(1)   Information of the study "A Coordinated Sea-ice Assimilation Scheme Jointly Using Sea-ice Concentration and Thickness Observations with a Global Coupled Climate System Model"

In this study, for jointly assimilating sea-ice concentration (SIC) and sea-ice thickness (SIT) data into a global coupled climate system model consisting of sea-ice component with multiple sea-ice categories, we propose a sea-ice assimilation analysis update scheme. Different from the conventional scheme that often uses SIC/SIT analysis to directly update the corresponding variables in model (i.e., direct-update scheme), the new scheme converts SIC/SIT analysis into ice heating term to adjust the ice enthalpy using model freezing/melting physics and further updates the model sea-ice state (i.e., enthalpy-adjusting scheme). Several sets of assimilation and forecast experiments are conducted to verify the performance of the new scheme. 


  (2)  Description of the files

"code.tar.gz" contains the codes for the Beijing Climate Center Climate System Model version 2 (BCC-CSM2) incorporating the various analysis update schemes used in the study. 

"FreeRun.tar.gz" is the experimental data from the model free run (long-term simulation without assimilation of any data).

"CTL-DA.tar.gz" is the experimental data from the control run (assimilation experiments assimilating ocean observations).

"SIC-DA.tar.gz" is the experimental data from the SIC-DA run (SIC assimilation experiments using the SIC-only update scheme).

"SICT-DA1.tar.gz" is the experimental data from the SICT-DA1 run (SIC/SIT assimilation experiments using the direct-update scheme).

"SICT-DA2.tar.gz" is the experimental data from the SICT-DA2 run (SIC/SIT assimilation experiments using the enthalpy-adjusting scheme).

"SICT-DAF1.tar.gz" is the experimental data from the SICT-DAF1 run (sea-ice forecast experiments using the initial conditions from SICT-DA1).

"SICT-DAF2.tar.gz" is the experimental data from the SICT-DAF2 run (sea-ice forecast experiments using the initial conditions from SICT-DA2).