Filter Results
12674 results
Abstract: The Democratic Republic of Timor-Leste, the first new sovereign state of the 21st century, is located in the Lesser Sunda Islands archipelago of Southeast Asia, occupying half the island of Timor. Situated in the south-eastern boundary of the Wallacea biogeographical region and within the Coral Triangle, Timor-Leste's marine habitats support a high diversity of marine plants and animals that provide critical resources for coastal communities and also species of conservation concern, including dugongs and marine turtles. However, until recently, efforts to map marine habitats have been limited to broad-scale remote assessments. Providing detailed field validation of marine benthic habitats is critical knowledge required to identify priority areas for conservation of dugongs and seagrasses. Seagrass meadows on selected fringing reefs of Atauro Island and northern Timor-Leste (Tibar Bay and Com), were assessed between the 05 April 2017 and 27 June 2018. Observers walked or free-dived at survey points positioned approximately 5¬-10 m apart along a series of transects orientated perpendicular to the shoreline. Visual estimates of above-ground seagrass percent cover, macroalgae percent cover and substrate type were recorded at each survey point. A differential handheld global positioning system (GPS) was used to locate each survey point (accuracy ±3m). A total of 464 benthic survey points were examined. Seagrass community data was derived by haphazardly placing 1 or 3 quadrats (50cm x50cm) at each survey point. Seagrass percent cover was determined by estimating the total percentage of each quadrat occupied by seagrass leaves, to the closest 10%. Seagrass species present were identified and the composition of the total percentage cover estimated, using globally standardised Seagrass-Watch protocols. Data are presented as the average of the quadrats at each point. The resulting seagrass and benthic cover data of each survey point was linked to GPS coordinates, saved as an ArcMap point shapefile and projected to Universal Transverse Mercator WGS84 Zone 51 South Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: Lake Karakul in the eastern Pamirs is a large and closed-basin lake in a partly glaciated catchment. Two parallel sediment cores were collected from 12 m water depth. The cores were correlated using XRF analysis and dated using radiocarbon and OSL techniques. The age results of the two dating methods are generally in agreement. The correlated composite core of 12.26 m length represents continuous accumulation of sediments in the lake basin since 31 ka. The lake reservoir effect (LRE) remained relatively constant over this period. High sediment accumulation rates (SedARs) were recorded before 23 ka and after 6.5 ka. The relatively close position of the coring location near the eastern shore of the lake implies that high SedARs resulted from low lake levels. Thus, high SedARs and lower lake levels before 23 ka probably reflect cold and dry climate conditions that inhibited the arrival of moist air at high elevation in the eastern Pamirs. Low lake levels after 6.5 ka were probably caused by declining temperatures after the warmer early Holocene, which had caused a reduction in water resources stored as snow, ice and frozen ground in the catchment. Low SedARs during 23e6.5 ka suggest increased lake levels in Lake Karakul. A short-lived increase of SedARs at 15 ka probably corresponds to the rapid melting of glaciers in the Karakul catchment during the Greenland Interstadial 1e, shortly after glaciers in the catchment had reached their maximum extents. The sediment cores from Lake Karakul represent an important climate archive with robust chronology for the last glacialeinterglacial cycle from Central Asia. Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: Not Available Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: Hopane and Sterane data from the K-Pg boundary Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: Sediment oxygenation was assessed in situ in rhizospheres of the intertidal salt marsh grass, Spartina anglica. Oxygen content of the rhizosphere was investigated in two populations of S. anglica with differing plant morphology growing in different sediment types. The oxygen content was assessed in situ using a novel multifiber optode system with 100 simultaneously operated oxygen probes. No oxygen was detected inside the rhizosphere at any depths indicating a limited impact of plant-mediated sediment oxygenation on the bulk anoxic sediment. Additional Planer optode investigations revealed that plant-mediated sediment oxygenation do occur, but it is restricted to small areas around the root-tips. Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: Soil moisture is an important variable linking the atmosphere and the terrestrial ecosystems. However, long-term satellite monitoring of surface soil moisture is still lacking at global scale. In this study, we conducted data fusion of up to 11 microwave remote sensing-based soil moisture products through a set of neural networks, with SMAP soil moisture data applied as the fundamental training target. The training efficiency proves to be high (R2 =0.95) due to the selection of 9 quality impact factors of microwave soil moisture products and the elaborate organization structure of multiple different neural networks (5 rounds of simulation; 8 substeps; 74 independent neural networks; and >106 regional subnetworks). We achieved global satellite monitoring of surface soil moisture during 2003~2018 at 0.1° resolution. This new dataset, once validated against the International Soil Moisture Network (ISMN) records, is found superior to the existing products (ASCAT-SWI, GLDAS Noah, ERA5-Land, CCI/ECV and GLEAM), and is applicable to studying both the spatial and temporal patterns. It suggests an increase in global surface soil moisture, and reveals that the surface moisture decline on rainless days is highest in summers over the low-latitudes but highest in winters in most mid-latitude areas. Notably, the error propagation with the extension of the simulation period to the past is well controlled, indicating that the fusion algorithm will be more meaningful in future when more advanced sensors are in operation. Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: Not Available Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: Not Available Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: Not Available Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
Data Types:
  • Other
Abstract: A suite of model simulations is used to investigate the spatiotemporal variability of the Arctic Ocean circulation and the observing systems required to capture it. A comparison with sea level observations shows that all model runs realistically simulate inter-annual sea level varia-bility, but the simulated seasonal sea level variability and underlying changes in the model salinity need to be further improved. At periods <30 days, sea level variability is equivalent barotropic and strongly captured by bottom pressure observations. At the seasonal period, both barotropic and baroclinic processes contribute involving variations in the mass and densi-ty fields. Over the entire Arctic Ocean, steric height variability is dominated by halosteric effects in the upper layer. The salinity changes are related to sea ice processes, river runoff, and redistribution of the freshwater. At decadal timescales, sea level variations in the Canadi-an Basin relate to halosteric effects in the upper and intermediate layers. An adjoint sensitivi-ty analysis reveals that the decadal salinity variability is caused by anticyclonic/cyclonic wind stress, which accumulate/release freshwater in the upper layer and enhance/reduce geostrophic currents in the intermediate layer. The adjoint model simulations identify the importance of moorings and satellite altimetry on monitoring the Arctic salinity and circulation changes: while moorings capture more local salinity changes, the satellite altimetry may capture the influence of freshwater originating from the Bering Strait and the Eurasian Basin. Our study suggests that to capture basin-wide salinity changes, we need to deploy moorings in different positions spreading across the Arctic Ocean. Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: 90.000000 * LONGITUDE: 0.000000 * LOCATION: Arctic
Data Types:
  • Other
8