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  • Author or Editor: G. R. Ochs x
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A. G. Kjelaas and G. R. Ochs

Abstract

A wind-measuring system using three separate optical systems, each consisting of a 3 mW He-Ne 1aser and two photodiode receivers, forming an equilateral triangle 300 m on a side, has successfully measured the divergence over the area of the triangle, and the space-averaged horizontal wind vector. Good correlation was found between the flow into the triangle and occurrences of thermal plumes seen by an adjacent acoustic sounder. The flow into the triangle was proportional to the vertical velocity. During large convective activity, there was a certain periodicity in the occurrence of plumes.

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A. S. Frisch and G. R. Ochs

Abstract

Aircraft measurements of C T2 in an unstable marine boundary layer suggest a modification of the surface layer free-convection model. This modification is given by a function of z/zi, where z is the observation height and zi the height to the inversion base. This variation of C T2 with height may be expressed as z −4/3[1 + 0.84(z/zi) + 4.13(z/zi)2] for 0 ≤ z/zi ≤ 0.8.

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Mu-King Tsay, Ting-I. Wang, R. S. Lawrence, G. R. Ochs, and R. B. Fritz

Abstract

In a cooperative field study of the planetary boundary layer, three optical wind sensors were placed around a 300 m meteorological tower in a 450 m equilateral triangle 3–4 m above the terrain. It was found that the convergence measured by the three-sensor system correlates well with in situ measurements of vertical wind by anemometers located on the tower at heights up to 300 m during the occurrence of thermal plumes. By analyzing the correlation between the optically measured convergence and the vertical wind measurements made on the tower, the inversion layer, if below the top of the tower, can usually be located in the early morning when thermal plumes are active. The space-averaged horizontal wind vectors measured by the optical system have good, though not perfect, agreement with the tower measurements at the lowest layer (10 m above the ground), and with the measurements of a nearby network of surface anemometers. A comparison of the optically measured convergence with the direction of the surface horizontal wind indicates some effect of irregular terrain.

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Ting-I. Wang, R. Lataitis, R. S. Lawrence, and G. R. Ochs

Abstract

Prototype Laser Weather Identifier (LWI) systems designed to detect fog, rain and snow were tested for several months at Stapleton International Airport in Denver, and at the AFGL Weather Test Facility at Otis Air Force Base, Massachusetts. We present a detailed analysis of the performance of these systems, compared with human weather observations and tipping-bucket raingages, and suggest modifications for future operational instruments.

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