Monthly NAO data for GRL paper "Understanding the Signal-to-noise Paradox with a Simple Markov Model"

The datasets include monthly NAO data for GRL paper "Understanding the Signal-to-noise Paradox with a Simple Markov Model". The monthly NAO index is estimated based on the leading empirical orthogonal function mode of the Mean Sea Level Pressure (SLP) over the North Atlantic. The monthly NAO index has been normalized for each dataset seperately. The description of each file is shown as follows: monthly_nao_cmip5_models_1871_2005.nc: monthly NAO index derived from 40 CMIP5 model outputs (historical run; first realization) cmip5_model_list: list of 40 CMIP5 models monthly_nao_era20c_1900_2005.nc: monthly NAO index derived from the ECMWF's twentieth-century reanalysis data (ERA20C) monthly_nao_noaa20c_1871_2005.nc: monthly NAO index derived from the NOAA's twentieth-century reanalysis version-2 data (NOAA20C)