EGU2020-19821, updated on 04 Jun 2020
https://doi.org/10.5194/egusphere-egu2020-19821
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Exploring long-term satellite observations of global 3-D gravity wave characteristics in the stratosphere

Neil Hindley1, Corwin Wright1, Lars Hoffmann2, Tracy Moffat-Griffin3, M. Joan Alexander4, and Nicholas Mitchell1
Neil Hindley et al.
  • 1Centre for Space, Atmospheric and Oceanic Sciences, University of Bath, Bath, UK (n.hindley@bath.ac.uk)
  • 2Jülich Supercomputing Centre, Forschungszentrum Jülich, Jülich, Germany (l.hoffmann@fz-juelich.de)
  • 3Atmosphere, Ice and Climate Group, British Antarctic Survey, Cambridge, UK
  • 4NorthWest Research Associates, Boulder, Colorado, USA

Atmospheric gravity waves are a fundamental component of the Earth’s dynamical system. These mesoscale waves play a key role in the coupling of different atmospheric layers, acting as crucial drivers of the middle atmospheric circulation through the transport and deposition of energy and momentum. As Global Circulation Models (GCMs) achieve ever higher resolution in the stratosphere, there is a need to ensure that the simulated gravity waves resolved in these models are well constrained by observations, which in turn ensures that modelled circulations are realistic and not over-dependent on tuning with parameterisations. However, obtaining 3-D gravity-wave measurements in the real atmosphere is notoriously difficult. Global 3-D observations of wave properties in the stratosphere are required in order to accurately estimate gravity wave fluxes that can be compared to models. Here we analyse a unique long-term satellite dataset of specialised high-resolution 3-D temperature measurements from NASA’s AIRS/Aqua instrument from 2002-2020. By analysing these data with a 3-D Stockwell transform (3DST) using high-performance computing, we can reveal global distributions of gravity-wave amplitudes, wavelengths, intermittency and directional momentum fluxes in the stratosphere across two decades - the largest such 3-D study of stratospheric gravity waves performed yet. This long-term dataset reveals solar-cycle variability of gravity-wave amplitudes in the tropics, significant reductions in gravity-wave fluxes during southern Sudden Stratospheric Warmings (SSWs) and the persistent oblique propagation of wintertime gravity waves into the southern polar vortex around 60S each year, a phenomenon that is not observed in the northern hemisphere. With these new observations we can begin to better constrain simulated gravity waves and their impacts in GCMs, ultimately leading to better forecasts of weather and climate.

How to cite: Hindley, N., Wright, C., Hoffmann, L., Moffat-Griffin, T., Alexander, M. J., and Mitchell, N.: Exploring long-term satellite observations of global 3-D gravity wave characteristics in the stratosphere, EGU General Assembly 2020, Online, 4–8 May 2020, https://doi.org/10.5194/egusphere-egu2020-19821, 2020

Comments on the presentation

AC: Author Comment | CC: Community Comment | Report abuse

Presentation version 1 – uploaded on 08 May 2020
  • CC1: Comment on EGU2020-19821, Paul Pukite, 15 May 2020

    Interesting that the region near the southern Andes is an origin of gravity wave momentum transfer for the earth, with strong annual and semi-annual impulses.

    Regarding the Drake Passage near the southern Andes, Woodworth and Hibbert (Ocean Science, vol. 14, no. 4, pp. 711–730, 2018) were able to extract the long-period tidal forcing from bottom-pressure readings. These long-period tides can then be used to calibrate the forcings used to drive ENSO and other climate dipole cycles. Crucially, impulses of an annual and semi-annual cycle are required to amplify the tidal cycles to generate the correct synchronizaton.  

    https://geoenergymath.com/2019/02/25/long-period-tides/

    Cheers!