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Interaction of Waves, Surface Currents, and Turbulence: the Application of Surface-Following Coordinate Systems

Journal of Ocean University of China 2007年第4期6卷 319-331页

作者： Jenkins Alastair D bjerknes Centre for climate research Geophysical Institute Allegaten 70 N-5007 Bergen Norway

Surface waves comprise an important aspect of the interaction between the atmosphere and the ocean, so a dynamically consistent framework for modelling atmosphere-ocean interaction must take account of surface waves, either implicitly or explicitly. In order to calculate the effect of wind forcing on waves and currents, and vice versa, it is necessary to employ a consistent formula- tion of the energy and momentum balance within the airflow, wave field, and water column. It is very advantageous to apply sur- face-following coordinate systems, whereby the steep gradients in mean flow properties near the air-water interface in the cross-interface direction may be resolved over distances which are much smaller than the height of the waves themselves. We may account for the waves explicitly by employing a numerical spectral wave model, and applying a suitable theory of wave–mean flow interaction. If the mean flow is small compared with the wave phase speed, perturbation expansions of the hydrodynamic equations in a Lagrangian or generalized Lagrangian mean framework are useful: for stronger flows, such as for wind blowing over waves, the presence of critical levels where the mean flow velocity is equal to the wave phase speed necessitates the application of more general types of surface-following coordinate system. The interaction of the flow of air and water and associated differences in temperature and the concentration of various substances (such as gas species) gives rise to a complex boundary-layer structure at a wide range of vertical scales, from the sub-millimetre scales of gaseous diffusion, to several tens of metres for the turbulent Ekman layer. The bal- ance of momentum, heat, and mass is also affected significantly by breaking waves, which act to increase the effective area of the surface for mass transfer, and increase turbulent diffusive fluxes via the conversion of wave energy to turbulent kinetic energy.

关键词： wind-wave-current interaction coordinate systems upper-ocean turbulence air-sea exchange of momentum, heat, andmass

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The Relationship between Extreme Precipitation Events in East Africa during the Short Rainy Season and Indian Ocean Sea Surface Temperature

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Journal of Geoscience and Environment Protection 2024年第9期12卷 1-16页

作者： Jafari Swalehe Chobo Liwei Huo School of Atmospheric Sciences Key Laboratory of Meteorological Disaster of Ministry of Education Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and Technology Nanjing China Tanzania Meteorological Authority (TMA) Research and Applied Meteorology Climatology and Climate Change Section Tanzania Meteorological Authority Dar es Salaam Tanzania

The East African short rainy season (October-November-December) is one of the major flood seasons in the East African region. The amount of rainfall during the short rainy season is closely related to the lives of the people and the socio-economic development of the area. By using precipitation data and sea surface temperature data, this study reveals the spatial and temporal variation patterns of extreme precipitation during the East African short rainy season. Key findings include significant rainfall variability, with Tanzania experiencing the highest amounts in December due to the southward shift of the Intertropical Convergence Zone (ITCZ), while other regions receive less than 100 mm. Extreme rainfall events (90th percentiles) are evenly distributed, averaging 2 to 10 days annually. Historical data shows maximum seasonal rainfall often peaks at 15 mm, with frequent occurrences of daily rainfall exceeding 10 mm during OND. Additionally, a positive correlation (0.48) between OND precipitation extremes and Indian Ocean Dipole (IOD) anomalies is statistically significant. These findings highlight the climatic variability and potential trends in extreme rainfall events in East Africa, providing valuable insights for regional climate adaptation strategies.

