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Surface Site Validation

Model results have been validated extensively (See References). Recent validations have included ground measurements obtained from the Baseline Surface Radiation Network (BSRN), the Swiss Federal Institute of Technology’s Global Energy Balance Archive (GEBA) and NOAA’s Climate Montitoring and Diagnostics Laboratory (CMDL). Results of monthly averaged SW and LW radiative fluxes show that generally flux errors are within 10 Wm-2. Larger errors were found where there are larger uncertainties in the input data such as over snow/ice covered surfaces and where the site data did not represent the entire grid box. Larger errors in downward SW flux were also found over African and South American locations where aerosols from biomass burning are not accounted for in the SW model (Konzelman et al., 1995).

GEWEX Longwave (LW) and Langley Parameterized (LPLA) Data Sets

An assessment of the quality of the global fluxes was accomplished by comparisons with corresponding ground-measured fluxes from a number of sites of BSRN. Uncertainties associated with operational BSRN measurements during this period are believed to be about +/- 5 Wm-2 (1.5%, Ellsworth Dutton, NOAA, BSRN Manager). Thus, mean bias results are within the uncertainty for BSRN measurements. Errors for individual 3-hourly values are subject to bias and random errors due to local meteorological conditions.

Longwave (1992-2007)
LW LPLA
Time Ave Bias RMS Bias RMS
Monthly 0.2 11.1 3.6 12.8
Daily 0.48 22.1 4.0 22.5
3-hourly monthly 0.57 13.4 4.0 15.5
3-hourly 0.67 30.2 4.2 30.2

GEWEX Shortwave (SW) and Langley Parameterized (LPSA) Data Sets

An assessment of the quality of the global fluxes was accomplished by comparisons with corresponding ground-measured fluxes from a number of sites of the Baseline Surface Radiation Network (BSRN). Uncertainties associated with operational BSRN measurements during this period are believed to be about +/- 5-20 Wm-2 (Ellsworth Dutton, NOAA, BSRN Manager). This includes a possible thermal offset which would result in a systematic bias of up to 3% (personal communication, Rolf Philipona, World Radiation Center) depending on atmospheric humidity and cloudiness conditions. Errors for individual values are subject to bias and random errors due to local meteorological conditions. Thus, mean bias results are within the uncertainty for BSRN measurements.

Shortwave (1992-2007)
SW LPSA
Time Ave Bias RMS Bias RMS
Monthly -4.3 23.1 -6.7 18.7
Daily -3.2 35.7 -6.4 37.7
3-hourly monthly -6.7 41.0 N/A N/A
3-hourly -5.9 87.9 N/A N/A

References