共查询到20条相似文献，搜索用时 15 毫秒
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W. van Dijk 《Meteorology and Atmospheric Physics》1955,9(1):158-177
Summary In order to study the effect of the differential heating on the large scale sea surface flow pattern of the atmosphere vergence charts of the horizontal wind were constructed (January and July) and compared with the isotherm charts of the surface temperatures. For January a significant relation between the temperature field and the vergence field was found and this relation was as anticipated: convergence over the relatively warmer areas and divergence over the relatively colder areas. This effect is more pronounced at lower latitudes.The vergence chart of the ocean currents (January) shows in the region of the equatorial counter current a distribution of the vergence that is in good agreement with the scheme of the vertical circulation within the equatorial region of the Atlantic as proposed byA. Defant.
With 10 Figures 相似文献
Zusammenfassung Zur Untersuchung der Auswirkung einer unterschiedlichen Erwärmung auf die großräumigen Strömungsformen der Atmosphäre über der Meeresoberfläche wurden Vergenzkarten der horizontalen Winde für Januar und Juli konstruiert und mit den Isothermenkarten der Oberflächentemperaturen verglichen. Für Januar wurde eine signifikante Beziehung zwischen dem Temperaturfeld und dem Vergenzfeld gefunden. Es zeigte sich Konvergenz über relativ wärmeren Gebieten und Divergenz über relativ kälteren Gebieten. Dieser Zusammenhang tritt in niedrigeren Breiten deutlicher in Erscheinung. Die Vergenzkarte der Meeresströmungen (Januar) zeigt im Gebiete des äquatorialen Gegenstromes eine Vergenzverteilung, die mit dem vonA. Defant angegebenen Schema der Vertikalzirkulation im äquatorialen Gebiet des Atlantiks in guter Übereinstimmung steht.
Résumé Dans le but d'étudier l'effet d'un réchauffement inégal sur les systèmes de circulation atmosphérique à grande échelle au-dessus des océans, l'auteur a dressé des cartes de divergence des vents horizontaux en janvier et en juillet, et les a comparées aux cartes d'isothermes de surface. En janvier il existe une relation significative entre les champs de température et de divergence; il y a convergence sur les régions relativement chaudes, et divergence sur les régions relativement froides. Cette relation est particulièrement nette aux basses latitudes. La carte de divergence des courants marins (janvier) montre dans la région du contre-courant équatorial une distribution de la divergence qui s'accorde avec le schéma de la circulation verticale donné parA. Defant pour la zone équatoriale de l'Atlantique.
With 10 Figures 相似文献
4.
On the cool skin of the ocean 总被引：1，自引：0，他引：1
Jin Wu 《Boundary-Layer Meteorology》1985,31(2):203-207
Previous data relating sea-surface temperature to heat flux across the air-sea interface were reanalyzed with a common formula for the wind-stress coefficient. An expression is proposed for the nondimensional thickness of the thermal sublayer: the expression increases with wind velocity at light winds and has a value of 7 when the wind velocity reaches 7 m s–1. 相似文献
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Charles Elachi 《Boundary-Layer Meteorology》1978,13(1-4):165-179
Radar sensors are being used to provide two-dimensional imagery of the ocean surface. The radar image has a brightness variation which is proportional to the local backscatter cross-section of the surface at the wavelength of observation. The backscatter cross-section is, in turn, a function of the local surface topography and, in the case of a coherent radar system, of the surface dynamics. The synthetic-aperture radar imaging technique produces very high resolution images essentially independent of the distance to the surface being imaged. This technique is discussed in some detail. The emphasis is on recent observations of a large variety of ocean surface patterns. Deep ocean waves have been observed under a variety of weather conditions, including hurricanes. Breaking waves are observed because of the increase in roughness and the presence of foam. Discrete wave-like patterns, which resemble internal wave trains, have been observed in numerous locations; and eddy-shaped, linear, curvilinear and periodic slicks have also been seen. The different models for wave image formations are briefly reviewed. Specifically, the roughness modulation, tilt modulation, and orbital velocity models are discussed. Finally, it is shown that surface randomness does not destroy the coherence of the signal needed to generate the synthetic-aperture image because of the short-term coherence of the small Bragg waves.This paper presents the result of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract NAS7-100, sponsored by the National Aeronautics and Space Administration. 相似文献
7.
