scholarly journals The LGM surface climate and atmospheric circulation over East Asia and the North Pacific in the PMIP2 coupled model simulations

2007 ◽  
Vol 3 (2) ◽  
pp. 655-678 ◽  
Author(s):  
W. Yanase ◽  
A. Abe-Ouchi
Keyword(s):  
East Asia ◽  
Atmospheric Circulation ◽  
North Pacific ◽  
General Circulation ◽  
Circulation Model ◽  
Boreal Summer ◽  
Boreal Winter ◽  
The North ◽  
Surface Climate ◽  
The North Pacific

Abstract. The surface climate and atmospheric circulation over East Asia and the North Pacific at the last glacial maximum has been investigated using the outputs from several coupled atmosphere-ocean general circulation model in PMIP2 database. In boreal summer, the weakening of high pressure over the North Pacific and less precipitation over East Asia are analyzed in most models. The reduced moisture transport seems to result in the less precipitation over East Asia. In boreal winter, the intensification of the Aleutian low and southward shift of the upper-level jet are analyzed in most models. Some of these results are consistent with geological records such as pollen, lake status and dust transport.

scholarly journals Sensitivity of the Simulated Distributions of Water Masses, CFCs, and Bomb 14C to Parameterizations of Mesoscale Tracer Transports in a Model of the North Pacific

2006 ◽  
Vol 36 (3) ◽  
pp. 273-285 ◽  
Author(s):  
Yongfu Xu ◽  
Shigeaki Aoki ◽  
Koh Harada
Keyword(s):  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Circulation Model ◽  
Water Masses ◽  
Intermediate Water ◽  
North Pacific Intermediate Water ◽  
The North ◽  
The North Pacific

Abstract A basinwide ocean general circulation model of the North Pacific Ocean is used to study the sensitivity of the simulated distributions of water masses, chlorofluorocarbons (CFCs), and bomb carbon-14 isotope (14C) to parameterizations of mesoscale tracer transports. Five simulations are conducted, including a run with the traditional horizontal mixing scheme and four runs with the isopycnal transport parameterization of Gent and McWilliams (GM). The four GM runs use different values of isopycnal and skew diffusivities. Simulated results show that the GM mixing scheme can help to form North Pacific Intermediate Water (NPIW). Greater isopycnal diffusivity enhances formation of NPIW. Although greater skew diffusivity can also generate NPIW, it makes the subsurface too fresh. Results from simulations of CFC uptake show that greater isopycnal diffusivity generates the best results relative to observations in the western North Pacific. The model generally underestimates the inventories of CFCs in the western North Pacific. The results from simulations of bomb 14C reproduce some observed features. Greater isopycnal diffusivity generates a longitudinal gradient of the inventory of bomb 14C from west to east, whereas greater skew diffusivity makes it reversed. It is considered that the ratio of isopycnal diffusivity to skew diffusivity is important. An increase in isopycnal diffusivity increases storage of passive tracers in the subtropical gyre.

scholarly journals Data Sensitivity of the ECCO State Estimate in a Regional Setting

2009 ◽  
Vol 26 (11) ◽  
pp. 2420-2443 ◽  
Author(s):  
Elizabeth Douglass ◽  
Dean Roemmich ◽  
Detlef Stammer
Keyword(s):  
North Pacific ◽  
General Circulation ◽  
Initial Conditions ◽  
North Pacific Ocean ◽  
Circulation Model ◽  
Data Consistency ◽  
Consistent Estimate ◽  
Regional Setting ◽  
The North ◽  
The North Pacific

Abstract The Estimating the Circulation and Climate of the Ocean (ECCO) consortium provides a framework in which the adjoint method of data assimilation is applied to a general circulation model to provide a dynamically self-consistent estimate of the time-varying ocean state, which is constrained by observations. In this study, the sensitivity of the solution to the constraints provided by various datasets is investigated in a regional setting in the North Pacific. Four assimilation experiments are performed, which vary by the data used as constraints and the relative weights associated with these data. The resulting estimates are compared to two of the assimilated datasets as well as to data from two time series stations not used as constraints. These comparisons demonstrate that increasing the weights of the subsurface data provides overall improvement in the model–data consistency of the estimate of the state of the North Pacific Ocean. However, some elements of the solution are degraded. This could result from incompatibility between datasets, possibly because of hidden biases, or from errors in the model physics made more evident by the increased weight on subsurface data. The adjustments to the control parameters of surface forcing and initial conditions necessary to obtain the more accurate fit to the data are found to be within prior error bars.

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