In the last decade, substantial advances have been made in the remote sensing of tropospheric temperature and water vapor. Techniques include measurement of virtual temperature by Radio Acoustic Sounding Systems (RASS), the combination of RASS with satellite soundings, the measurement of precipitable water vapor by Global Positioning Systems, the measurement of water vapor profiles by Raman and differential absorption lidar, and the measurement of both temperature and water vapor profiles by Fourier Transform Infrared Radiometers. However, none of the techniques, by itself, is capable of satisfying most meteorological and climate needs. Thus, determination of profiles from combinations of data and sensors is the only practical way of satisfying these needs. In this paper, some of the techniques used for combining remote sensor data are outlined, some of the current sensors are described, and then examples of data derived from these combinations are presented. The role of the radiosonde in remote sensor evaluation, retrievals, and calibration is discussed. Finally, some of the new possibilities for combined remote sensors are presented.
*This lecture was presented at the First Symposium on Integrated Observing Systems, which was part of the 77th Annual Meeting of the American Meteorological Society, in Long Beach, California, on 4 February 1997.
