ESA / ECSAT CCIWV.REP.022 Water Vapour Climate Change Initiative (WV_cci) - CCI+ Phase 2 D2.2 Original data have been carefully screened according to recommendations given in relevant quality documents, in the published literature, or according to the best knowledge of the involved instrument scientists. Monthly zonal mean products are calculated as the average of all of the measurements on a given pressure level within each latitude bin and month. An exception is MIPAS, for which measurements are interpolated to the centre of the latitude bin after averaging. For some instruments, averaging was done in log10(VMR) space.
If not otherwise mentioned, a minimum of five measurements within the bin is required to calculate a monthly zonal mean for each instrument. Figure 2-1: Example of SPARC Data Initiative climatology variables. The example shown here is for MIPAS April 2008. 2.4 CDR-3 merging algorithm The merging algorithm is described in detail in Hegglin et al. (2014) [RD-1] and summarised here. It consists of the following steps that are also exemplified in Figure 2-2: The monthly zonal mean SPARC Data Initiative data of the individual instruments described in Section 2.3, are used as input to the merging algorithm. 9