7Be and 210 Pb, two atmospherically delivered radionuclides, have been broadly applied to study the processes including air mass transport, soil erosion, and particle cycling in aqueous systems. These studies require temporal variations of their depositional fluxes. In the present work, monthly atmospheric bulk depositional fluxes of Pb. There were strong seasonal variations in the depositional fluxes of these nuclides. The seasonal fraction of depositional fluxes was >30% of the total annual depositional fluxes of Pb depositional fluxes increase with the distance from the coast in inland regions (distance from the coast >50 km) and increase with the amount of precipitation in onshore region (distance from the coast ≤50 km). We also report that Shanghai, China, has the second highest bulk depositional fluxes of 210 Pb in literature.

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Spacecraft formation flying (SFF) in highly elliptical orbit (HEO) has attracted a great deal of attention in many space exploration applications, while precise guidance, navigation, and control (GNC) technology—especially precise ranging—are the basis of success for such SFF missions. In this paper, we introduce a novel K-band microwave ranging (MWR) equipment for the on-orbit verification of submillimeter-level precise ranging technology in future HEO SFF missions. The ranging technique is a synchronous dual one-way ranging (DOWR) microwave phase accumulation system, which achieved a ranging accuracy of tens of microns in the laboratory environment. The detailed design and development process of the MWR equipment are provided, ranging error sources are analyzed, and relative orbit dynamic models for HEO formation scenes are given with real perturbations considered. Moreover, an adaptive Kalman filter algorithm is introduced for SFF relative navigation design, incorporating process noise uncertainty. The performance of SFF relative navigation while using MWR is tested in a hardware-in-the-loop (HIL) simulation system within a high-precision six degrees of freedom (6-DOF) moving platform. The final range estimation errors from MWR using the adaptive filter were less than 35 μm and 8.5 μm/s for range rate, demonstrating the promising accuracy for future HEO formation mission applications.

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