ALBERT

Description: Clouds continue to pose challenges to predict weather, climate and renewable energy due partly to knowledge gaps in microphysics-turbulence interactions. Particle-resolved direct numerical simulations (PR-DNS) that not only resolve the smallest turbulent eddies but also track growing histories of individual particles arguably constitute a fundamental tool to address the special challenges facing microphysics-turbulence interactions in clouds. This study consists of two parts. First, a major bottleneck issue of existing PR-DNS models is the small model domain size (e.g., less or about 1m3) due to high computational cost, which is smaller than many energy-containing eddies and typical grid sizes of large-eddy simulation (LES) models. We will introduce our HPC/AI accelerated PR-DNS model that aims to simulate a domain size of ~ 103m3 to address this computational challenge. Second, we will apply this PR-DNS to investigate three outstanding microphysics-turbulence problems: stochastic condensation/evaporation, turbulent entrainment-mixing, and droplet clustering. Results under different turbulence intensity (e.g., energy dissipation rate), environment conditions (e.g., relative humidity), and microphysical properties (e.g., initial droplet concentration and spectral shape of cloud droplet size distributions) will be analyzed. Also explored will be the role of turbulence-induced supersaturation fluctuations in determining aerosol activation into cloud droplets and droplet deactivation into aerosol particles. The AI/HPC accelerated PR-DNS further allows for examination of dependence of the results on the DNS domain size (or Reynolds number), by running the model with the domain spanning over several order of magnitudes (linear dimension varying from a few centimeters to about 10 meter).

Description: The Xing'an-Mongolian Orogenic Belt (XMOB) is a key area to study the tectonic evolution of northeast Asia, as it has retained the records for the processes of both the closure of the Paleo-Asian Ocean and the Mongol-Okhotsk Ocean and the subduction of the (Paleo-)Pacific plate. We constrained the lithospheric structure across the XMOB by receiver function imaging and shear wave splitting analysis from a dense seismic array. The lithosphere–asthenosphere boundary (LAB) is coherently imaged in different tectonic blocks. The mid-lithospheric discontinuity is also identified at ~75-100 km depth over the deeper LAB (~110-130 km) beneath the western side of the North-South Gravity Lineament (NSGL), roughly at the same depth as the LAB beneath the eastern side of the NSGL. Distinct patterns in seismic anisotropy were identified which are roughly separated by the NSGL. The large variations in lithospheric thickness, seismic anisotropy and crustal structure between the two sides of the NSGL indicate that it might likely caused by different tectonic processes in the two sides, indicating that the NSGL might represent the western boundary influenced by the subduction of the (Paleo-)Pacific Plate. The eastern side of the NSGL is characterized by a thinned lithosphere of less than 100 km and dominant NW-SE fast shear wave polarization direction, which reflects considerable lithospheric deformation probably related to the Mesozoic-Cenozoic subduction of the (Paleo-)Pacific plate. An integration of our results and geological observations suggests that the area in the west of the NSGL may not have been affected by the (Paleo-)Pacific subduction.

Description: The Relin Mo–W (–Cu) deposit in the northern Sanjiang area is bound to a Late Cretaceous intracontinental porphyry showing variable alteration. Here we present whole-rock chemistry and Sr, Nd, Pb, Li, and B isotope data to constrain the sources of ore-magmas and to understand how magmatic-hydrothermal processes mobilize the ore elements and alter the magmatic rocks. Chemical variations indicate the ore-bearing porphyries reflect two processes: fractional crystallization and late-magmatic alteration. Fresh and weakly altered porphyries are metaluminous to weakly peraluminous, showing I-type affinity. Chemical variation among these rocks can be explained by fractional crystallization. Most of these rocks show narrow ranges of isotopic compositions with –8.6 to –6.6 for εNd80, 0.70660 to 0.71028 for 87Sr/86Sr80, and high 207Pb/204Pb80 (15.57–15.66) and 208Pb/204Pb80 (39.21–39.51) values at 206Pb/204Pb80 values of 17.37 to 18.96. The chemical and isotopic compositions of these rocks indicate that the porphyries represent mantle melts that mixed with partial melts from the Paleoproterozoic crust. Fresh and weakly altered porphyries have uniform δ7Li (–2.3 to 1.5 ‰) and δ11B (–8.0 to –12.0 ‰). The strong sericite alteration of the porphyries resulted in the loss of Na2O and Sr (breakdown of feldspar) and the strong enrichment of the ore elements Cu, Mo, W, and Sn. Porphyries with varying degrees of alteration show large ranges of δ7Li (–6.0 ‰ to 11.4 ‰) and δ11B (–8.0 to –29.2 ‰). The anomalously high δ7Li and low δ11B values of the altered rocks indicate that the intrusions drove the flow of external fluids that altered the magmatic rocks and leached the ore elements W, Mo, Cu, and Sn from the porphyries and possibly the local wall rocks.

Description: GRACE time-variable gravity fields need proper filtering to depress the North-South Stripes (NSS) noise before correctly inferring geophysical signals. The NSS noise is spatially correlated with the satellites’ ground track, manifesting as being larger with the latitude reduced because of the polar inclined orbit design for GRACE. Such a behavior has been utilized by some previous work to design GRACE filters in spectral domain, however, it is still challenging to design one that can fully coincide with the NSS noise because of the limits in spectrum. In this work, we start with spherical 2D convolution and design the filter in spatial domain, so that the NSS’s spatial behavior can be easily taken into account. In this way, we develop a Variable-scale non-isotropic Gaussian-variant Convolution filter (abbreviated as VGC), which has been verified through a number of simulation and GRACE real data tests by comparing to the most popular filters, that is, Gaussian filter, Non-isotropic Gaussian filter and DDK filter. The real data test results show a good agreement between DDK filter and VGC, and both outperform the others in space and spectrum. In particular, the simulation results after VGC obtains the best correlation (0.85 overall) with the ground-truth. In addition, theoretical error analysis (relative error 〈3%) and efficiency tests (〈4s) are made to prove the feasibility of VGC in practice. We think, VGC can be an alternative to the state-of-the-art GRACE filters, and even probably a candidate for the future gravity mission for its mathematical flexibility and simplicity.