TY - JOUR
T1 - Gravity Wave Ducting Observed in the Mesosphere Over Jicamarca, Peru
AU - Lehmacher, Gerald A.
AU - Kudeki, Erhan
AU - Reyes, Pablo M.
AU - Lee, Kiwook
AU - Heale, Christopher J.
AU - Snively, Jonathan B.
N1 - G. Lehmacher was supported by NSF grant AGS-1143514. E. Kudeki, P. Reyes, and K. Lee were supported by NSF grant AGS-1143523. The authors have stated no conflicts of interest. The data are available at the http:// remote2.ece.illinois.edu/MST_ISR_ EEJ_V3 website. G. L. appreciates valuable discussions with J. Chau. C. J. Heale, and J. B. Snively were supported under NASA grant 80NSSC18K1037 to Embry-Riddle. We thank the staff of the Jicamarca Radio Observatory for their excellent work in operating the radar and collecting data. The Jicamarca Radio Observatory is a facility of the Instituto Geofisico del Peru operated with support from the NSF grant AGS-1433968 through Cornell University.
PY - 2019/5/27
Y1 - 2019/5/27
N2 - Short-period gravity waves are ubiquitous in the mesosphere, but the vertical structures of their perturbations are difficult to observe. The Jicamarca 50-MHz very high frequency radar allows observations of winds and turbulent scatter with high temporal and vertical resolution. We present a case of a quasi-monochromatic gravity wave with period 520 (±40) s that is likely ducted below a southward wind jet between 68 and 74 km. Above this layer of evanescence, a northward wind enables it to emerge into a more stable layer, where it is refracted to a short vertical wavelength of 2.2 (±0.2) km; data show evidence of weak nonlinearity, and possible overturning or partial reflection from higher altitudes, above the observable region, in the form of a standing wave structure in vertical velocity at approximately 75 km. Based on the dispersion relation, and with help of a two-dimensional model, we determine that most likely the wave is propagating northward and is being ducted below and tunneling through the regions of evanescence created by the wind flow and typical mesospheric thermal structure. This is the first time that such an event has been identified in the Jicamarca mesospheric echoes, and it is distinct from Kelvin-Helmholtz billows also commonly seen with this sensitive radar—instead apparently revealing tunneling of the gravity wave through ambient winds.
AB - Short-period gravity waves are ubiquitous in the mesosphere, but the vertical structures of their perturbations are difficult to observe. The Jicamarca 50-MHz very high frequency radar allows observations of winds and turbulent scatter with high temporal and vertical resolution. We present a case of a quasi-monochromatic gravity wave with period 520 (±40) s that is likely ducted below a southward wind jet between 68 and 74 km. Above this layer of evanescence, a northward wind enables it to emerge into a more stable layer, where it is refracted to a short vertical wavelength of 2.2 (±0.2) km; data show evidence of weak nonlinearity, and possible overturning or partial reflection from higher altitudes, above the observable region, in the form of a standing wave structure in vertical velocity at approximately 75 km. Based on the dispersion relation, and with help of a two-dimensional model, we determine that most likely the wave is propagating northward and is being ducted below and tunneling through the regions of evanescence created by the wind flow and typical mesospheric thermal structure. This is the first time that such an event has been identified in the Jicamarca mesospheric echoes, and it is distinct from Kelvin-Helmholtz billows also commonly seen with this sensitive radar—instead apparently revealing tunneling of the gravity wave through ambient winds.
KW - VHF radar
KW - gravity waves
KW - mesospheric winds
KW - wave ducting
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U2 - 10.1029/2019JD030264
DO - 10.1029/2019JD030264
M3 - Article
AN - SCOPUS:85066158997
SN - 2169-897X
VL - 124
SP - 5166
EP - 5177
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
IS - 10
ER -