An ecosystem modeling approach to predicting cod recruitment     

Einar Svendsen  Morten Skogen  Paul Budgell  Geir Huse  Jan Erik Stiansen  Bjrn dlandsvik  Frode Vikeb  Lars Asplin  Svein Sundby 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2810

The Norwegian Ecological Model (NORWECOM) biophysical model system implemented with the ROMS ocean circulation model has been run to simulate conditions over the last 25 years for the North Atlantic. Modeled time series of water volume fluxes, primary production, and drift of cod larvae through their modeled ambient temperature fields have been analyzed in conjunction with VPA estimated time series of 3-year-old cod recruits in the Barents Sea. Individual time series account for less than 50% of the recruitment variability; however, a combination of simulated flow of Atlantic water into the Barents Sea and local primary production accounts for 70% of the variability with a 3-year lead. The associated regression predicts increased recruitment between 2007 and 2008 from about 450–700 million individuals with a standard error of nearly 150 million.  相似文献   

High-Latitude Springtime Photochemistry. Part I: NOx, PAN and Ozone Relationships     

Harald J. Beine  Daniel a. Jaffe  John a. Herring  Jennifer a. Kelley  Terje Krognes  Frode Stordal 《Journal of Atmospheric Chemistry》1997,27(2):127-153

Springtime measurements of NO_x, ozone, PAN,J(NO₂), and other compounds were made near Ny-Ålesund,Svalbard (78°54N, 11°53E), in 1994 and Poker Flat,Alaska (65°08N, 147°29W), in 1995. At Svalbard medianmixing ratios for PAN and NO_x of 237 and 23.7 pptv,respectively, were observed. The median mixing ratios at Poker Flat for PANand NO_x were 79.5 and 85.9 pptv, respectively. These data areused to estimate thermal PAN decomposition using several differentapproaches. At Svalbard PAN decomposition was very small, while at PokerFlat up to 30 pptv/h PAN decomposed. At both sites the NO_x/PANratio increased with temperature between –10 and 20°C implyingthat PAN decomposition is an important NO_x source. In-situozone production was calculated from the measured NO, NO₂,O₃, J(NO₂), and temperature data, using thesteady state assumption Median ozone production was 605 pptv/h at PokerFlat, and one order of magnitude smaller at Svalbard during the daytime.Only at Poker Flat could a direct influence on the diurnal ozone cycle beobserved from in-situ production. These results imply that PAN decompositionis a major source of NO_x in the high latitude troposphere, andthat this contributes to the observed spring maximum in surface ozone.  相似文献   

Abatement of Greenhouse Gases: Does Location Matter?     

Terje Berntsen  Jan Fuglestvedt  Gunnar Myhre  Frode Stordal  Tore F. Berglen 《Climatic change》2006,74(4):377-411

Today's climate policy is based on the assumption that the location of emissions reductions has no impact on the overall climate effect. However, this may not be the case since reductions of greenhouse gases generally will lead to changes in emissions of short-lived gases and aerosols. Abatement measures may be primarily targeted at reducing CO₂, but may also simultaneously reduce emissions of NO_x, CO, CH₄ and SO₂ and aerosols. Emissions of these species may cause significant additional radiative forcing. We have used a global 3-D chemical transport model and a radiative transfer model to study the impact on climate in terms of radiative forcing for a realistic change in location of the emissions from large-scale sources. Based on an assumed 10% reduction in CO₂ emissions, reductions in the emissions of other species have been estimated. Climate impact for the SRES A1B scenario is compared to two reduction cases, with the main focus on a case with emission reductions between 2010 and 2030, but also a case with sustained emission reductions. The emission reductions are applied to four different regions (Europe, China, South Asia, and South America). In terms of integrated radiative forcing (over 100 yr), the total effect (including only the direct effect of aerosols) is always smaller than for CO₂ alone. Large variations between the regions are found (53–86% of the CO₂ effect). Inclusion of the indirect effects of sulphate aerosols reduces the net effect of measures towards zero. The global temperature responses, calculated with a simple energy balance model, show an initial additional warming of different magnitude between the regions followed by a more uniform reduction in the warming later. A major part of the regional differences can be attributed to differences related to aerosols, while ozone and changes in methane lifetime make relatively small contributions. Emission reductions in a different sector (e.g. transportation instead of large-scale sources) might change this conclusion since the NO_x to SO₂ ratio in the emissions is significantly higher for transportation than for large-scale sources. The total climate effect of abatement measures thus depends on (i) which gases and aerosols are affected by the measure, (ii) the lifetime of the measure implemented, (iii) time horizon over which the effects are considered, and (iv) the chemical, physical and meteorological conditions in the region. There are important policy implications of the results. Equal effects of a measure cannot be assumed if the measure is implemented in a different region and if several gases are affected. Thus, the design of emission reduction measures should be considered thoroughly before implementation.  相似文献   

Comparison of Five Eulerian Air Pollution Forecasting Systems for the Summer of 1999 Using the German Ozone Monitoring Data     

Stefan Tilmes  JØrgen Brandt  Frode FlatØy  Robert Bergström  Johannes Flemming  Joakim Langner  Jesper H. Christensen  Lise M. Frohn  Øystein Hov  Ingo Jacobsen  Eberthard Reimer  Rainer Stern  Jörg Zimmermann 《Journal of Atmospheric Chemistry》2002,42(1):91-121

Eulerian state-of-the-art air pollution forecasting systems on the European scale are operated routinely by several countries in Europe. DWD and FUB, both Germany, NERI, Denmark, NILU, Norway, and SMHI, Sweden, operate some of these systems. To apply such modeling systems, e.g. for regulatory purposes according to new EU directives, an evaluation and comparison of the model systems is fundamental in order to assess their reliability. One step in this direction is presented in this study: The model forecasts from all five systems have been compared to measurements of ground level ozone in Germany. The outstanding point in this investigation is the availability of a huge amount of data – from forecasts by the different model systems and from observations. This allows for a thorough interpretation of the findings and assures the significance of the observed features. Data from more than 300 measurement stations for a 5-month period (May–September 1999) of the German monitoring networks have been used in this comparison. Different spatial and temporal statistical parameters were applied in the evaluation. Generally, it was found that the most comprehensive models gave the best results. However, the less comprehensive and computational cheaper models also produced good results. The extensive comparison made it possible to point out weak points in the different models and to describe the individual model behavior for a full summer period in a climatological sense. The comparison also gave valuable information for an assessment of individual measurement stations and complete monitoring networks in terms of the representativeness of the observation data.  相似文献   

Quantitative evaluation of bioturbation rates in deep ocean sediments. II. Comparison of rates determined by 210Pb and 239,240Pu     

M.C Stordal  J.W Johnson  N.L Guinasso  D.R Schink 《Marine Chemistry》1985,17(2):99-114

Excess ²¹⁰Pb was determined in six abyssal cores from the Eastern Atlantic, Hatteras Abyssal Plain, and Puerto Rico Trench. A bioturbation rate for each core was evaluated using the mixing model of Guinasso and Schink. The rates were compared to mixing rates evaluated for the same cores using ^239,240Pu. In all cases, the excess ²¹⁰Pb-derived mixing rates were lower than the plutonium-derived mixing rates. ^239,240Pu was also present at greater depths than excess ²¹⁰Pb. One possible explanation for these observations is the association of plutonium with particles of greater food value which are bioturbated at faster rates.  相似文献