# Interaction of Submeso Motions in the Antarctic Stable Boundary Layer

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## Abstract

Submeso motions add complexities to the structure of the stable boundary layer. Such motions include horizontal meandering and gravity waves, in particular when the large-scale flow is weak. The coexistence and interaction of such submeso motions is investigated through the analysis of data collected in Antarctica, in persistent conditions of strong atmospheric stratification. Detected horizontal meandering is frequently associated with temperature oscillations characterized by similar time scales (30 min) at all levels (2, 4.5 and 10 m). In contrast, dirty gravity waves superimposed on horizontal meandering are detected only at the highest level, characterized by time scales of a few minutes. The meandering produces an energy peak in the low-frequency spectral range, well fitted by a spectral model previously proposed for low wind speeds. The coexistence of horizontal and vertical oscillations is observed in the presence of large wind-direction shifts superimposed on the gradual flow meandering. Such shifts are often related to the variation of the mean flow dynamics, but also to intermittent events, localized in time, which do not produce a variation in the mean wind direction and that are associated with sharp decreases in wind speed and temperature. The noisy gravity waves coexisting with horizontal meandering persist only for a few cycles and produce bursts of turbulent mixing close to the ground, affecting the exchange processes between the surface and the stable boundary layer. The results confirm the importance of sharp wind-direction changes at low wind speed in the stable atmosphere and suggest a possible correlation between observed gravity waves and dynamical instabilities modulated by horizontal meandering.

## Keywords

Gravity waves Horizontal meandering Intermittent turbulence Stable boundary layer Wind-direction variability## Notes

### Acknowledgements

This work was supported by PNRA (Progetto Nazionale di Ricerche in Antartide). We would like to acknowledge the collaboration with the Marche Region, and in particular the “Environmental assessments and authorizations, air quality and natural protection” section. We thank Dr. Karl Lapo and the three anonymous reviewers for their constructive comments that contributed to improve the quality of this manuscript.