Poleward heat transport in the ocean 总被引：1，自引：0，他引：1
KIRK BRYAN 《Tellus. Series B, Chemical and physical meteorology》1991,43(4):104-115
8.
Peter Winkler 《Journal of Atmospheric Chemistry》1988,7(1):73-91
During the past decade (1977–1986) ozone has been measured on board various research vessels between 83° N and 76° S. The latitudinal distribution shows nearly twice as high an ozone concentration in the Northern Hemisphere (30 ppb) as compared to the Southern Hemisphere (15 ppb). North of 70° N the concentration rapidly drops to low values (17 ppb). In the ITCZ we frequently observed a pronounced secondary maximum which indicates that tropospheric-stratospheric exchange may be induced by deep convection. During other occasions, ozone concentrations below 10 ppb were observed in the ITCZ. Secondary maxima are also found in each hemisphere, indicating the latitudes in which stratospheric-tropospheric exchange occurs. One such pronounced maximum is found between 60 and 65° N. A comparable counterpart does not, however, occur in the respective southern latitudes.The observations, although incomplete, allow for conclusions with respect to seasonal cycles, at least in some of the latitudes or for some part of the year. In the tropics differences between continental and maritime yearly cycles are found. In mid to high northern latitudes, a sharp maximum is found which extends to the summer months over continental European sites. In the respective southern latitudes, such a spring maximum is only indicated.Comparison with occasionally concurrent Kr 85 measurements by other groups allows for the conclusion that in some cases photochemically produced ozone in polluted air masses is seen over the Atlantic ocean. 相似文献
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The sensitivity of the upper ocean thermal balance of an ocean-atmosphere coupled GCM to lateral ocean physics is assessed.
Three 40-year simulations are performed using horizontal mixing, isopycnal mixing, and isopycnal mixing plus eddy induced
advection. The thermal adjustment of the coupled system is quite different between the simulations, confirming the major role
of ocean mixing on the heat balance of climate. The initial adjustment phase of the upper ocean (SST) is used to diagnose
the physical mechanisms involved in each parametrisation. When the lateral ocean physics is modified, significant changes
of SST are seen, mainly in the southern ocean. A heat budget of the annual mixed layer (defined as the “bowl”) shows that
these changes are due to a modified heat transfer between the bowl and the ocean interior. This modified heat intake of the
ocean interior is directly due to the modified lateral ocean physics. In isopycnal diffusion, this heat exchange, especially
marked at mid-latitudes, is both due to an increased effective surface of diffusion and to the sign of the isopycnal gradients
of temperature at the base of the bowl. As this gradient is proportional to the isopycnal gradient of salinity, this confirms
the strong role of salinity in the thermal balance of the coupled system. The eddy induced advection also leads to increased
exchanges between the bowl and the ocean interior. This is both due to the shape of the bowl and again to the existence of
a salinity structure. The lateral ocean physics is shown to be a significant contributor to the exchanges between the diabatic
and the adiabatic parts of the ocean.
Received: 24 January 2000 / Accepted: 11 September 2000 相似文献
12.
David P. Rogers 《Boundary-Layer Meteorology》1986,37(1-2):167-182
The marine atmospheric boundary layer is characterized by cool temperatures and high humidity. Clouds are observed over most of the oceans. It is generally accepted that these overcast cloud decks break up into scattered fragments due to cloud-top entrainment instability. That is, if the air above the boundary layer is sufficiently cool and dry relative to cloud top, the buoyancy flux will be directed upwards and entrainment can occur freely.A boundary-layer model is used to test the sensitivity of the model atmosphere to the various processes which promote the onset of cloud-top entrainment instability. It is found that the transition from a solid cloud deck to scattered cumulus clouds depends on a rate process. The cloud cover is sensitive to mesoscale variations in sea surface temperature only if the cloud-top inversion is sufficiently weak. 相似文献
13.
