Meridional energy flux in the Arctic from data of the radiosonde archive IGRA

The meridional energy transport into high latitudes of the Northern Hemisphere is an important climate-forming factor in the Arctic. This work presents the results of calculating the meridional energy flux across 70° N based on the Integrated Global Radiosonde Archive (IGRA) data from the radio sounding of the atmosphere. The long-term mean energy flux over the period 1992–2007 in the layer from the Earth’s surface to 30 hPa is 70.6 W m^?2. The fraction of the sensible heat flux is 23.2 W m^?2, i.e., 33% of the total energy flux; the fraction of the latent heat flux is 28.0 W m^?2 (40% of the total energy flux); the fraction of the potential energy is 20.0 W m^?2 (27%); and the fraction of the kinetic energy is 0.53 W m^?2, i.e., less than 1% of the total energy flux. The vertical structure of the flux shows that the main energy transport into the Arctic takes place in the middle troposphere-lower stratosphere layer, whereas the energy is transported mainly out of the Arctic in the lower troposphere, which agrees well with the schematic notion about the polar circulation cell. The spatial structure of the flux shows that the key regions with a positive (directed into the Arctic) energy flux are located in the vicinity of 160° E (the northwestern part of Eurasia, Pacific sector) and 50° W (Greenland sector). The regions with a negative (directed out of the Arctic) energy flux are located near 120° W (Canadian Arctic Archipelago) and from 20° E to 90° E (Atlantic sector). In the period from 1992 to 2007, the meridional energy transport into the Arctic weakened by ?0.26 W m^?2 yr^?1. The changes were mutually correlated; namely, positive and negative energy fluxes weakened in amplitude, almost without changing their locations.     

北极楚科奇海及其附近海域海底底栖贝类遗壳分布

对采自北极的23个站的底栖贝类遗壳进行鉴定,结果表明这些贝类遗壳计有17个种,其中双壳纲13种,腹足纲4种.根据鉴定到种的13个种可将所鉴定的软体动物分为两个区系:北极和环北极寒温带种,它们是Astarte montagui,Liocyma fluctusa,Macoma calcarea,M.moesta alas-kana,Mya pseudoarenaria,Nuculana pernula,N.radiata,Nucula bellotii,Serripes groenlan-dicus和Turritella polaris,共计10种,它们是北极水域软体动物区系组成中的主要成分;北极北太平洋寒温带种,它们是Argobuccinum oregonense,Cyclocardia crebricostata和Trichotropis cor-onata有3种.根据食性又可将它们分成滤食性、肉食性和碎食性三种,其中摄食沉积物中有机碎屑的碎食性种类占优势,包括双壳类中的Macoma calcarea,M.moesta alaskana,Macoma sp.,Nuculana pernula,N.radiata,Nucula bellotii,和腹足类的Trichotropis coronata,共计7种,它们不仅种类多,丰度高,而且在调查区的分布同细颗粒的沉积物有密切关系.     

Distribution of molluscan remains in the sediment of the Chukchi Sea and its vicinity, the Arctic

INTRODUCTIONInordertostudythemarinesedimentationoftheChukchiSeaandBeringSeaandgathertheinformationofpaleoceanographyandpaleoenvironment,theFirstChineseNationalArcticResearchExpeditionTeamcollectedbenthonicmolluscansamplesintheChukchiSea ,BeaufortSeaandBeringSeafromJuly 1sttoSeptember 9th ,1 999byicebreakerXuelong .ItwasnotonlythefirstsamplingthatChinesescientistscollectedmolluscaremainsinabove mentionedar eas,butalsooneofinvestigationsinasinglecruisewithhighersamplingrateandalotofb…     

