Predicting September Arctic Sea Ice: A Multi-Model Seasonal Skill Comparison

Abstract This study quantifies the state-of-the-art in the rapidly growing field of seasonal Arctic sea ice prediction. A novel multi-model dataset of retrospective seasonal predictions of September Arctic sea ice is created and analyzed, consisting of community contributions from 17 statistical models and 17 dynamical models. Prediction skill is compared over the period 2001–2020 for predictions of Pan-Arctic sea ice extent (SIE), regional SIE, and local sea ice concentration (SIC) initialized on June 1, July 1, August 1, and September 1. This diverse set of statistical and dynamical models can individually predict linearly detrended Pan-Arctic SIE anomalies with skill, and a multi-model median prediction has correlation coefficients of 0.79, 0.86, 0.92, and 0.99 at these respective initialization times. Regional SIE predictions have similar skill to Pan-Arctic predictions in the Alaskan and Siberian regions, whereas regional skill is lower in the Canadian, Atlantic, and Central Arctic sectors. The skill of dynamical and statistical models is generally comparable for Pan-Arctic SIE, whereas dynamical models outperform their statistical counterparts for regional and local predictions. The prediction systems are found to provide the most value added relative to basic reference forecasts in the extreme SIE years of 1996, 2007, and 2012. SIE prediction errors do not show clear trends over time, suggesting that there has been minimal change in inherent sea ice predictability over the satellite era. Overall, this study demonstrates that there are bright prospects for skillful operational predictions of September sea ice at least three months in advance.</jats:p

Receiver function data in the western Tian Shan, Pamir Plateau and adjacent regions

Waveforms of receiver functions in the western Tian Shan and Pamir Plateau and stacked receiver functions after common conversion point stacking based on the IASP91 and velocity models from Koulakov (2011)

Receiver functions in the Pamir Plateau and western Tian Shan and adjacent regions

Datasets of receiver functions used to generate mantle transition zone structure beneath Pamir Plateau and western Tian Shan and adjacent regions. Please note that this data is provided for reproduction purposes only

Datasets for "The mantle transition zone structure beneath the Pamir Plateau and western Tian Shan and adjacent regions "

&lt;p&gt;The raw 3 component waveform data of XJ array used to compute receiver functions and further to generate detailed mantle transition zone structure together with other publicly available seismic data. Please note that this data is provided for reproduction purposes only.&lt;/p&gt

Large variations in lithospheric thickness of western Laurentia:Tectonic inheritance or collisional reworking?

Post-print version of article deposited according to Elsevier open access agreement: https://www.elsevier.com/about/open-science/open-access#greenOAThe ca. 2.0–1.8 Ga tectonic assembly of Laurentia provides a record of complex processes resulting in amalgamation of distinct lithospheric domains. In global and continental-scale teleseismic tomographic models, however, the subcontinental lithosphere beneath western Laurentia appears to have a deceptively simple structure that lacks a clear correlation with mapped crustal domains. Here we present a new shear-velocity model of the upper mantle beneath western Laurentia through Rayleigh-wave tomography, using data from several newly deployed broadband seismic arrays. Our models show prominent heterogeneities that appear to correlate well with crustal domains and other geophysical observations. The tomographic results delineate high-velocity keel-shaped anomalies beneath the Archean Hearne Province and the Paleoproterozoic Buffalo Head Terrane; these features are inferred to extend to depths of up to 260 km and likely represent ancient thick cratonic roots, whereas relatively thin lithosphere characterizes the adjacent Wabamun domain and Medicine Hat Block. A regional isostatic residual gravity anomaly in the foreland of the Cretaceous–Paleocene southern Canadian Rockies coincides with an area of inferred thick lithosphere in the Hearne Province, suggesting that along-strike variations in flexural rigidity correlate with lithospheric thickness. Taken together, our results suggest that high-amplitude basal topography of the lithosphere–asthenosphere boundary beneath cratons reflects a complex lithospheric evolution that combines effects of both tectonic inheritance and collisional reworking.Ye

