Stratosphere Troposphere exchange (STE) is important to study as it controls the chemical composition of the upper troposphere/lower stratosphere (UTLS) and thus the radiative balance of this region. STE also controls the transport of chemicals into the stratosphere which are vital to ozone depletion. The troposphere and the stratosphere have specific chemical characteristics and the transition region between these regions displays characteristics of both. Ozone and water vapour concentrations can be used as tracers for the characteristics of the troposphere and stratosphere. This thesis develops measures in tracer space, which allow the determination of the strength and depth of atmospheric mixing between the troposphere and the stratosphere in extratropical regions. The application of entropy as a measure of atmospheric mixing as introduced by Patmore and Toumi [2006], is improved in this study. This is a measure of how the ozone and water vapour mixing ratios vary as a result of mixing. An additional metric to give further information on the form of the mixing line in tracer space is also developed. This measure uses the ozone and water vapour mixing ratios at the boundaries of the transition region (BO3 and BH2O). This study uses data from ozonesondes and hygrometers, along with satellite data from the Atmospheric Infrared Sounder (AIRS). The ozone product from AIRS is also validated as part of this study. The entropy, BO3 and BH2O measures from this study, are successfully shown to detect regions of enhanced mixing in comparison studies. A key comparison shows that the measures developed in this study are able to produce comparable conclusions to higher resolution aircraft data, with regards to mixing. The separation of entropy, BO3 and BH2O, into different categories allows mixing processes to be assigned to some of the categories. Mixing is shown to have geographic preference, with some regions having significantly more mixing. Some categories have preference with regards to their location either poleward or equatorward of the jet stream. In addition, some information as to the direction of the vertical transport, whether stratosphere to troposphere or vice versa, is obtained.

Surface gravity waves alter the turbulence of the bottom atmosphere and the upper ocean. Accordingly, they can affect momentum flux, heat fluxes, gas exchange and atmospheric mixing. However, in most state-of-the-art Earth System Models (ESMs), surface wave influences are not fully considered or even included. Here, applying surface wave influences into ESMs is investigated from different aspects. Tuning parameterisations for including instantaneous wave influences has difficulties to capture wave influences. Increasing the horizontal resolution of models intensifies storm simulations for both atmosphere-wave coupled (considering the influence of instantaneous wave-induced stress) and stand-alone atmospheric models. However, coupled models are more sensitive to the horizontal resolution than stand-alone atmospheric models. Under high winds, wave states have a big impact on the sea spray generation. Introducing a wave-state-dependent sea spray generation function and Charnock coefficient into a wind stress parameterisation improves the model performance concerning wind speed (intensifies storms). Adding sea spray impact on heat fluxes improves the simulation results of air temperature. Adding sea spray impact both on the wind stress and heat fluxes results in better model performance on wind speed and air temperature while compared to adding only one wave influence. Swell impact on atmospheric turbulence closure schemes should be taken into account through three terms: the atmospheric mixing length scale, the swell-induced momentum flux at the surface, and the profile of swell-induced momentum flux. Introducing the swell impact on the three terms into turbulence closure schemes shows a better performance than introducing only one of the influences. Considering all surface wave impacts on the upper-ocean turbulence (wave breaking, Stokes drift interaction with the Coriolis force, Langmuir circulation, and stirring by non-breaking waves), rather than just one effect, significantly improves model performance. The non-breaking-wave-induced mixing and Langmuir circulation are the most important terms when considering the impact of waves on upper-ocean mixing. Accurate climate simulations from ESMs are very important references for social and biological systems to adapt the climate change. Comparing simulation results with measurements shows that adding surface wave influences improves model performance. Thus, an accurate description of all important wave impact processes should be correctly represented in ESMs, which are important tools to describe climate and weather. Reducing the uncertainties of simulation results from ESMs through introducing surface gravity wave influences is necessary.

Stratosphere Troposphere exchange (STE) is important to study as it controls the chemical composition of the upper troposphere/lower stratosphere (UTLS) and thus the radiative balance of this region. STE also controls the transport of chemicals into the stratosphere which are vital to ozone depletion. The troposphere and the stratosphere have specific chemical characteristics and the transition region between these regions displays characteristics of both. Ozone and water vapour concentrations can be used as tracers for the characteristics of the troposphere and stratosphere. This thesis develops measures in tracer space, which allow the determination of the strength and depth of atmospheric mixing between the troposphere and the stratosphere in extratropical regions. The application of entropy as a measure of atmospheric mixing as introduced by Patmore and Toumi [2006], is improved in this study. This is a measure of how the ozone and water vapour mixing ratios vary as a result of mixing. An additional metric to give further information on the form of the mixing line in tracer space is also developed. This measure uses the ozone and water vapour mixing ratios at the boundaries of the transition region (BO3 and BH2O). This study uses data from ozonesondes and hygrometers, along with satellite data from the Atmospheric Infrared Sounder (AIRS). The ozone product from AIRS is also validated as part of this study. The entropy, BO3 and BH2O measures from this study, are successfully shown to detect regions of enhanced mixing in comparison studies. A key comparison shows that the measures developed in this study are able to produce comparable conclusions to higher resolution aircraft data, with regards to mixing. The separation of entropy, BO3 and BH2O, into different categories allows mixing processes to be assigned to some of the categories. Mixing is shown to have geographic preference, with some regions having significantly more mixing. Some categories have preference with regards to their location either poleward or equatorward of the jet stream. In addition, some information as to the direction of the vertical transport, whether stratosphere to troposphere or vice versa, is obtained.