The accuracy of water vapor and cloud liquid determination by dual-frequency ground-based microwave radiometry

A dual frequency ground-based radiometer operating in the 1 to 1.4 cm wavelength range can provide continuous measurements of integrated water vapor and cloud liquid water. Using climatological data, the accuracy of the vapor and liquid determinations is estimated as a function of cloud amount. Limiting factors in the water determination are uncertainties in water vapor absorption coefficients and, during cloudy conditions, uncertainties in cloud temperature. For integrated water vapor content greater than 10 mm, the accuracy of the vapor determination is better than 15% for a wide range of cloudy conditions.