Evaluation of Surface Fluxes in ERA-Interim Using Flux Tower Data

Chunlüe Zhou; Kaicun Wang

doi:10.1175/JCLI-D-15-0523.1

Zhou, Chunlüe; Wang, Kaicun

2015-07-26 00:00:00

Surface air temperature T a is largely determined by surface net radiation R n and its partitioning into latent (LE) and sensible heat fluxes ( H ). Existing model evaluations by comparison of absolute flux values are of limited help because the evaluation results are a blending of inconsistent spatial scales, inaccurate model forcing data, and imperfect parameterizations. This study further evaluates the relationships of LE and H with R n and environmental parameters, including T a , relative humidity (RH), and wind speed (WS), using ERA-Interim data at a 0.125° × 0.125° grid with observations at AmeriFlux sites from 1998 to 2012. The results demonstrate ERA-Interim can roughly reproduce the absolute values of environmental parameters, radiation, and turbulent fluxes. The model performs well in simulating the correlation of LE and H with R n , except for the notable correlation overestimation of H against R n over high-density vegetation (e.g., deciduous broadleaf forest, grassland, and cropland). The sensitivity of LE to R n in the model is similar to that observed, but that of H to R n is overestimated by 24.2%. Over the high-density vegetation, the correlation coefficient between H and T a is overestimated by over 0.2, whereas that between H and WS is underestimated by over 0.43. The sensitivity of H to T a is overestimated by 0.72 W m −2 °C −1 , whereas that of H to WS in the model is underestimated by 16.15 W m −2 (m s −1 ) −1 over all of the sites. The model cannot accurately capture the responses of evaporative fraction (EF; EF = LE / (LE + H )) to R n and environmental parameters. This calls for major research efforts to improve the intrinsic parameterizations of turbulent fluxes, particularly over high-density vegetation.

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Journal of Climate American Meteorological Society

http://www.deepdyve.com/lp/american-meteorological-society/evaluation-of-surface-fluxes-in-era-interim-using-flux-tower-data-qcXycsBloO

Evaluation of Surface Fluxes in ERA-Interim Using Flux Tower Data

$Surface air temperature T a is largely determined by surface net radiation R n and its partitioning into latent (LE) and sensible heat fluxes ( H ). Existing model evaluations by comparison of absolute flux values are of limited help because the evaluation results are a blending of inconsistent spatial scales, inaccurate model forcing data, and imperfect parameterizations. This study further evaluates the relationships of LE and H with R n and environmental parameters, including T a , relative humidity (RH), and wind speed (WS), using ERA-Interim data at a 0.125° × 0.125° grid with observations at AmeriFlux sites from 1998 to 2012. The results demonstrate ERA-Interim can roughly reproduce the absolute values of environmental parameters, radiation, and turbulent fluxes. The model performs well in simulating the correlation of LE and H with R n , except for the notable correlation overestimation of H against R n over high-density vegetation (e.g., deciduous broadleaf forest, grassland, and cropland). The sensitivity of LE to R n in the model is similar to that observed, but that of H to R n is overestimated by 24.2%. Over the high-density vegetation, the correlation coefficient between H and T a is overestimated by over 0.2, whereas that between H and WS is underestimated by over 0.43. The sensitivity of H to T a is overestimated by 0.72 W m −2 °C −1 , whereas that of H to WS in the model is underestimated by 16.15 W m −2 (m s −1 ) −1 over all of the sites. The model cannot accurately capture the responses of evaporative fraction (EF; EF = LE / (LE + H )) to R n and environmental parameters. This calls for major research efforts to improve the intrinsic parameterizations of turbulent fluxes, particularly over high-density vegetation.$

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Evaluation of Surface Fluxes in ERA-Interim Using Flux Tower Data

Evaluation of Surface Fluxes in ERA-Interim Using Flux Tower Data

Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

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Evaluation of Surface Fluxes in ERA-Interim Using Flux Tower Data

Evaluation of Surface Fluxes in ERA-Interim Using Flux Tower Data

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