An evaluation of the Arctic clouds and surface radiative fluxes in CMIP6 models

To assess the performances of state-of-the-art global climate models on simulating the Arctic clouds and surface radiation balance, the 2001–2014 Arctic Basin surface radiation budget, clouds, and the cloud radiative effects(CREs) in 22 coupled model intercomparison project 6(CMIP6) models are evaluated against satellite observations. For the results from CMIP6 multi-model mean, cloud fraction(CF) peaks in autumn and is lowest in winter and spring, consistent with that from three satellite observation products(Cloud Sat-CALIPSO, CERESMODIS, and APP-x). Simulated CF also shows consistent spatial patterns with those in observations. However,almost all models overestimate the CF amount throughout the year when compared to CERES-MODIS and APP-x.On average, clouds warm the surface of the Arctic Basin mainly via the longwave(LW) radiation cloud warming effect in winter. Simulated surface energy loss of LW is less than that in CERES-EBAF observation, while the net surface shortwave(SW) flux is underestimated. The biases may result from the stronger cloud LW warming effect and SW cooling effect from the overestimated CF by the models. These two biases compensate each other,yielding similar net surface radiation flux between model output(3.0 W/m~2) and CERES-EBAF observation(6.1 W/m~2). During 2001–2014, significant increasing trend of spring CF is found in the multi-model mean,consistent with previous studies based on surface and satellite observations. Although most of the 22 CMIP6 models show common seasonal cycles of CF and liquid water path/ice water path(LWP/IWP), large inter-model spreads exist in the amounts of CF and LWP/IWP throughout the year, indicating the influences of different cloud parameterization schemes used in different models. Cloud Feedback Model Intercomparison Project(CFMIP)observation simulator package(COSP) is a great tool to accurately assess the performance of climate models on simulating clouds. More intuitive and credible evaluation results can be obtained based on the COSP model output. In the future, with the release of more COSP output of CMIP6 models, it is expected that those inter-model spreads and the model-observation biases can be substantially reduced. Longer term active satellite observations are also necessary to evaluate models' cloud simulations and to further explore the role of clouds in the rapid Arctic climate changes.     

Interannual variability of the primary production and organic carbon fluxes in the Arctic seas of Russia

To estimate the response of the primary production to the climate warning, the trends of the production changes within 1998–2006 were considered in tests areas in the Barents, Kara, and Chukchi seas using satellite and field data. Both positive and negative trends were revealed with a general tendency to an increase in the primary production and in the extent of the organic carbon burial in the bottom sediments.     

不考虑局地引潮势的南海正压潮能通量与潮能耗散

利用ECOM模式模拟南海正压M2、S2、K1、O1分潮, 对南海潮能通量及潮能耗散进行研究.结果显示, M2、S2、K1和O1分潮分别有38.93、5.77、29.73和28.97GW的能通量经吕宋海峡传入南海, 并有2.42、0.36、8.67和7.86GW的能通量由南海经卡里马塔海峡传入爪哇海.由东海及吕宋海峡西北部传入台湾海峡的M2分潮能通量为25.28GW.半日潮进入北部湾和泰国湾的能通量较少(6.52GW), 全日潮则较大(24.74GW).通过民都洛和巴拉巴克海峡断面, 全日潮由南海向苏禄海共输送12.28GW的能通量, 而半日潮则由苏禄海向南海输送1.92GW的能通量.由模式输出结果估计得到的南海各局部海域的底摩擦耗散与净潮能通量存在差异, 为使二者平衡, 可对南海不同海域的底摩擦系数进行调整.依净潮能通量与底摩擦耗散平衡关系计算得到台湾海峡、北部湾、泰国湾及南海深水海域的底摩擦系数分别为0.0023、0.0024、0.0023和0.0021.     

Comparison of airsea fluxes of CO2 in the Southern Ocean and the western Arctic Ocean

The data were collected during Chinese Arctic and Antarctic Expeditions in the western Arctic Ocean and the marginal sea ice zone (MSIZ) of the Southern Ocean, respectively in the boreal summer from July to September of 1999 and in the austral summer from December of 1999 to January of 2000. The concentrations of CO2 in surface water of the survey regions would mostly present lower than those in the atmosphere. A significant biological driving force could also been observed in summer waters in both of the above oceans. Air to sea CO2 fluxes were also calculated to compare oceanic uptake capacity of CO2 in both oceans with the world oceans using Liss, Wanninkhof, and Jacobs‘s methods. The averaged CO2 fluxes of air to sea in the western Arctic Ocean or in the MSIZ of the Southern Ocean doubled that in the world oceans.     

