Variabilidade da pressão atmosférica nas Américas

Abstract

The climatic variability imposes a significant influence in the social and economical activities. The objective of this work was to study the variability of the atmospheric pressure (SLP) on Americas, since it is a variable widely available. Data of SLP were used among 46 to 100 years (1900 to 2000), coming of the National Institute of Meteorology (INMET) and Global Historical Climate Network (GHCN). The indices of Pacific Decadal Oscillation (PDO) and South Oscillation (SO), 100 years series (1900 to 2000), were taken from JISAO and of CGD – UCAR respectively. NCEP/NOAA Reanalysis data of SLP, sea surface temperature (SST) and zonal wind (U), with 50 years (1948 to 1998) for an area from pole to pole and 30ºW to 140ºW were also used in this work. Power spectrum analysis was applied to PDO and SO series to determined the characteristics frequencies, or cycles. Data were, then, filtered to eliminate the high frequency climatic variability. Statistical methods were used for constructing a time series of the Normalized Pressure Index (NPI) for each of the 29 stations studied. In general, the correlation coefficients (CC) between IPN and SOI were positive in the West Coast and negative in the East Coast of the Americas. The CC between IPN and ODP presented opposite signs. The relation between PDO and the Multivariate ENSO Index (MEI) series showed a high frequency of El Niño (La Niña) during the warm (cold) PDO phase. Considering that the Pacific Ocean occupies 1/3 of the Earth’s surface and that TSM are the most important lower boundary conditions for the atmosphere, it is suggested that the results of diagnostic studies of PDO impacts on global climate are used in Global Climate Models as sceneries for long-term forecasting, a key factor to achieving sustainable development.