The Period Of Validity roughly indicates the time period directly constrained by data. Outside this period, the seasonality is still well-constrained in most parts of the ocean (through temporal extrapolation), but interannual variations may miss important features (only comprising temperature-related features from the prior).
In any interpretation of the results, this limitation needs to be taken into account (see usage notes).
Please note that the given Period Of Validity is an indication only. Depending on location, good data constraint may even exist before the given period, but may also start later or have substantial gaps. Please contact us for more detailed information.