INFLUENCE OF HETEROGENEOUS LAND SURFACES ON SURFACE-ENERGY AND MASS FLUXES

Citation
J. Song et al., INFLUENCE OF HETEROGENEOUS LAND SURFACES ON SURFACE-ENERGY AND MASS FLUXES, Theoretical and applied climatology, 58(3-4), 1997, pp. 175-188
Citations number
32
ISSN journal
0177798X
Volume
58
Issue
3-4
Year of publication
1997
Pages
175 - 188
Database
ISI
SICI code
0177-798X(1997)58:3-4<175:IOHLSO>2.0.ZU;2-9
Abstract
Land-surface heterogeneity affects surface energy fluxes. The magnitud es of selected land-surface influences are quantified by comparing obs ervations with model simulations of the FIFE (First ISLSCP Field Exper iment) domain. Several plausible heterogeneous and homogeneous initial and boundary conditions are examined, although soil-moisture variabil ity is emphasized. It turns out that simple spatial averages of surfac e variation produced biased flux values. Simulated maximum latent-heat fluxes were approximately 30 to 40 W m(-2) higher, and air temperatur es similar or equal to 0.4 degrees C lower (at noon), when computation s were initialized with spatially averaged soil-moisture and leaf-area -index fields. The planetary boundary layer (PBL) height and turbulent exchanges were lower as well. It additionally was observed that (larg ely due to the nonlinear relationship between initial soil-moisture av ailability and the evapotranspiration rate), ''real'' latent-heat flux can be substantially less than simulated latent-heat flux using model s initialized with spatially averaged soil-moisture fields. Difference s between ''real'' and simulated fluxes also vary with the resolution at which ''real'' soil-moisture heterogeneity is discretized.