Responses of polar mesospheric cloud brightness to stratospheric gravity waves at the South Pole and Rothera, Antarctica

Chu, Xinzhao; Yamashita, Chihoko; Espy, P. J.; Nott, G. J.; Jensen, E. J.; Liu, Hanli; Huang, Wentao; Thayer, J. P.

doi:10.1016/j.jastp.2008.10.002

Cited by 25 publications

(31 citation statements)

References 43 publications

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“…This anticorrelation for short period gravity waves has been confirmed by lidar measurements at the South Pole (Chu et al, 2009) and in Sondrestrom, Greenland (Thayer et al, 2003;Gerrard et al, 2004). On the contrary, no such anticorrelation was found in Rothera, Antarctica (Chu et al, 2009), Davis, Antarctica (Innis et al, 2008) and ALOMAR, Norway (Schöch, 2007). The applied methodology was basically the same at all locations: density fluctuations in the stratosphere serve as a measure for gravity wave activity, which is then correlated to mesospheric cloud parameters.…”

Section: Introductionmentioning

confidence: 74%

Gravity wave influence on NLC: experimental results from ALOMAR, 69° N

Wilms

Rapp

Hoffmann³

et al. 2013

Atmos. Chem. Phys.

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Abstract. The influence of gravity waves on noctilucent clouds (NLC) at ALOMAR (69 • N) is analysed by relating gravity wave activity to NLC occurrence from commonvolume measurements. Gravity wave kinetic energies are derived from MF-radar wind data and filtered into different period ranges by wavelet transformation. From the dataset covering the years 1999-2011, a direct correlation between gravity wave kinetic energy and NLC occurrence is not found, i.e., NLC appear independently of the simultaneously measured gravity wave kinetic energy. In addition, gravity wave activity is divided into weak and strong activity as compared to a 13 yr mean. The NLC occurrence rates during strong and weak activity are calculated separately for a given wave period and compared to each other. Again, for the full dataset no dependence of NLC occurrence on relative gravity wave activity is found. However, concentrating on 12 h of NLC detections during 2008, we do find an NLC-amplification with strong long-period gravity wave occurrence. Our analysis hence confirms previous findings that in general NLC at ALOMAR are not predominantly driven by gravity waves while exceptions to this rule are at least possible.

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Section: Introductionmentioning

confidence: 74%

Gravity wave influence on NLC: experimental results from ALOMAR, 69° N

Wilms

Rapp

Hoffmann³

et al. 2013

Atmos. Chem. Phys.

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“…In this section we analyze two cases where fishbone structures are seen in temperature data measured by an Fe Boltzmann temperature lidar at Arrival Heights (166.69°E, 77.84°S) near McMurdo, Antarctica (Chu et al, ; Chu, Huang, et al, ; Chu, Yu, et al, ). For the cases shown here, we derive the temperatures from the pure Rayleigh scattering region at z ∼ 30–70 km using the Rayleigh integration technique (Alexander et al, ; Chu et al, ; Fong et al, ; Kaifler et al, ; Klekociuk et al, ; Lu et al, , ; Wilson et al, ; Yamashita et al, ; Zhao et al, ). All lidar data used here have 1‐hr temporal resolution and 1‐km vertical resolution.…”

Section: Secondary Gws Within Fishbone Structures In Mcmurdo Lidar Datamentioning

confidence: 99%

The Excitation of Secondary Gravity Waves From Local Body Forces: Theory and Observation

et al. 2018

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We examine the characteristics of secondary gravity waves (GWs) excited by a localized (in space) and intermittent (in time) body force in the atmosphere. This force is a horizontal acceleration of the background flow created when primary GWs dissipate and deposit their momentum on spatial and temporal scales of the wave packet. A broad spectrum of secondary GWs is excited with horizontal scales much larger than that of the primary GW. The polarization relations cause the temperature spectrum of the secondary GWs generally to peak at larger intrinsic periods τIr and horizontal wavelengths λH than the vertical velocity spectrum. We find that the one‐dimensional spectra (with regard to frequency or wave number) follow lognormal distributions. We show that secondary GWs can be identified by a horizontally displaced observer as “fishbone” or “>” structures in z − t plots whereby the positive and negative GW phase lines meet at the “knee,” zknee, which is the altitude of the force center. We present two wintertime cases of lidar temperature measurements at McMurdo, Antarctica (166.69°E, 77.84°S) whereby fishbone structures are seen with zknee=43 and 52 km. We determine the GW parameters and density‐weighted amplitudes for each. We show that these parameters are similar below and above zknee. We verify that the GWs with upward (downward) phase progression are downward (upward) propagating via use of model background winds. We conclude that these GWs are likely secondary GWs having ground‐based periods τr=6–10 hr and vertical wavelengths λz=6–14 km, and that they likely propagate primarily southward.

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“…If average temperatures are already below the frost point like at polar latitudes, a (small) change in frost point temperature does not change the NLC occurrence rate. A similar argument has been published with respect to the influence of gravity wave activity on southern hemisphere NLC, with the larger influence being observed at lower latitudes [ Chu et al ., ].…”

Section: Conclusion and Summarymentioning

confidence: 99%

Noctilucent cloud variability and mean parameters from 15 years of lidar observations at a mid‐latitude site (54°N, 12°E)

et al. 2013

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[1] Noctilucent clouds (NLC) are an important tracer of temperature and dynamics of the summer mesopause region. Our site at Kühlungsborn (Germany, 54 N) is at the equatorward edge of the NLC region and therefore of special interest for the understanding of these clouds. 41 nights (63 h) of NLC are observed since 1997. They form the largest lidar data set from mid-latitudes. NLC are typically weak, with nearly 70% having a backscatter coefficient b max,532nm < 2 Á 10 À10 m À1 sr À1 . The seasonal variation of NLC shows maximum occurrence around the temperature minimum (saturation maximum) but lower temperatures (higher saturation) at the beginning compared to the end of the season. Mean centroid altitude is 82.7 AE 0.03 km, with strong NLC being typically lower and vertically thinner compared to weak clouds.

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Responses of polar mesospheric cloud brightness to stratospheric gravity waves at the South Pole and Rothera, Antarctica

Cited by 25 publications

References 43 publications

Gravity wave influence on NLC: experimental results from ALOMAR, 69° N

Gravity wave influence on NLC: experimental results from ALOMAR, 69° N

The Excitation of Secondary Gravity Waves From Local Body Forces: Theory and Observation

Noctilucent cloud variability and mean parameters from 15 years of lidar observations at a mid‐latitude site (54°N, 12°E)

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