HR: 0830h
AN: A31E-0095    [PDF]
TI: Observed Global Cloud and Radiation Flux Changes Since 1952
AU: * Norris, J R
EM: jnorris@ucsd.edu
AF: Scripps Institution of Oceanography, UCSD 9500 Gilman Drive 0224, La Jolla, CA 92122 United States
AB: Gridded 72-day surface-observed cloud cover anomalies are converted to top-of-atmosphere radiation flux anomalies by scaling by climatological cloud radiative forcing measured by the ERBE scanner. The resulting cloud-estimated radiation anomalies are well-correlated with measured ERBS non-scanner radiation anomalies during the overlapping period of record (1985-1997). The surface-observed cloud dataset independently reproduces the large change in tropical LW and SW radiation flux in the early 1990's previously documented by ERBS. This agreement provides confidence that surface observations of clouds provide reliable information about cloud-related radiation changes during the pre-satellite era. Analysis of a surface-observed cloud cover and estimated radiation flux indicates upper-level cloud cover has decreased and outgoing LW radiation had increased over much of the tropical and extratropical oceans during the past several decades. Low-level stratiform cloud cover and SW reflection have increased over extratropical oceans during the past several decades. The spatial pattern of cloud trends suggests that they are in part related to warming of the central and eastern tropical Pacific since the mid 1970's. These results indicate that changes in cloudiness over the past fifty years have acted to slow the rate of global warming, but it is not yet known whether cloud trends will continue in the same direction in the future.
DE: 1620 Climate dynamics (3309)
DE: 3319 General circulation
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3359 Radiative processes
DE: 3374 Tropical meteorology
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting