Journal cover Journal topic
Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 3.400 IF 3.400
  • IF 5-year value: 3.841 IF 5-year
    3.841
  • CiteScore value: 3.71 CiteScore
    3.71
  • SNIP value: 1.472 SNIP 1.472
  • IPP value: 3.57 IPP 3.57
  • SJR value: 1.770 SJR 1.770
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 70 Scimago H
    index 70
  • h5-index value: 49 h5-index 49
Volume 9, issue 6
Atmos. Meas. Tech., 9, 2545–2565, 2016
https://doi.org/10.5194/amt-9-2545-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Meas. Tech., 9, 2545–2565, 2016
https://doi.org/10.5194/amt-9-2545-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 09 Jun 2016

Research article | 09 Jun 2016

A two-dimensional Stockwell transform for gravity wave analysis of AIRS measurements

Neil P. Hindley1, Nathan D. Smith1, Corwin J. Wright1, D. Andrew S. Rees2, and Nicholas J. Mitchell1 Neil P. Hindley et al.
  • 1Centre for Space, Atmosphere and Ocean Science, University of Bath, Bath, UK
  • 2Department of Mechanical Engineering, University of Bath, Bath, UK

Abstract. Gravity waves (GWs) play a crucial role in the dynamics of the earth's atmosphere. These waves couple lower, middle and upper atmospheric layers by transporting and depositing energy and momentum from their sources to great heights. The accurate parameterisation of GW momentum flux is of key importance to general circulation models but requires accurate measurement of GW properties, which has proved challenging. For more than a decade, the nadir-viewing Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite has made global, two-dimensional (2-D) measurements of stratospheric radiances in which GWs can be detected. However, one problem with current one-dimensional methods for GW analysis of these data is that they can introduce significant unwanted biases. Here, we present a new analysis method that resolves this problem. Our method uses a 2-D Stockwell transform (2DST) to measure GW amplitudes, horizontal wavelengths and directions of propagation using both the along-track and cross-track dimensions simultaneously. We first test our new method and demonstrate that it can accurately measure GW properties in a specified wave field. We then show that by using a new elliptical spectral window in the 2DST, in place of the traditional Gaussian, we can dramatically improve the recovery of wave amplitude over the standard approach. We then use our improved method to measure GW properties and momentum fluxes in AIRS measurements over two regions known to be intense hotspots of GW activity: (i) the Drake Passage/Antarctic Peninsula and (ii) the isolated mountainous island of South Georgia. The significance of our new 2DST method is that it provides more accurate, unbiased and better localised measurements of key GW properties compared to most current methods. The added flexibility offered by the scaling parameter and our new spectral window presented here extend the usefulness of our 2DST method to other areas of geophysical data analysis and beyond.

Publications Copernicus
Download
Short summary
Gravity waves are medium-sized momentum-carrying atmospheric waves that nearly all weather and climate models struggle to represent. Thus, the accurate global measurement of gravity-wave properties in the real atmosphere is of key importance. Here we use a new two-dimensional Stockwell transform (2-DST) method to measure key GW properties in 2-D satellite data. We show that our 2-DST approach greatly improves upon current methods, particularly if a new elliptical spectral window is used.
Gravity waves are medium-sized momentum-carrying atmospheric waves that nearly all weather and...
Citation