PRELIMINARY RESULTS AND ANALYSIS OF AERIAL FLIGHT TEST OF TYPICAL GLACIERS ON THE QINGHAI TIBET PLATEAU USING DUAL FREQUENCY ULTRA WIDEBAND ACTIVE AND PASSIVE GLACIER DETECTOR

The cryosphere plays an important role in the climate system and the interaction of multiple spheres. The key elements of the cryosphere, such as ice sheet, sea ice, snow cover, and frozen soil, are the recorders and main driving factors of global climate change. The change of glacier reserves in the Asian water tower area, with Qinghai Tibet Tianshan Altai Mountains as the core, has a significant impact on the runoff recharge function of major rivers in the lower reaches of China. Microwave detection has the advantages of strong penetration, sensitivity to the distribution and changes of water, and not limited by light. It can penetrate the sub surface layer several meters to several kilometers below the surface of the ice cover. By detecting the radiation and scattering characteristics of the material under the ice, the layered structure, temperature profile, density, and dielectric constant of the sub surface layer of the ice cover can be inverted. This project has developed a P/L dual frequency ultra wideband active and passive glacier radar. P-band microwaves can penetrate ice sheets several meters to several kilometers below the surface, while L-band microwaves are suitable for detecting snow information on ice sheet surfaces. Combined with the high resolution and strong detectability provided by the ultra wideband linear frequency modulation pulse compression system, it can achieve precise detection of glacier radiation and scattering characteristics. Through airborne flight tests conducted on the  Guliya Glaciers and Laohugou No.12 Glacier in 2024, it was proven that P-band signals have glacier depth detection capabilities, with a penetration distance of over 370 meters . L-band signals provide richer information on the ice surface and shallow ice, with a detection depth of over 100 meters. In terms of ice depth calculation, a simulation model was established based on actual measurement data, and the ice depth at the ice core position was calculated to be about 309.81 meters, which is 0.08 meters different from the ice core length of 309.73 meters.. Radiant brightness temperature also shows a correlation with altitude and glacier volume. These pieces of information provide data basis and model foundation for future polar glacier detection and spaceborne cryosphere detection in the future.