Atmospheric Sciences Research Spotlight

Global Atmospheric Model Simulates Fine Details of Gravity Waves

Whole-atmosphere general circulation model captures many aspects of mesoscale gravity wave structures—down to the tens of kilometers—and resulting temperatures and tides.

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When a stable atmosphere is disturbed vertically, gravity tries to restore equilibrium, producing a wave, similar to what happens when a rock is dropped in water. So-called gravity waves play a number of important roles in the middle and upper atmosphere, where the wave amplitudes become increasingly large with decreasing air density. These roles include transferring energy and momentum from one atmospheric region to another, perturbing the densities of ions and neutral molecules, and inducing instability.

However, scientists still struggle to quantify how gravity waves are distributed and structured and how they change over time. They operate on such a large range of scales—from several kilometers to thousands of kilometers—that any one observational technique cannot completely capture them.

Liu et al. use a whole-atmosphere general circulation model that for the first time, resolves gravity waves on the mesoscale—down to the tens of kilometers level—from Earth’s surface to the lower thermosphere to try to better understand these waves’ structure, function, and impacts. This model, developed from the National Center for Atmospheric Research’s Whole Atmosphere Community Climate Model, simulates a number of gravity wave features, including their spectra, intensity, and distribution both horizontally and vertically. The authors also used the model to assess the resulting impacts on larger-scale Earth conditions such as temperatures, tides, and easterly and westerly zonal winds.

The resulting simulations suggest that the modeling generally produced realistic results. The spatial structure and magnitudes of gravity waves generally echoed those derived from temperature observations in the Sounding of the Atmosphere using Broadband Emission Radiometry satellite mission, the authors found.

Vertical winds, a proxy for gravity wave activity, grew stronger and more widespread at higher levels in the simulations, suggesting that the same holds true for gravity waves. Moreover, the model simulation also yielded daily and semidaily tides that agreed with observational data, an improvement from previous models. However, the model still could not resolve many mesoscale waves on the smallest scales (less than 100 kilometers) very well, which the authors suggest means their model can only partially capture the mesoscale waves in the middle and upper atmosphere. (Geophysical Research Letters, doi:10.1002/2014GL062468, 2014)

—Puneet Kollipara, Freelance Writer

Citation: Kollipara, P. (2015), Global atmospheric model simulates fine details of gravity waves, Eos, 96, doi:10.1029/2015EO029115. Published on 6 May 2015.

© 2015. The authors. CC BY-NC 3.0
  • Tim G. Meloche

    Establishing 3-D model dynamic atmospheric models in conjunction with gravitationally
    induced low pressure zones introduced into atmospheres by orbiting gravity
    signatures such as moons and ring structures.

    Introduction of gravitational parameters is most important to strengthening dynamic
    atmospheric 3-D models and alignment to observational data.

    My academic background is in Aerospace Engineering (1983); currently semi-retired
    and continue work in both the real estate industry and the physics department
    at the University of Windsor.

    Dr. Gordan Drake at the University of Windsor and I agree the gravitational energy input
    from each orbiting moon is known. The calculated gravitational influence from
    each moon is unique and each can be incorporated into a 3-D dynamic atmospheric
    system model.

    The relative gravity signature “size, distance and velocities” of each moon induces
    an area of low pressure in the upper atmosphere as each transits over the
    surface of Jupiter. The solar system’s gas giants including the Sun readily
    respond to orbiting gravity signature mainly due to each structure’s fluid
    nature. The transiting ocean bulge induced by our orbiting moon is a
    demonstration of gravitational energy induction here on Earth.

    A precision model of Jupiter’s moons will help determine if any gravitational
    induced intensification in the atmosphere are due to reoccurring alignments of
    moons in their transits over the atmosphere. Reoccurring alignments produce a
    gravitational pumping effect that would enhance an induced low pressure zone;
    possibly supporting an active area such as the great red spot.

    Initially a team may want to consider addressing a less complex system to model. Neptune
    has a system of orbiting gravity signatures that more readily complies with
    modeling. It’s most intriguing and interesting moon (Triton) rules the system
    with respect to relative “size, distance and velocities”. This natural feature
    will prove to be the main influence to the creation of Neptune’s unique
    transient storm system (Great Dark Spot).

    Uranus is missing a multitude of gravitational induced low pressure zones introduced into
    its atmosphere due to its lack of significant moons and ring structures.
    Therefore very little relative activity is observed in the upper atmosphere of
    Uranus.

    It is the combination of planets with a deep natural fluid structure in conjunction with
    a multitude of unique orbiting gravity signatures that help generate the
    observed upper atmospheric features created by gravitational induced low
    pressure zones in gas giants.

    Much work with atomic gravitational fluctuation within atmospheres is required in this area of research moving forward. Having the skills to model dynamic 3-D planetary systems is an advantage. I offer my assistance to you and your team to adding the gravitational parameter within the models. I
    look forward to your response.

    Best Regards,
    Tim G. Meloche