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The diurnal cycle over land in “Forests at the Land-Atmosphere interface”

This paper reviews, initially from an observational perspective, the nature of the diurnal cycle overland, using illustrations from high latitudes to the tropics. Understanding the coupling between different processes at the land surface is of fundamental importance, because in global models, many processes are parameterized, and are poorly constrained by routine observational inputs. Yet the diurnal cycle is observed synoptically, so it is an excellent indicator of whether the surface processes and their interaction with the boundary layer (BL) are modeled correctly. In addition, the diurnal range of surface temperature and humidity are important prognostic variables for society. First some basic concepts are reviewed, with illustrative examples, and then additional controls on the diurnal cycle at high latitudes are discussed. Finally a tropical example (over Rôndonia in the southern Amazon basin) will be used to illustrate the difficulty in getting the diurnal cycle of precipitation right in a forecast model, because of the interaction of many processes.

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Betts, A.K. (2003), The diurnal cycle over land in “Forests at the Land-Atmosphere interface” [ISBN: 0-85199-677-9], Eds.,.M. Mencuccini, J. Grace, J. Moncrieff and K..McNaughton, pp. 73-93, CABI Publishing, Wallingford, Oxon OX10 8DE, UK.