R. M. Worthington

Equinor (United Kingdom)

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L. Thomas

Max Planck Institute of Geoanthropology

S. Fukao

Kyoto Bunkyo University

Robert D. Palmer

University of Oklahoma

M. Yamamoto

Princeton University

G. Vaughan

University of Manchester

I. Astin

University of Bath

Shoichiro Fukao

Kyoto University

L. Thomas

Swansea University

William R. Cotton

Colorado State University

I. T. Prichard

University of Wales

Cooperative Institutions

Aberystwyth University

University of Canterbury

NSF National Center for Atmospheric Research

University of Wales

Equinor (United Kingdom)

Colorado State University

Cooperative Institute for Research in Environmental Sciences

Kyoto University

United Nations University Institute for Sustainability and Peace

Kyoto Bunkyo University

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Lenticular wave cloud above the convective boundary layer of the Rocky Mountains

Weather (2002)

R. M. Worthington

Convective Boundary Layer

Free convective layer

10.1002/wea.6080570303

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Citations (5)

Demonstration of all-weather volume-Doppler-imaging of the troposphere using the MU radar

大会講演予講集 (2002)

R. M. Worthington M. Yamamoto S. Fukao

Weather radar

Source

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Citations (1)

Combined lidar and in-situ measurements of waves in the stable night-time boundary layer above Kansas

Aspen Meeting (2000)

R. M. Worthington

Source

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Citations (0)

Calculating the azimuth of mountain waves, using the effect of tilted fine-scale stable layers on VHF radar echoes

Annales Geophysicae (1999)

R. M. Worthington

Abstract. A simple method is described, based on standard VHF wind-profiler data, where imbalances of echo power between four off-vertical radar beams, caused by mountain waves, can be used to calculate the orientation of the wave pattern. It is shown that the mountain wave azimuth (direction of the horizontal component of the wavevector), is given by the vector [ W (PE - P W ) ,W (PN - P S ) ]; PN, PS, PE, PW are radar echo powers, measured in dB, in beams pointed away from vertical by the same angle towards north, south, east and west respectively, and W is the vertical wind velocity. The method is applied to Aberystwyth MST radar data, and the calculated wave vector usually, but not always, points into the low-level wind direction. The mean vertical wind at Aberystwyth, which may also be affected by tilted aspect-sensitive layers, is investigated briefly using the entire radar output 1990-1997. The mean vertical-wind profile is inconsistent with existing theories, but a new mountain-wave interpretation is proposed.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides; instruments and techniques).

Wind profiler

Echo (communications protocol)

10.1007/s00585-999-0257-4

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Citations (26)

Radar measurement of the effect of boundary-layer saturation on mountain-wave amplitude

Meteorology and Atmospheric Physics (2009)

R. M. Worthington

Saturation (graph theory)

10.1007/s00703-009-0032-9

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Citations (2)

Inertia-gravity waves in the troposphere and lower stratosphere associated with a jet stream exit region

Annales Geophysicae (1999)

L. Thomas R. M. Worthington Adrian McDonald

Abstract. Radar measurements at Aberystwyth (52.4° N, 4.1° W) of winds at tropospheric and lower stratospheric heights are shown for 12-13 March 1994 in a region of highly curved flow, downstream of the jet maximum. The perturbations of horizontal velocity have comparable amplitudes in the troposphere and lower stratosphere with downward and upward phase propagation, respectively, in these two height regions. The sense of rotation with increasing height in hodographs of horizontal perturbation velocity derived for hourly intervals show downwards propagation of energy in the troposphere and upward propagation in the lower stratosphere with vertical wavelengths of 1.7 to 2.3 km. The results indicate inertia-gravity waves propagating in a direction similar to that of the jet stream but at smaller velocities. Some of the features observed contrast with those of previous observations of inertia-gravity waves propagating transverse to the jet stream. The interpretation of the hodographs to derive wave parameters has taken account of the vertical shear of the background wind transverse to the direction of wave propagation.Key words. Meteorology and atmospheric dynamics (mesoscale meteorology; middle atmosphere dynamics; waves and tides)

