Characteristics of the surface perturbation potential energy in the local atmospheric energetic efficiency

Based on the previous theoretical analyses of the local perturbation potential energy, the surface perturbation potential energy (SPPE) component associated with topography and its features are further been investigated by using the NCEP reanalysis dataset in this study. The results show that the SPPE has particular thermal and dynamical properties, and close relationships with the large topography in lands. Furthermore, the seasonal variation of the SPPE is closely dependent upon the seasonal variation of land surface properties. Analyses show that the negative perturbation potential energy primarily distributes over the polar region and the positive one is over the tropical region, where the SPPE almost keeps constant throughout the year or slightly changes only at the seasonal scale. The extrema of the SPPE at both the seasonal and annual scales are located over midlatitude areas in the north hemisphere where lots of large topography lie. These extrema show positive in boreal summertime and negative in boreal wintertime. Such characteristics is the most typical over the QinghaiTibet Plateau, where the SPPE is featured by evident interdecadal variability in time and frequency domains, and interannual variability with a leading period of 2-4 years.