3 edition of Gravity wave momentum flux in the lower stratosphere over convection found in the catalog.
Gravity wave momentum flux in the lower stratosphere over convection
by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, D.C, Springfield, Va
Written in English
|Statement||M. Joan Alexander, Leonhard Pfister.|
|Series||NASA contractor report -- NASA CR-200038.|
|Contributions||Pfister, Leonhard., United States. National Aeronautics and Space Administration.|
|The Physical Object|
A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation Lars Hoffmann 1, Reinhold Spang 2, Andrew Orr 3, M. Joan Alexander 4, Laura A. Holt 4, and Olaf Stein 1 1 Jülich Supercomputing Centre, Forschungszentrum Jülich, Jülich, Germany 2 Institut für Energie- und Klimaforschung, Forschungszentrum Jülich, Jülich, Germany. From these procedures, we found that the gravity waves identified in the OH images were mainly propagating southward or southeastward with horizontal wavelengths of 60–90 km and apparent phase speeds of 40–80 m/s. The estimated momentum fluxes on this night was 1–15 m2 s−2, with an average of m2 s− by:
Gravity waves are also found to vary as wave sources change. At tropical regions (especially in the summer hemisphere), convectively generated gravity waves increase due to enhanced deep convection following SSW. At higher latitudes, orographic waves vary during SSW as the wind changes extend from the stratosphere down into the by: 1. • The gravity-wave drag is so strong that it reverses the winter-to-summer-pole temperature gradient in the upper mesosphere • Summer mesopause is the coldest region on Earth! • Reversal of winds above implies the gravity-wave induced torques are acting to accelerate the flow Cold summer mesopause Shepherd ( Chem. Rev.).
Gravity waves and convection A&OS C/C - Spring, Parcel displaced vertically in Wave trapping leads to downslope windstorms, jumps, lee waves. Idealized simulation of ﬂow over Laguna Mountains (in San Diego Cty), where a station reported a 91 mph gust. Blue contours: isentropes (K); black contours: wind speed (mph). changes. Gravity wave parameterizations require detailed information on global variations in the spectrum of wave vertical flux of horizontal pseudomomentum, hereafter referred to as simply momentum flux. Important known sources for gravity waves include topography, convection, and unbalanced winds. Waves emanating from these sources.
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Get this from a library. Gravity wave momentum flux in the lower stratosphere over convection. [M Joan Alexander; Leonhard Pfister; United States.
National Aeronautics and Space Administration.]. Absolute momentum flux at 18 UTC as a function of (top) ground-based phase speed and as a function of (bottom) horizontal wave number.
The spectra are shown in area-preserving form.  Using the model output, gravity wave ray tracing was undertaken in order to study the temporal variation of wave fluxes in the MLT. Because we do not know the. To determine the morphology of inertial gravity wave (IGW) activity in the lower stratosphere (18–25 km) over Northern China and provide observational data constraints for IGW parameterization in atmospheric circulation models, the seasonal variation and longitudinal distribution of IGW parameters were analyzed statistically using 4 years (–) of radiosonde data from 20 Cited by: 1.
Radiosonde observations made from Davis station, Antarctica, (°S, °E) between and are used to compile a climatology of lower stratosphere inertial gravity wave characteristics. Wavelet analysis extracts single wave packets from Cited by: T.P. Lane, in Encyclopedia of Atmospheric Sciences (Second Edition), Impacts.
Gravity waves generated by convection have important impacts on the surrounding atmosphere. As described above, convective gravity waves in the troposphere can influence the morphology and longevity of convective systems and thereby play key roles in the dynamics of moist and dry convection.
 The Tropical Warm Pool International Cloud Experiment campaign centered on Darwin (12°S, °E) in northern Australia in January–February provided an opportunity to study gravity wave generation by convection and the associated wave propagation and momentum transport.
In this study, we discuss wave generation by a single mesoscale convective system (MCS) that occurred on Cited by: On the Intermittency of Gravity Wave Momentum Flux in the Stratosphere Article (PDF Available) in Journal of the Atmospheric Sciences 69(11) April with Reads How we measure 'reads'.
Gravity Wave Momentum Flux Lower Stratosphere Middle Atmosphere Vertical Wavelength These keywords were added by machine and not by the authors.
