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A three-dimensional, multi-level model was used to study the energy dissipation of semidiurnal internal Kelvin waves due to their interaction with bottom topography. A simplified topography consisting of a channel with an additional shallow bay was used to clarify the wave’s scattering process. When the first mode semidiurnal internal wave given at an open boundary arrives at the bay mouth, higher-mode internal waves are generated at a step bottom of the bay mouth. As a result, the energy of the first mode internal Kelvin wave is effectively decayed. The decay rate of the internal Kelvin wave depends on both the width and length of the additional bay. The maximum decay rate was found when a resonance condition occurs the bay, that is, the bay length is equal to a quarter of wave length of the first mode internal wave on the shallow region. The decay rate in the wide bay cases is higher than that in a narrow case, due to a contribution from the scattering due to the Poincare wave that emanates from the corners of the bay head. The decay rate with the additional bay is 1.1–1.8 times that of the case without the additional bay. The decay rate due to the scattering process is found to be of the same order as that of the internal and bottom friction. 相似文献
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Izmir Bay is one of the most polluted estuaries in the whole Mediterranean Sea. The inner part of the Bay (Inner Bay) is heavily
affected by domestic and industrial discharge. As a result of these loads, strong eutrophication occurs in the Inner Bay,
which is temporally anaerobic. The ecologically sensitive approach of the local authorities during the last decade has given
rise to a wide variety of monitoring and research studies on this bay. On the other hand, the municipality of Izmir started
to operate wastewater treatment facilities since January 2000. The Institute of Marine Sciences and Technology — Izmir (IMST)
with its research vessel R/V K Piri Reis has been conducting an intensive monitoring program since 1988 and especially during
the recent few years. These investigations provide an opportunity for the evaluation of the performance of the wastewater
treatment plant in terms of the change in the optical properties of Izmir Bay water in a positive manner. The turbidity values
measured in these monitoring studies indicate that the values have changed drastically after January 2000. Their spatial variation
indicates that the values decrease from the Inner Bay towards the Aegean Sea. The turbidity (light transmission) values are
measured with an automatic CTD (conductivity, temperature and depth) system during each cruise. The seiche disc depth measurement
is carried out only occasionally. The accuracy of the seiche disc depth is dependent on certain daylight conditions and depends
on the operator. The seiche disc depth (D
s) is an important parameter to estimate primary production of organic matter (hereafter called production). A relation between
light transmission (turbidity) value and seiche disc depth (D
s) is found with very good agreement. The correlations are very high (approximately 0.94) with slight seasonal variation. 相似文献
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C. G. Quilter 《新西兰海洋与淡水研究杂志》2013,47(1):225-231
The sporozoan Thelohania contejeani Henneguy (Microsporida: Nosematidae) is recorded from Paranephrops zealandicus (White) for the first time. It is an intracellular parasite invading musculature throughout the crayfish, causing a gradual decrease in locomotor activity, and it may eventually cause the death of the host. Infected crayfish were found in the northern part of Leith Stream, Dunedin, where the infection rate reached a maximum of 20%. This parasite has formerly been recorded only from Northern Europe. 相似文献
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探讨了1597年10月6日（明万历二十五年八月二十六日）地震的烈度特征,地震伴随的湖震和火山喷发,以及地震类型与规模．结果表明, 1597年10月6日地震为可能发生在ldquo;珲春——汪清深震区rdquo;的一次Mge;8深源地震;地震在中国东部地区产生了广泛的湖震,其多种形态可与1775年葡萄牙里斯本地震产生的湖震比拟;地震触发了望天鹅火山的一次中小规模爆发式喷发,其地点在中国吉林省长白县境内． 相似文献
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利用水动力学方程对口本琵琶湖表面定振波进行了计算和分析,结果表明其主要周期约为69．5min,另外,利用实测水位资料,采用最大熵谱法进行分析,得到了主要周期约为68min,两者吻合很好。 相似文献
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This study focused on the effects of upstream reservoir thermal dynamics and downstream tidal influences on temperatures in a 25-km reach of Alouette River (coastal British Columbia, Canada) below a control dam and upstream of its confluence with Pitt River. Temperature was monitored during summer 2013 using 25 sensors. Water was released from the reservoir through a low level outlet at approximately 2.7 m3 s−1, except during late spring when a higher flow was released over the dam spillway. Temperature variations in the lowest section of Alouette River, and in the lower portion of a tributary, were distinct from those further upstream due to backwatering effects associated with a semi-diurnal tide, which can cause flow reversals in Pitt River. An internal seiche was identified in the reservoir during mid-summer that resulted in oscillating releases of warmer and cooler water with an amplitude of up to 6°C and a period of approximately 12 hr. Wavelet analysis and band-pass filtering indicated that the 12-hr signal declined in strength with downstream distance, but remained detectable about 15 km below the dam. In contrast, the 24-hr diel signal increased in strength with distance below the dam. Travel times computed via cross-correlation of the 12-hr signals with that at the low level outlet were within ±10% of those estimated from measured mean velocities. Lagrangian tracking of water parcels using the derived travel times indicated that the cooling effect of periodic releases of cold water during the seiching period persisted to the lower extent of the non-tidal reach. The tidally influenced locations experienced higher temperatures than those recorded in the non-tidal portion of Alouette River, although the relative roles of heating in the upstream tidal reach versus upstream advection of water associated with tide-driven flow reversals in Pitt River require further study. 相似文献
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Field investigations in 1999 confirmed that the tsunami that struck the Aitape coast of Papua New Guinea on 17 July, 1998
caused damage at points as far as 230 km to the west-northwest, particularly at locations where the coast is indented. Eyewitnesses
saw the sea withdraw (in most cases), then surge to levels around 2 m higher than normal in a series of three waves. In some
cases the time of arrival of the waves is known approximately by reference to the onset of darkness and to felt earthquakes.
Seiche waves followed in some bays, notably in Yos Sudarso Bay, Indonesia, where waves persisted for 3–5 days. Damage was
caused by the backwash from the waves. Bodies presumed to be those of Aitape victims were seen floating at sea off Jayapura
five days after the tsunami. We record the recollections of people in the Yos Sudarso Bay area who experienced a number of
tsunamis in the past 60 years; people that we interviewed on the Papua New Guinea side of the border recollected few or none. 相似文献