Errant inferences of gravity wave momentum and heat fluxes using airglow and lidar instrumentation: Corrections and cautions

Fritts, David C.

doi:10.1029/2000jd900312

Cited by 16 publications

(19 citation statements)

References 26 publications

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“…The technique assumes that all the observed waves are propagating upward, that the frequency spectrum follows a canonical power law with spectral slope = 2, and that the velocity spectrum is separable in frequency and azimuth. While these assumptions should not lead to serious errors given the low mean wind environment at Halley [ Fritts and Alexander , 2003], the method does not distinguish between propagating and ducted waves, which have no contribution to the vertical flux of horizontal momentum [ Fritts , 2000]. This is a shortcoming of the method and hence these results represent an upper limit to the momentum flux.…”

Section: Analysis and Resultsmentioning

confidence: 99%

Seasonal variations of the gravity wave momentum flux in the Antarctic mesosphere and lower thermosphere

et al. 2004

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[1] Airglow imager and dynasonde/imaging Doppler interferometer (IDI) radar wind measurements at Halley Station, Antarctica (75.6°S, 26.6°W) have been used to estimate the seasonal variation of the vertical fluxes of horizontal momentum carried by highfrequency atmospheric gravity waves. The cross-correlation coefficients between the vertical and horizontal wind perturbations were calculated from sodium (Na) airglow imager data collected during the austral winter seasons of 2000 and 2001. These were combined with wind velocity variances from coincident radar measurements to estimate the daily averaged upper limit of the vertical flux of horizontal momentum due to gravity waves. The resulting momentum flux at the Na airglow altitudes, while displaying a large day-to-day variability, showed a marked rotation from the northwest to the southeast throughout the winter season. Calculations show that this rotation is consistent with seasonal changes in the wind field filtering of gravity waves below the Na airglow region. The calculations also indicate that while the magnitude of the meridional wind is small, this filtering leads to the observed seasonal changes in the meridional momentum flux.

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Section: Analysis and Resultsmentioning

confidence: 99%

Seasonal variations of the gravity wave momentum flux in the Antarctic mesosphere and lower thermosphere

et al. 2004

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“…For the exact form of G and uncertainties of the zonal and meridional cross-correlation coefficients, the reader is referred to Gardner et al (1999). As the method assumes that all waves propagate upwards and are not ducted, it provides an upper limit to the momentum flux (Fritts, 2000). However, this does not appear to be a serious shortcoming.…”

Section: Discussionmentioning

confidence: 99%

Regional variations of mesospheric gravity-wave momentum flux over Antarctica

et al. 2006

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Abstract. Images of mesospheric airglow and radar-wind measurements have been combined to estimate the difference in the vertical flux of horizontal momentum carried by highfrequency gravity waves over two dissimilar Antarctic stations. Rothera (67 • S, 68 • W) is situated in the mountains of the Peninsula near the edge of the wintertime polar vortex. In contrast, Halley (76 • S, 27 • W), some 1658 km to the southeast, is located on an ice sheet at the edge of the Antarctic Plateau and deep within the polar vortex during winter. The cross-correlation coefficients between the vertical and horizontal wind perturbations were calculated from sodium (Na) airglow imager data collected during the aus- . These cross-correlation coefficients were combined with wind-velocity variances from coincident radar measurements to estimate the daily averaged upper-limit of the vertical flux of horizontal momentum due to gravity waves near the peak emission altitude of the Na nightglow layer, 90 km. The resulting momentum flux at both stations displayed a large day-to-day variability and showed a marked seasonal rotation from the northwest to the southwest throughout the winter. However, the magnitude of the flux at Rothera was about 4 times larger than that at Halley, suggesting that the differences in the gravity-wave source functions and filtering by the underlying winds at the two stations create significant regional differences in wave forcing on the scale of the station separation.

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“…As with any instrument, lidars can only observe part of the gravity wave spectrum, an effect known as observational filtering [ Alexander , 1998]. High frequency gravity waves are commonly observed throughout the mesosphere and lower thermosphere (MLT) both in the polar regions [ Espy et al , 2004; Dowdy et al , 2007; Nielsen et al , 2009] and at lower latitudes [ Fritts , 2000; Hu et al , 2002]. Waves with periods less than 1 h carry a large portion of the total energy flux into the MLT [ Vincent , 1984].…”

Section: Lidar Configuration Observations and Analysismentioning

confidence: 99%

Rayleigh lidar observations of gravity wave activity in the winter upper stratosphere and lower mesosphere above Davis, Antarctica (69°S, 78°E)

2011

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Gravity wave activity in the upper stratosphere and lower mesosphere (USLM) is investigated using temperature data retrieved from a Rayleigh lidar at Davis, Antarctica (69°S, 78°E) during the 2007 and 2008 winters. The temporal and height variabilities of waves with ground‐based periods greater than 2 h and vertical wavelengths between 4 km and 20 km are analyzed. Stratospheric gravity wave potential energy per unit mass shows a weaker correlation with stratospheric winds at Davis than that reported in the Arctic. Gravity waves dissipate above 40 km during winter, while there is no dissipation in the autumn mesosphere. A separate analysis of gravity waves with ground‐based periods of 2–6 h revealed lower dissipation in the winter mesosphere. The seasonal cycle of gravity wave activity is evident throughout the USLM, with peak activity observed during winter. The gravity wave potential energy and vertical wavenumber power spectral density at Davis are similar to that recorded at other high‐latitude sites.

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Errant inferences of gravity wave momentum and heat fluxes using airglow and lidar instrumentation: Corrections and cautions

Cited by 16 publications

References 26 publications

Seasonal variations of the gravity wave momentum flux in the Antarctic mesosphere and lower thermosphere

Seasonal variations of the gravity wave momentum flux in the Antarctic mesosphere and lower thermosphere

Regional variations of mesospheric gravity-wave momentum flux over Antarctica

Rayleigh lidar observations of gravity wave activity in the winter upper stratosphere and lower mesosphere above Davis, Antarctica (69°S, 78°E)

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