Reconstruction of monthly mean oceanic sea level pressure based on COADS and station data (1854-1997)

Abstract

An extended reconstruction of monthly mean oceanic historical sea level pressure (SLP) based on Comprehensive Ocean-Atmosphere Data Set (COADS) release-2 observations is produced for the 1854-1997 period. The COADS data are first screened using an adaptive quality-control procedure. Land SLP data from coastal and island stations are used to supplement the COADS data. The SLP anomalies are analyzed monthly to a 2° grid using statistics based on 20 yr of assimilated atmospheric reanalysis. A first-order correction is applied to the reconstruction to minimize variations associated with spurious long-term changes in the atmospheric mass over the oceans. In the nineteenth century, the reconstruction appears to underestimate the SLP-anomaly amplitudes, and error estimates for the reconstruction are largest. After 1900 the reconstruction variance is stronger, although there are periods in the first half of the twentieth century when sampling is poor and the variance decreases. Spatial correlations between the reconstruction and several comparison analyses are highest in the second half of the twentieth century, suggesting greater reconstruction reliability after 1950.