Wednesday, 16 January 2002: 3:59 PM
High-resolution observations of the boundary layer using multiple-frequency range imaging
The atmosphere has been shown to be replete with distinct sheets and layers on an order of meter and sub-meter from the lower troposphere up to the middle of stratosphere through the use of high resolution in-situ measurements.
Observations of such fine structures are important for the understanding of small-scale atmospheric dynamics.
However, the ambiguity in space and time is raised when these in-situ data are used. In contrast, remote-sensing instruments can provide vertical profiles of the atmosphere continuously but the vertical resolution is often limited.
In this study, a newly developed technique termed range imaging (RIM) is introduced to improve the range resolution of a conventional pulse radar. In RIM, atmospheric structure with vertical extent smaller than the range resolution can be revealed by transmitting multiple frequencies.
Recently, RIM was implemented on the multiple antenna profiler (MAPR) of the National Center for Atmospheric Research (NCAR). As a result, the MAPR system can provide measurements of three-dimensional winds and the vertical reflectivity field in fine-scale simultaneously with a temporal resolution of a few minutes. Additionally, the potential of revealing the three-dimensional reflectivity field using both multiple-receiver and multiple-frequency
techniques is to be exploited. Preliminary results of RIM analysis are shown and compared to data from other instruments such as radiosondes, ceilometers, and the tethered atmospheric observing system (TAOS) of NCAR.
Applications of RIM on studies of boundary layer heights and entrainment zone are also discussed.