely 43 resemble observed flows suggest a range of mechanical energy dissipation rates of ε ~10 -3 -10 44Wkg -1 that is consistent with the range of in-situ measurements at ~80-90 km in summer. 45 46 dynamics 48 49 50 51 throughout the atmosphere for more than five decades (e.g., Panofsky
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