Here are a collection of plots (see tar file link at left) showing time series of surface observed total cloud and ISCCP total
cloud globally averaged over land only, ocean only, and land+ocean during the time period that the datasets overlap.
I also show the spatial pattern of correlation of each local grid box time series with the global time series.
It seems that there is more agreement between ISCCP and surface-observed cloudiness over land than over ocean, something
that I have previously found.
The surface-observed land total cloud time series exhibits no trend, unlike the case for the ISCCP land total cloud time
series, which exhibits a maximum in the late 1980s and a minimum in the mid 1990s. Most land grid boxes have a positive
correlation with the surface land total cloud time series, especially Africa and southwest Asia. Anticorrelations with the
global time series occur in southeast Asia.
The surface-observed ocean total cloud time series exhibits an upward trend, in contrast to the downward trend in the
ISCCP ocean total cloud time series. Most ocean grid boxes have a small positive correlation with the surface ocean total
cloud time series.
Given the larger area of the ocean, the land+ocean time series resemble the ocean time series. The ISCCP land+ocean
correlation plot also exhibits satellite artifacts, and the surface observed land+ocean plot shows no physically intuitive pattern,
and positive correlations predominate.
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