Monsoon has earned increasing attention from the climate community since the last century, yet only recently have regional monsoons been recognized as a global system. It remains a debated issue, ...however, as to what extent and at which timescales the global monsoon can be viewed as a major mode of climate variability. For this purpose, a PAGES (Past Global Changes) working group (WG) was set up to investigate the concept of the global monsoon and its future research directions. The WG's synthesis is presented here. On the basis of observation and proxy data, the WG found that the regional monsoons can vary coherently, although not perfectly, at various timescales, varying between interannual, interdecadal, centennial, millennial, orbital and tectonic timescales, conforming to the global monsoon concept across timescales. Within the global monsoon system, each subsystem has its own features, depending on its geographic and topographic conditions. Discrimination between global and regional components in the monsoon system is a key to revealing the driving factors in monsoon variations; hence, the global monsoon concept helps to enhance our understanding and to improve future projections of the regional monsoons. This paper starts with a historical review of the global monsoon concept in both modern and paleo-climatology, and an assessment of monsoon proxies used in regional and global scales. The main body of the paper is devoted to a summary of observation data at various timescales, providing evidence of the coherent global monsoon system. The paper concludes with a projection of future monsoon shifts in a warming world. The synthesis will be followed by a companion paper addressing driving mechanisms and outstanding issues in global monsoon studies.
Highlights • Substance P signaling contributed to spinal glial activation and nociceptive sensitization. • C-fiber afferent signaling induced spinal glial activation and hypersensitivity. • ...Neuroglial activation contributed to the maintenance of chronic post fracture hypersensitivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Various modeling studies have examined the climatic effects of either the Central American Seaway or the Indonesian seaway. The co‐existence of these two tropical seaways may have a greater influence ...than the existence of a single seaway. Although the dual seaway situation is closer to that reconstructed during Miocene/Pliocene, relevant studies remain scarce. Here, we investigate the co‐effects of dual tropical seaway changes on the Pacific circulation through a set of sensitivity experiments. Our results show that the combined shallow opening of tropical seaways can generate an active Pacific meridional overturning circulation and maintain strong upwelling conditions along the equatorial Pacific, which may have helped favor a “biogenic bloom” during the late Miocene and early Pliocene. Moreover, the logically successive closure of the tropical seaways can provide patterns of zonal sea surface temperature gradients that are similar to those recorded in the equatorial Pacific from the late Miocene to the Pliocene.
Plain Language Summary
During the late Miocene and the Pliocene, changes in the Central American and the Indonesian seaways geometry are very important for ocean circulation and global climate. Various modelling studies have examined the separate effects of these two tropical seaways, especially their link to the onset of the Northern Hemisphere ice sheets through changes in the Atlantic meridional overturning circulation and associated heat and moisture transport. Although the existence of dual tropical seaways is closer to the reality, there are very scarce modelling studies exploring the co‐effects of dual tropical seaway changes, especially on the Pacific ocean circulation. Here we provide the results of modelling study on this issue. Our results show that the combined shallow opening of tropical ways can generate an active Pacific meridional overturning circulation (i.e., absent in modern conditions) by which the meridional and zonal sea surface temperature gradient in the Pacific largely reduce. In contrast, a deeper opening of tropical seaways can not produce these changes in the Pacific ocean circulation. This study provides insights into and a better understanding of the role of tropical seaways in shaping the Pacific climate and highlights the importance of the sill depth of each seaway.
Key Points
The co‐effects of opening of two tropical seaways on the Pacific circulation are investigated with climate model
Shallow opening of tropical seaways can generate an active Pacific meridional overturning circulation, whilst a deeper condition can not
The stepwise closure of the tropical seaways can provide similar‐to‐record patterns of zonal sea surface temperature gradients
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The initial desertification in the Asian interior is thought to be one of the most prominent climate changes in the Northern Hemisphere during the Cenozoic era. But the dating of this transition is ...uncertain, partly because desert sediments are usually scattered, discontinuous and difficult to date. Here we report nearly continuous aeolian deposits covering the interval from 22 to 6.2 million years ago, on the basis of palaeomagnetic measurements and fossil evidence. A total of 231 visually definable aeolian layers occur as brownish loesses interbedded with reddish soils. This new evidence indicates that large source areas of aeolian dust and energetic winter monsoon winds to transport the material must have existed in the interior of Asia by the early Miocene epoch, at least 14 million years earlier than previously thought. Regional tectonic changes and ongoing global cooling are probable causes of these changes in aridity and circulation in Asia.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Effective capture and release of circulating tumor cells (CTCs) with high viability is still a challenge in medical research. We design a novel approach with efficient yield and high cell activity ...for the capture and release of CTCs. Our platform is based on TiO2 nanorod arrays coated with transparent MnO2 nanoparticles. We use hydrothermal synthesis to prepare TiO2 nanorod arrays, the MnO2 nanoparticles are fabricated through in situ self-assembly on the substrate to form a monolayer and etched by oxalic acid with low concentration at room temperature. Up to 92.9% of target cells are isolated from the samples using our capture system and the captured cells can be released from the platform, the saturated release efficiency is 89.9%. Employing lower than 2 × 10–3 M concentration of oxalic acid to dissolve MnO2, the viability of MCF-7 cancer cells exceed 90%. Such a combination of the two-dimensional and three-dimensional platforms provides a new approach isolate CTCs from patient blood samples.
