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Introduction to CRU, GHCN, NCEP2, CAM3.5

This brief introduction provides an overview of CRU, GHCN, NCEP2, and CAM3.5 datasets, including their variables, grid resolutions, and temporal coverage.

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Introduction to CRU, GHCN, NCEP2, CAM3.5

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  1. A Brief Introduction to CRU, GHCN, NCEP2, CAM3.5 Yi-Chih Huang

  2. CRU (I) • Gridded dataset produced by the Climate Research Unit at the University of East Anglia • CRUTEM3 • Land surface temperature anomalies • Monthly since January 1850, on a 5x5 degree grid • HadCRUT3 • A blend of CRUTEM3 and HadSST2 • Monthly since January 1850, on a 5x5 degree grid

  3. CRU (II) • TS3 • Variables: precipitation, wet-day frequency, mean temperature, diurnal temperature range, vapor pressure, sunshine, cloud cover, ground frost frequency • Monthly during 1901~2006 on a 0.5° × 0.5° grid

  4. GHCN • Global Historical Climatology Network • Anomaly Method • Monthly precipitation anomalies 1900-2009 • Monthly temperature anomalies 1880-2009 • 5 X 5 degree grid

  5. NCEP-DOE Reanalysis 2 (I) • Monthly, Daily, Sub-Daily for 1979/1/1 -2008/12/31 • An improved version of the NCEP/NCAR Reanalysis I • Same resolution as N/N Reanalysis: T62 L28 • Same raw observed data • Same dependence of satellite temperature retrievals • Fixed known errors in N/N Reanalysis • S. H. PAOBs • Snow cover • Oceanic albedo • Discontinuities in radiation fluxes

  6. NCEP-DOE Reanalysis 2 (II) • Improved diagnostics • Snow/water budget • Cloud diagnostics field • Winter time precipitation, surface temp and fluxes in high latitudes • Tropical precipitation • Some improvements in the assimilation system • Soil wetness, especially the interannual variations

  7. NCEP-DOE Reanalysis 2 (III) • Possible drawbacks • Overestimates OLR over warm pool • Equatorial upper level moisture much drier over convection area • Summer precipitation rates in Arctic region • Long term spin-down of soil wetness in polar latitudes

  8. CAM3.5 (I) • Community Atmospheric Model • 1.9x2.5 deg / 26 levels • Separates parameterization suite from dynamical core • Slab Ocean Model • Mixed layer temperature • Thermodynamic sea ice model • Snow depth, surface temperature, ice thickness, ice fractional coverage, and internal energy

  9. CAM3.5 (II) • Lin-Rood finite volume dynamic core • Flux-form semi-Lagrangian scheme • Sub-cycling within the 2D Lagrangian dynamics • Deep Convection • Convective momentum transports • Dilute plume calculation • Cloud Fraction • Polar cloud freeze-drying

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