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Gravity Waves in the Earth's Atmosphere

Observations & Analyses with MLS and Other Satellite Data

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General Information

        Gravity waves (GWs) play important roles in determining atmospheric general circulations and thermal structures [e.g., Lindzen, 1981; Holton, 1982]. The scales of most GWs are too small to be resolved by general circulation models, and therefore GW drag parameterizations are needed in global models to account for wave momentum and energy depositions in the atmosphere. Without small-scale wave forcing, for instance, the stratospheric polar vortices would be too strong and the temperature in the polar upper stratosphere would be too cold [Hamilton et al., 1994; Pawson et al., 2000; Shepherd, 2000]. The importance of GWs has also been recognized in the ozone depletion problem because of their role in enhancing polar stratospheric cloud (PSC) formation [Cariolle et al., 1989; Carslaw et al., 1998]. Our GW research has been focused to address the following scienfic questions on a global basis:
        1. What GW sources are important to the middle and upper atmosphere, and how are these sources distributed?
        2. What are the propagation and saturation properties of these GWs, and how do these properties vary with time and region?
        3. What are the impacts of these GWs on stratospheric ozone chemistry (e.g., PSCs) and transport (e.g., STE)?
        4. How are these GWs coupled to other planetary or convective scale processes?

        UARS MLS 63 GHz radiance fluctuations have been used to study global activities and distributions of meso-scale GWs in the stratosphere and mesosphere [Wu and Waters, 1996a,b].  UARS MLS GW variances are available at 8 altitudes (28, 33, 38, 43, 48, 53, 61, and 80km) and contributed mostly by waves of vertical wavelengths > ~10km due to the instrument field-of-view filtering . Depending on the truncation length used in the analysis, the derived GW variances can represent waves of horizontal wavelengths from 30km to 1000s km. For limb-scan observations, the radiances are often truncated by 3-6 measurement points to meet the saturation criteria, which yields a horizontal scale of 50-100km. For limb-tracking observations, where the radiance sequences can be orbit-long, the truncation lengths can be as long as 1000s km. UARS MLS results revealed good correlations of GW activities with stratospheric jetstreams, surface topography, and tropospheric deep convection zones. The background mean winds play a dominant role in enhancing and filtering GWs observed in the stratosphere by satellite sensors like MLS.  Over the wave conducting regions, longitudianl variations of wave activity contain valuable information on GW sources [McLandress et at, 2000; Jiang et al., 2002]. The GWs survived from the filtering in the troposphere and lower lower stratosphere are believed to have important impacts on the dynamics in the upper atmosphere.

       Aura MLS 118 GHz measurements will provide new information on GW source and propagation properties. Simulations show that these radiance measurements are quite sensitive to waves of vertical wavelengths > 5 km propagating in the south-north direction (due to the instrument pointing and Aura orbit).

       Many GW features in satellite measurements remain unexplored. Joint data analyses among different observing techniques and investigations with wave modeling will continue to provide better understanding of the roles of gravity waves in the atmosphere.

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For more MLS GW observations and instrument properties:
MLS Seasonal Maps   MLS Zonal Means Convection-induced Gravity Waves Mountain Waves Gravity Waves and Polar Stratospheric Clouds Sudden Warming and Wave Activitives MLS Weighting Functions, Sampling Patterns, and Wave Filters

Other gravity-wave related data
AMSU data New!
AIRS data New!
 MLS Cloud Measurements MLS Temperature Data (20-90 km)

MLS Publications on Gravity Wave Studies

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Contact Informationgraphic of a letter being written

Dr. Dong L. Wu                                                  Dr. Jonathan H. Jiang
Email: dwu@mls.jpl.nasa.gov                               Email: jonathan@mls.jpl.nasa.gov
Tel: 818-393-1954                                                Tel: 818-354-7135

MLS Group FAX: 818-393-5065
MLS Post Mail: M/S: 183-701, 4800 Oak Grove Drive, Pasadena, CA 91109-8099
Copyright MLS  Team JPL Caltech NASA

This page is maintained by   Jonathan H Jiang