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IJS, KILJ, NUK, PNG, UL, UM
We report, for the first time, the long-awaited detection of diffuse gamma rays with energies between 100 TeV and 1 PeV in the Galactic disk. Particularly, all gamma rays above 398 TeV are observed ...apart from known TeV gamma-ray sources and compatible with expectations from the hadronic emission scenario in which gamma rays originate from the decay of π^{0}'s produced through the interaction of protons with the interstellar medium in the Galaxy. This is strong evidence that cosmic rays are accelerated beyond PeV energies in our Galaxy and spread over the Galactic disk.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
The global climate system experienced a series of drastic changes during the Cenozoic. In Asia, these include the climate transformation from a zonal pattern to a monsoon-dominated pattern, the ...disappearance of typical subtropical aridity, and the onset of inland deserts. Despite major advances in the last two decades in characterizing and understanding these climate phenomena, disagreements persist relative to the timing, behaviors and underlying causes. This paper addresses these issues mainly based on two lines of evidence. First, we compiled newly collected data from geological indicators of the Cenozoic environment in China as paleoenvironmental maps of ten intervals. In confirming the earlier observation that a zonal climate pattern was transformed into a monsoonal one, the maps within the Miocene indicate that this change was achieved by the early Miocene, roughly consistent with the onset of loess deposition in China. Although a monsoon-like regime would have existed in the Eocene, it was restricted to tropical-subtropical regions. The latitudinal oscillations of the climate zones during the Paleogene are likely attributable to the imbalance in evolution of polar ice-sheets between the two hemispheres. Secondly, we examine the relevant depositional and soil forming processes of the Miocene loess-soil sequences to determine the circulation characteristics with emphasis on the early Miocene. Continuous eolian deposition in the middle reaches of the Yellow River since the early Miocene firmly indicates the formation of inland deserts, which have been constantly maintained during the past 22 Ma. Grain-size gradients between loess sections indicate northerly dust-carrying winds from northern sources, a clear indication of an Asian winter monsoon system. Meanwhile, well-developed Luvisols show evidence that moisture from the oceans reached northern China. This evidence shows the coexistence of two kinds of circulations, one from the ocean carrying moisture and another from the inland deserts transporting dust. The formation of the early Miocene paleosols resulted from interactive soil forming and dust deposition processes in these two seasonally alternating monsoonal circulations. The much stronger development of the early Miocene soils compared to those in the Quaternary loess indicates that summer monsoons were either significantly stronger, more persistent through the year, or both. These lines of evidence indicate a joint change in circulation and inland aridity by the early Miocene and suggest a dynamic linkage of them. Our recent sensitivity tests with a general circulation model, along with relevant geological data, suggest that the onset of these contrasting wet/dry responses, as well as the change from the "planetary" subtropical aridity pattern to the "inland" aridity pattern, resulted from the combined effects of Tibetan uplift and withdrawal of the Paratethys seaway in central Asia, as suggested by earlier experiments. The spreading of South China Sea also helped to enhance the south-north contrast of humidity. The Miocene loess record provides a vital insight that these tectonic factors had evolved by the early Miocene to a threshold sufficient to cause this major climate reorganization in Asia.
We report on the highest energy photons from the Crab Nebula observed by the Tibet air shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of a muon ...number measured in an air shower, we successfully suppress 99.92% of the cosmic-ray background events with energies E>100 TeV. As a result, we observed 24 photonlike events with E>100 TeV against 5.5 background events, which corresponds to a 5.6σ statistical significance. This is the first detection of photons with E>100 TeV from an astrophysical source.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
Noble metal nanoparticles (NPs) such as Au and Ag have shown many applications in the field of catalysis, sensing etc. due to their excellent photoelectric properties. But agglomeration and a low ...recovery rate are big problems for their applications. In this research, a novel Ag NPs/graphene (reduced graphene oxide)-loading loofah sponge (Ag NPs/RGO-LS) was synthesized through a one-step reduction method. Where the RGO is used as a nano-support with the high specific surface area and the high conductivity to prevent the agglomeration of Ag NPs and provide a conductive layer. The natural, green, low-cost and high-yield LS is designed as a macro-support to reduce the loss of Ag NPs during recycling. The as-prepared Ag NPs/RGO-LS is stable, uniform, and exhibits high efficiency and reusability in the catalytic reduction of 4-nitrophenol (4-NP) with a high rate constant of 1.893 min−1 as well as an average conversion of 98% in 6 min during five cycles. The results have not only paved the way for the wide application of Ag NPs but also provide a new road for the application of other metal NPs.
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