Covariability of Components of Poleward Atmospheric Energy Transports on Seasonal and Interannual Timescales

Abstract

Vertically integrated atmospheric energy and heat budgets are presented with a focus on the zonal mean transports and divergences of dry static energy, latent energy, their sum (the moist static energy), and the total (which includes kinetic energy), as well as their partitioning into the within-month transient and quasi-stationary components. The latter includes the long-term mean and interannual variability from 1979 to 2001 and, in the Tropics, corresponds to the large-scale overturning global monsoon and the embedded Hadley and Walker circulations. In the extratropics, it includes the quasi-stationary planetary waves, which are primarily a factor in the Northern Hemisphere winter. In addition to the mean annual cycle, results are presented for the interannual variability. In the extratropics, poleward transports of both latent and dry static energy reinforce one another. However, the results highlight strong cancellations between the transports of latent and dry static energy in the Tropics as moisture is converted into latent heat, and also between quasi-stationary and transient components in the extratropics. Hence the total energy transports and divergences are fairly seamless with latitude and the total interannual variability is substantially less than that of the components. The strong interplay between the transient and quasi-stationary waves in the atmosphere highlights the symbiotic relationship between them, as the stationary waves determine the location and intensity of the storm tracks while the transient disturbances help maintain the stationary waves. These results highlight that observationally there is a very strong constraint that the global energy budget places on atmospheric dynamics.