Annual Mean of Monthly Sea-Level Pressure

Time series of the annual mean of leading more of monthly sea- level pressure variability described by Johnstone and Mantua (JM) from four different datasets. Note that the National Center for Atmospheric Research (NCAR) dataset used by JM to reach their conclusions shows a significant decline over the period of record relative to the other datasets. Linear trends for the different datasets are provided and statistical significance is denoted. (NNR: National Centers for Environmental Prediction/NCAR Reanalysis; HADSLP: Hadley Centre Sea Level Pressure dataset; 20CR: National Oceanic and Atmospheric Administration 20th Century Reanalysis)