Planetary Climate Dynamics

Abstract:

Bringing global warming to a halt requires that worldwide net emissions of carbon dioxide be brought to essentially zero, and the sooner this occurs, the less warming our descendants for the next thousand years and more will need to adapt to. The widespread fear that the actions needed to bring this about conflict with economic growth is a major impediment to efforts to protect the climate. However, much of this fear is pointless, and the magnitude of the task, while great, is no greater than challenges human ingenuity has surmounted in the past. To light the way forward, there is a need for examining success stories in which nations have greatly reduced their carbon dioxide emissions while simultaneously maintaining vigorous growth in the standard of living. In this article, the example of Sweden is showcased. Through a combination of sensible government infrastructure policies and free-market incentives, Sweden has managed to successfully decarbonize, cutting its per capita emissions by a factor of three since the 1970s, while doubling its pre capita income and providing a wide range of social benefits. This has all be accomplished within a vigorous capitalistic framework which in many ways embodies freemarket principles better than the economy of the United States.

Abstract:

The response of the period of the quasi-biennial oscillation (QBO) to increases in tropical upwelling are considered using a one-dimensional model. We find that the imposition of the annual cycle in tropical upwelling creates substantial variability in the period of the QBO. The annual cycle creates synchronisation regions in the wave forcing space, within which the QBO period locks onto an integer multiple of the annual forcing period. Outside of these regions, the QBO period undergoes discrete jumps as it attempts to find a stable relationship with the oscillator forcing. The resulting set of QBO periods can be either discrete or broad-banded, depending on the intrinsic period of the QBO.

We use the same model to study the evolution of the QBO period as the strength of tropical upwelling increases as would be expected in a warmer climate. The QBO period lengthens and migrates closer towards 36 and 48 month locking regions as upwelling increases. The QBO period does not vary continuously with increased upwelling, however, but instead transitions through a series of 2- and 3-cycles before becoming locked to the annual cycle. Finally, some observational evidence for the cyclical behaviour of the QBO periods in the real atmosphere is presented.

Abstract:

Large-scale planetary waves are diagnosed from an analysis of profiles retrieved from the Thermal Emission Spectrometer aboard the Mars Global Surveyor spacecraft during its scientific mapping phase. The analysis is conducted by assimilating thermal profiles and total dust opacity retrievals into a Mars global circulation model. Transient waves are largest throughout the northern hemisphere autumn, winter and spring period and almost absent during the summer. The southern hemisphere exhibits generally weaker transient wave behaviour. A striking feature of the low-altitude transient waves in the analysis is that they show a broad subsidiary minimum in amplitude centred on the winter solstice, a period when the thermal contrast between the summer hemisphere and the winter pole is strongest and baroclinic wave activity might be expected to be strong. This behaviour, here called the 'solsticial pause,' is present in every year of the analysis. This strong pause is under-represented in many independent model experiments, which tend to produce relatively uniform baroclinic wave activity throughout the winter. This paper documents and diagnoses the transient wave solsticial pause found in the analysis; a companion paper investigates the origin of the phenomenon in a series of model experiments.