Detailed meteorological interpretation of acoustic sounder records.

Abstract

To quantify further the facsimile records from a monostatic acoustic sounder, a series of balloon and near surface meteorological measurements were made in the lower atmosphere under maritime conditions. Tests were concentrated on echo patterns associated with the developing atmospheric mixing layer and arrival of the sea breeze. Similar comparisons where made with an acoustic sounder operating at an inland location with continental climatic conditions. Extrapolation techniques were used to estimate the mixing layer depth between sunrise and initial emergence of the rising echo on the facsimile record. There was reasonable agreement in absolute height and rate of rise of the layer from comparison of the balloon and acoustic sounder measurements. The simple Carson model [D.J. Carson [1973] Q.J.R. Meterol. Soc., 99:450-467] was also tested to allow extrapolation beyond disappearance of the rising echo. Under sea breeze conditions, the low altitude, elevated echo was associated with a stable temperature profile, a decrease in wind speeds and, frequently, a vertical shear in wind direction to the overlying background flow.