Optical properties and surface energy flux of spring fast ice in the Arctic

Over the past decades, sea ice in the polar regions has been significantly affecting local and even hemispheric climate through a positive ice albedo feedback mechanism. The role of fast ice, as opposed to drift ice, has not been well-studied due to its relatively small coverage over the earth. In this paper, the optical properties and surface energy balance of land fast ice in spring are studied using in situ observations in Barrow, Alaska. The results show that the albedo of the fast ice varied between 0.57 and 0.85 while the transmittance increased from 1.3×10?3 to 4.1×10?3 during the observation period. Snowfall and air temperature affected the albedo and absorbance of sea ice, but the transmittance had no obvious relationship with precipitation or snow cover. Net solar shortwave radiation contributes to the surface energy balance with a positive 99.2% of the incident flux, with sensible heat flux for the remaining 0.8%. Meanwhile, the ice surface loses energy through the net longwave radiation by 18.7% of the total emission, while the latent heat flux accounts for only 0.1%. Heat conduction is also an important factor in the overall energy budget of sea ice, contributing 81.2% of the energy loss. Results of the radiative transfer model reveal that the spectral transmittance of the fast ice is determined by the thickness of snow and sea ice as well as the amount of inclusions. As major inclusions, the ice biota and particulates have a significant influence on the magnitude and distribution of the spectral transmittance. Based on the radiative transfer model, concentrations of chlorophyll and particulate in the fast ice are estimated at 5.51 mg/m2 and 95.79 g/m2, which are typical values in the spring in Barrow.     

The directivity of energy radiation of the tsunami generated in the vicinity of a continental shelf

The radiation pattern of the tsunami generated by a broad crustal deformation on or near the continental shelf is examined analytically in the framework of a linear long-wave approximation. Detailed discussion, however, is made only for a model of step-type bottom topography.The proportion of the energy trapped on the shelf as edge wave modes relative to that radiated into deep water increases with the decrease of the long-shore dimension of the source. The nearer is the source to the coastline, the greater is the rate of total edge wave generation. However, the proportion of higher modes increases for the source near the shelf edge.The proportion of the wave energy radiated in deep water, normal to the coastline, increases with the increase of the long-shore dimension of the source and/or the decrease of the depth difference between the shelf and deep water. Furthermore, this proportion increases with the increased distance of the source location from the coastline and approaches the value for the case without a shelf. For a source of the square shape, the directive difference of energy radiation in deep water is mainly caused by the refractive effect of the shelf edge. For larger long-shore dimension of the source, however, the geometric shape effect of the source is more important to cause the directive difference.     

Primary production and fluxes of organic carbon to the seabed in the Russian Arctic seas as a response to the recent warming

The primary production and fluxes of organic matter to the seabed and their variations were estimated in the Norwegian, Greenland, Barents, Kara, Laptev, East Siberian, and Chukchi seas in 2003–2008 on the basis of satellite and field data. When counting the open water area with the assumptions made for the assessment of the primary production in the regions hidden under clouds, the reliable trends of its variability (increasing) were revealed only in the Greenland, Barents, and Kara seas.     

Southern Ocean transformation in a coupled model with and without eddy mass fluxes

A coupled air–sea general circulation model is used to simulate the global circulation. Different parameterizations of lateral mixing in the ocean by eddies, horizontal, isopycnal, and isopycnal plus eddy advective flux, are compared from the perspective of water mass transformation in the Southern Ocean. The different mixing physics imply different buoyancy equilibria in the surface mixed layer, different transformations, and therefore a variety of meridional overturning streamfunctions. The coupled‐model approach avoids strong artificial water mass transformation associated with relaxation to prescribed mixed layer conditions. Instead, transformation results from the more physical non‐local, nonlinear interdependence of sea‐surface temperature, air–sea fluxes, and circulation in the model's atmosphere and ocean. The development of a stronger mid‐depth circulation cell and associated upwelling when eddy fluxes are present, is examined. The strength of overturning is diagnosed in density coordinates using the transformation framework.     

