This study examines associations between California Central Valley(CCV) heat waves and the Madden Julian Oscillation(MJO). These heat waves have major economic impact. Our prior work showed that CCV heat waves are frequently preceded by convection over the tropical Indian and eastern Pacific oceans, in patterns identifiable with MJO phases. The main analysis method is lagged composites(formed after each MJO phase pair) of CCV synoptic station temperature, outgoing longwave radiation(OLR), and velocity potential(VP). Over the CCV, positive temperature anomalies occur only after the Indian Ocean(phases 2-3) or eastern Pacific Ocean(phases 8-1) convection(implied by OLR and VP fields). The largest fractions of CCV hot days occur in the two weeks after onset of those two phase pairs. OLR and VP composites have significant subsidence and convergence above divergence over the CCV during heat waves, and these structures are each part of larger patterns having significant areas over the Indian and Pacific Oceans. Prior studies showed that CCV heat waves can be roughly grouped into two clusters: Cluster 2 is preceded by a heat wave over northwestern North America, while Cluster 1 is not. OLR and VP composite analyses are applied separately to these two clusters. However, for Cluster 2, the subsidence and VP over the CCV are not significant, and the large-scale VP pattern has low correlation with the MJO lagged composite field. Therefore, the association between the MJO convection and subsequent CCV heat wave is more evident in Cluster 1 than Cluster 2. 相似文献
Due to the topography and local nonuniform distribution of heating, extratropical cyclones in the lower troposphere usually have complex shapes and structures, and there remain some uncertainties in identifying them. Using a modified cyclone area automatic objective recognition algorithm for cyclones, we investigated the patterns of spring cyclone activities affecting Changjiang River-Huaihe River valleys (CHV) of China during the previous 37 years. The results indicated that the algorithm performs well in reproducing the cyclogenesis, movement, and cyclolysis of cyclones in CHV. Three new perspectives were noted. (1) Most influential cyclones have relatively short travel distances and lifetimes, they are typically excluded when conducting synoptic-scale cyclone tracking. (2) The cyclogenesis location of influential cyclones in spring displays multi-source characteristics. In particular, the influential cyclones originated in northern China account for 43% with more marked mobility compared to the locally generated cyclones, although most of their centers do not enter CHV. (3) Multi-center cyclones appear mainly in Da Hinggan Mountains which is on the east side of the Mongolian Plateau and over the East China Sea. These cyclones are relatively large in horizontal scale and have relatively long lifetimes. 相似文献
Russia has significant potential for reducing its carbon emissions. However, investment in new low-carbon technologies has significant risks. Ambiguous energy and climate policy in Russia, along with deterioration of the country's investment climate, create investment barriers that are well described in qualitative terms in the literature. This paper attempts to provide a quantitative analysis of these barriers. For this numerical experiment, we apply the RU-TIMES model. Using a real options methodology, we estimate the risk-adjusted cost of capital in the Russian energy sector (including energy production and consumption technologies represented in the TIMES framework) to be approximately 43% (including a risk-free interest rate) and demonstrate the high risk of investment into energy-efficient and low-carbon technologies. Any future low-carbon emissions pathway depends on the ability of the Russian government to reduce climate and energy policy uncertainties, and to reduce financial risks through improvements of the general investment climate.
Key policy insights
The high cost of capital investment into Russian energy production and consumption may prevent the adoption of new energy-efficient and low-carbon technologies.
These investment risks, if not addressed, will delay Russia's low-carbon transition for the coming decades.
Adopting a clear and unambiguous long-term climate and energy policy is important to reduce these risks and alleviate some of the barriers to the new technologies.
The first step could be ratification of the Paris Agreement and adoption of a long-term emission target for the period up to 2050.