Chris Garrett 《Dynamics of Atmospheres and Oceans》1996,23(1-4)
Models for the evolution of the surface mixed layer need to be improved to include dominant processes such as Langmuir circulation. It is shown that the wave forcing in Langmuir circulation models is much stronger than that due to a surface buoyancy loss, and studies of the erosion by the cells of a pre-existing stratification are described. Mixed layer models will also need to allow for horizontal inhomogeneity. It is shown, for example, that the horizontal buoyancy gradient that may be left behind after a storm produces restratification that can be significant. The nonlinearity of the equation of state is another real-world factor; it gives rise to an annual average surface buoyancy that is misleading as it is compensated by interior cabbeling. Current work linking the mixed layer to water mass formation is also introduced. 相似文献
14.
《Dynamics of Atmospheres and Oceans》1987,11(1):1-17
An investigation of properties of the solutions of the steady state inviscid barotropic vorticity equation in a rectangular basin was performed for various functional relationships between potential vorticity and the streamfunction. All computed solutions which have slow interior flow and satisfy Arnol'd-Blumen condition are qualitatively similar to Fofonoff's inertial gyre. A new class of solutions with a small vortex near the boundary current is described. Such solutions are not stable under finite amplitude perturbations and instability is manifested in the drift of the vortex. It is shown that the vortex is robust and decays only after collision with the boundary or under the influence of very large perturbations. We also show that the inertial boundary current may be much wider than in Fofonoff's model due to the appearance of a countercurrent on its seaward side. 相似文献
15.
We discuss the potential variations of the biological pump that can be expected from a change in the oceanic circulation
in the ongoing global warming. The biogeochemical model is based on the assumption of a perfect stoichiometric composition
(Redfield ratios) of organic material. Upwelling nutrients are transformed into organic particles that sink to the deep ocean
according to observed profiles. The physical circulation model is driven by the warming pattern as derived from scenario computations
of a fully coupled ocean-atmosphere model. The amplitude of the warming is determined from the varying concentration of atmospheric
CO2. The model predicts a pronounced weakening of the thermohaline overturning. This is connected with a reduction of the transient
uptake capacity of the ocean. It yields also a more effective removal of organic material from the surface which partly compensates
the physical effects of solubility. Both effects are rather marginal for the evolution of atmospheric pCO2. Running climate models and carbon cycle models separately seems to be justified.
Received: 9 August 1995 / Accepted: 22 April 1996 相似文献
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Karl J. Eidsvik 《Boundary-Layer Meteorology》1985,32(2):103-132
The best quality wind data from the Norwegian sector of the North Sea, consisting of 3662 20-min time series measured at the top of the Statfjord A drilling derrick, are analyzed. Identification of Autoregressive wind models with Akaike's AIC and Achwarz's BIC measures appears to give rather arbitrary results. Spectral estimation with FFT- and AIC-identified AR-methods give almost identical results in the mean. At the higher frequencies (% MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOzaaaa!36D7!\[f\] > 10–2 s–1) the spectrum is estimated to follow the usual inertial subrange law with little variability. The small-scale turbulent intensity is estimated to be very low, even in hurricane conditions. Comparatively, the low-frequency (% MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOzaaaa!36D7!\[f\] ~ 10–3 s–1) fluctuations are more energetic than expected. None of the chosen low-frequency characteristica appear to be significantly linearly correlated to the available mean weather variables. However, some nonlinear relations appear to exist. 相似文献
18.
B. Haurwitz 《Meteorology and Atmospheric Physics》1954,7(1):406-424
A brief introductory discussion is given of the importance of internal waves for theoretical and applied oceanography. The temperature series obtained at four oceanographic stations in the North Atlantic are subjected to harmonic analysis and to the expectancy test in order to determine the possible presence of periodic variations coinciding with the length of the principal lunar semidiurnal tide. Only in one case is it possible to regard the computed harmonic coefficients as representative of tidal effects, with a reasonable degree of assurance while in the other three cases any possible tidal effects are either more or less strongly obscured by random variations or absent. Because of the shortness of the existing oceanographic series a completely statisfactory decision concerning the presence or absence of significant variations of tidal character in the observations is impossible. It is pointed out that oceanographic serial observations of longer duration made simultaneously at different stations would lead to substantial progress in the study of internal waves.
