Atmospheric Science Letters

A method based on artificial neural network for atmospheric temperature profile retrieval from spectra measured by nadir viewing high resolution Fourier transform spectrometers is presented. Very fast retrieval of temperature profile is approached. Impact of instrument noise on the retrieval results is considered. Copyright © 2003 Royal Meteorological Society. Published by Elsevier Ltd. All rights reserved.

Carbon cycle feedbacks have been shown to be very important in predicting climate change over the next century. The response of the terrestrial carbon cycle to climate change depends on the competition between increased respiration due to warmer temperatures and increased uptake due to elevated CO₂levels. Whether the terrestrial carbon cycle remains a sink for anthropogenic carbon, or switches to become a source, depends particularly on the response of soil respiration to temperature. Here we use observed global atmospheric CO₂concentration to constrain the behaviour of soil respiration in a coupled climate–carbon cycle GCM. Copyright © 2001 British Crown Copyright.

A comparison is made of the mean monsoon climatology in five different general circulation models (GCMs) which have been used by the participants of a project, funded by the European Union, entitled Studies of the Influence, Hydrology and Variability of the Asian summer monsoon (SHIVA). The models differ considerably, in horizontal and vertical resolution, numerical schemes and physical parametrizations, so that it is impossible to isolate the cause of differences in their monsoon simulations. Instead, the purpose of this comparison is to document and compare the representation of the mean monsoon in models which are being used to investigate the characteristics of the monsoon, its variability and its response to different boundary forcings. All of the models produce a reasonable representation of the monsoon circulation, although there are regional variations in the magnitude and pattern of the flow at both 850 hPa and 200 hPa. Considerable differences between the models are seen in the amount and distribution of precipitation. The models all reproduce the basic monsoon seasonal variation, although the timing of the onset and retreat, and the maxima in the winds and precipitation during the established phase, differ between them. There are corresponding differences in the evolution of the atmospheric structure between the pre‐monsoon season and its established phase. It is hoped that this study will set in context the investigations of the monsoon system and its impacts carried out using these models, both during SHIVA and in the future. Copyright © 2000 Royal Meteorological Society.

The adiabatic assumption that the vertical velocity can be estimated from the displacement of isotherms is examined for solitary wave events propagating in the stable boundary layer overlying an Antarctic ice shelf. Implications for the mathematical modelling of such waves when this assumption is invalid are discussed. Copyright © 2003 Royal Meteorological Society. Published by Elsevier Ltd. All rights reserved.

Chaotic nonlinear low order systems are often regarded as paradigms of the atmospheric behaviour, not least because of their limited predictability. In this paper, the predictability of a forced nonlinear system proposed by Lorenz is examined. The system is a compelling heuristic model of the mid‐latitude global circulation; it exhibits limited predictability. While weak error growth takes place throughout most of the phase space of the system, strong error growth is confined to very limited regions of phase space. A “discrete scattering” model of error growth is proposed. Copyright © 2003 Royal Meteorological Society.

To assist model intercomparison and development of a set of eight numerical experiments is proposed as a test‐bed for the interaction of dynamics and physical parameterizations in atmospheric GCMs. The framework for the experiments is that of an aqua‐planet and the prescribed sea‐surface temperatures (SSTs) are highly idealized. Copyright © 2001 Royal Meteorological Society.

A modelling system comprising a regional climate model nested within a GCM is used to simulate the observed interannual variability of tropical cyclone formation off the east coast of Australia. The model's interannual variability of cyclone formation is weaker than that observed, with shortcomings in the model's simulation of vertical wind shear the likely cause. Copyright © 2003 Royal Meteorological Society. Published by Elsevier Ltd. All rights reserved.

It is now possible to generate large quantities of sky view factor (SVF) values due to advances in digital techniques for calculating SVF from hemispherical images. Coupling image acquisition with Global Positioning System (GPS) data now enables transects to be accurately placed, enabling site‐specific SVF analysis in relation to street geometry. This paper examines SVF transects through four land cover classes. The findings indicate that although SVF averages are distinctly different in each of the land cover types, an average SVF value for a particular land use type is not a sufficient estimate at street resolution. Copyright © 2003 Royal Meteorological Society.

Using observational datasets and coupled model simulations, it is shown that a surface heat flux pattern associated with Gulf Stream variability plays a role in forcing the winter North Atlantic oscillation. It is suggested that by monitoring the Gulf Stream, it may be possible to produce a useful long‐range NAO forecast. By analysing surface heat flux patterns rather than sea‐surface temperatures (as used in previous studies), we find agreement between observational and model‐based results. The results suggest that there may be systematic errors in the modelled surface heat‐flux sensitivity to SST anomalies but that the modelled atmosphere tends to respond correctly to the heat fluxes it is ‘given’. Copyright © 2004 Published by Elsevier Ltd on behalf of Royal Meteorological Society.

A continuous superposition of gravity waves, propagating upward in a shearing background wind, is analyzed. Starting from the gravity wave equations, it is proven, analytically and numerically, that a uniform spectrum has a resultant Doppler‐shifted power spectrum with a −3 power law at large vertical wavenumber contrasting with the −1 power law that characterizes the power spectrum of the monochromatic wave perturbation profile. The preliminary results presented here show that, assuming conservative propagation (no dissipative processes), the Doppler shifting effect can account for observations. Copyright © 2003 Royal Meteorological Society.