New record of <Emphasis Type="Italic">Lobophora rosacea</Emphasis> (Dictyotales; Phaeophyceae) from the South China Sea

Lobophora rosacea C.W. Vieira, Payri et De Clerck is reported from the South China Sea for the first time. Our specimens are very similar to L. rosacea recently described from New Caledonia, not only in morphology but also in rbcL and cox3 gene sequences. The fan-shaped thallus grows erectly, attaching to the substrate by a basal holdfast. The thallus is composed of a single layer of large medullary cells and three to four layers of cortical cells on both sides of the medulla. Mature sporophytes are detected, with sporangium sori scattered on both surfaces of the thallus.     

Re-Estimation of Annual Anthropogenic Carbon Input from Oyashio into North Pacific Intermediate Water

The annual transport of anthropogenic carbon (C_anth) to the North Pacific Intermediate Water (NPIW) from the Western Subarctic Gyre (WSG) has been re-estimated by using newly estimated Oyashio transport and C_anth concentration, the latter calculated by the recently-established “ΔC*” method with some modifications. Estimated annual C_anth transport through the nearshore Oyashio west of 146°E was 0.020 ± 0.010 GtC y⁻¹, closely approximating the previous estimation based on a 1-D model calibrated with the CFC vertical distribution. The present study, however, found that an additional 0.025 ± 0.010 GtC y⁻¹ of C_anth was transported into NPIW in the region east of 146°E. Total C_anth transport, 0.045 GtC y⁻¹, contributes about 35% of annual C_anth accumulation of the whole temperate North Pacific. This revised version was published online in July 2006 with corrections to the Cover Date.     

A 27-kyr record of environmental change in central Asia inferred from the sediment record of Lake Hovsgol,northwest Mongolia

Geochemistry of a sediment core from Lake Hovsgol, northwest Mongolia provides a continuous, 27-kyr history of the response of the lake and the surrounding catchment to climate change. Principle component (PC) analysis of 19 major and trace elements, total inorganic carbon (TIC), and total organic carbon (TOC) in the bulk sediment samples revealed that the 21 chemical components can be grouped into four assemblages—group-1: Na, Mg, Ca, Sr, and TIC, hosted in carbonate minerals (calcite, dolomite, and magnesian calcite); group-2: Ni, Cu, and Zn, recognized as biophilic trace metals, and TOC; group-3: Al, K, Ti, V, Fe, Rb, Cs, Ba, and Pb, composed of rock-forming minerals; and group-4: Cr, Mn, and As, sensitive to the redox condition of the sediment. The four element assemblages originated from three relevant processes. Group-1 and group-2 components are authigenic products and comprise the end member on the PC-1 score, whose variation reflects changes in the water volume, i.e. the balance between precipitation and evaporation (P/E). Group-3 components from detrital materials of the catchment contribute to the PC-2 score, whose variability indicates erosion/weathering intensity in the drainage basin, which might be controlled by the amount of vegetation cover associated with moisture change. The group-4 components of redox-sensitive elements contribute to the PC-3 score and are not an end member because of their small amount. The first two PC scores suggest a sequential record of paleo-moisture evolution in central Asia. The P/E balance in the Lake Hovsgol region, inferred from the PC-1 score, gradually increased during the glacial/interglacial transition. This resembles climate change of the North Atlantic region on the glacial–interglacial scale, but does not reflect the abrupt climate shifts such as the warm Bølling-Allerød and the cold Younger Dryas of the North Atlantic on the millennial scale. A periodic variation of ~8.7 kyr was observed in the PC-2 score profile of detrital input to Lake Hovsgol over the last glacial and Holocene. The decrease in detrital input coincided with the copious supply of moisture from the Asian monsoon regime and the North Atlantic westerly winds to the Baikal drainage basin, which includes Lake Hovsgol. Our geochemical records from Lake Hovsgol demonstrate that the climate system of interior continental Asia was strongly influenced by change on both Milankovitch and sub-Milankovitch scales.     

Research and development of the New Generation Sea Surface Temperature for Open Ccean (NGSST-O) product and its demonstration operation

Real-time generation and distribution of the New Generation Sea Surface Temperature for Open Ocean (NGSST-O) product began in September 2003 as a demonstration operation of the Global Ocean Data Assimilation Experiment (GODAE) High-Resolution Sea Surface Temperature Pilot Project. Satellite sea surface temperature (SST) observations from infrared radiometers (AVHRR, MODIS) and a microwave radiometer (AMSR-E) are objectively merged to generate the NGSST-O product, which is a quality-controlled, cloud-free, high-spatial-resolution (0.05° gridded), wide-coverage (13–63° N, 116–166° E), daily SST digital map. The NGSST-O demonstration operation system has been developed in cooperation with the Japanese Space Agency (JAXA) and has produced six years of continuous data without gaps. Comparison to in situ SSTs measured by drifting buoys indicates that the root mean-square error of NGSST-O has been kept at approximately 0.9°C.     

