Influence of the ITCZ on the Flow of Thermocline Water from the Subtropical to the Equatorial Pacific Ocean

Lu, Pingping; McCreary, Julian P.

doi:10.1175/1520-0485(1995)025<3076:iotiot>2.0.co;2

Cited by 101 publications

(97 citation statements)

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“…For example, convective events in the atmosphere that communicate the influence of the surface conditions deep into the tropical troposphere occur on time scales of days and spatial scales of tens of kilometers. On the other hand, the adjustment of the thermal structure of the equatorial thermocline involves the meridional overturning ocean circulation, which extends into the subtropics (Fine et al 1987;Gu and Philander 1997;Liu et al 1994;Lu and McCreary 1995;Rodgers et al 1999) and, some argue, involves higher-latitude water masses (Liu et al 2002;Rodgers et al 2003). The time scales of these physical processes range from months to centuries.…”

Section: Paleo-enso Modeling a Backgroundmentioning

confidence: 99%

Progress in Paleoclimate Modeling*

et al. 2006

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This paper briefly surveys areas of paleoclimate modeling notable for recent progress. New ideas, including hypotheses giving a pivotal role to sea ice, have revitalized the low-order models used to simulate the time evolution of glacial cycles through the Pleistocene, a prohibitive length of time for comprehensive general circulation models (GCMs). In a recent breakthrough, however, GCMs have succeeded in simulating the onset of glaciations. This occurs at times (most recently, 115 kyr B.P.) when high northern latitudes are cold enough to maintain a snow cover and tropical latitudes are warm, enhancing the moisture source. More generally, the improvement in models has allowed simulations of key periods such as the Last Glacial Maximum and the mid-Holocene that compare more favorably and in more detail with paleoproxy data. These models now simulate ENSO cycles, and some of them have been shown to reproduce the reduction of ENSO activity observed in the early to middle Holocene. Modeling studies have demonstrated that the reduction is a response to the altered orbital configuration at that time. An urgent challenge for paleoclimate modeling is to explain and to simulate the abrupt changes observed during glacial epochs (i.e., Dansgaard-Oescher cycles, Heinrich events, and the Younger Dryas). Efforts have begun to simulate the last millennium. Over this time the forcing due to orbital variations is less important than the radiance changes due to volcanic eruptions and variations in solar output. Simulations of these natural variations test the models relied on for future climate change projections. They provide better estimates of the internal and naturally forced variability at centennial time scales, elucidating how unusual the recent global temperature trends are.

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Section: Paleo-enso Modeling a Backgroundmentioning

confidence: 99%

Progress in Paleoclimate Modeling*

et al. 2006

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“…In the eastern basin, there is also a cyclonic gyre generated by Ekman upwelling in the intertropical convergence zone (ITCZ). As a result, within this area surface layers are thin; thus, a high potential vorticity area exists, which is often called a "potential vorticity barrier" for the NIP (Lu and McCreary 1995). Local cyclonic circulation prevents a direct communication between the subtropics and Tropics.…”

Section: Flow and Pathways On Isopycnal Surfacesmentioning

confidence: 99%

“…Tritium data collected from the oceans in the 1980s provide strong evidence for the existence of pycnocline flows from the subtropical North Pacific to the equator (Fine et al 1987;McPhaden and Fine 1988). Subsequent modeling studies, including simple reduced-gravity models and ocean general circulation models (OGCMs), clearly demonstrate dynamical connection through this cell (McCreary and Lu 1994;Liu 1994;Liu et al 1994;Lu and McCreary 1995;Lu et al 1998;Liu and Huang 1998;Rothstein et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Decadal Variability of Pycnocline Flows from the Subtropical to the Equatorial Pacific*

Wang

Huang

2005

Journal of Physical Oceanography

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A method based on isopycnal trajectory analysis is proposed to quantify the pathways from the subtropics to the Tropics. For a continuous stratified ocean a virtual streamfunction is defined, which can be used to characterize these pathways. This method is applied to the climatological dataset produced from a dataassimilated model. Analysis indicates that in each layer contours of the virtual streamfunction are a good approximation for streamlines, even if there is a cross-isopycnal mass flux. The zonal-integrated meridional transport per unit layer thickness through each pathway varies in proportion to 1/sin, where is latitude. The vertical-integrated total transport through pathways behaves similarly. Transport through pathways has a prominent decadal variability. Results suggest that in decadal time scales the interior pathway transport (IPT) anomaly may be mainly caused by the wind stress anomaly at low latitude. The western boundary pathway transport (WBPT) anomaly often has a sign opposite to the IPT anomaly, reflecting compensation between the IPT and the WBPT. However, more often than not the wind stress anomaly within tropical latitudes can also be used to explain the WBPT anomaly.

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“…Simulations of oceanic general circulation models (OGCMs) show that subtropical water can be transported to the equatorial ocean in both the LLWBC and the interior ocean [Liu, 1994;Liu et al, 1994;McCreary and Lu, 1994;Rothstein et al, 1998]. Recent studies [Lu and McCreary, 1995;Liu and Huang, 1998] further suggest that the equatorward interior transport is stronger in the South Pacific than in the North Pacific owing to the existence of the Intertropical Convergence Zone (ITCZ).…”

Section: Introductionmentioning

confidence: 99%