关键词： East Africa Sea Surface Temperature (SST) Extreme Rainfall Short Rains Season Indian Ocean Dipole (IOD)

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Status and trends in the stability of the three largest ice shelves in Antarctica

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Science China Earth Sciences 2024年第8期67卷 2615-2632页

作者： Rongxing LI Guojun LI Lu AN Menglian XIA Da LV Yuan CHENG Aiguo ZHAO Tian CHANG Xiangbin CUI Shengkai ZHANG Shijie LIU Yixiang TIAN Weian WANG center for Spatial Information Science and Sustainable Development Applications Tongji UniversityShanghai 200092China College of Surveying and Geo-informatics Tongji UniversityShanghai 200092China Postdoctoral research Station of Shanghai Surveying and Mapping Institute Shanghai 200063China Key Laboratory of Spatial-temporal Big Data Analysis and Application of Natural Resources in Megacities Shanghai 200063China Institute for Conservation of Cultural Heritage School of Cultural Heritage and Information ManagementShanghai UniversityShanghai 200444China Polar research Institute of China Shanghai 200136China Chinese Antarctic center of Surveying and Mapping Wuhan UniversityWuhan 430079China

The Ross,Filchner-Ronne,and Amery ice shelves are the three largest ice shelves in Antarctica,playing a crucial role in supporting the Antarctic ice ***,current studies on the stability of the three largest ice shelves primarily focus on singular or limited factors,lacking a comprehensive assessment of multiple *** systematically and in-depth study the stability and trend of the three largest ice shelves,we comprehensively collected and analyzed key parameters,including elevation changes,basal melting,surface meltwater,major rifts propagation rate,suture zones,ice front area change rate,grounding lines,ice velocity,and mass ***,we selected the collapsed Larsen B Ice Shelf(LBIS),the rapidly changing and structurally weakened Pine Island Ice Shelf(PIIS),and the accelerating Totten Ice Shelf(TIS)as reference ice *** comparing and analyzing the key parameters between these reference ice shelves and the three largest ice shelves,we find the status and trends in the stability of the *** findings reveal that most key parameters of the three largest ice shelves present relatively minor variations compared to those of the reference ice ***,50%of the parameters are smaller than those of the accelerating TIS,88%are smaller than those of the rapidly changing PIIS,and all parameters are smaller than those of the collapsed ***,after analyzing parameters that are not smaller than those of the TIS,it is observed that they remain in a stable ***,the three largest ice shelves are currently undergoing natural changes that do not threaten their stability in the short ***,the evolution of the ice shelves under global climate change remains uncertain,making long-term observation and monitoring essential to assess their impact on sea level rise.

关键词： Three largest ice shelves in Antarctica Key parameters Remote sensing monitoring Ice shelf stability Sea level change

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The First Ground-based White Light Lunar Polarization Imaging:A New Kind of FeO Observation on the Near Side of the Moon

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research in Astronomy and Astrophysics 2024年第6期24卷 1-6页

作者： Wei-Nan Wang Jin-Song Ping Ming-Yuan Wang Wen-Zhao Zhang Han-Lin Ye Xing-Wei Han Song-Feng Kou Changchun Observatory National Astronomical ObservatoriesChinese Academy of SciencesChangchun 130117China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 101408China Astronomy Department Beijing Normal UniversityBeijing 100875China International center for climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Nanjing Institute of Astronomical Optics and Technology Chinese Academy of SciencesNanjing 210042China

Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes *** study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the *** obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the *** findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria *** the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the *** study may serve as a new diagnostic tool for the Moon.

关键词： techniques:photometric polarization methods:observational Moon

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Differential response of radial growth and δ^(13)C in Qinghai spruce(Picea crassifolia) to climate change on the southern and northern slopes of the Qilian Mountains in Northwest China

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Journal of Forestry research 2024年第3期35卷 205-218页

作者： Li Qin Huaming Shang Weiping Liu Yuting Fan Kexiang Liu Tongwen Zhang Ruibo Zhang Key Laboratory of Tree-Ring Physical and Chemical research(CMA)/Xinjiang Key Laboratory of Tree-Ring Ecology Institute of Desert MeteorologyChina Meteorological AdministrationUrimqi 830002People's Republicof China Xinjiang Meteorological Information center Urimqi 830002People's Republic of China

Tree radial growth can have significantly differ-ent responses to climate change depending on the *** elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic ***-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the ***-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing *** conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate *** response between tree rings and climate in mountains gradually weakened as climate *** in radial growth and stable carbon isotope fractionation of *** in response to climate in the Qilian Mountains may be further complicated by continued climate change.

