The Periodic Behavior of Tropical Available Potential Energy

The concept of Jet Available Potential Energy (JAPE) is explained as a mass anomaly of geopotential energy, as a function of height. The data set used represents a thirty-six year period spanning from January 1979 through December 2014, and contains measurements of JAPE and layer mass integrated over one dimension, taken from 180° W to 180° E in longitude, at the tropics (30° S-30° N). This study focuses on layers representing the lower half (330-356 K) and upper half (356-420 K) in addition to a central (370-380 K) isentropic layer in each of these areas. The intent of this study is to determine the prevailing frequencies of fluctuations of JAPE over the period and area sampled. It is found that the prevailing frequencies in the tropics are dependent on isentropic layer. Primary frequencies are found on both diurnal and annual cycles, while frequencies fall secondarily on annual, seasonal, and diurnal cycles. It can also be seen that there is a broad maxima spanning from 30-60 days per cycle.