Classification of acoustically stable areas using empirical orthogonal functions

Sonar performance modeling is crucial for submarine and anti–submarine operations. The validity of sonar performance models is generally limited by environmental uncertainty, and particularly uncertainty in the vertical sound speed profile (SSP). Rapid environmental assessment (REA) products, such as oceanographic surveys and ocean models may be used to reduce this uncertainty prior to sonar operations. Empirical orthogonal functions (EOF) applied on the SSPs inherently take into account the vertical gradients and therefore the acoustic properties. We present a method that employs EOFs and a grouping algorithm to divide a large group of SSPs from an ocean model simulation into smaller groups with similar SSP characteristics. Such groups are henceforth called acoustically stable groups. Each group represents a subset in space and time within the ocean model domain. Regions with low acoustic variability contain large and geographically contiguous acoustically stable groups. In contrast, small or fragmented acoustically stable groups are found in regions with high acoustic variability. The main output is a map of the group distribution. This is a REA product in itself, but the map may also be used as a planning aid for REA survey missions.     

The feasibility of low CO2 concentration targets and the role of bio-energy with carbon capture and storage (BECCS)

The United Nations Framework Convention on Climate Change (UNFCCC 1992) calls for stabilization of atmospheric greenhouse gas (GHG) concentrations at a level that would prevent dangerous anthropogenic interference with the climate system. We use three global energy system models to investigate the technological and economic attainability of meeting CO₂ concentration targets below current levels. Our scenario studies reveal that while energy portfolios from a broad range of energy technologies are needed to attain low concentrations, negative emission technologies—e.g., biomass energy with carbon capture and storage (BECCS)—significantly enhances the possibility to meet low concentration targets (at around 350 ppm CO₂).     

Climate change impacts on water management and irrigated agriculture in the Yakima River Basin, Washington, USA

The Yakima River Reservoir system supplies water to ~180,000 irrigated hectares through the operation of five reservoirs with cumulative storage of ~30% mean annual river flow. Runoff is derived mostly from winter precipitation in the Cascade Mountains, much of which is stored as snowpack. Climate change is expected to result in earlier snowmelt runoff and reduced summer flows. Effects of these changes on irrigated agriculture were simulated using a reservoir system model coupled to a hydrological model driven by downscaled scenarios from 20 climate models archived by the 2007 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. We find earlier snowmelt results in increased water delivery curtailments. Historically, the basin experienced substantial water shortages in 14% of years. Without adaptations, for IPCC A1B global emission scenarios, water shortages increase to 27% (13% to 49% range) in the 2020s, to 33% in the 2040s, and 68% in the 2080s. For IPCC B1 emissions scenarios, shortages occur in 24% (7% to 54%) of years in the 2020s, 31% in the 2040s and 43% in the 2080s. Historically unprecedented conditions where senior water rights holders suffer shortfalls occur with increasing frequency in both A1B and B1 scenarios. Economic losses include expected annual production declines of 5%–16%, with greater probabilities of operating losses for junior water rights holders.     

Coarse-scale data assimilation as a generic alternative to localization

Coarse-scale data assimilation (DA) with large ensemble size is proposed as a robust alternative to standard DA with localization for reservoir history matching problems. With coarse-scale DA, the unknown property function associated with each ensemble member is upscaled to a grid significantly coarser than the original reservoir simulator grid. The grid coarsening is automatic, ensemble-specific and non-uniform. The selection of regions where the grid can be coarsened without introducing too large modelling errors is performed using a second-generation wavelet transform allowing for seamless handling of non-dyadic grids and inactive grid cells. An inexpensive local-local upscaling is performed on each ensemble member. A DA algorithm that restarts from initial time is utilized, which avoids the need for downscaling. Since the DA computational cost roughly equals the number of ensemble members times the cost of a single forward simulation, coarse-scale DA allows for a significant increase in the number of ensemble members at the same computational cost as standard DA with localization. Fixing the computational cost for both approaches, the quality of coarse-scale DA is compared to that of standard DA with localization (using state-of-the-art localization techniques) on examples spanning a large degree of variability. It is found that coarse-scale DA is more robust with respect to variation in example type than each of the localization techniques considered with standard DA. Although the paper is concerned with two spatial dimensions, coarse-scale DA is easily extendible to three spatial dimensions, where it is expected that its advantage with respect to standard DA with localization will increase.     

Will the Clean Development Mechanism be effectively implemented in China?

The on-going process of setting up a national system for identification, approval and implementation of CDM-projects in China illustrates the changes in the Chinese attitude towards the CDM after COP7. This is a very important process, and the outcome could strongly influence investors’ willingness to invest in Chinese CDM-projects. The massive interest and capacity building by international assistance organisations, bilateral and multilateral donors, for preparing the implementation of the CDM will provide China with information and experience. Nevertheless, potential factors that may negatively influence efficient implementation of CDM-projects are: the domestic implementation system is not yet finalised and may impact on China’s ability to compete for CDM-projects; the priorities of the Chinese authorities may not match those of foreign investors; the main expertise regarding CDM is found in a few ministries and research institutes in Beijing, and there is a need to increase capacity for CDM among local project developers and authorities; most research carried out concerned technical issues, and there is a need to include economists and market experts in order to increase understanding of the market.     

Sediments in the estuarine environment of the tigris/euphrates delta; Iraq; Arabian Gulf

Studies on surface water characters of the estuarine environment of Iraq, northwestern Arabian Gulf, define three subdivisions of salinity: oligohaline, polyhaline, and euhaline. Textural analysis reveals that surface sediments covering the bottom are composed of six distinct classes: silty clay, clayey silt, sand-silt-clays, clayey sand, silty sand and sand. Five physiographic subdivisions are identified and described fluvial-estuarine, tidal mud flats (subtidal flat, lower intertidal flat, upper intertidal flat, supratidal flat), sand bars, Abdallah-Shetana channel and submerged estuarine distributary channel and bar systems. The content of organic matter in the sediments ranges from 0.24-3.69 per cent by weight. High values were recorded from the Abdallah-Shetana channel while lower values are confined to sand bars and submerged estuarine distributary channel and bar systems. Carbonates, quartz, feldspar, and halite are the main mineral constituents of the non-clay grade sediments; carbonates are present mainly as low-magnesium calcite followed by dolomite and high-magnesium calcite. Aragonite is present only in trace amounts. Both detrital and biogenic sources are suggested for low-magnesium calcite. A detrital source for dolomite and a biogenic source for high-magnesium calcite and aragonite are proposed.