MOISTURE PROFILING OF THE CLOUDY WINTER ATMOSPHERE USING COMBINED REMOTE SENSORS

A new method for deriving profiles of tropospheric water vapor and liq uid water from a combination of ground-based remote sensors was applie d and tested under winter conditions in Colorado. The method is an ext ension of physical retrieval techniques used to derive coarse profiles from passive microwave radiometer measurements. Unlike an earlier met hod, it does not depend on climatological data for first-guess profile inputs. Instead, information about current cloud conditions aloft, ob tained with active remote sensors, is used to determine physically rea listic, first-guess vertical distributions of the radiometer's integra ted vapor and liquid measurements. In preliminary tests, the retrieved profiles were compared with in situ measurements by aircraft and radi osondes during the Winter Icing and Storms Project. The shape of the r etrieved liquid profiles agreed well with the aircraft measurements, b ut heights, thicknesses, and amplitudes differed considerably in some cases. The derived vapor profiles agreed better with radiosonde measur ements than the traditional climatological retrievals, but standard de viations of the dewpoint differences were still quite large (5 degrees C). In an integrated, unattended instrument design, the new method ha s the potential to provide continuous real-time profiles of temperatur e, wind, humidity, liquid water, and pressure.