cloud cover historical data

[claudio cortes]

greetings

when I need historical data for climatological studies, I download
datasetes from this ftp:
ftp://ftp.cdc.noaa.gov/pub/Datasets/ncep.reanalysis/pressure/
where can I find historical values of temperature, geotential heights,
humidity and wind
and this information I can extract it using grads

but at this moment, I need cloud cover historial data and
where can I find cloud cover historical datasets ?

thaks !

--
Claudio Cortes
+56 (2) 2994121

Meteorologo
Laboratorio de Meteorologia y Calidad de Aire
Centro Nacional del Medio Ambiente (CENMA)
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Claudio Cortes
+56 (2) 2994121

Meteorologist
Meteorology and Air Quality Labs
National Enviroment Center, Chile (CENMA)