Comparison of NCEP-NCAR cloud radiative forcing reanalyses with observations
- Univ. of California, Davis, CA (United States)
Longwave and shortwave cloud radiative forcing from the recently released National Center for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalyses are compared to Earth Radiation Budget Experiment (ERBE) observations. The observed differences are analyzed utilizing concurrent International Satellite Cloud Climatology Project (ISCCP) estimates of cloudiness and other satellite observations. The results show that the NCEP-NCAR longwave cloud forcing agrees well with that of ERBE not only for the annual means but also for seasonal and climatic variations. Areas of disagreement are generally related to disagreements between NCEP-NCAR high cloudiness and observations. Overall, the NCEP-NCAR shortwave cloud forcing is in poorer agreement with ERBE observations. NCEP-NCAR annual means in the Tropics are often 20-30 W m{sup -2} too negative. On the other hand the NCEP-NCAR total cloud cover in this region is 10%-20% less than the ISCCP observations, which should lead to less, rather than more, negative shortwave cloud forcing. Thus the primary error in the mean shortwave cloud forcing is likely due to specification of clouds that are too reflective in the NCEP analysis model. Moderate errors in the variability of NCEP-NCAR SWCF are apparently related to errors in the analyzed seasonal variability of total cloudiness, which are exacerbated by NCEP model specification of clouds that are too bright and underestimates of the seasonal variability of the clear-sky fluxes. 29 refs., 11 figs.
- OSTI ID:
- 588603
- Journal Information:
- Journal of Climate, Vol. 10, Issue 9; Other Information: PBD: Sep 1997
- Country of Publication:
- United States
- Language:
- English
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