--- MITgcm_contrib/articles/ceaice/ceaice_intro.tex	2008/02/26 19:27:26	1.1
+++ MITgcm_contrib/articles/ceaice/ceaice_intro.tex	2008/03/01 01:01:52	1.2
@@ -1,6 +1,21 @@
 \section{Introduction}
 \label{sec:intro}
 
+In the past five years, oceanographic state estimation has matured to the
+extent that estimates of the evolving circulation of the ocean constrained by
+in-situ and remotely sensed global observations are now routinely available
+and being applied to myriad scientific problems \citep{wun07}.  Ocean state
+estimation is the process of fitting an ocean general circulation model (GCM)
+to a multitude of observations.  As formulated by the consortium Estimating
+the Circulation and Climate of the Ocean (ECCO), an automatic differentiation
+tool is used to calculate the so-called adjoint code of a GCM.  The method of
+Lagrange multipliers is then used to render the problem one of unconstrained
+least-squares minimization.  Although much has been achieved, the existing
+ECCO estimates lack intercative sea ice.  This limits the ability of ECCO to
+utilize satellite data constraints over sea-ice covered regions.  This also
+limits the usefulness of the ECCO ocean state estimates for describing and
+studying polar-subpolar interactions.
+
 The availability of an adjoint model as a powerful research tool
 complementary to an ocean model was a major design requirement early
 on in the development of the MIT general circulation model (MITgcm)
