Premium
Satellite observations of long‐term changes in tropical cloud and outgoing longwave radiation from 1985 to 1998
Author(s) -
Wang PiHuan,
Minnis Patrick,
Wielicki Bruce A.,
Wong Takmeng,
Vann Lelia B.
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl014264
Subject(s) - outgoing longwave radiation , longwave , environmental science , cloud cover , climatology , atmospheric sciences , satellite , troposphere , emissivity , tropics , cloud height , meteorology , cloud computing , radiation , convection , geology , geography , physics , quantum mechanics , astronomy , fishery , computer science , optics , biology , operating system
Cloud vertical distributions and radiation data from satellites taken between 1985 and 1998 were analyzed to determine the impact of clouds on outgoing longwave radiation (OLR) in the Tropics. Clouds with a 1‐μm optical depth greater than 0.025 above 12 km decreased, while those below 12 km increased. The OLR mean and decadal trend were 254 Wm −2 and 3.9 Wm −2 /decade, respectively. The mean cloud and OLR results were used to derive a value of 0.36 for the tropical mean cloud longwave effective emissivity. Changes in cloud vertical distributions account for 40% of the OLR trend. A change in cloud effective emissivity of −0.026/decade could account for the remainder of the OLR changes. These changes suggest reduced mean cloud opacity, a drier troposphere, and a strengthened large‐scale circulation in the Tropics during the period.