Influence that interannual variations in Siberian river discharge have on redistribution of freshwater fluxes in Arctic Ocean and North Atlantic

A numerical simulation with a coupled sea-ice model of the Arctic and North Atlantic oceans is used to study the influence that the interannual variations in the Siberian river discharge have on the distribution and propagation of freshwater in this region. In numerical experiments we compared simulations with the use of observational data on the discharge of the most significant Siberian rivers (Ob, Yenisei, and Lena) against the results of climatic seasonally average variations of their discharges. This comparison showed that the interannual variations may have significant consequences despite their smallness when compared with oceanic-scale water transport. These consequences include (1) the intensification of either cyclonic or anticyclonic components of motion of the subsurface Arctic Ocean waters and, as a result, the redistribution of freshwater fluxes from Arctic regions between the Fram Strait and the straits of the Canadian Archipelago. A change in the store of fresh Arctic Ocean waters due to interannual variations in the Ob, Yenisei, and Lena discharges is approximately ±400 km³, whereas the volume of water redirected in this regard, which forms a link between some straits, reaches 15 thousand km³. On the other hand, (2) insignificant changes in the propagation direction of freshwaters are multiply enhanced in the process of their motion in the North Atlantic as part of the subpolar gyre because of their smaller or larger involvement in the processes of vertical mixing. As a result of this, anomalies of freshwater develop considerably far from the river mouths, like in the region of the Azores islands, and are 5–6 times larger than the maximum values of the accumulated variability volumes of the river discharge.     

Large-scale mass wasting on the north Spitsbergen continental margin, Arctic Ocean

 Closely spaced, single-beam bathymetric and side-scan sonar investigations on the northern slope of the western Svalbard insular platform have revealed the presence of a Late Quaternary slump complex forming a hanging-wall slump canyon near the head of the Malene Bukta (Malene Bay) bathymetric embayment in the northern continental margin. Repeated slump erosion may be responsible for development of this young feature and the Malene Bukta Embayment. Focusing of the slumping may be due to the trapping of gas at shallow sea-floor depths by gas hydrate, with the consequent formation of subjacent gas-rich, low shear-strength decollement zones. Faults have likely controlled the upward migration of gas into the younger sedimentary prism.     

Temporal variation in mass fluxes and the major components of sinking particles in Sagami Bay, off Japan

Sinking particles were collected using time-series sediment traps deployed at 350 and 20 mab at Site SB (34° 58.5’N, 139° 20.9’E, 1544 m depth) near the center of Sagami Bay, off Japan with high time resolutions of 5-8 days (March 1997 to August 1998) and 3-4.5 days (March 1998 to August 1998), respectively. The major components (CaCO₃, OM, opal, and clay) of these sinking particles and surface bottom sediments were determined using a stepwise leaching method combined with gravimetry. Average total mass fluxes were 1480, 5560 and 3068 mg/m²/year at 350 mab, at 20 mab, and in the surface sediments, respectively, indicating an enhanced collection of sinking particles at 20 mab. Clay was the dominant component and biogenic components (opal+OM+CaCO₃) were dominated mainly by opal and secondly by OM. On average, opal and CaCO₃ contents decreased gradually as clay content increased with increasing depth from 350 mab-20 mab and in the surface sediments, indicating dissolution of opal and CaCO₃ through sinking, rebound, resuspension or sedimentation processes. Thirteen total mass flux peaks at 17--40-day intervals were observed at 350 mab during the period from March 1997 to August 1998 except for winter, while eight peaks were observed at 20 mab for the period from March 1998 to August 1998. Two types of total mass peaks can be distinguished: one with a clear increase in biogenic flux (opal+OM+CaCO₃) and little or no increase in clay flux and termed a bloom type (B-type), and the other with a clear increase in clay flux, little increase in biogenic flux and termed a resuspension type (R-type). Some R-type peaks, but not all, coincided with total mass flux peaks observed at the mouth of Tokyo Bay and suggested the possibility of the effect of particulate materials transported from Tokyo Bay to site SB. The enormously large peak observed at 20 mab in late May 1998 and that at 350 mab in early June 1998 were considered to be due to some physical perturbations from an earthquake swarm near site SB during the period from April to June 1998. The 17--40-day periodicity was associated clearly with the change in biogenic flux dominated by opal flux and is thought to reflect the periodicity of biological productivity dominated by diatoms in the euphotic zone of Sagami Bay.     

