Search Results
You are looking at 1 - 3 of 3 items for :
- Author or Editor: Mirko Orlić x
- Journal of Physical Oceanography x
- Refine by Access: All Content x
Abstract
The influence of planetary atmospheric waves on the Adriatic sea level is investigated for the year 1976 on the basis of 500 mb surface height and sea level data. Analysis is performed in time and frequency domains. It is found that—in the first approximation—the lower layers of the atmosphere are characterized by barotropic structure in the scope of the mentioned processes, while the equilibrium of sea-elevation gradient with air-pressure gradient is realized in the sea. Accordingly, sea level changes are opposite in phase to the oscillations of a selected isobaric surface; the ratio of their amplitudes is the same as the one between (sea surface) air density and density of the sea. Departures from this simple relationship result from the baroclinic atmospheric disturbances that occasionally influence the sea in the frequency band corresponding to planetary atmospheric waves.
Abstract
The influence of planetary atmospheric waves on the Adriatic sea level is investigated for the year 1976 on the basis of 500 mb surface height and sea level data. Analysis is performed in time and frequency domains. It is found that—in the first approximation—the lower layers of the atmosphere are characterized by barotropic structure in the scope of the mentioned processes, while the equilibrium of sea-elevation gradient with air-pressure gradient is realized in the sea. Accordingly, sea level changes are opposite in phase to the oscillations of a selected isobaric surface; the ratio of their amplitudes is the same as the one between (sea surface) air density and density of the sea. Departures from this simple relationship result from the baroclinic atmospheric disturbances that occasionally influence the sea in the frequency band corresponding to planetary atmospheric waves.
Abstract
A simple diagnostic model, reproducing circulation in lakes and marginal seas in which low-density waters are found close to the coasts while high-density waters dominate the offshore areas, is developed. An explicit solution is obtained for the central transverse section of an elongated basin, assuming that the Boussinesq and hydrostatic approximations are valid and that the alongshore variability vanishes. The model reveals cyclonic circulation that may either extend throughout the vertical (type C) or may top anticyclonic circulation developed in the bottom layer (type C/A). With the amplitude of the imposed density anomaly being fixed, the flow type is controlled by the frictional processes and by the basin dimensions. In a typical basin, type C/A flow is supported by weak bottom and vertical friction and by moderate lateral friction, unlike type C flow, which is supported by moderate bottom and vertical friction and by weak lateral friction. Strong frictional influence, especially in the basin interior, suppresses the flow everywhere. The flow is also suppressed in a basin that is narrow O(1 km) and shallow O(10 m), even without the frictional control being too strong. A basin that is narrow and deep favors type C/A flow, whereas a basin that is wide and shallow tends to support type C flow. The theoretical findings are related to observations, particularly those originating from the Adriatic Sea where type C flow prevails but may occasionally be replaced by type C/A flow, as well as to previous modeling results.
Abstract
A simple diagnostic model, reproducing circulation in lakes and marginal seas in which low-density waters are found close to the coasts while high-density waters dominate the offshore areas, is developed. An explicit solution is obtained for the central transverse section of an elongated basin, assuming that the Boussinesq and hydrostatic approximations are valid and that the alongshore variability vanishes. The model reveals cyclonic circulation that may either extend throughout the vertical (type C) or may top anticyclonic circulation developed in the bottom layer (type C/A). With the amplitude of the imposed density anomaly being fixed, the flow type is controlled by the frictional processes and by the basin dimensions. In a typical basin, type C/A flow is supported by weak bottom and vertical friction and by moderate lateral friction, unlike type C flow, which is supported by moderate bottom and vertical friction and by weak lateral friction. Strong frictional influence, especially in the basin interior, suppresses the flow everywhere. The flow is also suppressed in a basin that is narrow O(1 km) and shallow O(10 m), even without the frictional control being too strong. A basin that is narrow and deep favors type C/A flow, whereas a basin that is wide and shallow tends to support type C flow. The theoretical findings are related to observations, particularly those originating from the Adriatic Sea where type C flow prevails but may occasionally be replaced by type C/A flow, as well as to previous modeling results.
Abstract
An existing reduced-gravity model that reproduces the response of the coastal sea to alongshore wind forcing at subinertial frequencies is extended by allowing for cross-shore wind forcing and by considering superinertial frequencies. The obtained explicit solution shows that the wind-driven currents are predominantly controlled by friction and the Coriolis force at subinertial frequencies and by friction and local acceleration at superinertial frequencies. The effect of the coast is manifested by coastal-trapped variability at subinertial frequencies and baroclinic inertia–gravity waves propagating away from the coast at superinertial frequencies. The pycnocline oscillates at the coast not only at subinertial but also at superinertial frequencies, with the alongshore wind contributing more to the former and the cross-shore wind influencing more the latter. The oscillations are most pronounced when the periodic wind forcing is resonantly coupled to the local inertial oscillations (but only if the wind is not rotating counter to the inertial currents) and at near-zero frequencies (but not when the wind is purely cross-shore). These theoretical findings are related to recent observations of diurnal temperature oscillations in the near-shore water column.
Abstract
An existing reduced-gravity model that reproduces the response of the coastal sea to alongshore wind forcing at subinertial frequencies is extended by allowing for cross-shore wind forcing and by considering superinertial frequencies. The obtained explicit solution shows that the wind-driven currents are predominantly controlled by friction and the Coriolis force at subinertial frequencies and by friction and local acceleration at superinertial frequencies. The effect of the coast is manifested by coastal-trapped variability at subinertial frequencies and baroclinic inertia–gravity waves propagating away from the coast at superinertial frequencies. The pycnocline oscillates at the coast not only at subinertial but also at superinertial frequencies, with the alongshore wind contributing more to the former and the cross-shore wind influencing more the latter. The oscillations are most pronounced when the periodic wind forcing is resonantly coupled to the local inertial oscillations (but only if the wind is not rotating counter to the inertial currents) and at near-zero frequencies (but not when the wind is purely cross-shore). These theoretical findings are related to recent observations of diurnal temperature oscillations in the near-shore water column.
