ALBERT

Description: The change of atmospheric pressure will lead to long-period noise (T〉10s) in the gravity observation data, which will cover up the weak geodynamic signals in the superconducting gravimeter (SG) records, such as the Slichter mode. Therefore, it is very important to select a reasonable atmospheric admittance value to eliminate atmospheric pressure noise. This paper studies a method to calculate the atmospheric admittance value, which can calculate the admittance value at the specified frequency. Taking the Mw9.0 earthquake in the Pacific Ocean of Tohoku, northeastern Japan, on March 11, 2011, as an example, the gravity and pressure data sampled at the same site of the global superconducting gravimeter stations are taken, and the effects of the time domain admittance value and the frequency-dependent admittance value on the extraction of the Slichter mode are discussed respectively, and the results are further verified by the multi-station superposition method; It is considered that the method of calculating the admittance value at the specified frequency is better; When detecting the weak signal of normal mode, this method is helpful to improve the signal-to-noise ratio, highlight the signal, and analyze the deep structure of the earth's interior.

Description: We explore the spatial and temporal variations in denudation rates in the northern Pamir—Tian Shan region using 10Be-derived denudation rates from modern (n = 110) and buried sediment (2.0–2.7 Ma; n = 3), and long-term exhumation rates from published apatite fission track (AFT; n = 705) and apatite (U-Th-Sm)/He (AHe; n = 211) thermochronology. We found moderate correlations between denudation rates and topographic metrics and weak correlations between denudation rates and annual rainfall, highlighting complex linkages among tectonics, climate, and surface processes that vary locally. The 10Be data show a spatial trend of decreasing modern denudation rates from west to east, suggesting that deformation and precipitation control denudation in the northern Pamir and western Tian Shan. Farther east, the denudational response of the landscape to Quaternary glaciations is more pronounced and reflected in our data. Modern 10Be denudation rates are generally higher than the long-term AFT and AHe exhumation rates across the studied area. In the Kyrgyz Tian Shan, on average, the highest 10Be denudation rates are recorded in the Terskey range, south of Lake Issyk-Kul. Here, modern denudation rates are higher than 10Be-derived paleo-denudation rates, which are comparable in magnitude with the long-term exhumation rates inferred from AFT and AHe. We propose that denudation in the region, particularly in the Terskey range, remained relatively steady during the Neogene and early Pleistocene. Denudation increased due to glacial-interglacial cycles in the Quaternary, but this occurred after the onset and intensification of the Northern Hemisphere glaciations at 2.7 Ma.

Description: Skin temperatures, shearing forces, surface static pressures, and boundary layer pitot pressures and total temperatures were measured on a hollow cylinder 3.04 meters long and 0.437 meter in diameter mounted beneath the fuselage of the YF-12A airplane. The data were obtained at a nominal free stream Mach number of 3.0 and at wall-to-recovery temperature ratios of 0.66 to 0.91. The free stream Reynolds number had a minimal value of 4.2 million per meter. Heat transfer coefficients and skin friction coefficients were derived from skin temperature time histories and shear force measurements, respectively. Boundary layer velocity profiles were derived from pitot pressure measurements, and a Reynolds analogy factor of 1.11 was obtained from the measured heat transfer and skin friction data. The skin friction coefficients predicted by the theory of van Driest were in excellent agreement with the measurements. Theoretical heat transfer coefficients, in the form of Stanton numbers calculated by using a modified Reynolds analogy between skin friction and heat transfer, were compared with measured values. The measured velocity profiles were compared to Coles' incompressible law-of-the-wall profile.