With 3 Figures.
Contribution from the Woods Hole Oceanographic Institution No. 678. The research reported in this paper was supported by the Office of Naval Research under Contract N6onr-27701 (NR-083-004). 相似文献
Zusammenfassung In einer kurzen Einführung wird die Bedeutung der internen Wellen für die theoretische und die angewandte Ozeanographie besprochen. Die im Nordatlantischen Ozean an vier Stationen erhaltenen Temperaturserien wurden harmonisch analysiert und mittels der Expektanz-methode untersucht, um das Vorhandensein periodischer Schwankungen zu bestimmen, die die Länge der wichtigsten halbtägigen Mond-Tide haben. Nur in einem Falle können die berechneten harmonischen Koeffizienten mit genügender Sicherheit als durch Gezeitenvorgänge hervorgebracht angesehen werden, während in den anderen drei Fällen die möglichen Gezeiteneffekte entweder fehlen oder mehr oder weniger stark durch Zufallsschwankungen verdeckt sind. Wegen der kurzen Dauer der vorhandenen ozeanographischen Beobachtungsreihen ist es unmöglich, eine befriedigende Entscheidung darüber zu treffen, ob Schwankungen von Gezeitencharakter in den Beobachtungen vorhanden sind. Längere ozeanographische Beobachtungsreihen, die gleichzeitig an verschiedenen Stationen angestellt werden, könnten das Studium der internen Wellen sehr wesentlich fördern.
Résumé Dans une courte introduction, l'auteur discute l'importance qu'ont les vagues internes pour l'océanographie théorique et pratique. Les séries de température obtenues dans quatre stations de l'Atlantique-Nord ont été soumises à l'analyse harmonique et à la «méthode d'expectance», afin de déterminer la présence possible de variations périodiques ayant la longueur des principales marées lunaires semi-diurnes. Les coefficients harmoniques d'une seule station peuvent être considérés comme suffisamment sûrs pour relever du phénomène des marées, tandis que dans les trois autres cas les effets de marée possibles manquent ou sont plus ou moins fortement voilés par des variations accidentelles. Vu la courte durée des dites séries océanographiques, il est impossible de décider clairement si les observations contiennent des variations dues aux marées. Des séries d'observations océanographiques plus longues, effectuées simultanément à différentes stations, seraient aptes à pousser bien en avant l'étude des vagues internes.
With 3 Figures.
Contribution from the Woods Hole Oceanographic Institution No. 678. The research reported in this paper was supported by the Office of Naval Research under Contract N6onr-27701 (NR-083-004). 相似文献
19.
A simple transient two-dimensional (latitude-depth) upwelling-diffusion ocean model coupled with an energy balance climate model is used to determine the surface temperature response to changes in the deep water formation rate. The changes in surface temperature are large and rapid with a large magnification at high latitudes, suggesting that rapid climate changes during the Glacial-Holocene transition could have been the result of variations in the rate of deep water formation. If this is true, the mechanism is essentially transient in nature and cannot be predicted using steady state models. 相似文献
20.
《Dynamics of Atmospheres and Oceans》1999,29(2-4):335-364
Stochastic wind forcing of ocean gyre circulations is examined using the ideas of generalized linear stability theory applied to the barotropic vorticity equation of a idealized ocean. The barotropic vorticity equation is linearized about a time-evolving basic state flow, and the spatial patterns of stochastic surface wind stress curl that are optimal for increasing the variability of the ocean are computed. The most disruptive pattern of stochastic forcing is found to be insensitive to: measures of variance, the optimization time, the temporal decorrelation time of the stochastic forcing, the time evolution of the basic state flow, the stability of the basic state flow, basin size, gyre symmetry, and the presence of bathymetry. In addition, the most disruptive pattern of wind stress curl is reminiscent of that which would be associated with individual large-scale weather systems in the atmosphere, and changes in the amplitude of the atmospheric teleconnection patterns. The response of a nonlinear model to stochastic forcing described by the optimal patterns is examined, and the dynamics of the response discussed. 相似文献