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Features of coastal upwelling regions that determine net air-sea CO<Subscript>2</Subscript> flux 总被引：1，自引：0，他引：1
Debby Ianson Richard A. Feely Christopher L. Sabine Lauren W. Juranek 《Journal of Oceanography》2009,65(5):677-687
The influence of the coastal ocean on global net annual air-sea CO2 fluxes remains uncertain. However, it is well known that air-sea pCO2 disequilibria can be large (ocean pCO2 ranging from ∼400 μatm above atmospheric saturation to ∼250 μatm below) in eastern boundary currents, and it has been hypothesized
that these regions may be an appreciable net carbon sink. In addition it has been shown that the high productivity in these
regions (responsible for the exceptionally low surface pCO2) can cause nutrients and inorganic carbon to become more concentrated in the lower layer of the water column over the shelf
relative to adjacent open ocean waters of the same density. This paper explores the potential role of the winter season in
determining the net annual CO2 flux in temperate zone eastern boundary currents, using the results from a box model. The model is parameterized and forced
to represent the northernmost part of the upwelling region on the North American Pacific coast. Model results are compared
to the few summer data that exist in that region. The model is also used to determine the effect that upwelling and downwelling
strength have on the net annual CO2 flux. Results show that downwelling may play an important role in limiting the amount of CO2 outgassing that occurs during winter. Finally data from three distinct regions on the Pacific coast are compared to highlight
the importance of upwelling and downwelling strength in determining carbon fluxes in eastern boundary currents and to suggest
that other features, such as shelf width, are likely to be important. 相似文献
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A method based on time-series of conductivity, temperature and depth (CTD) profiles which successfully determines favourable
phytoplankton growth conditions for the spring bloom in nearshore temperate coastal waters was developed. The potential for
shallow embayments to influence phytoplankton species composition in larger adjacent waters was also investigated. At temperate
latitudes, such embayments should have favourable phytoplankton growth conditions earlier in the spring than open waters as
bathymetry limits vertical mixing and thus increases light availability. The study area was Nanoose Bay, which is connected
to the Strait of Georgia, British Columbia. Data were collected 2–3 times per week during the winter-spring of 1992 and 1993.
A mooring with 5 current meters was placed at the mouth of the bay in 1992. The conservation equation for a scalar was used
to estimate the balance between advective transport and biological source and sink terms. Variability in physical conditions
and biological response between years was tremendous. Results indicate that seeding from the bay was not possible in 1992
but could have been in 1993. However, to conclusively determine the importance of Nanoose Bay on the spring bloom species
composition in the Strait of Georgia, more extensive work is required.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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In 1988, Drs. JoAnn Burkholder and Ed Noga of North Carolina State University discovered a previously unknown toxic dinoflagellate that eventually was named Pfiesteria piscicida. Accumulating data indicate that this dinoflagellate is a significant source of environmental stress in estuarine ecosystems. It has been estimated that since its discovery, outbreaks of this single-celled aquatic organism, and a second recently discovered species called Pfiesteria shumwayae, have killed millions of fish in estuaries along the eastern United States, and their toxins have harmed people. It has been implicated as the causative agent of major annual fish kills in these estuaries. Its prevalence is greatest in regions affected by anthropogenic nutrient loading from municipal wastewater, phosphate mining, fish processing plant discharge, and other sources. Over the last 20 years, the harmful public health and economic effects of algal blooms appear to have increased in frequency, intensity and geographic distribution. The recent toxic Pfiesteria outbreaks in estuaries of the middle and southern Atlantic coast indicate that anthropogenic stresses on the environment may also influence the effects of these blooms on fish and humans. 相似文献
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Evaluating Errors in a Digital Vegetation Map with Forest Inventory Data and Accuracy Assessment Using Fuzzy Sets 总被引：1，自引：0，他引：1
Janet Franklin Dena K. Simons Debby Beardsley John M. Rogan & Hazel Gordon 《Transactions in GIS》2001,5(4):285-304
In large-area mapping projects, existing reference data, often collected for a different purpose, are increasingly being used for map accuracy assessment. Multi-attribute digital vegetation maps have been developed for all National Forest lands in California (8.1 million ha). We developed decision rules that could be applied to quantitative Forest Inventory and Analysis (FIA) plot data in order to score the fuzzy membership of plot locations in all possible map classes. We compare the accuracy of the vegetation map attributes estimated using this method to accuracy estimated from fuzzy class membership scores assigned by experts (inventory crews) during field work. Accuracy of the vegetation life form attribute was estimated to be higher when expert label assignments were used as reference data (76–87%), instead of FIA plot data (62–79%). This suggests that automated decision rules applied to detailed data from FIA plots, which have smaller area than map polygons, may systematically underestimate map accuracy. However, assignment of the actual map labels to FIA plot locations by inventory crews appears to be a robust method for using the FIA data for accuracy assessment. 相似文献
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