Linear Trends in Northern Hemisphere Tropospheric Geopotential Height and Temperature Patterns

Elmar R. Reiter Department of Atmospheric Science, Colorado State University, Fort Collins 80523

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Daniel R. Westhoff Department of Atmospheric Science, Colorado State University, Fort Collins 80523

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Abstract

Gridded NMC data for 500 mb geopotential height, and 300–500 mb and 500–700 mb thickness for the period 1951–78 wore subjected to linear trend analyses. These analyses were performed for each calendar month. Significant geographical and seasonal distributions of cooling and warming patterns emerged. An atmospheric cooling trend over the North Pacific during the winter months appears in a region where oceanic cooling has also been observed, but planetary-wave adjustments rather than ocean-atmosphere feedback mechanisms appear to dominate the atmospheric cooling on climatic time scales. Consistently large temperature trends also appear over the Asian continent. Comparisons between thickness trends in the layer 300–500 mb with those in the. layer 500–700 mb reveal well-pronounced patterns of stabilization and destabilization.

Abstract

Gridded NMC data for 500 mb geopotential height, and 300–500 mb and 500–700 mb thickness for the period 1951–78 wore subjected to linear trend analyses. These analyses were performed for each calendar month. Significant geographical and seasonal distributions of cooling and warming patterns emerged. An atmospheric cooling trend over the North Pacific during the winter months appears in a region where oceanic cooling has also been observed, but planetary-wave adjustments rather than ocean-atmosphere feedback mechanisms appear to dominate the atmospheric cooling on climatic time scales. Consistently large temperature trends also appear over the Asian continent. Comparisons between thickness trends in the layer 300–500 mb with those in the. layer 500–700 mb reveal well-pronounced patterns of stabilization and destabilization.

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