Effects of the Change in ambient air temperature and wind on radiation obserbation by Funk-Type radiometer

Abstract

A Funk-type net radiometer was calibrated under various conditions. Errors appeared when the temperature of the dome's inner surface is changed by the ambient condition.A Fnk-type net radiometer has been operated in the field, several monthes during 1967-69, together with platinumresistance thermometers on the ground surface and 0.3, 0.5, 1.0, 1.5meter above the ground.Various types of the change in nocturnal net flux are classified into three types in view of the change in ambient temperature and sky cover. They are as follows.Type 1: continuous small fluctuations corresponding to similar fluctuations in air temperatures, with larger amplitudes in the temperature at higher levels.This type seems to be caused by eddy turbulence which changes the temperature of the radiometer's dome.Tyre 2: slitly longer periods, and larger amplitudes than former in the surface temperature and occurs more frequently.This type indicates the change in upward radiation.Type 3: Similar to Type 2 but, with longer periods. Corresponding surface temperature change shows apparent time lag, and that of air temperature lags further behind with smaller amplitude.This type indicates the change in downward nocturnal radiation. This type is further classified into three sub-types.Type 4-1: The phase coincides with the surface temperature. This type occurs when a spec of cloud passes overhead or a thin high cloud layer appears for a time.Type 4-2: The phases of the change in the surface temperature and net radiation are opposite. This type occurs with a break in the cloud layer or disappearance of thin cloud layer or fog.Type 4-3: Radiation and air temperatures change gradually and independently accompanied by gradual change in sky cover. This type indicates gradual chang in downward flux.