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Sabine von Hünerbein, Stuart Bradley, and Ed Browell

deriving other physical parameters from the sodar observables, applications in complex terrain, and more sophisticated acoustic and/or signal-processing design. The four papers by Lokoshchenko, Kramar and Kouznetsov, Pan, and Raabe et al. are all concerned with obtaining a better description of the atmospheric boundary layer by combining acoustic measurements to estimate other parameters, such as heat fluxes. An example of the utility of sodars in dynamical studies is provided by von Hünerbein and

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Wayne M. Angevine, W. L. Ecklund, D. A. Carter, K. S. Gage, and K. P. Moran

(Manuscript received I April 1992, in final form 29 December 1992)ABSTRACT Improved radio acoustic sounding system (RASS) technology for use with radar wind profilers has beendeveloped and applied to 915-MHz and 50-MHz profilers. The most important advance is the simultaneousmeasurement of the wind velocity to correct the acoustic velocity measurement for air motion. This eliminatesthe primary source of error in previous RASS measurements, especially on short time scales. Another improvementis the use of an

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Armin Raabe, Klaus Arnold, and Astrid Ziemann

gradient in the air temperature field surrounding the energy balance measurements is one reason for the unknown residuum D. The application of acoustic travel time tomography to the atmospheric surface layer, first verified by Spiesberger and Fristrup (1990) , as well as Wilson and Thomson (1994) , makes it possible to observe horizontal distributions of wind and air temperature fields over an area around the conventional flux measurements. Such observations allow for the study of the

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Gerhard Peters

APRIL1994 NOTES AND CORRESPONDENCE 593Second-Order Doppler Shift GERHARD PETERSMeteorological Institute, University Hamburg, Hamburg, Germany2 November 1992 and 16 June 1993ABSTRACT High-resolution measurements of the frequency shift of radio acoustic sounding system echoes show small(~< 10-3) systematic deviations from values that are expected according to basic theory. It is shown that

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V. Klaus, G. Chérel, P. Goupil, and N. Pénetier

the analysis outputs from the numerical model of the European Centre for Medium-Range Weather Forecasts (ECMWF). REFERENCES Adachi, T. , Tsuda T. , Masuda Y. , Takami T. , Kato S. , and Fukao S. , 1993 : Effects of the acoustic and radar pulse length ratio on the accuracy of Radio Acoustic Sounding System (RASS). Temperature measurements with monochromatic acoustic pulses. Radio Sci. , 28 , 571 – 583 . 10.1029/93RS00359 Angevine, W. M. , Ecklund W. L. , Carter D. A. , Gage K

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D. Di Iorio, D. Lemon, and R. Chave

, Di Iorio and Farmer (1998) experimentally verified this mathematical relationship. The log-amplitude variance allows measurement of C 2 n eff through the equation where k is the acoustic wavenumber and L is the acoustic pathlength. Using a single transmitter and receiver ( r x = 0 m), the variance measurement that is obtained is from the refractive index variability weighted at the center of the acoustic path ( Farmer et al. 1987 ). Diffraction effects from the Fresnel scale ( λL

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Steve Elgar, Britt Raubenheimer, and R. T. Guza

to the complex flow field, although substantial errors in velocity measurements may occur when the sensor is near the free surface or seabed ( Guza et al. 1988 ). Antialiasing filters in the electromagnetic current meter attenuated EMC1 signal levels above about 1.5 Hz. The acoustic travel time current meter measures the average cross-shore, alongshore, and vertical velocity along the 10-cm-long acoustic path between two 12-cm diameter rings separated 7 cm in the vertical. Previous studies have

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Alvaro Cuerva, Angel Sanz-Andrés, and Oscar López

could correspond to more than one real magnitude, making the application of the correction functions ineffective. To illustrate this statement, a mathematical model of the measurement process of a sonic anemometer that takes into account the effect of the wake of a body (e.g., a sensor head wake) on the wind speed deficit along the acoustic path has been developed. A two-path sonic model is studied in order to simplify the mathematical formulation and clarify the interpretation of the results. The

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Clementina R. Russo and Emmanuel S. Boss

1. Introduction Acoustic Doppler velocimeters (ADVs) are marine acoustic sensors manufactured to measure current flow. These single-frequency, logarithmic instruments utilize the three-directional, Doppler-shifted acoustic backscatters to determine the velocity of particles passing through the sampling volume, which is a proxy for the velocity of the water. To determine when velocity measurements are likely to be robust, the ADV also measures the acoustic backscattering strength ( Sontek

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William L. Rubin

-established technique for measuring vertical temperature profiles of the atmosphere. The hardware and software of a standard National Oceanic and Atmospheric Administration (NOAA) radar–acoustic sensor which makes measurements all over the world was modified for vortex detection. Sensor electronics were housed in a small unheated trailer box at JFK and suffered only a few contact problems during 6 yr of operation. For completeness, it should be mentioned that the acoustic emission of radar–acoustic sensors used for

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