海水物质平衡浮标对北冰洋中心区海冰温度与物质平衡的观测

利用中国第3次北极科学考察所布放海冰物质平衡浮标(Ice Mass-Balance buoy,IMB)的观测数据,分析了北冰洋中心区多年冰2008年8月-2009年7月温度与物质平衡的变化特征.结果表明,冰温廓线呈现明显的季节变化,秋季降温过程从海冰表面开始向冰体内部传播.海冰底部的生长/消融率受海水温度控制,随水温的...     

Meridional Mass Transport of Bottom Water in the South Atlantic

Izvestiya, Atmospheric and Oceanic Physics - Estimates of the meridional mass transport of Antarctic Bottom Water, calculated using the coupled ocean-atmosphere Earth System Model on the basis of...     

热带气旋下海浪对大气向海洋输入的动量和能量的影响

海浪不仅决定着海洋表面的粗糙度,由热带气旋引起的海浪,还通过其发展演化控制着大部分的海气之间的动量和能量传递。本文采用热带气旋观测数据IBTrACS和海浪模式WW III的模拟结果探究了热带气旋下海浪对大气向海洋输入的动量和能量的影响。结果发现,近30 a热带气旋的强度约每10 a增加 1 m/s,但移速没有明显变化。热带气旋的强度越大,从大气输入到海浪和从海浪输入到海流中的动量之差和能量之差也越大。由于热带气旋的风场和海浪场都有较强的不对称性,海气动量差和能量差也表现出非均匀分布：动量差较大的区域在热带气旋移动方向的后方,能量差的最大值则分布在右后象限,且二者均为左前方比较小。逆波龄与动量差和能量差呈高度正相关,相关系数约为0.95,说明波越年轻吸收的动量和能量越多。气旋移速越快逆波龄越大,且热带气旋移动速度与动量差和能量差呈正相关,相关系数在0.8以上。因此,海浪影响着大气向海洋输入的动量和能量的分布和大小,在以后关于海洋边界动力学和热力学的研究中,考虑海浪的演化可能会使结果更加准确。     

Meridional carbon dioxide transport in the northern North Atlantic

Combination of estimated water transport and accurate measurements of total carbon dioxide (TCO₂) on a hydrographic section at 58 °N allows the assessment of meridional inorganic carbon transport in the northern North Atlantic Ocean. The transport has been decomposed into contributions from the large-scale baroclinic overturning, the Ekman transport, baroclinic and a barotropic eddy terms, and an estimated contribution of the East Greenland Current. These terms are −0.27 · 10⁶, +0.03 · 10⁶, +0.03 · 10⁶, +0.10 · 10⁶, and +0.05 · 10⁶ mol s⁻¹, respectively, which result in a total southward inorganic carbon transport of only −0.06 · 10⁶ mol s⁻¹. An order of magnitude estimate of the meridional transport of dissolved organic carbon (DOC) has shown that in general this term cannot be ignored in the total carbon flux, this being +0.04 · 10⁶ to +0.16 · 10⁶ mol s⁻¹ at 58 °N. A simple carbon budget has been formulated for the temperate North Atlantic, using our flux estimates as well as those of Brewer et al. (1989). This budget shows that the divergence of the meridional carbon flux, connected with the freshwater balance of the ocean may be of the same order of magnitude as the divergence of the total inorganic carbon flux. For an accurate estimate of the total carbon budget of the ocean it will be necessary to take both the DOC transport and the effects of the freshwater balance into account.