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291.
O. V. Kopelevich S. V. Sheberstov O. Yunev O. Basturk Z. Z. Finenko S. Nikonov V. I. Vedernikov 《Journal of Marine Systems》2002,36(3-4)
Absolute values of chlorophyll a concentration and its spatial and seasonal variations in the Black Sea were assessed by using satellite CZCS and in situ data. Since the satellite CZCS had operated for the 1978–1986 period, CZCS data was used for assessing the past state of the Black Sea just before the onset of drastic changes observed in late 1980s. The approach used for the calculation of the absolute values of chlorophyll a concentration from CZCS data was based on the direct comparison of in situ chlorophyll a data and those of CZCS and by applying the algorithm developed for the transformation of CZCS data into chlorophyll a values. CZCS Level 2 data related with pigment concentration having a spatial resolution of 1 km at nadir were used. The daily Level 3 files were derived by binning Level 2 values into 4-km grid cells and the monthly and seasonal Level 3 files were created by averaging the daily Level 3 files over the corresponding period. In situ chlorophyll a data were obtained by spectrophotometric and fluorometric methods in 15 scientific cruises over the 1978–1986 period. Total number of ship-measured data used for the comparison with those CZCS values was 590.Chlorophyll a concentration (Chl) was derived from CZCS values (C) with regression equations Chl=kC; the coefficient of transformation k was calculated from six different data sets by taking into account distinctions between subregions and seasons. The reasons for difference in the k values have been analyzed.Statistical comparison of the chlorophyll a values measured in situ and those derived from CZCS data was based on log-transformed data and gave the following results: regression SLOPE=0.842, regression INTERCEPT=−0.081, coefficient of determination (R2)=0.806, root–mean–square ERROR=0.195. The mean monthly chlorophyll a distributions derived from CZCS data over 1978–1986 have been constructed and the mean seasonal chlorophyll a values in different regions have been calculated and analyzed. The significant difference in chlorophyll concentration between the western shelf regions and the open part of the Black Sea has been demonstrated, especially in warm season. At almost all seasons, the highest chlorophyll concentration is observed in the western interior shelf region which is under strong influence of Danube. The summer mean chlorophyll concentration in this region is 18 times higher than that in the open parts and about nine times higher than in the eastern shelf region. The greatest seasonal variations are observed in the open part of the Black Sea: chlorophyll concentration in cold season is four to six times higher than in summer and three to five times higher than in April and October. To the contrary, in the western interior shelf regions, the concentration is higher in May–October (about twice than that in November–March). Seasonal variations in the western outer shelf regions are smoothed out as compared with both the western interior shelf and the open regions. 相似文献
292.
以实测资料为依据,应用海流理论,对秦皇岛港海域的余流及余流输沙进行分析,最后得出在1~#、2~#抛泥地抛泥对锚地均无影响的结论。 相似文献
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295.
悬沙模型的水流输沙相似条件 总被引:3,自引:3,他引:0
水流输沙相似是悬沙模型必须满足的基本条件。众所周知 ,目前所流行的所谓沉降和悬浮相似条件在变态模型中互为矛盾。理论分析表明 ,在变态模型中该两个相似条件均不能成立 ,替代它们的是一个所谓垂向泥沙通量比相似条件。这样可使悬沙输移和河床平面变形相似条件得到满足 相似文献
296.
青藏铁路客车供氧系统 总被引:3,自引:1,他引:2
简要介绍了青藏铁路客车供氧系统的组成及工作过程,针对其使用情况,指出了青藏铁路客车供氧系统在运用中的注意事项。 相似文献
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298.
从两相流的基本方程出发建立了一个研究悬移质泥沙非平衡输移的数值模型。基本方程中考虑了相间相对运动的影响,水相和颗粒相通过相间作用力进行耦合,雷诺方程毒用后k-ε-A,紊流模型封闭。对模型进行验证后将其应用于航道横断面的悬移质泥沙运动数值模拟。 相似文献
299.
介绍了南昌铁路局针对现行发射光谱分析金属磨损诊断理论的不足,运用数理统计原理通过建立金属磨损真实值,创建新的一元线性回归模型,完善发射光谱分析金属磨损诊断理论的研究过程。 相似文献
300.
高速电动车组的发展及其在我国的应用探讨 总被引:1,自引:0,他引:1
分析国外300km/h高速动车组发展动态,认为受关键参数的限制,300km/h的速度是一个重要临界值。在此速度之下,动力集中与动力分散两种方式都能适应;在此速度之上,动力分散为佳。提出我国必须坚持科研开发与应用紧密结合的原则,在充分试验并巩固200—250km/h电动车组技术的平台上,应向开发300km/h电动车组技术推进。建议对总体方案进行深入比较后,再确立最佳方案为好。 相似文献