Assessment of model performance of precipitation extremes over the mid-high latitude areas of Northern Hemisphere:from CMIP5 to CMIP6

This study explores the model performance of the Coupled Model Intercomparison Project Phase 6(CMIP6)in simulating precipitation extremes over the mid–high latitudes of Asia,as compared with predecessor models in the previous phase,CMIP5.Results show that the multimodel ensemble median generally outperforms the individual models in simulating the climate means of precipitation extremes.The CMIP6 models possess a relatively higher capability in this respect than the CMIP5 models.However,discrepancies also exist between models and observation,insofar as most of the simulated indices are positively biased to varying degrees.With respect to the temporal performance of indices,the majority are overestimated at most time points,along with large uncertainty.Therefore,the capacity to simulate the interannual variability needs to be further improved.Furthermore,pairwise and multimodel ensemble comparisons were performed for 12 models to evaluate the performance of individual models,revealing that most of the new-version models are better than their predecessors,albeit with some variance in the metrics amongst models and indices.

基于Storey模型的影响风险企业成长的因素研究

本文基于Storey模型,将影响风险企业成长的因素划分为管理者的素质、中小企业的内在素质和企业业务发展的战略范围3个维度,分别讨论高管的受教育程度和年龄、企业的年龄和股权结构以及企业的政治背景和管理力量专业背景6个指标对企业成长性的影响。

An Interdecadal Change of Summer Atmospheric Circulation over Asian Mid-High Latitudes and Associated Effects

The atmospheric circulation over the mid-high latitudes in Asia has an important influence on regional climate,yet its long-term variation has not been fully explored.The main task of this study is to reveal the interdecadal variation features of summer atmospheric circulation over Asian mid-high latitudes in recent decades.The results show that the atmospheric circulation over mid-high latitudes of Asia has stronger interdecadal fluctuations than that over low latitudes and one significant change center appears near Lake Baikal.It is found that the atmospheric circulation near Lake Baikal has a significant interdecadal change around 1996 and a deep anomalous anticyclonic circulation has been controlling this region since then,which contributes to the significant increase in the surface temperature near Lake Baikal since 1997 and makes the region a remarkable warming center in Asia in recent 40 years.During 1997-2015,the pattern of less precipitation in the north and more precipitation in the south of east China is closely related to the anomalous anticyclonic circulation near Lake Baikal.Especially,this anomalous circulation near Lake Baikal has been found to contribute to the obvious interdecadal decrease of the precipitation in northeast China and north China near1997.The sea surface temperature(SST)of northwestern Atlantic is an important influence factor to the interdecadal change in the atmospheric circulation near Lake Baikal around 1996.

An experimental study on fire characteristics of urban complex underground space based on BIM

Compared with the space on the ground,if there is a fire in the urban complex underground space,the loss will be greatly harmful.In addition,the complex underground space is usually connected with other large space areas and densely populated.Once a fire occurs in the complex underground space,it will cause huge property losses and casualties.In order to reduce the risk of fire,it is necessary to deeply understand the development rules and characteristics of fire in the complex underground space of the city.This article has mainly carried on the following work:(I)A particularly complex model of the multi‐storey subway station was built.On this basis,three groups of comparative experiments were conducted to study the effects of fire power,fire location and smoke control system on fire development,and the conclusion that fire location is the most important factor for fire development was obtained;(II)In order to explore the entire space fire and the local space fire,CFD(Computational Fluid Dynamics)is used to build a large‐size fire model and a small‐size fire model respectively;(III)Multiple detector data as temperature slices were built,and it is expected to make full use of the simulation data to deduce the important index of fire location in the early stage of fire.All of the works in this paper will provide reference experimental data for the prevention and firefighting of a sudden fire in the complex underground space.

Magneto-electric integrated design strategy of NiCo@C composites for synergistic absorption and conversion in mid-high frequency microwaves

Achieving synergistic absorption of electromagnetic waves(EMWs)in the mid-high frequency and absorption band conversion is an urgent problem.However,the present solution is usually a straightforward mixture of magnetic component-carbon component.Hereby,we optimize the magnetic properties and electrical relaxation response from a chemical synthesis perspective.Through integrated design,the contents of carbon components and multi-dimensional morphology are controlled by retaining strong magnetic properties.The morphology design and the construction of heterogeneous interfaces will boost the intense response of charge in the surrounding to enhance the polarization effect.The multi-dimensional structure and electromagnetic(EM)properties of the sample after optimized engineering have an extremely powerful absorption conversion effect on EMW energy.NiCo@C particles ultimately achieve synergistic absorption effects at low thickness(d<3.5 mm)at middle frequencies(6–10 GHz)and high frequencies(10.5–18 GHz).Our work establishes a correlation mechanism between the physical and chemical properties of materials and EM parameters.It also provides insight into the synergistic absorption of EMWs in the mid-high frequency and absorption band conversion strategies.

