Preconditioned Optimizing Utility for Large-dimensional analyses (POpULar)

I present the derivation of the Preconditioned Optimizing Utility for Large-dimensional analyses (POpULar), which is developed for adopting a non-diagonal background error covariance matrix in nonlinear variational analyses (i.e., analyses employing a non-quadratic cost function). POpULar is based on the idea of a linear preconditioned conjugate gradient method widely adopted in ocean data assimilation systems. POpULar uses the background error covariance matrix as a preconditioner without any decomposition of the matrix. This preconditioning accelerates the convergence. Moreover, the inverse of the matrix is not required. POpULar therefore allows us easily to handle the correlations among deviations of control variables (i.e., the variables which will be analyzed) from their background in nonlinear problems. In order to demonstrate the usefulness of POpULar, we illustrate two effects which are often neglected in studies of ocean data assimilation before. One is the effect of correlations among the deviations of control variables in an adjoint analysis. The other is the nonlinear effect of sea surface dynamic height calculation required when sea surface height observation is employed in a three-dimensional ocean analysis. As the results, these effects are not so small to neglect.     

Summer distribution and geochemical composition of suspended-particulate matter in the east china sea

The distribution and geochemical composition of suspended-particulate matter (SPM) in the East China Sea (ECS) were investigated during the summer period of high continental runoff to elucidate SPM sources, distribution and cross-shelf transport. The spatial variability of SPM distribution (0.3–6.5 mg l⁻¹) and geochemical composition (POC, Al, Si, Fe, Mn, Ca, Mg and K) in the ECS was pronounced during summer when the continental fluxes of freshwater and terrestrial materials were highest during the year. Under the influences of Changjiang runoff, Kuroshio intrusion, surface production and bottom resuspension, the distribution generally showed strong gradients decreasing seaward for both biogenic and lithogenic materials. Particulate organic carbon was enriched in surface water (mean ∼18%) due to the influence of biological productivity, and was diluted by resuspended and/or laterally-transported materials in bottom water (mean 9.4%). The abundance of lithogenic elements (Al, Si, Fe, Mn) increased toward the bottom, and the distribution correlations were highly significant. Particulate CaCO₃ distribution provided evidence that the SPM of the bottom water in the northern part of the study area was likely mixed with sediments originally derived from Huanghe. A distinct benthic nepheloid layer (BNL) was present in all seaward transects of the ECS shelf. Sediment resuspension may be caused by tidal fluctuation and other forcing and be regarded as the principal agent in the formation of BNL. This BNL was likely responsible for the transport of biogenic and lithogenic particles across or along the ECS shelf. Total inventories of SPM, POC and PN are 46, 2.8 and 0.4 Tg, respectively, measured over the total area of 0.45 × 10⁶ km² of the ECS shelf. Their mean residence times are about 27, 13 and 11 days, respectively. The inventory of SPM in the water column was higher in the northernmost and southernmost transects and lower in the middle transects, reflecting the influences of terrestrial inputs from Changjiang and/or resuspended materials from Huanghe deposits in the north and perhaps from Minjiang and/or Taiwan’s rivers in the south. The distribution and transport patterns of SPM and geochemical elements strongly indicate that continental sources and cross-shelf transport modulate ECS particulate matter in summer.     

北黄海长山群岛海域沉积环境初步研究

本文在获取１９８９－１９９３年黄海北部长山群岛海域沉积物大量数据基础上，借助沉积物粒度分析（Ｑ型），揭示出该海域具有在“岛屿效应”影响下的４种环境能量类型，分析了与其适应的环岛沉积环境及其分布特征。     

东部沿海滩涂和浅海资源大开发之我见

介绍了浙江东南沿海的台州市及所属玉环县、温州市及所属乐清市、瓯海区等地面实施海洋“蓝色工程”的丰富实践和新鲜经验。文中借鉴浙东南沿海大开发的成功经验,结合我国东部沿海其它地区特别是苏北沿海的实际,提出了做出滩涂开发利用、发展海洋经济的总体战略构想。     

Spatial and temporal variation of water mass mixing characteristic in the East China Sea

On the basis of the observation data of Kuroshio since 1984 and relative historical data in the East China Sea, spatial and temporal variation of water mass mixing characteristic in the observation area is analysed. The main results are as follows.     

