物理海洋学名词-A 8

Glossary of Physical Oceanography and Related Disciplines

Steven K. Baum Department of Oceanography Texas A&M University

May 26, 2004

 

adiabatic Involving or allowing neither gain nor loss of heat.


adiabatic compressibility A quantity arising from taking derivatives of the density in the (p,θ,S) representation of the equation of state. It is defined by
κ =1/ρ(∂ρ/∂p)_(θ,S)
where ρ is the fluid density, p the pressure, θ the potential temperature, and S the salinity. See Muller [1995], McDougall et al. [1987] and the related saline contraction coefficient and thermal expansion coefficient.


ADIOS Acronym for Asian Dust Input to the Oceanic System. See Betzer et al. [1988].


adjoint model See Errico [1997].


adjustment time A time scale characterizing the decay of an instantaneous input pulse into a reservoir.
It is also used to characterize the adjustment of the mass of a reservoir following a change in the source strength.


Adriatic Bottom Water (ABW) A water mass – also known as Adriatic Deep Water – formed in the southern Adriatic Sea that exits into the Ionian Sea via Otranto Strait. The temperature and salinity of ABW are 13℃ and 38.6 psu, respectively. There are a couple of competing conjectures as to the origin of the ABW:
• some postulate that North Adriatic Deep Water flowing into the canyon in the shelf of Bari mixes with Modified Levantine Intermediate Water (MLIW) to form ABW; and
• others think that contribution of NADW is minor and that the ABW is formed mainly by the mixing of the surface water in the center of the South Adriatic Pit with the underlying MLIW during periods of deep convection. 

Either way, most studies confirm that ABW represents the most important component of the bottom water of the entire Eastern Mediterranean. See Artegiani et al. [1993].


Adriatic Deep Water (ADW) Another name for Adriatic Bottom Water (ABW).


Adriatic Sea A part of the eastern basin of the Mediterranean Sea located between Italy and the Balkan Peninsula. It is landlocked on the north, east and west, and is linked with the Mediterranean through the Otranto Strait to the south. The Adriatic is a rectangular basin oriented in a NW–SE direction with a length of about 800 km and a width of about 200 km. It can be divided into three sub–basins:

• a northernmost shallow basin with the bottom sloping gently to the south and reaching at most 100 m;
• three pits located along the transversal line off Pescara (one of which is known as the Jabuka Pit), with a maximum depth of 280 m; and
• a southern basin called the South Adriatic Pit (separated from the middle basin by the 170 m deep Palagruza Sill) characterized by approximately circular isobaths, with a maximum depth of about 1200 m in the center.

The bottom rises toward the Strait of Otranto past the southern basin, with the strait having a maximum depth of 780 m, and average depth of 325 m, and a width of about 75 km.

The meteorological forcing has been summarized by Artegiani et al. [1993] as:
Mainly during the winter, the Adriatic Sea region is under a continuous influence of passing mid–latitude meteorological perturbations and of the wind systems associated with them. The two main wind systems are the bora and the scirocco. The bora is a dry and cold wind blowing in an offshore direction from the eastern coast. The scirocco blows from the southeast (i.e. along the longitudinal axis of the basin) bringing rather humid and relatively warm air into the region. In particular, the bora produces appreciable buoyancy fluxes through evaporative and sensible heat loss, induces both wind–driven and thermohaline circulation, and, most importantly, is responsible for deep water formation processes.
This is one of the two regions within the Mediterranean where freshwater input exceeds evaporation (the other being the Black Sea). This is due mostly to outflow from the Po River in the north, which accounts for 1700 m3s-1 of the 4000 m3s−1 total river discharge in the Adriatic.
The flow between the Adriatic and the greater Mediterranean through the Otranto Strait is that of a typical dilution basin wherein low salinity water exits near the surface and high salinity water enters at depth. The Mediterranean inflow is of surface Ionian water and, in a deeper layer from 200–300 m, of Modified Levantine Intermediate Water (MLIW). This inflow occurs over a wide area along the eastern shore of the strait, with near–surface outflow concentrated in a thin layer along the western coast. The latter consists of relatively fresh water originating mostly from the northern Adriatic. The remainder of the outflow consists of Adriatic Bottom Water (ABW), a water mass formed in the southern basin that flows over the sill of the Otranto Strait into the Ionian Sea.
The mean basin–wide circulation is generally a cyclonic pattern with several smaller, more or less permanent gyres embedded therein. A topographically controlled cyclonic gyre sitting over the South Adriatic Pit partially isolates the northern Adriatic from Mediterranean influence. This gyre causes a bifurcation of the incoming MLIW, with part of it entering the northern basins over the Palagruza Sill, while the rest is entrained into the South Adriatic cyclonic circulation cell. The circulation regime varies seasonally and interannually in response to changes in the heating and wind regimes. Seasonally, the winter circulation is characterized by a prevalence of warmer Mediterranean inflow reinforced by southerly winds. In summer, there is a stronger outflow of fresher and warmer Adriatic water along the western coast supported by the Etesian winds. See Buljan and Zore-Armanda [1976], Orlic et al. [1992], Artegiani et al. [1993], Tomczak and Godfrey [1994], Artegiani et al. [1997a], Artegiani et al. [1997b], Poulain [2001] and Vilibic and Orlic [2002].

 

LZZ@108,20170717

 

共收到 0 | 阅读次数 45
发表评论
请先登录再发表评论