Projected changes in Köppen-Trewartha climate zones under 1.5-4℃global warming targets over mid-high latitudes of Northern Asia using an ensemble of RegCM4 simulations

Mid-high latitude Northern Asia is one of the most vulnerable and sensitive areas to global warming,but relatively less studied previously.We used an ensemble of a regional climate model(RegCM4)projections to assess future changes in surface air temperature,precipitation and Köppen-Trewartha(K-T)climate types in Northern Asia under the 1.5-4℃global warming targets.RegCM4 is driven by five CMIP5 global models over an East Asia domain at a grid spacing of 25 km.Validation of the present day(1986-2005)simulations shows that the ensembles of RegCM4(ensR)and driving GCMs(ensG)reproduce the major characters of the observed temperature,precipitation and K-T climate zones reasonably well.Greater and more realistic spatial detail is found in RegCM4 compared to the driving GCMs.A general warming and overall increases in precipitation are projected over the region,with these changes being more pronounced at higher warming levels.The projected warming by ensR shows different spatial patterns,and is in general lower,compared to ensG in most months of the year,while the percentage increases of precipitation are maximum during the cold months.The future changes in K-T climate zones are characterized by a substantial expansion of Dc(temperature oceanic)and retreat of Ec(sub-arctic continental)over the region,reaching∼20%under the 4℃warming level.The most notable change in climate types in ensR is found over Japan(∼60%),followed by Southern Siberia,Mongolia,and the Korean Peninsula(∼40%).The largest change in the K-T climate types is found when increasing from 2 to 3℃.The results will help to better assess the impacts of climate change and in implementation of appropriate adaptation measures over the region.

Impacts of the MJO on Winter Rainfall and Circulation in China

Impacts of the MJO on winter rainfall and circulation in China are investigated using a real-time multivariate MJO index.Composite results using the daily rainfall anomalies and "rainy day" anomalies according to eight different MJO phases show that the MJO has considerable influence on winter rainfall in China. Rainfall anomalies show systematic and substantial changes(enhanced/suppressed) in the Yangtze River Basin and South China with the eastward propagation of the MJO convective center from the Indian Ocean to the western Pacific.When the MJO is in phase 2 and 3(MJO convective center is located over the Indian Ocean),rainfall probability is significantly enhanced.While in phase 6 and 7(MJO convective center is over the western Pacific),rainfall probability is significantly reduced. MJO in winter influences the rainfall in China mainly through modulating the circulation in the subtropics and mid-high latitudes.For the subtropics,MJO influences the northward moisture transport coming from the Bay of Bengal and the South China Sea by modulating the southern trough of the Bay of Bengal and the western Pacific subtropical high.For the mid-high latitudes,the propagation of the low frequency perturbations associated with the eastward-propagating MJO convection modulate the circulation in the mid-high latitudes,e.g.the East Asian winter monsoon and the low trough over central Asia.

Pathways of Influence of the Northern Hemisphere Mid–high Latitudes on East Asian Climate: A Review

This paper reviews recent progress made by Chinese scientists on the pathways of influence of the Northern Hemisphere mid-high latitudes on East Asian climate within the framework of a“coupled oceanic-atmospheric(land-atmospheric or seaice-atmospheric)bridge”and“chain coupled bridge”.Four major categories of pathways are concentrated upon,as follows:Pathway A—from North Atlantic to East Asia;Pathway B—from the North Pacific to East Asia;Pathway C—from the Arctic to East Asia;and Pathway D—the synergistic effects of the mid-high latitudes and tropics.In addition,definitions of the terms“combined effect”,“synergistic effect”and“antagonistic effect”of two or more factors of influence or processes and their criteria are introduced,so as to objectively investigate those effects in future research.

