The surface energy balance at local and regional scales - A comparison of general circulation model results with observations

Journal Article · Tue Jun 01 04:00:00 EDT 1993 · Journal of Climate; (United States)

DOI:https://doi.org/10.1175/1520-0442(1993)006<1090:TSEBAL>2.0.CO;2· OSTI ID:6017185

Garratt, J R; Krummel, P B; Kowalczyk, E A ^[1]

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1. CSIRO Division of Atmospheric Research, Aspendale, Victoria (Australia)

The mean monthly energy balance at continental surfaces are examined through general circulation model (GCM) simulations, climatological maps of surface fluxes, and direct observations. Emphasis is on net radiation and evaporation for (i) five continental regions within Africa, Australia, Eurasia, South America, and the United States; (ii) a number of continental sites in both hemispheres. Both the mean monthly values of the local and regional fluxes and the mean monthly diurnal cycles of the local fluxes are described. GCMs tend to overestimate the mean monthly levels of net radiation by about 15%-20% annually, probably the result of (i) undervalued continental surface albedos, resulting in overestimates of the net shortwave flux at the surface; (ii) incoming shortwave fluxes overestimated due to uncertainties in cloud schemes and clear-sky absorption; (iii) land-surface temperatures under-estimated resulting in an underestimate of the outgoing longwave flux. In contrast, there is no obvious overall bias in mean monthly levels of evaporation determined in GCMs. Rather, and far more so than with net radiation, there is a wide range in values of evaporation for all regions investigated. For continental regions and at times of the year of low to moderate rainfall, there is a tendency for the simulated evaporation to be closely related to the precipitation-this is not surprising. In contrast, for regions where there is sufficient or excessive rainfall, the evaporation tends to follow the behavior of the net radiation. Again, this is not surprising given the close relation between potential evaporation and net radiation, as discussed by Priestley and Taylor. Finally, the introduction into GCMs of an [open quotes]improved[close quotes] surface scheme (incorporating more realistic representations of soil and canopy processes and revised albedos) does tend to improve the calculations of both regional net radiation and evaporation. 46 refs., 9 figs., 6 tabs.

• OSTI ID: 6017185
• Journal Information: Journal of Climate; (United States), Journal Name: Journal of Climate; (United States) Vol. 6:6; ISSN JLCLEL; ISSN 0894-8755
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110
540210* -- Environment
Terrestrial-- Basic Studies-- (1990-)
ABSORPTION
AFRICA
AUSTRALASIA
AUSTRALIA
CANOPIES
CLIMATES
CLOUD COVER
CONTINENTAL CRUST
DEVELOPED COUNTRIES
EARTH CRUST
ENERGY
ENERGY BALANCE
EVAPORATION
FREE ENERGY
GENERAL CIRCULATION MODELS
GLOBAL ASPECTS
HEAT FLUX
LATIN AMERICA
MATHEMATICAL MODELS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PRECIPITATION
SEPARATION PROCESSES
SOILS
SORPTION
SOUTH AMERICA
SURFACE ENERGY
SURFACE PROPERTIES
TEMPERATURE MEASUREMENT
THERMODYNAMIC PROPERTIES