Phytoplankton and iron: validation of a global three-dimensional ocean biogeochemical model     

Watson W. Gregg  Paul Ginoux  Paul S. Schopf  Nancy W. Casey 《Deep Sea Research Part II: Topical Studies in Oceanography》2003,50(22-26):3143

The JGOFS program and NASA ocean-color satellites have provided a wealth of data that can be used to test and validate models of ocean biogeochemistry. A coupled three-dimensional general circulation, biogeochemical, and radiative model of the global oceans was validated using these in situ data sources and satellite data sets. Biogeochemical processes in the model were determined from the influences of circulation and turbulence dynamics, irradiance availability, and the interactions among four phytoplankton functional groups (diatoms, chlorophytes, cyanobacteria, and coccolithophores) and four nutrients (nitrate, ammonium, silica, and dissolved iron).Annual mean log-transformed dissolved iron concentrations in the model were statistically positively correlated on basin scale with observations (P<0.05) over the eight (out of 12) major oceanographic basins where data were available. The model tended to overestimate in situ observations, except in the Antarctic where a large underestimate occurred. Inadequate scavenging and excessive remineralization and/or regeneration were possible reasons for the overestimation.Basin scale model chlorophyll seasonal distributions were positively correlated with SeaWiFS chlorophyll in each of the 12 oceanographic basins (P<0.05). The global mean difference was 3.9% (model higher than SeaWiFS).The four phytoplankton groups were initialized as homogeneous and equal distributions throughout the model domain. After 26 years of simulation, they arrived at reasonable distributions throughout the global oceans: diatoms predominated high latitudes, coastal, and equatorial upwelling areas, cyanobacteria predominated the mid-ocean gyres, and chlorophytes and coccolithophores represented transitional assemblages. Seasonal patterns exhibited a range of relative responses: from a seasonal succession in the North Atlantic with coccolithophores replacing diatoms as the dominant group in mid-summer, to successional patterns with cyanobacteria replacing diatoms in mid-summer in the central North Pacific. Diatoms were associated with regions where nutrient availability was high. Cyanobacteria predominated in quiescent regions with low nutrients.While the overall patterns of phytoplankton functional group distributions exhibited broad qualitative agreement with in situ data, quantitative comparisons were mixed. Three of the four phytoplankton groups exhibited statistically significant correspondence across basins. Diatoms did not. Some basins exhibited excellent correspondence, while most showed moderate agreement, with two functional groups in agreement with data and the other two in disagreement. The results are encouraging for a first attempt at simulating functional groups in a global coupled three-dimensional model but many issues remain.  相似文献   

FLOWER COLOR AND ENVIRONMENT: THE CASE OF BUTTERFLY WEED IN OKLAHOMA     

Lawrence J. Watson  Robert Q. Hanham 《The Professional geographer》1977,29(4):374-377

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Zr-in-rutile thermometry in blueschists from Sifnos, Greece   总被引：1，自引：0，他引：1  

Frank S. Spear  David A. Wark  John T. Cheney  John C. Schumacher  E. Bruce Watson 《Contributions to Mineralogy and Petrology》2006,152(3):375-385

Zr-in-rutile thermometry on samples of blueschist from Sifnos, Greece, yields temperatures that reflect progressive crystallization of rutile from ca. 445 to 505°C with an analytical precision of + 18/−27 and ± 10°C using the electron microprobe and ± 1.5–3.5°C using the ion microprobe. Individual grains are generally homogeneous within analytical uncertainty. Different grains within a single sample record temperature differences as large 55°, although in most samples the range of temperatures is on the order of 25°. In several samples, Zr-in-rutile temperatures from grains within garnet are lower than temperatures from matrix grains, reflecting growth of rutile with increasing temperature of metamorphism. Although the specific rutile-producing reactions have not been identified, it is inferred that rutile grows from either continuous reaction involving the breakdown of lower grade phases (possibly ilmenite), or from pseudomorph reactions involving the breakdown of relic igneous precursors at blueschist-facies conditions. No systematic variation in rutile temperatures was observed across the blueschist belt of northern Sifnos, consistent with the belt having behaved as a coherent block during subduction.  相似文献   

Implications of the relationship between catchment vegetation type and the variability of annual runoff   总被引：1，自引：0，他引：1  

Murray C. Peel  Thomas A. McMahon  Brian L. Finlayson  Fred G. R. Watson 《水文研究》2002,16(15):2995-3002

The impact of changing catchment vegetation type on mean annual runoff has been known for some time, however, the impact on the variability of annual runoff has been established only recently. Differences in annual actual evapotranspiration between vegetation types and the potential effect of changing vegetation type on mean annual runoff and the variability of annual runoff are briefly reviewed. The magnitude of any change in the variability of annual runoff owing to a change in catchment vegetation type is related to the pre‐ and post‐change vegetation types and the seasonality of precipitation, assuming that the variability of annual precipitation remains constant throughout. Significant implications of the relationship between vegetation type and the variability of annual runoff are presented and discussed for water resource management, stream ecology and fluvial geomorphology. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Diffusion of tetravalent cations in zircon   总被引：18，自引：1，他引：18  