Push-Over Analysis for Concrete Structures of Tall Building

In this paper, push-over analysis for tall concrete structures was made and a corresponding computer program was given. Several kinds of elements in the program were considered to meet the demand of tall buildings with complex structural type. These elements included beam-column element for beams and columns, single slice wall element and three vertical line element for walls, and tube-wall element for tubes. Computational example for verifying the models indicates that the result obtained by this method is identical with a well-known test result and the program can be used to search for the full process of structural reaction, even the softening stage of the structure. With this push-over analysis method, an actual tall building with complex structural type was analyzed, and the result has been put into practice of the structural design of the building. Key words push-over analysis - tall structure - complex type - nonlinearity - earthquake level - weak storey MSC2000 74S05 - 74L99 Project supported by the National Natural Science Foundation of China (Grant No. 50025821)

Phytosociology of stratification in a lowland tropical rainforest occurring north of the Tropic of Cancer in Meghalaya, India

Stratification in lowland rainforests of Meghalaya,India,which represent the westernmost limit of the rainforests north of the Tropic of Cancer,was studied in horizontal and vertical planes to elucidate the patterns in stacking of species diversity and community attributes,and to draw comparisons with rainforests of‘Indo-Malaya’ecozone(biogeographical realm).All individuals≥10 cm GBH(girth at breast height)were enumerated in six transects of 10 m width and up to 500 m length covering 2.45 ha area.The stratification of whole assemblage of species in vertical plane is referred to as‘storey structure’(=height class distribution),which explains structural complexity.In horizontal plane,it is typically referred to as‘stand structure’(=girth class distribution),which explains structural heterogeneity.The stratification of an individual species in vertical plane is referred to as‘loftiness’and in horizontal plane,it is frequently referred to as‘population structure’.The stand structure was characterized by a negative exponential relationship or a reverse J-shaped curve,which is typical of a well regenerating forest stand.The storey structure was characterized by the low stature of the rainforest(<30 m),subtle layering in the canopy with dearth of discrete multi-stories,narrower widths of the stories and a thick understory.The cluster analysis and‘candlestick charts’showed that the dominant species spatially segregated in canopy height to profile three strata,viz.,an understory of juveniles and shrubs below 5 m,a middle-storey of intermediate trees between 5 and 15 m,and an overstory of large trees between 15 and 25 m.Emergent trees of a few species may reach up to 30 m.The individuals tended to scatter in increasingly wider range of height classes from a lower to the next higher girth class,creating a‘torchlight scatter’pattern,with a tendency to concentrate towards smaller height classes due to stochastic factors,which potentially influence vertical growth proportionate to diametric growth.In comparison to equatorial rainforests of Malaysia and seasonal rainforests of southwestern China,the rainforests of Meghalaya are short-statured at the geographic extremity of the occurrence of rainforest biome in Asiae Pacific region,owing to floristic composition,site quality factors,excessively higher quantities of rainfall and high differential of precipitation and potential evapotranspiration.Despite limited diversity of megaphanerophytes,these rainforests deserve concerted conservation efforts as they stack high diversity of meso-,micro-and nano-phanerophytes.

INTERDECADAL VARIABILITY IN A MODEL ATMOSPHERE

By using the simulation results of an AGCM, which had been run from 1945 to 1993 forced by COADS SST, the interdecadal variability of the model atmosphere was investigated and compared with that of NCEP reanalysis data. It was found that, interdecadal variability exists significantly in both the tropical Pacific wind fields and the mid-high latitude atmospheric circulation of the model atmosphere. The tendency of time variation and spatial distributions of the interdecadal variability of the model atmosphere are basically consistent with observation. Relative to the mid-high latitude atmospheric circulation, the simulation of tropical Pacific wind is more satisfying, which suggests that anomalous variation of SST is still the main factor for the interdecadal variability of tropical Pacific wind. It might have more significant influence on the tropical wind than on the mid-high latitude atmosphere. However, there is still obvious difference between the simulation and observation. They could be attributed to both the simulation capability of the model and absence of other factors in the model which are important for the interdecadal climate variation.

