Role of CSEs to global water and energy balance study

Global data sets are needed for global budgets.
Global data are always indirect in some sense.
Satellite remote sensing
Obs. of radiation above atmosphere + theory of radiative transfer
Data assimilation (including "Reanalyses")
Observation by radiosonde etc. + theory of dynamics etc.

Quality of global data should be checked with direct observations.
Coverage of direct observations are local, except
radiation at the top of atmosphere 
discharge of large rivers.

Global <-> Regional (continental-scale river basins etc.) <-> Local, direct