Seasonal mean pressure reconstruction for the North Atlantic (1750–1850) based on early marine data

[摘要] Measurements of wind strength and direction abstracted from European ships'logbooks during the recently finished CLIWOC project have been used toproduce the first gridded Sea Level Pressure (SLP) reconstruction for the1750–1850 period over the North Atlantic based solely on marine data. Thereconstruction is based on a spatial regression analysis calibrated by usingdata taken from the ICOADS database. An objective methodology has beendeveloped to select the optimal calibration period and spatial domain of thereconstruction by testing several thousands of possible models. The finallyselected area, limited by the performance of the regression equations and bythe availability of data, covers the region between 28° N and52° N close to the European coast and between 28° N and44° N in the open Ocean. The results provide a direct measure of thestrength and extension of the Azores High during the 101 years of the studyperiod. The comparison with the recent land-based SLP reconstruction byLuterbacher et al. (2002) indicates the presence of a common signal. Theinterannual variability of the CLIWOC reconstructions is rather high due tothe current scarcity of abstracted wind data in the areas with best responsein the regression. Guidelines are proposed to optimize the efficiency offuture abstraction work.

[学科分类] 大气科学