关键词： Tree rings Qinghai spruce(Picea crassifolia Kom.) Stable carbon isotope(δ^(13)C) Qilian Mountains:climate change

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A study of the early warning signals of abrupt change in the Pacific decadal oscillation

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Chinese Physics B 2015年第8期24卷 662-673页

作者：吴浩侯威颜鹏程张志森王阔 Hunan climate center National climate center College of Atmospheric Sciences Lanzhou University Zhejiang climate center

In recent years, the phenomenon of a critical slowing down has demonstrated its major potential in discovering whether a complex dynamic system tends to abruptly change at critical points. This research on the Pacific decadal oscillation(PDO) index has been made on the basis of the critical slowing down principle in order to analyze its early warning signal of abrupt change. The chaotic characteristics of the PDO index sequence at different times are determined by using the largest Lyapunov exponent(LLE). The relationship between the regional sea surface temperature(SST) background field and the early warning signal of the PDO abrupt change is further studied through calculating the variance of the SST in the PDO region and the spatial distribution of the autocorrelation coefficient, thereby providing the experimental foundation for the extensive application of the method of the critical slowing down phenomenon. Our results show that the phenomenon of critical slowing down, such as the increase of the variance and autocorrelation coefficient, will continue for six years before the abrupt change of the PDO index. This phenomenon of the critical slowing down can be regarded as one of the early warning signals of an abrupt change. Through calculating the LLE of the PDO index during different times, it is also found that the strongest chaotic characteristics of the system occurred between 1971 and 1975 in the early stages of an abrupt change(1976), and the system was at the stage of a critical slowing down, which proves the reliability of the early warning signal of abrupt change discovered in 1970 from the mechanism. In addition, the variance of the SST,along with the spatial distribution of the autocorrelation coefficient in the corresponding PDO region, also demonstrates the corresponding relationship between the change of the background field of the SST and the change of the PDO.

关键词： abrupt climate change critical slowing down early warning signals largest Lyapunov exponent sea surface temperature

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Carbon emission reduction: Contribution of geothermal energy and practice in China

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China Geology 2024年第1期7卷 161-164页

作者： Liang Wang Li-qiong Jia Natural Resources Integrated Survey Command center China Geological SurveyMinistry of Natural ResourcesBeijing 100055China Development and research center China Geological SurveyMinistry of Natural ResourcesBeijing 100037China

As a kind of natural energy from the earth’s interior,geothermal energy is characterized by large reserve,wide distribution,good stability,high utilization coefficient,and positive effects of energy-saving and *** is of great significance for promoting green and low-carbon energy transition,reducing greenhouse gas emission,and achieving global climate goals and sustainable economic ***,it has been highly recognized and valued by lots of countries around the world,and has become one of the most important clean energy sources that countries are accelerating to develop and *** potential of the global geothermal energy resource is estimated to be 1.25×1027 J,equivalent to 4.27×10^(16) t of standard coal,among which the geothermal resource between 0 km and 5 km is 1.45×10^(26) J,equivalent to 4.95×1015 t of standard coal(China Geological Survey,2018).

关键词： energy utilize interior

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Diapycnal Mixing in Transient Responses of the Atlantic Meridional Overturning Circulation in an Enhanced Freshwater Perturbation Experiment

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Atmospheric and Oceanic Science Letters 2010年第4期3卷 201-206页

作者： Helge DRANGE Odd Helge OTTER Nansen-Zhu International research Centre Institute of Atmospheric PhysicsChinese Academy of Sciences Nansen Environmental and Remote Sensing center/bjerknes Centre for climate research

