1. A method for operating an internal combustion engine, comprising: determining a first integrated thermal state parameter corresponding to engine environment factors affecting a combustion parameter during engine operation in a homogeneous-charge compression-ignition combustion mode; determining a difference in the first integrated thermal state parameter corresponding to a difference between a monitored state for the combustion parameter and an estimated state for the combustion parameter; correcting the first integrated thermal state parameter in response to the difference in the first integrated thermal state parameter; and controlling operation of the internal combustion engine in response to the corrected first integrated thermal state parameter.