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How do we know about clouds?
Surface observations
Reanalysis
Surface observations are useful but scattered in space and time. It is difficult to compare results from a global climate model to scattered observations, and so a product called "reanalysis" is often used. Reanalysis uses observations and a model to create a dataset that is on a uniform grid in space and time. For example, the National Centers for Environmental Prediction (NCEP) has a reanalysis product that is available on a 1 degree latitude by 1 degree longitude grid every six hours from 1948 to the present. Some variables are also available on vertical levels throughout the atmosphere. However, the fact that reanalysis uses a computer model adds some uncertainty to the product. Some reanalysis products available online are:
Surface observations
ReanalysisSurface observations are useful but scattered in space and time. It is difficult to compare results from a global climate model to scattered observations, and so a product called "reanalysis" is often used. Reanalysis uses observations and a model to create a dataset that is on a uniform grid in space and time. For example, the National Centers for Environmental Prediction (NCEP) has a reanalysis product that is available on a 1 degree latitude by 1 degree longitude grid every six hours from 1948 to the present. Some variables are also available on vertical levels throughout the atmosphere. However, the fact that reanalysis uses a computer model adds some uncertainty to the product. Some reanalysis products available online are:
