Climate Forecast System Version 2.0

      The NCEP Climate Forecast System version 2 (CFSv2; Saha et al. 2013) is a state-of-the-art coupled climate model developed by the National Center for Environmental Prediction (NCEP), USA and it has been implemented to the Prithvi High Performance Computer (HPC) at Indian Institute of Tropical Meteorology (IITM), Pune. It is a fully coupled ocean- atmosphere-land model with advanced physics, increased resolution and refined initialization as compared to earlier version (CFSv1).

The atmospheric component of CFSv2 is Global Forecast System (GFS) with spectral resolution of T382 and 64 hybrid vertical levels and the ocean component is Geophysical Fluid Dynamics Laboratory (GFDL) Flexible Modeling System (FMS) & Modular Ocean Model version 4 (MOM4; Griffies et al. 2004). The convective parameterization utilizes simplified Arakawa-Schubert convection with momentum mixing. The model also implements orographic gravity wave drag based on Kim and Arakawa (1995) approach and sub-grid scale mountain blocking (Lott and Miller 1997).

The model employs Rapid radiative transfer model shortwave radiation with maximum random cloud overlap (Iacono et al. 2000; Clough et al. 2005). In addition, it has a four layer NOAH land surface model (Ek et al. 2003) and a two layer dynamical sea ice model (Wu et al. 1997; Winton 2000) coupled together with the Atmosphere and Ocean components in Earth System Modeling Framework (ESMF).

Type of system: Coupled Ocean-Atmospheric Dynamical System (Numerical)

System produces: probabilistic and deterministic forecast

Model type and resolution: T328L64

Ensemble size: 12 members for forecast and 40 members for hindcast

Details of forecasts period: 9 months

Lead-time: One-month lead forecasts

Period of verification: three-month

Period of Hindcast: 1981-2007

List of regions for each parameter. For all parameters: Northern Extratropics, Tropics, Southern Extratropics

Lead times for verification running season: 0, 1

Period of verification: 1981 – 2009 for MAM, JJA, SON and DJF and all running Season

List of parameters:Precipitation , T2m and SST

Details of verification data sets used :Precipitation: GPCP,T2m: ERA40, SST:NCEP