Thomas G. Kyle

High resolution laser imaging system

Computations indicate that a synthetic aperture laser imaging system can provide images with 10-cm resolution at satellite ranges using a 10-W cw laser. When imaging satellites from the ground, the synthetic aperture system reduces atmospheric degradations. The system uses 20-cm diam receiver optics. The low laser power is made possible by using separate transmitter and receiver optics and coded pulses with a 50% transmitter duty cycle. The coded pulses are derived from Hadamard matrices for which there is an efficient algorithm to transform the received data into images. The synthetic aperture yields spatial resolutions independent of range, and the coded pulses result in an effective range dependence of r(-2)2 instead of r(-4).

Pollution plume transport and diffusion studies using fluorescence lidar

Calculations have been performed to estimate the feasibility of conducting plume transport and diffusion. studies by creating a plume of fluorescent particles that are then interrogated by a lidar in both the fluorescent and elastically scattered modes. The computations were performed both for fluorescent and elastically scattered modes. The computations were performed both for daytime and nighttime operation and for cw as well as conventional pulsed operation. The incorporation of a cw transmitter facilitates plume search and also provides cross-sectional integration of the plume particle population. Experimental work has been initiated in the study of both liquid and solid fluorescent aerosols and methods for their generation.

Plume dispersion in a nocturnal drainage wind

Abstract A series of tracer experiments were conducted under nocturnal drainage wind conditions in a complex terrain setting in the Piceance Basin of western Colorado. Concurrent meteorological information including profiles of wind and temperature as well as gross turbulence fluctuations from fixed 2-m stations provided the basis to test plume growth and dilution prescriptions for this moderately complex site. Plume parameters exhibited slightly greater diffusion than would be indicated by simple stability-based prediction methods or the gross turbulence indicators. Two terrain-related mechanisms appear to contribute to the development of the plume. A meandering component immediately downwind of the confluence of two valleys gives the appearance of an abnormally wide time-integrated plume. Further downstream the mean wind direction stabilizes and the plume dimension reflects diffusive spread due to small-scale turbulence.

Fluorescent particle lidar

A lidar system designed to detect the return from small fluroescent particles has been built. (AIP)

Determining particle concentration by statistics

Abstract It is possible to determine the mean concentration of particles within a sample volume through the mean and mean square signal of the measuring system. This determination is possible for particles of an unknown size or when the instrument response is uncalibrated. The results, which will be obtained when there are two independent particle distributions within the same volume, are given and the conditions under which one of the distributions may be neglected are discussed.

Radiative cooling in valleys and hollows

Abstract A modular FORTRAN 77 program for calculating the net radiative energy absorbed by the air in a valley or hollow is presented. The net energy loss by the ground also can be calculated by altering an input parameter. The program assumes the existence of either a horizontal or vertical axis of symmetry and that the ground surface can be represented by a series of straight-line segments. The multiple integral involved in the calculation is evaluated by a Monte-Carlo technique. The example program uses band models for the transmission function, but the modularity and Monte-Carlo technique permits efficient computations to be carried out with higher resolution transmission functions.

Demonstration of a High Pulse Rate Lidar for Studying Airflow

Abstract In response to a recognized need for an inexpensive, low power, portable lidar for meteorological applications in remote areas, a system has been designed and constructed. The lidar, termed MELS (Mini-Environmental Lidar System), operates on 20 watts of power from a generator or battery, and can be easily deployed by two people on foot. After a series of calibration runs the MELS was demonstrated in two field experiments in Colorado valleys. One experiment was concerned with the measurement of natural aerosols and another with smoke released from a point source. Meteorological interpretation of the data shows consistency with expectations; the data provide a valuable adjunct to the conventional observations for deducing boundary layer dynamics.

Circuit for time‐resolved photon counting

A circuit providing 64 channels of photon counting with time resolutions as small as 50 ns is presented. The circuit requires the photon flux to be sparse enough to neglect multiple photons arriving during a single time‐resolution interval.