Small-Scale Motions Observed by Aircraft in the Tropical Lower Stratosphere: Evidence for Mixing and its Relationship to Large-Scale Flows

Pfister, Leonhard; Starr, W. L.; Craig, R. A.; Loewenstein, M.; Legg, M.

doi:10.1175/1520-0469(1986)043<3210:ssmoba>2.0.co;2

Cited by 44 publications

(33 citation statements)

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“…Hicks, 1969;Dutton and Panofsky, 1970;Browning et al, 1970;Browning, 1971;Browning et al, 1972), instrumented aircraft (e.g. Roach, 1969;Axford, 1970Axford, , 1973P®ster et al, 1986) and patterns in cirrus cloud (e.g. Reiter and Nania, 1964;Ludlam, 1967;Young, 1971;Hill, 1951), generally in regions of high wind shear, and also in the mesosphere by Reid et al (1987).…”

Section: Instability Of Long-period Wavesmentioning

confidence: 99%

Long-period unstable gravity-waves and associated VHF radar echoes

Worthington

Thomas

1997

Ann. Geophys.

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Abstract. VHF atmospheric radar is used to measure the wind velocity and radar echo power related to longperiod wind perturbations, including gravity waves, which are observed commonly in the lower stratosphere and tropopause region, and sometimes in the troposphere. These wind structures have been identi®ed previously as either inertia-gravity waves, often associated with jet streams, or mountain waves. At heights of peak wind shear, imbalances are found between the echo powers of a symmetric pair of radar beams, which are expected to be equal. The largest of these power di erences are found for conditions of simultaneous high wind shear and high aspect sensitivity. It is suggested that the e ect might arise from tilted specular re¯ectors or anisotropic turbulent scatterers, a result of, for example, Kelvin-Helmholtz instabilities generated by the strong wind shears. This radar power-di erence e ect could o er information about the onset of saturation in long-period waves, and the formation of thin layers of turbulence.

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Section: Instability Of Long-period Wavesmentioning

confidence: 99%

Long-period unstable gravity-waves and associated VHF radar echoes

Worthington

Thomas

1997

Ann. Geophys.

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“…Simultaneous ozone mixing ratio (Xo 3 ) measurements along the flight path [Proffitt et ai, 1989] show a very high degree of correlation with temperature (T) observations by the MMS, a property noted by Pfister et al [1986] in a similar set of measurements. The Flight 9 band-pass filtered data show this coherency quite clearly.…”

Section: Coherency Of Ozone and Temperature Measurementsmentioning

confidence: 99%

Gravity wave momentum flux in the lower stratosphere over convection

Alexander

Pfister

1995

Geophysical Research Letters

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159

104

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Abstract. This work describes a method for estimating vertical fluxes of horizontal momentum carried by short horizontal scale gravity waves (X x = 10-100 km) using aircraft measured winds in the lower stratosphere. We utilize the in situ wind vector and pressure altitude measurements provided by the Meteorological Measurement System (MMS) on board the ER-2 aircraft to compute the momentum flux vectors at the flight level above deep convection during the tropical experiment of the Stratosphere Troposphere Exchange Project (STEP-Tropical). Data from Flight 9 are presented here for illustration. The vertical flux of horizontal momentum in these observations points in opposite directions on either side of the location of a strong convective updraft in the cloud shield. This property of internal gravity waves propagating from a central source compares favorably with previously described model results.

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“…Gravity waves are triggered by a variety of sources. The most prominent sources are orography (Smith, 1985;Durran and Klemp, 1987;Nastrom and Fritts, 1992) and convection (Pfister et al, 1986;Tsuda et al, 1994;Alexander and Pfister, 1995). Other sources include the adjustment of unbalanced flows near jet streams and frontal systems (Fritts and Alexander, 2003;Wu and Zhang, 2004).…”

Section: Introductionmentioning

confidence: 99%

A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation

et al. 2017

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Abstract. Atmospheric gravity waves yield substantial small-scale temperature fluctuations that can trigger the formation of polar stratospheric clouds (PSCs). This paper introduces a new satellite record of gravity wave activity in the polar lower stratosphere to investigate this process. The record is comprised of observations of the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite from January 2003 to December 2012. Gravity wave activity is measured in terms of detrended and noise-corrected 15 µm brightness temperature variances, which are calculated from AIRS channels that are the most sensitive to temperature fluctuations at about 17-32 km of altitude. The analysis of temporal patterns in the data set revealed a strong seasonal cycle in wave activity with wintertime maxima at mid-and high latitudes. The analysis of spatial patterns indicated that orography as well as jet and storm sources are the main causes of the observed waves. Wave activity is closely correlated with 30 hPa zonal winds, which is attributed to the AIRS observational filter. We used the new data set to evaluate explicitly resolved temperature fluctuations due to gravity waves in the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis. It was found that the analysis reproduces orographic and non-orographic wave patterns in the right places, but that wave amplitudes are typically underestimated by a factor of 2-3. Furthermore, in a first survey of joint AIRS and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite observations, nearly 50 gravity-wave-induced PSC formation events were identified. The survey shows that the new AIRS data set can help to better identify such events and more generally highlights the importance of the process for polar ozone chemistry.

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Small-Scale Motions Observed by Aircraft in the Tropical Lower Stratosphere: Evidence for Mixing and its Relationship to Large-Scale Flows

Cited by 44 publications

References 0 publications

Long-period unstable gravity-waves and associated VHF radar echoes

Long-period unstable gravity-waves and associated VHF radar echoes

Gravity wave momentum flux in the lower stratosphere over convection

A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation

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