D. J. Cherniak  J. M. Hanchar  E. B. Watson 《Contributions to Mineralogy and Petrology》1997,127(4):383-390

Diffusion rates for the three tetravalent cations U, Th and Hf have been measured in synthetic zircon. Diffusant sources included oxide powders and ground pre-synthesized silicates. Rutherford backscattering spectrometry (RBS) was used to measure depth profiles. Over the temperature range 1400–1650 °C, the following Arrhenius relations were obtained (diffusion coefficients in m²sec⁻¹): log D _Th = (1.936 ± 0.9820) + (− 792 ± 34 kJ mol⁻¹ /2.303 RT) log D _U = (0.212 ± 2.440) + (− 726 ± 83 kJ mol⁻¹ /2.303 RT) log D _Hf = (3.206 ± 1.592) + (− 812 ± 54 kJ mol⁻¹ /2.303 RT) The data show a systematic increase in diffusivity with decreasing ionic radius (i.e., faster diffusion rates for Hf than for U or Th), a trend also observed in our earlier study of rare earth diffusion in zircon. Diffusive fractionation may be a factor in the Lu-Hf system given the much slower diffusion rates of tetravalent cations when compared with the trivalent rare earths. The very slow diffusion rates measured for these tetravalent cations suggest that they are essentially immobile under most geologic conditions, permitting the preservation of fine-scale chemical zoning and isotopic signatures of inherited cores. Received: 12 July 1996 / Accepted: 2 December 1996  相似文献   

Tree-Ring Based Reconstructions of Precipitation for the Southern Canadian Cordillera     

Emma Watson  Brian H. Luckman 《Climatic change》2004,65(1-2):209-241

This paper reconstructs precipitation variability in the southern Canadian Cordillera over the past 3–400 years using dendroclimatologicaltechniques. Fifty-three total ring-width (RW) chronologies, 28 earlywood (EW) and 28 latewood (LW) chronologies were developed from open-grown, low-elevation stands of Pseudotsuga menziesii (Douglas-fir) and Pinusponderosa (ponderosa pine) across the southern Canadian Cordillera. RW, EW and LW chronologies from both species were used to develop 13 annual (prior July to current June) precipitation reconstructions across the region. The reconstructions range in length from 165 to 688 years, pass verification tests and capture 39–64% of the variancein the instrumental record. Coincident, prolonged intervals of dry conditions are estimated for the years: 1717–1732, 1839–1859, 1917–1941 and1968–1979. Shorter dry intervals are identified between 1581–1586, 1626–1630,1641–1653 1701–1708, 1756–1761, 1768–1772, 1793–1800,1868–1875, 1889–1897 and 1985–1989. The historic drought of the 1920–1930s was the longest but not the most intense across this area in the last 300 years. Wet conditions occur in the majority of reconstructions for the years: 1689–1700, 1750–55,1778–1789, 1800–1830, 1880–1890, 1898–1916 and 1942–1960. Thesedata, in conjunction with data from adjacent areas, are used to provide the first maps of decadal precipitation anomalies for the region between 1700 and 1990.  相似文献   

Thermal infrared remote sensing of volcanic emissions using the moderate resolution imaging spectroradiometer   总被引：1，自引：0，他引：1  

I. M. Watson  V. J. Realmuto  W. I. Rose  A. J. Prata  G. J. S. Bluth  Y. Gu  C. E. Bader  T. Yu 《Journal of Volcanology and Geothermal Research》2004,135(1-2):75

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Sampling Fauna in Stream Sediments as well as Groundwater Using One Net Sampler     

Susanne I. Schmidt  Hans J. Hahn  Gerald D. Watson  Robert J. Woodbury  Thomas J. Hatton 《洁净——土壤、空气、水》2004,32(2):131-137

Groundwater bores act as traps. Net samplers are regularly used for sampling this type of trap for fauna. To enable direct comparisons of faunal communities in groundwater bores and stream sediments, stream sediment tubes were built similar to groundwater bores and were sampled with net samplers for fauna. These stream sediment tubes consisted of a tube anchored in the stream sediment, also called interstitial space. To test the efficacy of this trap method in stream sediments, it was compared to another type of trap, Hahn's trap. Faunal communities sampled by a net in the stream sediment tubes did not differ hugely from fauna in Hahn's trap samples. Physical and chemical factors of sampled water in both the stream sediment tubes, the surrounding interstitial sediments and the second type of traps, Hahn's traps, showed that water in both the tubes and Hahn's traps was closely related to interstitial water. The net sampler is inexpensive and easy to handle. It is suggested that sampling stream tubes with nets may be an appropriate method for long‐term monitoring studies.  相似文献   

Liberalism and Neo-liberal Capitalist Globalization: Contradictions of the Liberal Democratic State     

Hilbourne A. Watson 《GeoJournal》2004,60(1):43-59

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Diffusive fractionation of trace elements in basaltic melt     

Megan E. Holycross  E. Bruce Watson 《Contributions to Mineralogy and Petrology》2016,171(10):80

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