Diurnal sea surface temperature variation and its impact on the atmosphere and ocean: A review

The importance of the diurnal variability of sea surface temperature (SST) on air-sea interaction is now being increasingly recognized. This review synthesizes knowledge of the diurnal SST variation, mainly paying attention to its impact on the atmosphere or the ocean. Diurnal SST warming becomes evident when the surface wind is weak and insolation is strong. Recent observations using satellite data and advanced instruments have revealed that a large diurnal SST rise occurs over wide areas in a specific season, and in an extreme case the diurnal amplitude of SST exceeds 5 K. The large diurnal SST rise can lead to an increase in net surface heat flux from the ocean of 50–60 Wm⁻² in the daytime. The temporal mean of the increase exceeds 10 Wm⁻², which will be non-negligible for the atmosphere. A few numerical experiments have indicated that the diurnal SST variation can modify atmospheric properties over the Pacific warm pool or a coastal sea, but the processes underlying the modification have not yet been investigated in detail. Furthermore, it has been shown that the diurnal change of ocean mixing process near the surface must be considered correctly in order to reproduce SST variations on an intraseasonal scale in a numerical model. The variation of mixed-layer properties on the daily scale is nonlinearly related to the intraseasonal variability. The mixed-layer deepening/shoaling process on the daily scale will also be related to biological and material circulation processes.     

A Simple Energy Balance Model for Regular Building Arrays

A simple urban energy balance model for mesoscale simulations (SUMM) was tested using results from an outdoor scale-model experiment. The model geometry is assumed to be an infinitely extended regular array of uniform buildings, each of which is composed of six faces (roof, floor, and four vertical walls). The SUMM explicitly considers the three dimensionality of surface geometry and theoretically predicts the energy balance at each face without time-consuming iterations. The SUMM was compared with outdoor scale-model experiments. The simulated energy balance and surface temperatures agree well with the values measured on a reduced-scale hardware model corresponding to the numerical model geometry.     

Lost primordial continents

We investigate the bulk density variations of some representative compositions for the lower mantle based on the pressure–volume–temperature equation of state of the constituent mineral phases. The density variations of pyrolite, harzburgite, mid-ocean ridge basalt (MORB), tonalite–trondhjemite–granodiorite (TTG), and anorthosite are studied at a temperature of 300 K and at lower mantle pressures. The density of MORB is greater than that of pyrolite throughout the lower mantle, while the density of harzburgite is slightly lower than that of pyrolite. The density of anorthosite is comparable to that of pyrolite in the lower mantle in general, and greater in the lowermost mantle, while the density of TTG is lower than pyrolite throughout the lower mantle. The above results have important implications for the fate of primordial continents, TTG and anorthosite crust. While subducted TTG might be stagnant in the mantle transition zone, dense subducted anorthositic crust could be expected to sink to the core–mantle boundary (CMB) and thus might be a major component of the D" layer immediately above the CMB. Thus, we propose that significant bodies of continental material could be present in the mantle in the transition zone and immediately above the CMB, in addition to the continents on the Earth's surface.     

Uranium-series chronology for sediments of Lake Hovsgol, Mongolia, and the 1-Ma records of uranium and thorium isotopes from the HDP-04 drill core

Uranium and thorium isotopes in an 81-m long sediment core (HDP-04) of Lake Hovsgol, Mongolia, were measured to investigate their downcore distributions and to explore potential linkage to paleoenvironmental changes. Three-dimensional isochron techniques using isotope-ratio diagrams in ²³⁸U–²³⁴U–²³⁰Th–²³²Th system presented by Ludwig and Titterington were applied to age date the lake sediments at the depths of 11.42, 14.71 and 14.83 m in the HDP-04 section, the estimated ages of these horizons are 66 ± 8, 122 ± 11 and 128 ± 22 ka, respectively. The ²³⁸U concentration throughout the entire section fluctuated by a factor of 12, ranging from 19.9 to 232.1 mBq/g with anomalously high ²³⁸U peak at 23.8 m in depth, while the ²³²Th concentration varied only by a factor of about two between 24.3 and 54.0 mBq/g. The discrimination of the bulk ²³⁸U into authigenic and terrigenous ²³⁸U fractions was attempted, based on the measured ²³²Th as a correction index for terrigenous materials. In the upper 24 m corresponding to the last 250 ka, the authigenic ²³⁸U was higher in interglacials and lower in glacials. This depth profile of authigenic ²³⁸U contents was almost identical pattern with that found in a sediment core (VER98-1-6) from the Academician Ridge, Lake Baikal. Further, this profile can be correlated well with that of photosynthetic pigment contents, one of proxies of paleoproductivity, suggesting that the variation of authigenic ²³⁸U contents were associated with the environmental change around Lake Hovsgol.