Improvement of upper ocean simulation in a global OGCM: importance of vertical mixing parameterization

Title
Improvement of upper ocean simulation in a global OGCM: importance of vertical mixing parameterization
Author(s)
장찬주; 노의근; 김철호
KIOST Author(s)
Jang, Chan Joo(장찬주)
Publication Year
2002-06-28
Abstract
We investigate effects of vertical mixing parameterization on upper ocean simulation in a global ocean general circulation model (OGCM), focusing on the sea surface temperature (SST) and mixed layer depth (MLD). The vertical mixing schemes employed are the constant vertical mixing scheme, the scheme by Pacanowski-Philander (PP scheme), and a new scheme. The new scheme has been developed considering recent observational evidences such as the enhancement of turbulent kinetic energy near the sea surface. The global OGCM is based on GFDL MOM1.1, and has horizontal grid size of 1 degree and 21 vertical levels. Model simulations were started from the rest with annual-mean Levitus temperature and salinity fields, and integrated for about 30 years, forced by the monthly-mean climatology of Hellerman-Rosenstein wind stress and the NCEP/NCAR heat flux with a restoring term. Volume transport streamfunctions shows no significant difference regardless of vertical mixing schemes, confirming that the global circulation is driven mainly by the wind stress. Seasonal variation of the SST, on the other hand, is affect substantially by the vertical mixing schemes. The constant vertical mixing leads to overestimation/ underestimation of the SST during summer/winter, compared to climatological SST. This seasonal bias of the SST is removed by the new scheme. The PP scheme overestimates annual variation of the SST, especially near the Antarctic Circumpolar Current region, although improvement over simulation with the constant vertical mixing is obtained by the PP scheme largely in equatorial regions. The new scheme is also shown to satisfactorily reproduce the spatial distribution of the MLD, compared to that from Levitus data and other schemes. It is suggested that higher vertical resolution of the OGCM is required to improve upper ocean simulation further, particularly in thermocline.
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/32572
Bibliographic Citation
Proceedings of the 4th RIAM-RIO International Workshop on "Oceanic variability of the East Asian Marginal Seas", 2002
Publisher
Dynamics Simulations Research Center, Research Institute for Applied Mechanics, Kyushu University
Type
Conference
Language
English
Publisher
Dynamics Simulations Research Center, Research Institute for Applied Mechanics, Kyushu University
Related Researcher
Research Interests

upper ocean dynamics,regional climate modeling,ocean climate change,해양상층역학,지역기후모델링,해양기후변화

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