Ocean vertical structure

Lesson 1

OCEAN STRUCTURE AND CIRCULATION

Блок 3

Упражнение 1.

Прочитайте заголовок приводимого ниже текста. Подумайте, о чем в нем может идти речь. Приведите 10–15 слов, которые могут, с Вашей точки зрения, встретиться в тексте.

Прочитайте и переведите текст.

The oceans occupy 71 per cent of the earth's surface, with over 60 per cent of the global ocean area in the southern hemisphere. Three-quarters of the ocean area is between 3,000 and 6,000 m deep, whereas only 11 per cent of the land area exceeds 2,000 m altitude.

a Vertical

The major atmosphere-ocean interactive processes involve heat exchanges, evaporation, density changes and wind shear. The effect of these processes is to produce a major oceanic layering that is of great climatic significance:

1 At the ocean surface, winds produce a thermally mixed surface layer averaging a few tens of metres deep poleward of latitude 60°, 400 m at latitude 40° and 100-200 m at the equator.

2 Below the relatively warm mixed layer is the thermocline,
a layer in which temperature decreases and density increases (the pycnocline) markedly with depth. The thermocline layer, within which stable stratification tends to inhibit vertical mixing, acts as a barrier between the warmer surface water and the colder deep-layer water. In the open ocean between latitudes of 60° north and south the thermocline layer extends from depths of about 200 m to a maximum of 1,000 m (at the equator from about 200 to 800 m; at 40° latitude from about 400 to about 1,100 m). Poleward of 60° latitude, the colder deep-layer water approaches the surface. Within the thermocline layer, the location of the steepest temperature gradient is termed the permanent thermocline, which has a dynamically inhibiting effect in the ocean similar to that of a major inver­sion in the atmosphere. However, heat exchanges take place between the oceans and the atmos­phere by turbulent mixing above the permanent thermocline, as well as by upwelling and down-welling involving deep-layer water.

During spring and summer in the mid-latitudes, accentuated surface heating leads to the develop­ment of a seasonal thermocline occurring at depths of 50 to 100 m. Surface cooling and wind mixing tend to destroy this layer in autumn and winter. 3 Below the thermocline layer is a deep layer of cold, dense water. Within this, water move­ments are mainly driven by density variations, commonly due to salinity differences (i.e. having a thermohaline mechanism).

The ocean may be viewed as consisting of a large number of layers, the topmost subject to wind stress, the next layer down to frictional drag by the layer above, and so on; all layers being acted on by the Coriolis force. The surface water tends to be deflected to the right (in the northern hemisphere) by an angle averaging some 45 ° in the surface wind direction and to move at about 3 per cent of its velocity. This deflection increases with depth as the friction-driven velocity of the current decreases exponentially. On the equator, where there is no Coriolis force, the surface water moves in the same direction as the surface wind. This theo­retical Ekman spiral was developed under assump­tions of idealized ocean depth, wind constancy, uniform water viscosity and constant water pressure at a given depth. This is seldom the case in reality, and under most oceanic conditions the thickness of the wind-driven layer is about 100 to 200 m.

Упражнение 2.

Прочитайте следующие слова и определите их соответствия
в русском языке:

Hemisphere, thermocline, pycnocline, process, temperature, stratification, vertical, barrier, maximum, location, gradient, dynamically, upwelling, seasonal, exponentially, theory, spiral, idealize, constant, reality.

Упражнение 3.

Определите, к каким частям речи относятся следующие слова; напишите соответствующие английские сокращения для каждого из них (v., adv., n., adj., conj., part., prep., pron.):

Vertical, evaporation, as, with, which, within, colder, has, however, termed, occurring, mainly, thickness.

Упражнение 4.

В правой колонке найдите русские эквиваленты следующих английских словосочетаний:

1. heat exchange 2. vertical mixing 3. temperature gradient 4. water movement 5. density variation 6. wind stress 7. wind direction 8. ocean depth 9. surface layer

a. глубина океана b. движение воды c. направление ветра d. поверхностный слой e. температурный градиент f. теплообмен g. вертикальное перемешивание h. изменения плотности i. ветровое воздействие

Упражнение 5.

Заполните, где это возможно, таблицу, вставив недостающие части речи.

v.	n.	adj.	adv.
produce     extend	significance     variation	stable	dynamically     relatively

Упражнение 6.

Прочитайте следующие выражения:

206 km; 1-2 m/day; 30°C; 1700; 1,367; 2.68931.

Упражнение 7.

Вставьте соответствующий предлог и подберите определение к каждому слову :off about up away for down on out.

1. pass … 2. make … 3. bring … 4. clear … 5. cut … 6. do 7. fall 8. fill

a. выяснять b. продолжать c. расширять e. направляться f. снимать g. покидать h. вызывать i. сокращать

Упражнение 8.

Прочитайте текст и найдите в нем ответы на следующие вопросы:

1. Какова средняя скорость апвеллинга?

2. От чего она зависит?

3. Где расположен основной регион апвеллинга?

(Контрольное время – 7 минут)

Дата добавления: 2014-12-27