Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 5 2009 10.5194/acpd-9-22331-2009 http://www.atmos-chem-phys-discuss.net/9/22331/2009/ http://www.atmos-chem-phys-discuss.net/9/22331/2009/acpd-9-22331-2009.html http://www.atmos-chem-phys-discuss.net/9/22331/2009/acpd-9-22331-2009.pdf 22331 22336 2009-10-22 Comment on "Reinterpreting aircraft measurements in anisotropic scaling turbulence" by Lovejoy et al. (2009) E. Lindborg erikl@mech.kth.se K. K. Tung G. D. Nastrom J. Y. N. Cho K. S. Gage Linné Flow Centre, KTH Mechanics, 10044 Stockholm, Sweden Department of Applied Mathematics, University of Washington, Seattle, WA, USA St. Cloud State University, St. Cloud, MN, USA MIT Lincoln Laboratory, Lexington, MA, USA Cooperative Institute for the Environmental Sciences, Univ. of Colorado, Boulder, CO, USA Recently, Lovejoy et al. (2009) argued that the steep ~k−3 atmospheric kinetic energy spectrum at synoptic scales (≳1000 km) observed by aircraft is a spurious artefact of aircraft following isobars instead of isoheights. Without taking into account the earth's rotation they hypothesise that the horizontal atmospheric energy spectrum should scale as k−5/3 at all scales. We point out that the approximate k−3-spectrum at synoptic scales has been observed by a number of non-aircraft means since the 1960s and that general circulation models and other current models have successfully produced this spectrum. We also argue that the vertical movements of the aircraft are far too small to cause any strong effect on the measured spectrum at synoptic scales. Alisse, J.-M. and Sidi, C.: Experimental probability density functions of small scale fluctuations in the stably stratified atmosphere, J. Fluid. Mech., 402, 137–162, 2000. Charney, J. G.: Geostrophic turbulence, J. Atmos. Sci., 28, 1087–1095, 1971. Cho, J. Y. N. and Lindborg, E.: Horizontal velocity structure functions in the upper troposphere and lower stratosphere 1. Observations, J. Geophys. Res., 106(D10), 10223–10232, 2001. Boer, G. J. and Shepherd, T. G.: Large scale two-dimensional turbulence in the atmosphere, J. Atmos. Sci., 40, 164–184, 1984. Frehlich, R. and Sharman, R.: Climatology of velocity and temperature turbulence statistics determined from rawinsonde and ACARS/AMDAR data, Mon. Weather Rev., accepted, 2009. Hamilton, K., Takahashi, Y., and Ohfuchi, W.: The mesoscale spectrum of atmospheric motions investigated in a very fine resolution global general circulation model, J. Geophys. Res., 113, D18110, doi:10.1029/2008JD009785, 2008. Julian, P. R., Washington, W. M., Hembree, L., and Ridley, C.: On the spectral distribution of large-scale atmospheric kinetic energy, J. Atmos. Sci., 27, 376–387, 1970. Lovejoy, S., Tuck, A. F., Schertzer, D., and Hovde, S. J.: Reinterpreting aircraft measurements in anisotropic scaling turbulence, Atmos. Chem. Phys., 9, 5007–5025, 2009. Lovejoy, S., Tuck, A. F., Hovde, S. J., and Schertzer, D.: Is isotropic turbulence relevant in the atmosphere?, Geophys. Res. Lett., 34, L14802, doi:10.1029/2007GL029359, 2007. Nastrom, G. D. and Gage, K. S.: A climatology of atmospheric wavenumber spectra of wind and temperature observed by commercial aircraft, J. Atmos. Sci., 42, 950–960, 1985. Skamarock, W. C.: Evaluating mesoscale NWP models using kinetic energy spectra, Mon. Weather Rev., 132, 3019–3032, 2004. Straus, D. M. and Ditlevsen, P.: Two-dimensional turbulence properties of the ECMWF reanalyses, Tellus, 51A, 749–772, 1999. Takahashi, Y., Hamilton, K., and Ohfuchi, W.: Explicit Global Simulation of the Mesoscale Spectrum of Atmospheric Motions, Geophys. Res. Lett., 33, L12812, doi:10.1029/2006GL026429, 2006. Tung, K. K. and Orlando, W. W.: The $k^-3$ and $ k^-5/3 $ energy spectrrum of atmospheric turbulence: quasigeostrophic two-level simulation, J. Atmos. Sci., 60, 824–835, 2003. Wiin-Nielsen, A.: On the annual variation and spectral distribution of atmospheric energy, Tellus, 19, 540–559, 1967.