## References

- Acevedo O, Costa F, Oliveira PES, Puhales FS, Degrazia GA, Roberti DR (2014) The influence of submeso processes on stable boundary layer similarity relationships. J Atmos Sci 71:2017–2225. https://doi.org/10.1175/JAS-D-13-0131.1 CrossRefGoogle Scholar
- Anfossi D, Oettl D, Degrazia G, Goulart A (2005) An analysis of sonic anemometer observations in low wind speed conditions. Boundary-Layer Meteorol 114:179–203. https://doi.org/10.1007/s10546-004-1984-4 CrossRefGoogle Scholar
- Anfossi D, Alessandrini S, Trini Castelli S, Ferrero E, Oettl D, Degrazia G (2006) Tracer dispersion simulation in low wind speed conditions with a new 2D Langevin equation system. Atmos Environ 40:7234–7245. https://doi.org/10.1016/j.atmosenv.2006.05.081 CrossRefGoogle Scholar
- Bates DM, Chambers JM (1992) Nonlinear models. In: Chambers JM, Hastie TJ (eds) Chapter 10 of statistical models in
*S*. Wadsworth & Brooks/Cole, BerlinGoogle Scholar - Belušic D, Güttler I (2010) Can mesoscale models reproduce meandering motions? Q J R Meteorol Soc 136:553–565. https://doi.org/10.1002/qj.606 Google Scholar
- Cava D, Schipa S, Giostra U (2005) Investigation of low-frequency perturbations induced by a steep obstacle. Boundary-Layer Meteorol 115:27–45. https://doi.org/10.1007/s10546-004-2123-y CrossRefGoogle Scholar
- Cava D, Giostra U, Katul G (2015) Characteristics of gravity waves over an antarctic ice sheet during an Austral summer. Atmosphere 6:1271–1289. https://doi.org/10.3390/atmos6091271 CrossRefGoogle Scholar
- Cava D, Mortarini L, Giostra U, Richiardone R, Anfossi D (2017) A wavelet analysis of low-wind-speed submeso motions in a nocturnal boundary layer. Q J R Meteorol Soc 143:661–669. https://doi.org/10.1002/qj.2954 CrossRefGoogle Scholar
- de Baas AF, Driedonks GM (1985) internal gravity waves in a stably stratified boundary layer. Boundary-Layer Meteorol 31:303–323. https://doi.org/10.1007/BF00120898 CrossRefGoogle Scholar
- Durden DJ, Nappo CJ, Leclerc MY, Duarte HF, Zhang G, Parker MJ, Kurzeja RJ (2013) On the impact of wavelike disturbances on turbulent fluxes and turbulence statistics in nightime conditions: a case study. Biogeosciences 10:8433–8443. https://doi.org/10.5194/bg-10-8433-2013 CrossRefGoogle Scholar
- Grinsted A, Moore JC, Jevrejeva S (2004) Applications of the cross wavelet transform and wavelet coherence to geophysical time series. Nonlinear Process Geophys 11:561–566. https://doi.org/10.5194/npg-11-561-2004 CrossRefGoogle Scholar
- Güttler I, Belušic D (2012) The nature of small-scale non-turbulent variability in a mesoscale model. Atmos Sci Lett 13:169–173. https://doi.org/10.1002/asl.382 CrossRefGoogle Scholar
- Howell FJ, Mahrt L (1997) Multiresolution flux decomposition. Boundary-Layer Meteorol 83:117–137. https://doi.org/10.1023/A:1000210427798 CrossRefGoogle Scholar
- Kaimal JC, Finnigan JJ (1994) Atmospheric boundary layer flows. Oxford University Press, New York, p 289Google Scholar
- Kolmogorov AN (1941) The local structure of turbulence in incompressible viscous fluid for very large Reynolds number. Dokl. Akad. Nauk. SSSR 30:9–13Google Scholar
- Kumar P, Foufoula-Georgiou E (1997) Wavelet analysis for geophysical applications. Rev Geophys 35(4):385–412. https://doi.org/10.1029/97RG00427 CrossRefGoogle Scholar
- Lang F, Belušic D, Siems S (2018) Observations of wind-direction variability in the nocturnal boundary layer. Boundary-Layer Meteorol 166:51–68. https://doi.org/10.1007/s10546-017-0296-4 CrossRefGoogle Scholar
- Mahrt L (2007) Weak-wind mesoscale meandering in the nocturnal boundary layer. Environ Fluid Mech 7:331–347. https://doi.org/10.1007/s10652-007-9024-9 CrossRefGoogle Scholar
- Mahrt L (2008) Mesoscale wind direction shifts in the stable boundary-layer. Tellus 60A:700–705. https://doi.org/10.1111/j.1600-0870.2008.00324.x CrossRefGoogle Scholar
- Mahrt L (2011a) The near-calm stable boundary layer. Boundary-Layer Meteorol 140:343–360. https://doi.org/10.1007/s10546-011-9616-2 CrossRefGoogle Scholar