Relationship Between an Abrupt Drought-Flood Transition over Mid-Low Reaches of the Yangtze River in 2011 and the Intraseasonal Oscillation over Mid-High Latitudes of East Asia

NCEP/NCAR daily reanalysis data and Chinese daily gridded precipitation data are used to study the relationship between an aprupt drought-flood transition over the mid-low reaches of the Yangtze River in 2011 and the intraseasonal oscillation （ISO; 30-60 days） in the mid-high latitude meridional circulation of the upper troposphere over East Asia. The abrupt transition from drought to flood occurs in early June. The first two recovered fields of the complex empirical orthogonal function show that northward-propagating westerlies from low latitudes converge with southward-propagating westerlies from high latitudes over the mid-low reaches of the Yangtze River （MLRYR） in mid late May. The timing of this convergence corresponds to the flood period in early-mid June. The ISO index is significantly and positively correlated with rainfall over the MLRYR. During the dry phase （before the transition）, the upper troposphere over the MLRYR is characterized by cyclonic flow, easterly winds, and convergence. The regional circulation is dominated by a wave train with a cyclone over east of Lake Baikal, an anticyclone over northern China, and a cyclone over the MLRYR. During the wet phase, the situation is reversed. The configuration of the wave train during the dry phase favors the southward propagation of westerly wind disturbances, while the configuration of the wave train during the wet phase favors the development and maintenance of a pumping effect and sustained ascending motions over the MLRYR.

The zonal propagating characteristics of low-frequency oscillation over the Eurasian mid-high latitude in boreal summer

Using 32-yr National Centers for Environment Prediction-National Center for Atmospheric Research(NCEP-NCAR) reanalysis data,we investigated zonal propagation and circulation characteristics of the low-frequency circulation for the prevailing period over Eurasian mid-high latitude in boreal summer(May-August) in terms of empirical orthogonal function(EOF),linear regression,and phase analysis and so on.We found that the dominant periods of the low-frequency circulation are 10-30 days and it clearly shows meridional(southward) and zonal(westward) propagation features at the middle troposphere(500 hPa).The average zonal speed of the 10-30 days low-frequency oscillation(LFO) is about 9-10 longitudes per day.Further analysis shows that the southernmost part of the polar vortex in the northern hemisphere exhibits westward clockwise rotation in the eastern hemisphere in boreal summer.Also,the southernmost tips of 5400 and 5500 gpm contours,which indicate the site of the major trough in the eastern hemisphere,obviously move westwards.The southernmost tip of 5500 gpm contour line propagates westwards at the speed of about 9-10 longitudes per day,which is consistent with the mean zonal speed of the westward propagation of the low-frequency circulation.Moreover,the 10-30-day LFO-related cold air also shows west propagation feature with respect to LFO phases.The westward propagation of the LFO is the low-frequency-scale embodiment of the clockwise rotation of polar vortex.The cold air activities closely related to polar vortex or to ridge-trough system activities is the essential circulation of 10-30 days LFO circulation over the Eurasian mid-high latitude in boreal summer.

The Selection and Pricing of Mixed Multi-Channel Marketing Model for Mid-High Wines Under Experience Driven

The experience of consumers for products has great effect on the pre-sale strategy. Based on this, the paper studies the selection and pricing of multi-channel marketing models consisting of a brewer, an electronic retailer and a traditional retailer, constructing the non-cooperative game model of brewers and retailers with equal status in four contexts. Finally, the result shows that the introduction of direct channel is bene?cial to increase the brewer's revenue. When the pre-sale marginal revenue is greater than two times the average spot-sale marginal revenue, the total pro?t of supply chain will achieve the best under mode Ⅰ. i.e. both the brewer and e-retailer adopt pre-sale strategy.

Seismic analysis of a super high-rise steel structure with horizontal strengthened storeys

Horizontal strengthened storeys are widely used in super high-rise steel structures to improve the lateral structural rigidity.This use has great effects on the seismic properties of the entire structure.The seismic properties of the Wuhan International Securities Building (a 68-storey super high-rise steel structure with three horizontal strengthened storeys) were evaluated in this study.Two approaches,i.e.,mode-superposition response spectrum analysis and time-history analysis,were employed to calculate the seismic response of the structure.The response spectrum analysis indicated that transition parts near the three strengthened storeys were weak zones of the structure because of the abrupt change in rigidity.In the response spectrum analysis approach,the Square Root of Sum of Square (SRSS) method was recommended when the vertical seismic effects could be ignored.However,the complete quadratic combination (CQC) method was superior to SRSS method when the vertical seismic effects should be considered.With the aid of time-history analysis,the seismic responses of the structure were obtained.The whiplash effect that spectrum analysis cannot reveal was observed through time-history analysis.This study provides references for the seismic design of super high-rise steel structures with horizontal strengthened storeys.