The observations are assimilated every 5 days, with observations in a 10-day window centered at the time of the analysis. Seven sequential analyses of different types of observations are performed in sequence. While the k-th analysis uses the state from the (k-1)-th analysis for its background (first guess), the variance of the static ensemble used for the background error covariance stays the same. The sequence of analyses is as follows:

1. T(z) and S(z) from WOA09 at 1o degree resolution and from 0 to 4500m
2. Sea surface salinity (SSS) from WOA09
3. Sea level anomalies (SLA)
4. SST
5. T(z) from in-situ profiles
6. S(z) from in-situ profiles
7. Sea-ice concentration

The method and parameters used for each sequence of analysis are given in Table 1 for the parameters concerning the background error covariance P, and Table 2 for the observation error covariance matrix R. The justification for the choice of parameters is discussed in the following sections.