## 4 Results
### Time Series of Statistics of \(T_{IS}\) vs. \(T_{Sat}\) and Satellite-Based Retrospective QC
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**L4 Analysis**} & \multicolumn{2}{c}{**Access**} \\ \hline CCI & [[https://catalogue.ceda.ac.uk/uuid/aced40d7](https://catalogue.ceda.ac.uk/uuid/aced40d7) cb964f23a0 fd3e85772f2d48]([https://catalogue.ceda.ac.uk/uuid/aced40d7](https://catalogue.ceda.ac.uk/uuid/aced40d7) cb964f23a0 fd3e85772f2d48) & 01.09.1981–31.12.2016 \\ CMC0.2 & [[https://podaac.jpl.nasa.gov/dataset/CMC0.2](https://podaac.jpl.nasa.gov/dataset/CMC0.2) deg5-SCMC-L4-GLOB-v2.0]([https://podaac.jpl.nasa.gov/dataset/CMC0.2](https://podaac.jpl.nasa.gov/dataset/CMC0.2) deg5-SCMC-L4-GLOB-v2.0) & 01.09.1991–31.12.2015 \\ CMC0.1 & [[https://podaac.jpl.nasa.gov/dataset/CMC0.1](https://podaac.jpl.nasa.gov/dataset/CMC0.1) deg-CMC-L4-GLOB-v3.0]([https://podaac.jpl.nasa.gov/dataset/CMC0.1](https://podaac.jpl.nasa.gov/dataset/CMC0.1) deg-CMC-L4-GLOB-v3.0) & 01.01.2016–31.12.2021 \\ CRW & [[https://coralperfewatch.noaa.gov/product/5](https://coralperfewatch.noaa.gov/product/5) km/index.phpfdata_access]([https://coralperfewatch.noaa.gov/product/5](https://coralperfewatch.noaa.gov/product/5) km/index.phpfdata_access) & 01.01.1985–31.12.2021 \\ DMI & [[https://podaac.jpl.nasa.gov/dataset/DM](https://podaac.jpl.nasa.gov/dataset/DM)]([https://podaac.jpl.nasa.gov/dataset/DM](https://podaac.jpl.nasa.gov/dataset/DM))\_OI-DMI-L4-GLOB-v1.0 & 30.04.2013–31.12.2021 \\ GAMSSA & [[https://doi.org/10.5067/GHAGAM-4](https://doi.org/10.5067/GHAGAM-4) FA1A]([https://doi.org/10.5067/GHAGAM-4](https://doi.org/10.5067/GHAGAM-4) FA1A) & 23.07.2008–31.12.2021 \\ GMPE & [[http://ghrsst-pp.metoffice.gov.uk/ostia-website/gmpe-monitoring.html](http://ghrsst-pp.metoffice.gov.uk/ostia-website/gmpe-monitoring.html)]([http://ghrsst-pp.metoffice.gov.uk/ostia-website/gmpe-monitoring.html](http://ghrsst-pp.metoffice.gov.uk/ostia-website/gmpe-monitoring.html)) & 17.09.2009–31.12.2021 \\ GPB & [[https://coastwatch.noaa.gov/cwn/products/noaa-geo-polar-blended-global-sea-surface-temperature-analysis-level-4.html](https://coastwatch.noaa.gov/cwn/products/noaa-geo-polar-blended-global-sea-surface-temperature-analysis-level-4.html)]([https://coastwatch.noaa.gov/cwn/products/noaa-geo-polar-blended-global-sea-surface-temperature-analysis-level-4.html](https://coastwatch.noaa.gov/cwn/products/noaa-geo-polar-blended-global-sea-surface-temperature-analysis-level-4.html)) & 02.06.2014–31.12.2021 \\ OISST & [[https://psl.noaa.gov/data/griddded/data.noaa.oisst.v2.highres.html](https://psl.noaa.gov/data/griddded/data.noaa.oisst.v2.highres.html)]([https://psl.noaa.gov/data/griddded/data.noaa.oisst.v2.highres.html](https://psl.noaa.gov/data/griddded/data.noaa.oisst.v2.highres.html)) & 01.09.1981–31.12.2021 \\ OSITA & [[https://podaac.jpl.nasa.gov/dataset/OSITA-UKMO-L4-GLOB-v2.0](https://podaac.jpl.nasa.gov/dataset/OSITA-UKMO-L4-GLOB-v2.0)]([https://podaac.jpl.nasa.gov/dataset/OSITA-UKMO-L4-GLOB-v2.0](https://podaac.jpl.nasa.gov/dataset/OSITA-UKMO-L4-GLOB-v2.0)) & 31.12.2006–31.12.2021 \\ OSITA-RAN & [[https://doi.org/10.48670/moi-00168](https://doi.org/10.48670/moi-00168)]([https://doi.org/10.48670/moi-00168](https://doi.org/10.48670/moi-00168)) & 01.10.1981–31.12.2021 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The L4 SST products used in comparison of diurnal signals and periods of their averaging. All links accessed on 22 August 2023.  
condition (6) in the monthly sets of matchups range from 98.7% to 99%. The time series of monthly statistics of \(T_{IS}\) vs. \(T_{SAT}\) for 1981-2021 are shown in Figure 15.  
Figure 15a shows a time series of fractions of QL = 5 \(T_{IS}\) identified by the current \(i\)Quam QC, EXP QC, and SAT QC. The EXP QC performs more liberal screening than the current QC, producing 2.5% more quality \(T_{IS}\)'s counts in 1981-1989 and 6-7% more counts in the later years. The fraction of matchups passing the SAT QC increases over the years consistently with the numbers of available satellite MDSs (cf.