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721.
本文根据印度洋海-气热交换和海温信息区分布特征,得出阿拉伯海是印度洋海-气相互作用的一个重要区域。并讨论了阿拉伯海海温与北半球500hPa高度场和西太平洋副热带高压的一些联系。 相似文献
722.
723.
Akihiko Tanaka Motoaki Kishino Roland Doerffer Helmut Schiller Tomohiko Oishi Tadashi Kubota 《Journal of Oceanography》2004,60(3):519-530
An algorithm is presented to retrieve the concentrations of chlorophyll a, suspended pariclulate matter and yellow substance
from normalized water-leaving radiances of the Ocean Color and Temperature Sensor (OCTS) of the Advanced Earth Observing Satellite
(ADEOS). It is based on a neural network (NN) algorithm, which is used for the rapid inversion of a radiative transfer procedure
with the goal of retrieving not only the concentrations of chlorophyll a but also the two other components that determine the water-leaving radiance spectrum. The NN algorithm was tested using the
NASA's SeaBAM (SeaWiFS Bio-Optical Mini-Workshop) test data set and applied to ADEOS/OCTS data of the Northwest Pacific in
the region off Sanriku, Japan. The root-mean-square error between chlorophyll a concentrations derived from the SeaBAM reflectance data and the chlorophyll a measurements is 0.62. The retrieved chlorophyll a concentrations of the OCTS data were compared with the corresponding distribution obtained by the standard OCTS algorithm.
The concentrations and distribution patterns from both algorithms match for open ocean areas. Since there are no standard
OCTS products available for yellow substance and suspended matter and no in situ measurements available for validation, the result of the retrieval by the NN for these two variables could only be assessed
by a general knowledge of their concentrations and distribution patterns.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
724.
首先介绍数字式主动声呐的优点及实现上的特殊困难.采用时间相关积累信号处理方法,可以克服海洋背景噪声和船只自噪声的干扰,并具有强烈的抗起伏性能.在垂直向下探测或短距离、高频探测等特殊条件下,依混响的衰减规律,由微机组成精确的灵敏度时间控制网络,可以抑制混响的影响,并大大地简化了目标识别的难题.回声测深仪、垂直探鱼仪及本文介绍的浅海航行暗礁障碍探测仪的研制和海上实验,说明了这个结论. 相似文献
725.
Understanding of the temporal variation of oceanic heat content(OHC) is of fundamental importance to the prediction of climate change and associated global meteorological phenomena. However, OHC characteristics in the Pacific and Indian oceans are not well understood. Based on in situ ocean temperature and salinity profiles mainly from the Argo program, we estimated the upper layer(0–750 m) OHC in the Indo-Pacific Ocean(40°S–40°N, 30°E–80°W). Spatial and temporal variability of OHC and its likely physical mechanisms are also analyzed. Climatic distributions of upper-layer OHC in the Indian and Pacific oceans have a similar saddle pattern in the subtropics, and the highest OHC value was in the northern Arabian Sea. However, OHC variabilities in the two oceans were different. OHC in the Pacific has an east-west see-saw pattern, which does not appear in the Indian Ocean. In the Indian Ocean, the largest change was around 10°S. The most interesting phenomenon is that, there was a long-term shift of OHC in the Indo-Pacific Ocean during 2001–2012. Such variation coincided with modulation of subsurface temperature/salinity. During 2001–2007, there was subsurface cooling(freshening)nearly the entire upper 400 m layer in the western Pacific and warming(salting) in the eastern Pacific. During2008–2012, the thermocline deepened in the western Pacific but shoaled in the east. In the Indian Ocean, there was only cooling(upper 150 m only) and freshening(almost the entire upper 400 m) during 2001–2007. The thermocline deepened during 2008–2012 in the Indian Ocean. Such change appeared from the equator to off the equator and even to the subtropics(about 20°N/S) in the two oceans. This long-term change of subsurface temperature/salinity may have been caused by change of the wind field over the two oceans during 2001–2012, in turn modifying OHC. 相似文献
726.
727.
A regional ocean model was used to simulate the annual cycle of the upper-ocean dynamics and its influence on ocean properties in the tropical western Indian Ocean. Surface winds and heat fluxes from the National Centers for Environmental Prediction (NCEP) reanalysis forced the model (Model_NCEP) with initial and lateral boundary conditions derived from the Simple Ocean Data Assimilation (SODA). The model findings were in good agreement with previous research, satellite and observational data as well as another model configuration forced by Comprehensive Ocean and Atmosphere Data Sets (COADS). The initial and lateral boundary conditions for Model_COADS were extracted from World Ocean Atlas 2001. Anticyclonic wind stress curl occurred to the north of Madagascar, and extended towards the Tanzanian coast throughout the year, leading to Ekman convergence and downwelling in that region. The lowest sea-surface height values during the year occurred between 5° and 12° S with an elongated and contracted shape. The East African Coastal Current (EACC) was in phase with the westward North-East Madagascar Current (NEMC) throughout the year with volume transports peaking in June through July in the model forced by NCEP reanalysis. The variability of the volume transport, ocean currents, temperature and salinity to the north of Madagascar on the path of the NEMC mirrored those in the middle Tanzanian shelf on the path of the EACC throughout the year. The NEMC seemed to influence the water masses on the Tanzanian shelf, with cooler and lower-salinity water in the South-West Monsoon, and warmer and saltier water during the North-East Monsoon. 相似文献
728.
The popular methods to estimate wave height with high-frequency(HF) radar depend on the integration over the second-order spectral region and thus may come under from even not strong external interference. To improve the accuracy and increase the valid detection range of the wave height measurement, particularly by the smallaperture radar, it is turned to singular peaks which often exceed the power of other frequency components. The power of three kinds of singular peaks, i.e., those around ±1,±2~(1/2) and ±1(2~(1/2)) times the Bragg frequency, are retrieved from a one-month-long radar data set collected by an ocean state monitoring and analyzing radar,model S(OSMAR-S), and in situ buoy records are used to make some comparisons. The power response to a wave height is found to be described with a new model quite well, by which obvious improvement on the wave height estimation is achieved. With the buoy measurements as reference, a correlation coefficient is increased to 0.90 and a root mean square error(RMSE) is decreased to 0.35 m at the range of 7.5 km compared with the results by the second-order method. The further analysis of the fitting performance across range suggests that the peak has the best fit and maintains a good performance as far as 40 km. The correlation coefficient is 0.78 and the RMSE is 0.62 m at 40 km. These results show the effectiveness of the new empirical method, which opens a new way for the wave height estimation with the HF radar. 相似文献
729.
730.
K10(总理台)~K16海堤是孤东海堤重点防护岸段。通过2004年5月、2005年5月以及2005年12月三次测量资料和资料比较分析,K10~K16海堤近岸,距堤百米内水深一般小于5m,有些地段受水动力作用形成冲刷凹坑及沟槽。但海底地形变化在不同的地段是不同的,且冲淤变化差异明显。从K13~K16之间水深地形变化较微弱,K14附近局部略有淤积。K12附近及沿堤以南地段出现强侵蚀岸段,距离岸堤20m左右处,顺堤形成水深7m左右的强侵蚀地形沟槽,严重威胁孤东海堤的安全。因此,分析研究该段地形变化,可以为该段海堤防护提供最佳对策。 相似文献