Measurements of the Skin Temperature on Small Lakes

Abstract

An apparatus to measure the skin temperature and related variables on inland lakes is described. The apparatus is a transparent frame with sensors to measure the skin and bulk water temperature, the wind velocity, and the air temperature and humidity for periods of several days. The sensors are positioned within 1 m of the air?water interface and sample boundary layer variables every 2 s. Data for a 4-h period at midday are discussed, and the vertical fluxes of heat and momentum are calculated using bulk relationships for 1- and 5-min periods. It is shown that the measured water temperature at a depth of 1 cm correlates well with estimates based on the bulk heat flux. The skin temperature depression is calculated from the bulk heat and momentum fluxes and is found to vary between 0.4° and 0.5°C for the 4-h period and was in good agreement with the measured values. However, the calculated and measured skin temperatures were poorly correlated for both the 1- and 5-min averages. This is believed to be due to departures from the steady-state assumptions or to deficiencies in the theory.