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Partial pressure of CO2 in equilibrium with sample water (pCO2) for the coastal water in the Chukchi Sea was continuously observed in summer, 2008. Average daily CO2 flux calculated from the pCO2 and gas transfer coefficients ranged from −0.144 to −0.0701 g C m−2 day−1 depending on which gas transfer coefficient was used. The pCO2 before the landfast ice sheets melted appeared to be highly biologically controlled based on the following information: (1) the diurnal pattern of pCO2 was strongly correlated with Photosynthetic Photon Flux Density (PPFD); (2) high chlorophyll density was observed during periods of peak uptake; and (3) the day-to-day variation in the pCO2 strongly correlated with the presence or absence of near-shore ice sheets. The lowest pCO2 of 35 ppm together with the highest PPFD of 1362 μmol E m−2 s−1 were observed in the afternoon on June 28 in the presence of sea ice. The very low pCO2 observed in late June was likely caused by high photosynthetic rates related to high phytoplankton densities typically observed from spring to early summer near the ice edge, and by water low in salinity and CO2 released by melting sea ice early in the season. 相似文献
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This paper proposes a new method of integrated system calibration that uses the transmitting and receiving signals from the impulse ground penetrating radar itself. In order to eliminate the influence from each subsystem or part including antenna, transmitter, receiver, signal processing circuits and transmission cables, two new calibration parameters that are different from the conventional S-parameters are introduced. The characteristic and influence of all parts in the transmitting and receiving channels are incorporated into the calibration equation through the new parameters. The calibration results of the radar detection data show that the new integrated system calibration can improve the quality of the data greatly in many aspects. It removes direct coupled waves, suppresses wave distortion and tail oscillation, and improves the quality of waveform and signal-clutter-ratios. It also compresses the pulse width and enhances resolution. 相似文献
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通过对玉林新一代天气雷达情况的分析,根据综合防雷设计的要求提出了玉林新一代天气雷达的具体防雷设计方法,重点突出直击雷防护及电子设备线路的防护措施,从而提高雷达站防御雷击侵害的能力,确保雷达站安全、可靠运行。 相似文献