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The Amundsen Sea Embayment of the West Antarctic Ice Sheet contains Thwaites and Pine Island Glaciers, two of the most rapidly changing glaciers in Antarctica. To date, Pine Island and Thwaites Glaciers have only been observed by independent airborne radar sounding surveys, but a combined cross‐basin analysis that investigates the basal conditions across the Pine Island‐Thwaites Glaciers boundary has not been performed. Here, we combine two radar surveys and correct for their differences in system parameters to produce unified englacial attenuation and basal relative reflectivity maps spanning both Pine Island and Thwaites Glaciers. Relative reflectivities range from −24.8 to +37.4 dB with the highest values beneath fast‐flowing ice at the ice sheet margin. By comparing our reflectivity results with previously derived radar specularity and trailing bed echoes at Thwaites Glacier, we find a highly diverse subglacial landscape and hydrologic conditions that evolve along‐flow. Together, these findings highlight the potential for joint airborne radar analysis with ground‐based seismic and geomorphological observations to understand variations in the bed properties and cross‐catchment interactions of ice streams and outlet glaciers. Plain Language Summary: Pine Island Glacier (PIG) and Thwaites Glacier (TG) are the fastest‐changing outlet glaciers in West Antarctica. To understand how these glaciers move and evolve in the future, we need to understand processes that occur at the ice‐bed interface that control glacial motion. Here, we investigate the basal conditions of PIG and TG using radar sounding observations from two independent airborne surveys. By estimating the brightness and shape of radar power returns from the ice bed, we characterize the distribution of subglacial meltwater and how the subglacial landscape evolves along with ice flow. We also extend our radar interpretations using existing ground‐based seismic and geomorphology observations. These results show that PIG has a greater area of wet bed that extends far inland into the head of its ice tributaries. Meanwhile, TG has a patchier wet and locally frozen bed. Along the boundary of the two glaciers, we find that the presence of deformable sediments or subglacial meltwater, in addition to topography, also plays a role in explaining the present‐day configuration of ice flow. Future studies of ice sheet basal processes should more frequently combine airborne radar and ground‐based seismic and geomorphological observations to provide a unified interpretation. Key Points: We analyze two simultaneous 2004/2005 airborne radar surveys of Pine Island and Thwaites Glaciers conducted using different soundersWe produce catchment‐wide englacial attenuation and basal reflectivity maps for Pine Island and Thwaites GlaciersRadar analysis reveals a critical frozen basal patch that currently separates the two neighboring glaciers [ABSTRACT FROM AUTHOR]

Abstract: Curie depths beneath Greenland are revealed by spectral analysis of data from the World Digital Magnetic Anomaly Map 2. A thermal model of the lithosphere then provides a corresponding geothermal heat flux map. This new map exhibits significantly higher frequency but lower amplitude variation than earlier heat flux maps and provides an important boundary condition for numerical ice‐sheet models and interpretation of borehole temperature profiles. In addition, it reveals new geologically significant features. Notably, we identify a prominent quasi‐linear elevated geothermal heat flux anomaly running northwest–southeast across Greenland. We interpret this feature to be the relic of the passage of the Iceland hotspot from 80 to 50 Ma. The expected partial melting of the lithosphere and magmatic underplating or intrusion into the lower crust is compatible with models of observed satellite gravity data and recent seismic observations. Our geological interpretation has potentially significant implications for the geodynamic evolution of Greenland. [ABSTRACT FROM AUTHOR]

Antarctica is the largest reservoir of ice on Earth. Understanding its ice sheet dynamics is crucial to unraveling past global climate change and making robust climatic and sea level predictions. Of the basic parameters that shape and control ice flow, the most poorly known is geothermal heat flux. Direct observations of heat flux are difficult to obtain in Antarctica, and until now continent-wide heat flux maps have only been derived from low-resolution satellite magnetic and seismological data. We present a high-resolution heat flux map and associated uncertainty derived from spectral analysis of the most advanced continental compilation of airborne magnetic data. Small-scale spatial variability and features consistent with known geology are better reproduced than in previous models, between 36% and 50%. Our high-resolution heat flux map and its uncertainty distribution provide an important new boundary condition to be used in studies on future subglacial hydrology, ice sheet dynamics, and sea level change. [ABSTRACT FROM AUTHOR]