A detailed investigation has been made into the photochemistry of ozone in an atmosphere containing hydrogen. It is shown that for such an atmosphere a satisfactory ozone profile can be obtained, unlike the situation now existing for an oxygen only atmosphere. Equilibrium vertical distributions are calculated for nine gas concentrations, and the influence of atomic hydrogen in the mesosphere and the hydroxyl and perhydroxyl radicals in the stratosphere on the ozone concentration are shown to be significant factors. A nonequilibrium investigation is also made in which the variations of the gas concentrations are calculated as a function of the time of day. In particular, the results illustrate the variations of the gas concentrations at night and indicate that the altitude range 70 to 80 km appears to be very active photochemically at this time. The rate of formation of hydroxyl is analyzed to obtain an estimate of the diurnal variation of the hydroxyl airglow emission, as well as the vertical distribution of this emission. The theoretical results are shown to agree satisfactorily with observation, and it is concluded that the hydrogen‐ozone reaction can adequately account for most of the observed features of the hydroxyl emission. Finally, the need to incorporate some form of molecular and eddy diffusion into the model is clearly indicated by the results.

[1] The low frequency variability of the near surface temperature in a climate simulation is compared with Greenland ice core d 18 O time series during the holocene. The simulation is performed with the coupled CSIRO atmosphere-ocean model under present-day conditions. The variability, analyzed by the detrended fluctuation analysis, reveals power-law scaling of the power-spectrum for frequency f, S(f) $ f Àb , and long term memory (LTM) given by b > 0. The near surface temperature shows intense LTM in the North Atlantic south of Greenland, weak LTM in parts of the Antarctic ocean and the tropical Atlantic, and no LTM in the Pacific ocean. The power-law exponent b % 0.5 near Greenland agrees with ice core temperature proxies up to time scales of 1000 years. The LTM of the surface temperature is explained by the high low frequency variability of the zonally averaged streamfunction in the Atlantic with maxima in the Arctic ocean.

An analysis has been performed of three simulations made by forcing a global climatic model with observed sea-surface temperature and sea-ice distributions for the period 1979-1988. These simulations were started from different years of an extended control run, otherwise all conditions were identical. The analysis concentrates on the regional and local differences in the simulations caused by chaos attributable to the differing initial conditions interacting with the non-linearities of the model climatic system. Of particular interest is whether the presence of sea-surface temperature variations in individual years is able to overcome chaotic influences. This interest arises because of the increasing international appreciation that such temperature variations provide the basis for the development of multi-seasonal prediction schemes.The analysis shows that between about 20"N and 20"s a coherent climatic reponse is obtainable owing to the boundary value forcing associated with the sea-surface temperature field. At high latitudes the signal-to-noise ratio rapidly deteriorates. Even at low latitudes, in a sensitive variable such as rainfall, chaos creates substantial differences between the three simulations, except over the Pacific Ocean where a very coherent response is found. In general, over land areas, even those within recognized regions of ENSO (El Niiio-Southern Oscillation) influence, the impact of chaos is much higher. Examination of Pacific North American teleconnection patterns for 1988 reveals substantial differences between the three simulations, and the associated impact on rainfall and surface temperatures over the North American continent. Agreement with observations ranges from rather good to poor, indicating the need for multiple runs for any given situation. Overall the results establish that sea-surface temperature variations can overwhelm chaos in appropriate circumstances and specific regions. Importantly, this indicates that given accurate predictions of sea-surface temperature anomalies a few seasons in advance, then model-based predictions will be possible over many regions of the world despite the omnipresence of chaos.

An 18-vertical level primitive equation general circulation model was developed from previous models of the Geophysical Fluid Dynamics Laboratory in order to study t,he lower stratosphere in detail. The altitude range covered was from the surface to 4 mb. (37.5 km.), the vertical resolution being optimized in the tropopause region to permit a more accurate calculation of the vertical transport terms. A polar stereographic projection waa used and the model waa limited to a single hemisphere. The model now resolves two distinct jet streams, one in the troposphere and the other in the middle polar stratosphere. The wind systems produce a %cell meridional structure in the troposphere, which evolves into a 2-cell structure in the stratosphere. However, the wind structure and associated features of the model in the troposphere had a general equatorward shift compared with observation. A considerable improvement was also obtained in some features of the temperature distribution, in particular the local midlatitude temperature maximum in the lower stratosphere is well defined and shown to be dynamically maintained. The low temperature and sharpness of the equatorial tropopause temperature distribution are closely reproduced by the model, and these features are attributed to the action of the upwards branch of the direct meridional cell in the Tropics, aa is the basic cause of the difference in height of the tropopause a t low and high latitudes. The energy balance of the lower stratosphere in the present model agrees better with observation than previous models did, and confirms earlier work that this region is maintained from the troposphere by a vertical flux of energy. A similar flux of energy is also required to maintain the middle stratosphere, even though this region generates kinetic energy internally, and it is concluded that it is only marginally possible that this region may be baroclinically unstable. It appears that forcing from below extends to higher altitudes in winter than previously suspected.