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The structure, evolution, and breaking of a tidal internal wave on a steep shelf are discussed on the basis of the data of temperature measurements. The bottom slope at the measurement site is close to the critical slope for a tidal wave. The tidal wave and other waves are inclined coastward. The tidal-wave amplitude increases monotonically with increasing horizon depth. The tidal wave is nonlinear in amplitude and turns over on the outer shelf. On the inner shelf, the internal wave is close in shape to rectangular and generates harmonics of its own. The harmonics make the tidal wave steeper and form solitary rises similar to bilateral bores. All these features ensure a more rapid sink for the internal-tide energy. 相似文献
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Anatoliy Filonov 《Ocean Dynamics》2011,61(7):917-931
The dynamics of a semidiurnal internal tidal wave at a narrow Mexican Pacific shelf is discussed using the data of temperature
obtained by an anchored instrument and data of field surveys. The internal tide on the shelf is dominated by an inclined wave,
which propagates upward and onshore along a continental slope. Despite its reflection from the bottom and from the surface
of the ocean, they remain inclined and totally destroyed over the course of one wavelength. Due to wave reflection from the
inclined bottom, the horizontal and vertical wave number increase threefold when the wave goes into shallow waters. The wave
undergoes nonlinear transformation and overturns forming several homogeneous temperature layers up to 20 m thick. The most
intense disturbances of water layers are observed near the bottom, where the slope angle approaches its critical value. Because
of nonlinear effects, the wave carries cool deep water out to the shallow depth and causes coastal upwelling. Intense solar
warming together with vertical mixing results in a rapid rise of temperature in the 130-m water column that was observed. 相似文献
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Emilio Palacios-Hernández Laura E. Carrillo Anatoliy Filonov Luis Brito-Castillo Carlos E. Cabrera-Ramos 《Ocean Dynamics》2010,60(1):81-91
Sea surface temperature (SST) harmonic and empirical orthogonal function (EOF) analyses covering 18 years were performed for the area located from 114° to 105° W and from 18° to 25° N. The results indicate that the influence of the annual signal predominates over the semi-annual signal, and the closer to the coast, the stronger the annual harmonic. Several interannual anomalies arose that are connected with the main global indexes, especially the Oceanic Niño Index. Pearson correlations between the first temporal mode of the SST and regional rainfalls in Nayarit indicate that maximum correlations (r?>?0.7) are observed when there is a +1-month lag between the series. However, this result indicates that SST is delayed with 1 month after rainfall occurrence, which shows that the dominant influence in this relationship is not the SST forcing. 相似文献
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C. Franco-Gordo E. Godínez-Domínguez A.E. Filonov J. Freire 《Progress in Oceanography》2004,63(3):99-123
The temporal and spatial distributions of zooplankton biomass and larval fish recorded during 27 months (December 1995-December 1998) off the Pacific coast of central México are analyzed. A total of 316 samples were obtained by surface (from 40-68 to 0 m) oblique hauls at 12 sampling sites using a Bongo net. Two well-defined periods were observed: a pre-ENSO period (December 1995-march 1997) and an ENSO event (July 1997-September 1998) characterized by impoverishment of the pelagic habitat. The highest biomass concentrations occurred at coastal stations during the pre-ENSO period. During the El Niño period no spatial patterns were found in coastal waters. The months with highest biomass were those in which the lowest sea surface temperature (SST) occurred (January-May), and this pattern was also observed during the ENSO period. A typical, although attenuated, seasonal environmental pattern with enhanced phytoplankton (diatoms and dinoflagellates) was prevalent during the El Niño event in nearshore waters. During the El Niño period the phytoplankton was mainly small diatoms (microphytoplankton), while dinoflagellates were practically absent. The most parsimonious generalized linear models explaining spatial and temporal distribution of larval fish species included the ENSO index (MEI), upwelling index (UI) and distance to the coast. The environmental variability defined on an interannual time-scale by the ENSO event and the seasonal hydroclimatic pattern defined by the UI (intra-annual-scale) controlled the ecosystem productivity patterns. The small-scale distribution patterns (defined by a cross-shore gradient) of plankton were related to the hydroclimatic seasonality and modulated by interannual anomalies. 相似文献
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The present study reports on perturbations of the water column by large rainfall at Lake Alchichica, a saline lake in Central
Mexico. Alchichica is located in the “Llanos de San Juan,” a high-altitude plateau with a minimum elevation of 2,300 m above
sea level. The climate is arid with annual precipitation less than 400 mm and annual evaporation of 500–600 mm. A single day
large rainfall event delivered 1,810,000 m3 of water to the basin, raising the lake’s water level by about 1 m. Temperature and salinity profiles showed an atypical
temperature inversion up to 1°C in the upper layer accompanied by salinity decrease up to 0.5 g l−1. Transparency and pH were slightly altered, but dissolved oxygen, nutrients and chlorophyll a concentrations were not changed. In spite of the heavy rainfall and associated wind, the effects of the event were limited
to the upper half of the epilimnion. After 2 days, the lake water level returned to its original level. The rapid leakage
of the runoff minimized any long-term effects of the large rainfall. 相似文献
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INTRODUCTIONThelargestlakeinMexicoandthirdlargestinLatinAmerica,ChapalaLake(approximately2 0°N) ,is 1 50 0mabovesealevel,measures 75× 2 5km ,hasaveragedepthof6m (maximumdepthcloseto 1 1m)andamountainchainalongitsnorthernandsouthernshores (Fig .1a) .TheLermaRiverflowsintoit;theSantiagoRiverflowsoutofit.Thebeautifullandscape,andwarmclimateconducivetobreezecirculationalongitsshore ;absenceofabrupttemperaturevariations,andthemoderateairhumidityat tractmanytouriststothelake .Manyretirees… 相似文献
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