"Seasonal-to-Interannual Variability of the Ocean During WOCE
Estimated by the ECCO Routine Global Ocean Data Assimilation System"

Ichiro Fukumori, Benyang Tang, Tong Lee, Dimitris Menemenlis, Zhangfan
Xing, Benny Cheng, and Lee-Lueng Fu 

Seasonal-to-interannual variability is analyzed using WOCE
observations in conjunction with products of a global ocean data
assimilation system (ECCO, Consortium for "Estimating the Circulation
and Climate of the Ocean").  The assimilation products help interpret
the near decade-long WOCE observations placing them in context with  
seasonal-to-interannual variability, such as those associated with   
ENSO and the phase transition of PDO.  Particular focus is placed on 
variability of the upper ocean in the Pacific and Indian Oceans.  The
model equivalent of WOCE hydrography is compared with that from
observations.  Seasonal-to-interannual variability is analzyed by
examining changes in the hydrographic structure and their associated
variabilities in transport.  The model's coherent fields allow budgets
of mass, heat, and salt to be analyzed and the origin and fate of
water masses evaluated. 

The data assimilation system is based on a near-global primitive
equation model of high resolution (1-deg telescoping to 0.3-deg with
10m near surface layers).  The assimilation is based on a hierarchy of
approaches that consists of a Green's function method, approximate
Kalman filter and smoother, and the adjoint method.  Measurements from
satellite altimetry (TOPEX/POSEIDON) and in situ hydrography (CTDs and
XBTs) are assimilated on a routine basis.  Analyses are regularly
updated and are available via a Live Access Server at
http://www.ecco-group.org/las.