OBSERVATIONS OF LIQUID WATER, WATER VAPOR, AND DOWNWARD FLUX OF INFRARED RADIATION IN THE ARCTIC REGION WITH A MICROWAVE RADIOMETER AND A PYRGEOMETER

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Observations of cloud liquid water path, columnar water vapor amount, and downward flux of infrared radiation in the Arctic region Inuvik, Canada and Kiruna, Sweden, during winter were carried out with a microwave radiometer and a pyrgeometer. The algorithm used in this study for the retrieval of liquid water path and columnar water vapor amount from measured intensity of microwave radiation requires the atmospheric temperature profile and the cloud temperature, which were obtained from radiosonde measurements. It was shown from microwave radiometer measurements that the columnar water vapor amount changed between 1-13kgm^<-2> during about a month in both observation points, and supercooled liquid water existed on several days. At Inuvik liquid water path reached about 0.25kgm^<-2> at most; this is comparable to a typical value of summer clouds in mid-latitude. It was also shown that the downward flux of infrared radiation on the ground surface changed between 130 Wm^2∿300Wm^<-2>. Finally, the downward flux of infrared radiation was calculated using the liquid water path retrieved from the microwave radiometer and water vapor and temperature profiles obtained from radiosonde observations. A comparison between the calculated and the measured values shows that both are in good agreement and the downward flux of infrared radiation in the Arctic region is primarily dependent on the water vapor amounts and temperature profile.