Shallow Shear-Wave Velocity Structure beneath the West Lake Area in Hangzhou, China, from Ambient-Noise Tomography

Urban geophysical exploration plays an important role in the sustainable development of and the mitigation of geological hazards in metropolitan areas. However, it is not suitable to implement active seismic methods in densely populated urban areas. The rapidly developing ambient-noise tomography (ANT) method is a promising technique for imaging the near-surface seismic velocity structure. We selected the West Lake area of the city of Hangzhou as a case study to probe the shallow subsurface shear-wave velocity (Vs) structure using ANT. We conducted seismic interferometry on the ambient-noise data recorded by 28 seismograph stations during a time period of 17 days. Fundamental-mode Rayleigh-wave group- and phase-velocity dispersion data were measured from cross-correlation functions and then inverted for a 3D Vs model of the uppermost 1 km that covers an area of about 7 km × 8 km. The tomographic results reveal two prominent anomalies, with high velocities in the southwest and low velocities in the northeast. The fast anomaly corresponds to the presence of limestone and sandstone, whereas the slow anomaly is due to the relatively low-velocity rhyolite and volcanic tuff in the area. The boundary between the two anomalies lies to the NE of an NW–SE trending fault, indicating that the fault dips toward the NE. In addition, the pronounced low-velocity anomalies appear under the Baoshi mountain, likely due to the thick rhyolite and volcanic tuff beneath the extinct volcano. Our results correlate well with regional geological features and suggest that ANT could be a promising technique for facilitating the exploration of urban underground space

Southern Tibetan rifting since late Miocene enabled by basal shear of the underthrusting Indian lithosphere

Abstract Syncontractional extension is prominent in present-day Tibet, but its origin remains vigorously debated. Several deep-seated geodynamic processes (e.g., Indian underthrusting, horizontal flow, and mantle upwelling) have been linked to Tibetan rifting. Indian underthrusting is a good candidate because it can well explain why surface rifts are more prominent south of the Bangong–Nujiang suture; however, how Indian underthrusting causes extension is not well understood and lacks observational constraints. Seismic anisotropy, measured by exploiting the birefringence effect of shear waves, can be indicative of the deformation styles within the crust. Here, we unveil the dominant convergence-parallel alignment of anisotropic fabrics in the deep crust of the southern Tibetan rifts using seismic recordings collected from our recently deployed and existing seismic stations. This finding suggests that the strong north-directed shearing exerted by the underthrusting Indian plate is key to enabling present-day extension in southern Tibet

Evaluating Urban Community Sustainability by Integrating Housing, Ecosystem Services, and Landscape Configuration

Community is the core spatial unit for evaluating sustainable development. However, single data and method seem inadequate for conducting a scientific, effective, and innovative sustainable evaluation of complex community units. In this study, we perform a sustainable-oriented land use scheme using multisource remote sensing, machine learning, and object-based postclassification refinement. Furthermore, we assess the sustainability of the traffic community by data-driven and combined housing, ecosystem services, and landscape configuration. The results indicated that (1) the relationship between housing, ecosystem services, and landscape pattern has obvious synergistic effects, although with dissimilar importance in different sustainability levels. High sustainability level is intensely coordinated with landscape configuration, medium sustainability level is more affected by ecosystem services, and low sustainability level is more related to housing. (2) Community sustainability presents a significant spatial distribution. The communities of high sustainability level are mainly located in both sides of the Pearl River and emerging urban areas, while those of medium sustainability level are distributed sporadically in the study area and those of low sustainability level are concentrated in old towns. (3) Community transformation cannot be accomplished at one step. Along with the continuous optimization of landscape configuration, the priority should be given to housing reconstruction and improvement of ecosystem services further. We provide scientific and effective data-based evidence for urban decision-makers by integrating the advantages of the Earth Observation System and multifactor analysis