Next-generation coherent radar depth sounder for measurement of Greenland ice sheet thickness

Rising sea levels over the last century led to the initiation of a program by NASA to measure the surface elevation and thickness of the Greenland ice sheet. The University of Kansas with its radar depth sounder participates in the Greenland ice sheet measurements. The airborne depth sounder measures surface elevation and the thickness of the ice sheet. Over the past several years, the authors have made improvements to the depth sounder. During the 1996 field experiment the depth sounder performed to its theoretical limit. The authors collected a large volume of data and supplied the processed data to scientists worldwide. Having achieved the theoretical performance of the depth sounder, they wished to improve their measurements further and also to minimize the physical dimensions of the depth sounder system. They designed and built a Next-Generation Coherent Radar Depth Sounder (NG-CORDS) using today's technology to obtain a compact design as well as improved performance. They implemented the design using radio frequency integrated circuits (RFICs) and microwave monolithic integrated circuits (MMICs). The complete RF module is easily contained within a 8"/spl times/10.17"/spl times/4" enclosure. Tests of the laboratory performance of NO-CORDS show the improved performance over the previous depth sounder. At the time of writing, the NG-CORDS will fly on a NASA P-3 over the Greenland ice sheet in May 1997. From the May 1997 field experiments, the authors expect to see the improved performance of the NG-CORDS. One mark of improved performance will be the imaging of the ice sheet internal layers through the entire ice sheet. In this paper, they present the NG-CORDS system and experimental results.