GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 2010-2014  (4)
  • 2012  (4)
  • 1
    facet.materialart.
    Unknown
    An equatorial ocean bottleneck in global climate models (2012)
    American Meteorological Society
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2012. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 25 (2012): 343–349, doi:10.1175/JCLI-D-11-00059.1.
    Description: The Equatorial Undercurrent (EUC) is a major component of the tropical Pacific Ocean circulation. EUC velocity in most global climate models is sluggish relative to observations. Insufficient ocean resolution slows the EUC in the eastern Pacific where nonlinear terms should dominate the zonal momentum balance. A slow EUC in the east creates a bottleneck for the EUC to the west. However, this bottleneck does not impair other major components of the tropical circulation, including upwelling and poleward transport. In most models, upwelling velocity and poleward transport divergence fall within directly estimated uncertainties. Both of these transports play a critical role in a theory for how the tropical Pacific may change under increased radiative forcing, that is, the ocean dynamical thermostat mechanism. These findings suggest that, in the mean, global climate models may not underrepresent the role of equatorial ocean circulation, nor perhaps bias the balance between competing mechanisms for how the tropical Pacific might change in the future. Implications for model improvement under higher resolution are also discussed.
    Description: KBK gratefully acknowledges the J. Lamar Worzel Assistant Scientist Fund. GCJ is supported by NOAA’s Office of Oceanic and Atmospheric Research. RM gratefully acknowledges the generous support and hospitality of the Divecha Centre for Climate Change and CAOS at IISc, Bangalore, and partial support by NASA PO grants.
    Description: 2012-07-01
    Keywords: Tropics ; Ocean circulation ; Ocean dynamics ; Climate models ; Coupled models ; Ocean models
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 2
    facet.materialart.
    Unknown
    Oxygen decreases and variability in the eastern equatorial Pacific (2012)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Oceans, 117 (C11). C11019.
    Details
    Publication Date: 2019-09-24
    Description: Observations indicate increasingly large and strong oxygen minimum zones (OMZs) in the tropical Pacific over recent decades. Here we report on oxygen decreases and variability within the eastern equatorial Pacific OMZ. We construct time series from historical and profiling float oxygen data and analyze data from repeat hydrographic sections at 110°W and 85°50′W. Historical data are quite sparse for constructing oxygen time series, but floats with oxygen sensors prove to be good tools to fill measurement gaps in later parts of these time series. In the region just south of the equator a time series over the last 34 years reveals that oxygen decreases from 200 to 700 m at a rate between 0.50 and 0.83 μmol kg−1 yr−1. This strong decrease seems to be related to changes in the Pacific Decadal Oscillation (PDO). Oscillations on shorter time scales (e.g., an El Niño signal in the upper 350 m) are superimposed upon this trend. In the section data, a general trend of decreasing oxygen is present below the surface layer. While velocity differences appear related to oxygen differences in the equatorial channel, there is less correlation elsewhere. Contrasting with long-term trend computations, the trends derived from two repeat sections are obscured by the influence of seasonal and longer-term variability. Multidecadal variability (e.g., PDO) has the strongest influence on long-term trends, while El Niño, isopycnal heave, current variability, seasonal cycles, and temperature changes are less important. Key points: - Oxygen decrease in the Pacific OMZ over the last 34 years in 200-700 m depth - Trends in oxygen and their relation to variability on different timescales - Relation between oxygen and velocity changes in the equatorial channel
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2012JC008043
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
    facet.materialart.
    Unknown
    Multidecadal Warming and Shoaling of Antarctic Intermediate Water (2012)
    AMS (American Meteorological Society)
    In:  Journal of Climate, 25 (1). pp. 207-221.
    Details
    Publication Date: 2014-10-21
    Description: Antarctic Intermediate Water (AAIW) is a dominant Southern Hemisphere water mass that spreads from its formation regions just north of the Antarctic Circumpolar Current (ACC) to at least 20°S in all oceans. This study uses an isopycnal climatology constructed from Argo conductivity–temperature–depth (CTD) profile data to define the current state of the AAIW salinity minimum (its core) and thence compute anomalies of AAIW core pressure, potential temperature, salinity, and potential density since the mid-1970s from ship-based CTD profiles. The results are used to calculate maps of temporal property trends at the AAIW core, where statistically significant strong circumpolar shoaling (30–50 dbar decade−1), warming (0.05°–0.15°C decade−1), and density reductions [up to −0.03 (kg m−3) decade−1] are found. These trends are strongest just north of the ACC in the southeast Pacific and Atlantic Oceans and decrease equatorward. Salinity trends are generally small, with their sign varying regionally. Bottle data are used to extend the AAIW core potential temperature anomaly analysis back to 1925 in the Atlantic and to ~1960 elsewhere. The modern warm AAIW core conditions appear largely unprecedented in the historical record: biennially and zonally binned median AAIW core potential temperatures within each ocean basin are, with the notable exception of the subtropical South Atlantic in the 1950s–70s, 0.2–1°C colder than modern values. Zonally averaged sea surface temperature anomalies around the AAIW formation latitudes in each ocean and sectoral southern annular mode indices are used to put the AAIW core property trends and variations into context.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1175/JCLI-D-11-00021.1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
    facet.materialart.
    Unknown
    Relative contributions of temperature and salinity to seasonal mixed layer density changes and horizontal density gradients (2012)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research - Oceans, 117 (C4). ..
    Details
    Publication Date: 2014-10-21
    Description: Temperature and salinity both contribute to ocean density, including its seasonal cycle and spatial patterns in the mixed layer. Temperature and salinity profiles from the Argo Program allow construction and analysis of a global, monthly, mixed layer climatology. Temperature changes dominate the seasonal cycle of mixed layer density in most regions, but salinity changes are dominant in the tropical warm pools, Arctic, and Antarctic. Under the Intertropical Convergence Zone, temperature and salinity work in concert to increase seasonal stratification, but the seasonal density changes there are weak because the temperature and salinity changes are small. In the eastern subtropics, seasonal salinity changes partly compensate those in temperature and reduce seasonal mixed layer density changes. Besides a hemispheric seasonal reversal, the times of maximum and minimum mixed layer density exhibit regional variations. For instance, the equatorial region is more closely aligned with Southern Hemisphere timing, and much of the North Indian Ocean has a minimum density in May and June. Outside of the tropics, the maximum mixed layer density occurs later in the winter toward the poles, and the minimum earlier in the summer. Finally, at the times of maximum mixed layer density, some of the ocean has horizontal temperature and salinity gradients that work against each other to reduce the horizontal density gradient. However, on the equatorial sides of the subtropical salinity maxima, temperature and salinity gradients reinforce each other, increasing the density gradients there. Density gradients are generally stronger where either salinity or temperature gradients are dominant influences.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2011jc007651
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...