This process is experimental and the keywords may be updated as the learning algorithm by: A study of the dynamics of the equatorial lower stratosphere by use of ultra-long-duration balloons, 2, Gravity waves events to the total gravity-wave momentum flux, and show that only a small.
momentum-ﬂux probability density functions (pdfs). Recent studies have shown that pdfs of gravity wave potential energy (Baumgaertner and McDonald ) andmomentumﬂux(Alexanderetal)inthelower stratosphere exhibit broad tails that are associated with the occurrence of rare but intense gravity wave events.
The median momentum flux increases linearly with background wind speed: for winds stronger than 50 m s −1, the median gravity wave momentum fluxes are about 4 times larger than for winds weaker than 10 m s −1.
From model output, this relation is found to be relevant from the tropopause to the midstratosphere at by: 8.
The balloon dataset is used to map the geographic variability of gravity wave momentum fluxes in the lower stratosphere. This flux distribution is found to be very heterogeneous with the largest time-averaged value (28 mPa) observed above the Antarctic Peninsula.
This value exceeds by a factor of ∼10 the overall mean momentum flux measured Cited by: The majority of the waves observed in the lower stratosphere couple energy and momentum upward into the middle and upper atmosphere.
Largest momentum fluxes are observed over regions of high topography, but these regions have the greatest wave : Carmen J. Nappo. Abstract: The momentum fluxes of the lower-stratosphere gravity wave over Tibetan Plateau (TP) are analyzed on the base of three reanalysis data, i.e., data from an ensemble Kalman filter (EnKF) data assimilation system by using the ARW-WRF model, ERA-Interim global reanalysis data and ERA5 reanalysis data.
The diurnal low-stratosphere wave. –By conveying momentum from lower altitudes [source] to high altitudes [sink] waves link different altitude regimes in Earth's atmosphere (troposphere, stratosphere, mesosphere, thermosphere) • Wave sources are mostly located in the troposphere and tropopause • Waves are excited by many different sources - convection, weather.
convection. Therefore, our gravity wave analysis fo-cuses on the stratosphere. The remainder of the paper is set out as follows. Section 2 describes the Omega-sonde soundings that form the basis of our inertia–gravity wave analysis.
These soundings are decomposed into a background ﬂow and a perturbation that we identify as the gravity. Momentum in the moist convective process descends toward the stable layer, resulting in mass accumulation near the surface, as simultaneously, the updraft within the strengthening moist convection penetrates into the lower stratosphere.
The mesoscale gravity wave(s) is(are) initiated/maintained as the negative buoyancy perturbation and descent Author: Paul Samuel Suffern. geographic variability of gravity wave momentum fluxes in the lower stratosphere.
This flux distribution is found to be very heterogeneous with the largest time-averaged value (28 mPa) observed above the Ant-arctic Peninsula. This value exceeds by a factor of 10 the overall mean momentum flux measured during the balloon campaign.
The fluid returns to its original shape, overshoots and oscillations then set in which propagate as waves. Gravity or buoyancy is the restoring force hence the term - gravity waves. These waves (internal gravity or buoyancy waves) abound in the stable density layering of the upper atmosphere.
Gravity waves are also found to vary as wave sources change. At tropical region (especially in the summer hemisphere), convectively generated gravity waves increase due to enhanced deep convection following SSW.
At higher latitudes, orographic waves vary during SSW as the wind changes extend from the stratosphere down into the troposphere. anisms that generate them, such as flow over topography and convection are also poorly resolved processes, so even those waves resolved in GCMs may not be realistic.
The properties (e.g., horizontal and vertical wavelength and propagation direction) of a gravity wave or gravity-wave packet influences the group velocity and dissipation of the waves.) using the wave parameters estimated by Sato.
The height region of the MU radar observa-tion is, however, limited up to about 22 km in the lower stratosphere, although MST radars provid-ing accurate momentum flux estimates are an ideal observational tool to File Size: 2MB.eﬁects.
Recent observations discussed in section 3 show that gravity wave momentum °uxes in the lower stratosphere can vary considerably in individual measurements and can be traced to speciﬂc wave sources. The measurements also show seasonal and latitudinal patterns that may begin to describe a climatology.
Climate change may result in long.