Co–rich Mn crusts from the Magellan Seamount cluster: the long journey through time

The Magellan seamounts began forming as large submarine shield volcanoes south of the equator during the Cretaceous. These volcanoes formed as a cluster on the small Pacific plate in a period when tectonic stress was absent. Thermal subsidence of the seafloor led to sinking of these volcanoes and the formation of guyots as the seamounts crossed the equatorial South Pacific (10–0°S) sequentially and ocean surface temperatures became too high for calcareous organisms to survive. Guyot formation was completed between about 59 and 45 Ma and the guyots became phosphatized at about 39–34 and 27–21 Ma. Ferromanganese crusts began formation as proto-crusts on the seamounts and guyots of the Magellan Seamount cluster towards the end of the Cretaceous up to 55 Ma after the formation of the seamounts themselves. The chemical composition of these crusts evolved over time in a series of steps in response to changes in global climate and ocean circulation. The great thickness of these crusts (up to 15–20 cm) reflects their very long period of growth. The high Co contents of the outer parts of the crusts are a consequence of the increasing deep circulation of the ocean and the resulting deepening of the oxygen minimum zone with time. Growth of the Co-rich Mn crusts in the Magellan Seamount cluster can be considered to be the culmination of a long journey through time.     

Estimating the geostrophic velocity obtained by HF radar observations in the upstream area of the Kuroshio

A method to extract geostrophic current in the daily mean HF radar data in the Kuroshio upstream region is established by comparison with geostrophic velocity determined from the along-track altimetry data. The estimated Ekman current in the HF velocity is 1.2% (1.5%) and 48° (38°)-clockwise rotated with respect to the daily mean wind in (outside) the Kuroshio. Furthermore, additional temporal smoothing is found necessary to remove residual ageostrophic currents such as the inertial oscillation. After removal of the ageostrophic components, the HF geostrophic velocity agrees well with that from the altimetry data with rms difference 0.14 (0.12) m/s in (outside) the Kuroshio.     

The origin and biogeochemistry of organic matter in surface sediments of Lake Shihwa and Lake Hwaong

To understand the origin and biogeochemistry of the organic matter in surface sediments of Lake Shihwa and Lake Hwaong, organic nitrogen, inorganic nitrogen, labile organic carbon, and residual organic carbon contents as well as stable isotope ratios for carbon and nitrogen were determined by KOBr-KOH treatment. Ratios of organic carbon to organic nitrogen (C_org/N_org) (mean = 24) were much higher than ratios of organic carbon to total nitrogen (C_org/N_tot) (mean=12), indicating the presence of significant amounts of inorganic nitrogen in the surface sediments of both lakes. Stable isotope ratios for organic nitrogen were, on average, 5.2‰ heavier than ratios of inorganic nitrogen in Lake Shihwa, but those same ratios were comparable in Lake Hwaong. This might be due to differences in the origin or the degree of degradation of sedimentary organic matter between the two lakes. In addition, stable isotope ratios for labile organic carbon were, on average, 1.4‰ heavier than those for residual organic carbon, reflecting the preferential oxidation of¹³C-enriched organic matter. The present study demonstrates that KOBr-KOH treatment of sedimentary organic matter can provide valuable information for understanding the origin and degradation state of organic matter in marine and brackish sediments. This also suggests that the ratio of C_org/N_org and stable isotope ratios for organic nitrogen can be used as indexes of the degree of degradation of organic matter.     

改进的能量守恒方法及其在CHAMP重力场恢复中的应用(英文)

An efficient method for gravity field determination from CHAMP orbits and accelerometer data is referred to as the energy balance approach. A new CHAMP gravity field recovery strategy based on the improved energy balance approach IS developed in this paper. The method simultaneously solves the spherical harmonic coefficients, daily Integration constant, scale and bias parameters. Two 60 degree and order gravitational potential models, XISM-CHAMPO1S from the classical energy balance approach, and XISM-CHAMPO2S from the improved energy balance, are determined using about one year＇s worth of CHAMP kinematic orbits from TUM and accelerometer data from GFZ. Comparisons among XISM-CHAMPO1S, XISM-CHAMPO2S, EIGEN-CGO3C, EIGEN-CHAMPO3S, EIGEN2, ENIGNIS and EGM96 are made. The results show that the XISM-CHAMPO2S model is more accurate than EGM96, EIGENIS, EIGEN2 and XISM-CHAMPO1S at the same degree and order, and has almost the same accuracy as EIGEN-CHAMPO3S.