Aircraft measurements of wave momentum flux over the Colorado Rocky Mountains

Lilly, Douglas K.; NICHOLLS, JM; CHERVIN, ROBERT M; KENNEDY, PATRICK J; KLEMP, JOSEPH B

doi:10.1256/smsqj.45708

Cited by 13 publications

(14 citation statements)

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“…Other aircraft measurements of gravity wave activity near mountainous regions include those of Hoinka [1984,1985] and Lilly et al [1992]. McAfee et al [1989] showed that there are many problems associated with estimating momentum fluxes using the MST radar at Poker Flat, Alaska (66øN, 147øW), which is located in a valley surrounded by mountains.…”

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confidence: 99%

First results of tropospheric gravity wave momentum flux measurements over Christmas Island

Chang¹,

Avery²,

Riddle³

et al. 1997

Radio Science

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Abstract. The importance of gravity wave effe. cts on various dynamical processes has been well documented in the upper and middle atmosphere. However, less is known about these waves in the lower atmosphere. Whereas many studies of longer-period waves have previously been conducted using wind profiler data, this paper is an effort to quantify the short-term motions of the troposphere. We will present some of the initial tropospheric gravity wave horizontal variance and momentum flux estimates calculated from Christmas Island wind profiler data collected during 1994. A coplanar antenna beam configuration was used for this analysis. In addition to the high-frequency results, we will discuss some of the difficulties we encountered while processing the data. In order to determine the robustness of applying a coplanar beam analysis method to tropospheric data, we have compared the results of two data sets that were created using two independently developed cleaning algorithms on the same original raw data. These results show that the high-frequency calculations are sensitive to the quality of the cleaned data used for this analysis. As long as the uncertainties associated with cleaning the data are considered, it is possible to establish the magnitude of the vertical momentum fluxes and the resulting accelerations in the troposphere.

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mentioning

confidence: 99%

First results of tropospheric gravity wave momentum flux measurements over Christmas Island

Chang¹,

Avery²,

Riddle³

et al. 1997

Radio Science

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“…Known sources of waves include topographic effects and convection (Smith, 1979;Lilly et al, 1982;Bretherton and Smolarkiewitcz, 1989;Shutts and Gray, 1994;Fritts and Alexander, 2003, and specifically at the location considered in the present study, Kirkwood et al, 2010b;and Réchou et al, 2013), fronts (Eckermann and Vincent, 1993;Griffiths and Reeder, 1996), diabatic heating (Hooke, 1986), wind shear (Rosenthal and Lindzen, 1983;Fritts, 1982;Lott et al, 2009) and instability of the uppertropospheric jet (Ucellini and Koch, 1987;Zülicke and Peters, 2008). In the present study, we focus on IGWs generated by the jet at high latitudes.…”

Section: Introductionmentioning

confidence: 92%

Short vertical-wavelength inertia-gravity waves generated by a jet–front system at Arctic latitudes – VHF radar, radiosondes and numerical modelling

Réchou¹,

Kirkwood

Arnault³

et al. 2014

Atmos. Chem. Phys.

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Abstract. Inertia-gravity waves with very short vertical wavelength (λ z ≤ 1000 m) are a very common feature of the lowermost stratosphere as observed by the 52 MHz radar ESRAD (Esrange MST radar) in northern Scandinavia (67.88 • N, 21.10 • E). The waves are seen most clearly in radar-derived profiles of buoyancy frequency (N). Here, we present a case study of typical waves from 21 February to 22 February 2007. Good agreement between N 2 derived from radiosondes and by radar shows the validity of the radar determination of N 2 . Large-amplitude wave signatures in N 2 are clearly observed by the radar and the radiosondes in the lowermost stratosphere, from 9 km to 14-16 km height. Vertical profiles of horizontal wind components and potential temperature from the radiosondes show the same waves. Mesoscale simulations with the Weather Research and Forecasting (WRF) model are carried out to complement the analysis of the waves. Good agreement between the radar and radiosonde measurements and the model (except for the wave amplitude) shows that the model gives realistic results and that the waves are closely associated to the upper-level front in an upper-troposphere jet-front system. Hodographs of the wind fluctuations from the radiosondes and model data show that the waves propagate upward in the lower stratosphere confirming that the origin of the waves is in the troposphere. The observations and modelling all indicate vertical wavelengths of 700 ± 200 m. The radiosonde hodograms indicate horizontal wavelengths between 40 and 110 km and intrinsic periods between 6 and 9 h. The wave amplitudes indicated by the model are however an order of magnitude less than in the observations. Finally, we show that the profiles of N 2 measured by the radar can be used to estimate wave amplitudes, horizontal wavelengths, intrinsic periods and momentum fluxes which are consistent with the estimates from the radiosondes.

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“…The waves have been investigated using a number of dierent techniques, for example semi-Lagrangian techniques using instruments on board balloons, radio-sondes (Bretherton, 1969), gliders, and aircraft (Lilly et al, 1982;Nastrom et al, 1987), but also Eulerian techniques such as radar (Prichard et al, 1995), lidar (Blumen and Hart, 1988) and weather satellite images (Conover, 1964).…”

Section: Introductionmentioning

confidence: 99%

Mountain wave motions determined by the Esrange MST radar

Réchou¹,

Barabash

Chilson

et al. 1999

Ann. Geophys.

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Abstract. A European campaign of ground-based radar, lidar and optical measurements was carried out during the winter of 1996 to study lee waves in the northern part of Scandinavia. The participants operated ozone lidars, backscatter lidars and MST radars at ALOMAR/Andoya and Esrange/Kiruna, and an ALIS imaging system in Kiruna. The Andoya site was generally windward of the Scandinavian mountains, the Kiruna site on the leeward side. The goal of the experiment was to examine the in¯uence of lee waves on the formation of Polar Stratospheric Clouds (PSCs). This paper studies the radar data from MST-radar ESRAD located at Esrange [68. N, 21. E], i.e. in the lee of the mountains. We present three cases where strong lee waves were observed: in one case they propagated upwards to the lower stratosphere and in the other two cases they were trapped or absorbed in the troposphere. We examine the local waves and the direction and strength of the local wind using the radar, the synoptic meteorological situation using weather maps (European Meteorological Bulletin) and the synoptic stratospheric temperatures using ECMWF data. We observed that waves propagate up to the stratosphere during frontal passages. When anticyclonic ridges are present, the propagation to the stratosphere is very weak. This is due to trapping of the waves at or below the tropopause. We also show that the radar data alone can be used to characterise the dierent weather conditions for the three cases studied (through the variation of the height of the tropopause). The synoptic stratospheric temperatures in the three cases were similar, and were above the expected threshold for PSC formation. Lidar and visual observation of PSCs and nacreous clouds, respectively, showed that these were present only in the case when the lee waves propagated up to the lower stratosphere.

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Aircraft measurements of wave momentum flux over the Colorado Rocky Mountains

Cited by 13 publications

References 1 publication

First results of tropospheric gravity wave momentum flux measurements over Christmas Island

First results of tropospheric gravity wave momentum flux measurements over Christmas Island

Short vertical-wavelength inertia-gravity waves generated by a jet–front system at Arctic latitudes – VHF radar, radiosondes and numerical modelling

Mountain wave motions determined by the Esrange MST radar

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