The classical mechanism “source-transport-storage” of the formation of porphyry copper deposit has been advanced in recent studies, as the “source” is not the main factor for the mineralization in some Cu deposits, and the metallogeny may be affected by other variables factors during the magma-fluid transportation or storage. We recommend the essential role of trans-magmatic fluid in the ore-forming process, this fluid is released from the melting of the sedimentary overlying the subducted plate with high water and volatiles concentrations and high oxygen fugacity. The Baoshan granodioritic cryptoexplosion breccia representing the influence of hydrothermal events as well as the unaltered Baoshan granodiorite porphyry are conducted by LA-MC-ICP-MS analysis, to identify the contribution of trans-magmatic fluid. In case of the εNd(t) of whole rock do not increase with the MgO increasing and SiO2 decreasing, the large variations of zircons εHf(t) values in Baoshan granodiorite porphyry (BGP, ?14.24 to ?6.38) and Baoshan granodioritic crypto-explosion breccia (BGCB, ?25.24 to ?6.62) were considered to be the interaction of partial melting of ancient mafic lower crust and Neoproterozoic juvenile crust. However, the copper mineralization requires high oxygen fugacity and a large amount of water, according to the tectonic settings of Baoshan, we recommend that it is the trans-magmatic fluid trapping and concentrating Cu from the whole pluton during the upwelling driven by magma convection. The initial magma was stalled by the ductile-brittle transition at shallow depths of upper-crust. The trans-magmatic fluid leads to the pressure increases at the top of the initial magma, then the overlying rock is ruptured and cryptoexplosion produced. Moreover, after the cryptoexplosion, the sudden reduction of circumference temperature and pressure leads to the decrease in the oxygen fugacity of the ore-forming system, which will change the valence state of sulfur from S6+ to S2?. Finally, sulfur precipitates with chalcophile elements like copper in the metallogenic system and forms porphyry copper deposits with the low Sr/Y ratio. This study highlights the use of trans-magmatic fluid and ductile-brittle transition in the formation of the Baoshan porphyry copper deposits. 相似文献
Hybrid event beds comprising both clean and mud‐rich sandstone are important components of many deep‐water systems and reflect the passage of turbulent sediment gravity flows with zones of clay‐damped or suppressed turbulence. ‘Behind‐outcrop’ cores from the Pennsylvanian deep‐water Ross Sandstone Formation reveal hybrid event beds with a wide range of expression in terms of relative abundance, character and inferred origin. Muddy hybrid event beds first appear in the underlying Clare Shale Formation where they are interpreted as the distal run‐out of the wakes to flows which deposited most of their sand up‐dip before transforming to fluid mud. These are overlain by unusually thick (up to 4·4 m), coarse sandy hybrid event beds (89% of the lowermost Ross Formation by thickness) that record deposition from outsized flows in which transformations were driven by both substrate entrainment in the body of the flow and clay fractionation in the wake. A switch to dominantly fine‐grained sand was accompanied initially by the arrest of turbulence‐damped, mud‐rich flows with evidence for transitional flow conditions and thick fluid mud caps. The mid and upper Ross Formation contain metre‐scale bed sets of hybrid event beds (21 to 14%, respectively) in (i) upward‐sandying bed set associations immediately beneath amalgamated sheet or channel elements; (ii) stacked thick‐bedded and thin‐bedded hybrid event bed‐dominated bed sets; (iii) associations of hybrid event bed‐dominated bed sets alternating with conventional turbidites; and (iv) rare outsized hybrid event beds. Hybrid event bed dominance in the lower Ross Formation may reflect significant initial disequilibrium, a bias towards large‐volume flows in distal sectors of the basin, extensive mud‐draped slopes and greater drop heights promoting erosion. Higher in the formation, hybrid event beds record local perturbations related to channel switching, lobe relocations and extension of channels across the fan surface. The Ross Sandstone Formation confirms that hybrid event beds can form in a variety of ways, even in the same system, and that different flow transformation mechanisms may operate even during the passage of a single flow. 相似文献
We modelled thermo-rheological perturbations, related to the emplacement of a magmatic body in the upper crust. This approach was considered relevant for the areas characterized by elevated surface heat flow and chiefly for the geothermal fields. The numerical conductive thermal model applied to the Larderello geothermal area in Tuscany, allowed to constrain size, depth and timing of emplacement of the pluton. We inferred that the emplacement of a magmatic body, at a minimum depth of 3 km, having a horizontal extension of 14 km and a maximum thickness of 8 km, can reasonably reproduce the observed regional surface heat flow anomaly of the Larderello area, when 300 (± 100) kyr are elapsed from the magma emplacement. Even assuming an incremental growth, the first magma injection should not be older than 1 ± 0.3 Ma.
Results of the thermal model were used to set up a rheological model and to simulate the drifting of the brittle-ductile transition during the cooling of the pluton. A comparison with the K-horizon profile, a prominent seismic reflector in the Larderello area, was then performed. It was found that the K-horizon approximately corresponds with the pluton roof and with the current location of the brittle-ductile transition. 相似文献
Footwall rocks of the northern Snake Range detachment fault (Hampton and Hendry's Creeks) offer exposures of quartzite mylonites (sub-horizontal foliation) that were permeated by surface fluids. An S–C–C′ mylonitic fabric is defined by dynamically recrystallized quartz and mica. Electron backscatter diffraction analyses indicate a strong preferred orientation of quartz that is overprinted by two sets of sub-vertical, ESE and NNE striking fractures. Analyses of sets of three perpendicular thin sections indicate that fluid inclusions (FIs) are arranged according to macroscopic fracture patterns. FIs associated with NNE and ESE-striking fractures coevally trapped unmixed CO2 and H2O-rich fluids at conditions near the critical CO2–H2O solvus, giving minimum trapping conditions of T = 175–200 °C and ∼100 MPa H2O-rich FIs trapped along ESE-trending microcracks in single crystals of quartz may have been trapped at conditions as low as 150 °C and 50 MPa indicating the latest microfracturing and annealing of quartz in an overall extensional system. Results suggest that the upper crust was thin (4–8 km) during FI trapping and had an elevated geotherm (>50 °C/km). Footwall rocks that have been exhumed through the brittle-ductile transition in such extensional systems experience both brittle and crystal-plastic deformation that may allow for circulation of meteoric fluids and grain-scale fluid–rock interactions. 相似文献