Friday, 10 October 2014

How to represent different SSTs in the products

As previously discussed we aim in future products to include not only the skin SST (the primary geophysical retrieval) and, as before, a 20 cm estimate at a fixed local time (to minimise aliasing of the diurnal cycle in the long term trends), but also a UTC-day mean estimate. This combination hits a good fraction of the diverse range of user requirements we collected for depths and time.

We also need to provide an adjustment to the most consistent possible retrieval (default in product is the best available type of retrieval, but one might also want to analyse one type of retrieval through the whole record).

To deliver this information in a GHRSST-compatible form requires some thought, since the retrieval and the various model-derived adjustments all have up to three components of uncertainty as well as their values.

Project team discussions have concluded on the following: to store the best available skin SST as the primary variable, and give a set of adjustments that can be added to this, each with N (1 <= N <= 3) uncertainty components. This is a much smaller data volume than adding all the different SSTs each with three uncertainty components. Data volume is a concern for a significant set of users.

For the convenience of users faced with the complexity of adding adjustments to the primary data, we will need to provide a reader programme that configures the calculation of a desired SST type and its uncertainty. Even nicer would be configuration of the desired fields on the fly on download -- that is a technological solution we aim to discuss with those who will do the CCI programme data portal (invitation to tender currently published).

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