With the loss of scanner data from the ERBE in 1990, research into techniques to develop new clear sky flux products have commenced. Nimbus 7 data has been revisited [ Kyle et al., 1993], retrieval methods of outgoing longwave fluxes using spectral High Resolution Infrared Radiometer Sounder (HIRS) data were developed and tested [ Ellingson et al., 1993] and a hybrid of model and observational analyses were introduced [ Slingo and Webb, 1992].
Flux data compiled under ERBE have proved to be an invaluable research tool and a number of other global radiative flux products that are linked in one way or another to ERBE are under development. An important activity is the research on satellite algorithms for surface radiative fluxes such as Li and Leighton [1993], Darnell et al., [1992], Gupta et al., [1993], Pinker and Laszlo [1992[ and Rossow and Zhang [1994] although progress towards climatologies of longwave surface budget is severely limited by our inability to determine cloud base emission from present day satellites observations [ Stephens et al., 1994]. The retrieval of surface radiation budgets from satellite measurements is much less direct than is the retrieval of top of the atmospheric fluxes. Surface flux retrievals is an area of growing research and we can expect significant contributions to this activity from analyses of surface observations as they become available from dedicated surface measurement programs.