Abstract. New gravity fields from airborne gravimetry and from ERS-1 and -2 satellite altimetry cover extensive portions of the Arctic Ocean. These two data sets may constitute as much as 60% of the data contributions to the Arctic Gravity Project compilation. Here we evaluate the accuracy and resolution of these data and quantify their impact on the compilation. Both gravity determinations compare favorably with Geological Survey of Canada surface measurements in the Beaufort Sea (airborne, 1.86-2.09 mGal rms; ERS, 2.64-3.11 mGal rms). Comparisons between the airborne and ERS data over the Chukchi Borderlands reveal a 4.38 mGal rms difference over the smoother region of the field and 7.36 mGal rms over the rugose field generated by the shallow ridges and deep troughs. Coherency between the two data sets in the Chukchi region implies a resolution of 19 km. Comparison with Science Ice Expedition submarine measurements over Chukchi Plateau suggests that the ERS field resolves even shorter-wavelength signal than the airborne data, whereas in the Beaufort Sea the airborne data showed better coherence to ground truth data. Long-wavelength differences exist between the two data sets, expressed as a 2-3 mGal offset over the Chukchi region. This study highlights the respective strengths of the two data sets. The ERS gravity field has the advantage of ubiquitous coverage of the ocean south of 81.5øN, a denser sampling of the gravity field, and a recovery of signal down to -15 km. The airborne data cover a significant portion of the polar hole in the satellite coverage, have lower measurement noise, and recover somewhat higher anomaly amplitudes in the 25-100 km wavelength range.
IntroductionThe origin and evolution of the Arctic Ocean are two of the largest remaining uncertainties in plate tectonics. Whereas the opening histories of the world's other major ocean basins have been understood for more than 20 years, the formation of the Arctic's Amerasia Basin remains a mysteu. To date, the primary impediment to a fuller tectonic understanding has been the dearth of available geophysical data in the Arctic Ocean. Logistical problems, due to the year-round ice cover, were compounded by Cold War political sensitivities; as a result, the ocean basin was poorly sampled with bathymetry, gravity, and magnetics data. Moreover, much of the data actually collected , of which these two data sets will constitute a significant contribution, it is important to understand how these data sets compare in terms of accuracy and resolution. This study compares these two data sets over two regions of overlap in the Amerasia Basin. First, both sets are compared separately with high-quality ice surface gravity measurements in the Beaufort Sea region (Figure 1) of the Canada Basin, and then with each other and with Science Ice Expedition (SCICEX) submarine gravity measurements over the rugose gravity field of the Chukchi Borderland.