Jet stream

Tropopause

Atmospheric wave

10.1007/s00585-999-0115-4

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Citations (44)

A statistical study of underestimates of wind speeds by VHF radar

Annales Geophysicae (1997)

L. Thomas I. Astin R. M. Worthington

Comparisons are made between horizontal wind measurements carried out using a VHF-radar system at Aberystwyth (52.4Â°N, 4.1Â°W) and radiosondes launched from Aberporth, some 50 km to the south-west. The radar wind results are derived from Doppler wind measurements at zenith angles of 6Â° in two orthogonal planes and in the vertical direction. Measurements on a total of 398 days over a 2-year period are considered, but the major part of the study involves a statistical analysis of data collected during 75 radiosonde flights selected to minimise the spatial separation of the two sets of measurements. Whereas good agreement is found between the two sets of wind direction, radar-derived wind speeds show underestimates of 4â6% compared with radiosonde values over the height range 4â14 km. Studies of the characteristics of this discrepancy in wind speeds have concentrated on its directional dependence, the effects of the spatial separation of the two sets of measurements, and the influence of any uncertainty in the radar measurements of vertical velocities. The aspect sensitivity of radar echoes has previously been suggested as a cause of underestimates of wind speeds by VHF radar. The present statistical treatment and case-studies show that an appropriate correction can be applied using estimates of the effective radar beam angle derived from a comparison of echo powers at zenith angles of 4.2Â° and 8.5Â°.

Zenith

Wind profiler

10.1007/s005850050499

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Citations (1)

The measurement of gravity wave momentum flux in the lower atmosphere using VHF radar

Radio Science (1996)

R. M. Worthington L. Thomas

Radar measurements have often been used to estimate gravity wave momentum flux profiles in the troposphere, lower stratosphere, and mesosphere. The reliability of the measurements in the troposphere and lower stratosphere is investigated, with a comparison of three techniques employing various radar beam directions and zenith angles, including the standard “symmetric‐beam” method. The study uses the 46.5 MHz MST radar system at Aberystwyth, Wales (52.4°N, 4.1°W). For short‐period waves, errors in momentum flux profiles arising, for example, from differing data quality in the two radial beams sometimes prove difficult to eliminate in the symmetric‐beam method. For long‐period waves, including inertia‐gravity waves, problems arise from the vertical wind measurement which is implicit in any estimate of momentum flux. Furthermore, a difference is sometimes found between the echo powers of the two symmetric radial beams, and this fluctuates with the horizontal wind perturbations from long‐period waves. The possible influence in this power difference of tilted anisotropic scattering layers, which might also bias radial velocity measurements, is discussed. A momentum flux method which measures the vertical wind with a vertical beam, and the horizontal wind with a pair of radial beams, avoids some of the problems at both short and long periods. Agreement of this method with the symmetric‐beam results would allow improved confidence in momentum flux profiles.

Momentum (technical analysis)

Zenith

10.1029/96rs02190

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Citations (38)

An Unusually High Summertime Wave Flight

Technical soaring (2004)

Edward E. Hindman Ray L. McAnelly William R. Cotton Todd Pattist R. M. Worthington

One of the highest wave flights ever achieved over the Catskill Mountains of southern New York State USA occurred surprisingly on 5 July 2002 (17,990 ft, 5485 m MSL). Using observed meteorological conditions with numerical-simulation models, most features of the wave were reproduced. Using the simulations, it appears the flight could have gone much higher had IFR clearance been obtained. This extraordinary mountain wave appears to have been enhanced by convective activity within the boundary layer above the Catskill Mountains.

Convective Boundary Layer

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Motion of echo structures observed with volume imaging atmospheric radar

Journal of Atmospheric and Solar-Terrestrial Physics (2008)

R. M. Worthington

Echo (communications protocol)

10.1016/j.jastp.2008.06.004

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Citations (1)