Climate change during the twentieth century: detailed and comprehensive spatio-temporal evolution based on atmospheric and oceanic variables

The global warming signal is investigated during the period from 1911 to 2010 via cyclostationary EOF (CSEOF) analysis. Physically consistent responses to global warming in temperature, sea level pressure (SLP), circulation, and precipitation are analyzed using regression method in CSEOF space. The global warming signal in the 1000 hPa temperature exhibits overall positive patterns, with a nonlinear increasing trend of its amplitude. The spatial patterns reveal that northern hemispheric warming is amplified over the Eurasian Continent and the northern part of the North American Continent. Warming over high-latitude regions is more conspicuous than that over low-latitude regions. In mid-latitude regions, warming is more pronounced during the winter season than during the summer season. Consistent with the long-term global warming is the SLP increase in low-latitude regions and decrease in high-latitude regions. The meridional gradient of SLP anomaly is relatively large in the winter season. Southern hemispheric westerly wind in mid-latitude regions is strengthened due to a large meridional gradient in SLP. Although the zonal asymmetry in SLP over the tropics is small to compare the meridional gradient, this asymmetry is important for circulation and precipitation in the tropics. The increased SLP over the central Pacific results in low-level winds toward the western and eastern parts of the tropical Pacific. These low-level winds are associated with descending motion over the central Pacific and ascending motion over the Indochina Peninsula and the northern part of South America. These specific changes in vertical circulation drive precipitation decrease over the central Pacific and increase over the western and eastern tropical Pacific.