- Mahrt L (2011b) Surface wind direction variability. J Appl Meteorol Clim 50:144–152. https://doi.org/10.1175/2010JAMC2560.1 CrossRefGoogle Scholar
- Mahrt L (2014) Stably stratified atmospheric boundary layers. Annu Rev Fluid Mech 46:23–45. https://doi.org/10.1146/annurev-fluid-010313-141354 CrossRefGoogle Scholar
- Mahrt L, Mills R (2009) Horizontal diffusion by submeso motions in the stable boundary layer. Environ Fluid Mech 9:443–456. https://doi.org/10.1007/s10652-009-9126-7 CrossRefGoogle Scholar
- Mahrt L, Richardson S, Seaman N, Stauffer D (2012) Turbulence in the nocturnal boundary layer with light and variable winds. Q J R Meteorol Soc 138:1430–1439. https://doi.org/10.1002/qj.1884 CrossRefGoogle Scholar
- Mortarini L, Anfossi D (2015) Proposal of an empirical velocity spectrum formula in low-wind speed conditions. Q J R Meteorol Soc 141:85–97. https://doi.org/10.1002/qj.2336 CrossRefGoogle Scholar
- Mortarini L, Maldaner S, Moor L, Stefanello M, Acevedo O, Degrazia G, Anfossi D (2016a) Temperature autocorrelation and spectra functions in low-wind meandering conditions. Q J R Meteorol Soc 142:1881–1889. https://doi.org/10.1002/qj.2796 CrossRefGoogle Scholar
- Mortarini L, Stefanello M, Degrazia G, Roberti D, Trini Castelli S, Anfossi D (2016b) Characterization of wind meandering in low-wind-speed conditions. Boundary-Layer Meteorol 161:165–182. https://doi.org/10.1007/s10546-016-0165-6 CrossRefGoogle Scholar
- Mortarini L, Cava D, Giostra U, Acevedo O, Nogueira Martins LG, Soares de Oliveira PE, Anfossi D (2018) Observations of submeso motions and intermittent turbulent mixing across a low level jet with a 132-m tower. Q J R Meteorol Soc 144:172–183. https://doi.org/10.1002/qj.3192 CrossRefGoogle Scholar
- Nappo CJ (2002) An introduction to atmospheric gravity waves. Academic Press, New YorkGoogle Scholar
- Nappo CJ, Sun J, Mahrt L, Belušić D (2014) Determining wave–turbulence interactions in the stable boundary layer. Bull Am Meteorol Soc 95:ES11–ES13. https://doi.org/10.1175/bams-d-12-00235.1 CrossRefGoogle Scholar
- Pasquill F (1974) Atmospheric diffusion. Wiley, London, p 429Google Scholar
- R Core Team (2017) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. https://www.R-project.org/
- Sun J, Mahrt L, Banta RM, Pichugina YL (2012) Turbulence regimes and turbulence intermittency in the stable boundary layer during CASES-99. J Atmos Sci 69:338–351. https://doi.org/10.1175/JAS-D-11-082.1 CrossRefGoogle Scholar
- Sun J, Nappo CJ, Mahrt L, Belušic D, Grisogono B, Stauffer DR, Pulido M, Staquet C, Jiang O, Pouquet A, Yagüe C, Galperin B, Smith RB, Finnigan JJ, Mayor SD, Svensson G, Grachev AA, Neff WD (2015a) Review of wave-turbulence interactions in the stable atmospheric boundary layer. Rev Geophys 53:956–993. https://doi.org/10.1002/2015RG000487 CrossRefGoogle Scholar
- Sun J, Mahrt L, Nappo C, Lenschow DH (2015b) Wind and temperature oscillations generated by wave–turbulence interactions in the stably stratified boundary layer. J Atmos Sci 72:1484–1503. https://doi.org/10.1175/JAS-D-14-0129.1 CrossRefGoogle Scholar
- Thomas C, Foken T (2005) Detection of long- term coherent exchange over spruce forest using wavelet analysis. Theor Appl Climatol 80:91–104. https://doi.org/10.1007/s00704-004-0093-0 CrossRefGoogle Scholar
- Torrence C, Compo GP (1998) A practical guide to wavelet analysis. Bull Am Meteorol Soc 79:61–78. https://doi.org/10.1175/1520-0477(1998)079%3c0061:APGTWA%3e2.0.CO;2 CrossRefGoogle Scholar
- Viana S, Terradellas S, Yague C (2010) Analysis of gravity waves generated at the top of a drainage flow. J Atmos Sci 67:3949–3966. https://doi.org/10.1175/2010JAS3508.1 CrossRefGoogle Scholar
- Vickers D, Mahrt L (2006) A solution for flux contamination by mesoscale motions with very weak turbulence. Boundary-Layer Meteorol 118:431–447. https://doi.org/10.1007/s10546-005-9003-y CrossRefGoogle Scholar