It has been reported recently that the simulated Atlantic meridional overturning circulation(AMOC) using the coupled Bergen climate model(BCM) showed initial intensity declines followed by gradual recoveries over a 150-year enhanced freshwater input ***-dependent oceanic diapycnal mixing has been hypothesized as a reason for the simulated recovery of the *** study investigated the role of diapycnal mixing in transient responses of simulated *** results showed that stratification-dependent diapycnal mixing can cause stronger upwelling of deep water in the tropical Atlantic than that produced under conditions of fixed diapycnal ***,simulated AMOCs were more sensitive to active stratification-dependent diapycnal mixing than fixed ***,stratification-dependent diapycnal mixing cannot be conclusively singled out as the critical cause of the recoveries of simulated AMOCs under enhanced-freshwater inputs.

关键词： diapycnal mixing western tropical North Atlantic freshwater experiment

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Change in Sea Ice Cover is Responsible for Non-Uniform Variation in Winter Temperature over East Asia

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Atmospheric and Oceanic Science Letters 2015年第6期8卷 376-382页

作者： LI Fei WANG Hui-Jun GAO Yong-Qi Nansen-Zhu International research Centre Institute of Atmospheric Physics Chinese Academy of Sciences climate Change research center Chinese Academy of Sciences Collaborative Innovation center on Forecast and Evaluation of Meteorological Disasters Nanjing University for Information Science and Technology Nansen Environmental and Remote Sensing center and bjerknes Centre for climate research

Observed winter(December–February)surface air temperature over East Asia(0°–60°N,100–140°E)(TEA)shows non-uniform variation during 1979–2013,with cooling and weak warming north and south of40°*** understand this,the authors perform statistical analysis(linear regression and composite)on the observed *** results suggest that reduced(increased)autumn sea ice cover in the Barents-Kara Sea(BK-ASIC)lowers(warms)TEA over northern East Asia,which is consistent with previous *** comparison,increased(decreased)winter sea ice cover in the Sea of Okhotsk(O-WSIC),warms(cools)the air over southern East *** mechanism can be described as follows:When the BK-ASIC decreases,the East Asian winter monsoon tends to be stronger with an intensified Siberian high,leading to cooling over northern East *** O-WSIC increase is associated with cold anomalies north of 50°N,altering the meridional temperature gradient between the midlatitudes and tropics,and leading to a northward shift of the East Asian jet steam in the upper *** the low atmosphere,anomalous northeasterly winds prevail north of50°N and anomalous southerly winds control the southern coast of East Asia,contributing to the weak warming over southern East *** 3 of the Community Atmosphere Model also provides evidence for the impact of increased O-WSIC on the warm southern mode of TEA.

关键词： East Asia winter temperature Arctic sea ice cover

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Applicability of different indices for delineating the boundary of arid region: A case study in northwestern China

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Journal of Earth Science 2024年

作者： Xue Peng Xiang Li Yingyibing Shen Xuehua Che Shipei Dong Zhuolun Li Key Laboratory of Western China's Environmental Systems (Ministry of Education)， College of Earth and Environmental Sciences， center for Glacier and Desert research， Lanzhou University

Arid regions are vital components of Earth's land surface. Clarifying the area/boundary of arid region is crucial for comprehending area changes and potential mechanisms. However， the accuracy and applicability of arid region boundary delineated by different indices remain unclear. In this study， the annual precipitation （AP）， humidity index （H）， and aridity index （K） were calculated for delineating arid region of China using 106 meteorological stations during 1990–2019. The results suggest that AP and H can accurately delineate arid region， because they are consistent with the distribution of typical soil and vegetation in arid region， whereas K is not. Moreover， AP is the best index for delineating arid region in regions with limited meteorological data， especially in studying long-term patterns and mechanisms of area changes. The accuracy of delineating arid region using H is enhanced in regions with abundant meteorological data. Over the past 30 years， influenced by the increase of atmospheric moisture influx and precipitation， the area in arid region of northwestern China decreased by 70×103–90×103km2， resulting in the present area of approximately 1.55×106km2. This study provides appropriate indices for delineating arid region， contributing to improving our knowledge of regional responses difference to climate change.

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