[1] Detection and attribution studies of observed surface temperature changes have served to consolidate our understanding of the climate system and its past and future behaviour. Most recent studies analysing up-to-date observations have relied on general circulation models (GCMs) to provide estimates of the responses to various external forcings. Here we revisit a methodology which instead es...

We discuss and test the potential usefulness of single-column models (SCMs) for the testing of stochastic physics schemes that have been proposed for use in general circulation models (GCMs). We argue that although single-column tests cannot be definitive in exposing the full behaviour of a stochastic method in the full GCM, and although there are differences between SCM testing of deterministi...

Whereas fossil evidence indicates extensive treeless vegetation and diverse grazing megafauna in Europe and northern Asia during the last glacial, experiments combining vegetation models and climate models have to-date simulated widespread persistence of trees. Resolving this conflict is key to understanding both last glacial ecosystems and extinction of most of the mega-herbivores. Using a dyn...

We discuss and test the potential usefulness of single-column models (SCMs) for the testing of stochastic physics schemes that have been proposed for use in general circulation models (GCMs). We argue that although single column tests cannot be definitive in exposing the full behaviour of a stochastic method in the full GCM, and although there are differences between SCM testing of deterministi...

We construct an interactive ensemble of two different climate models to improve simulation of key aspects of tropical Pacific climate. Our so-called supermodel is based on two atmospheric general circulation models (AGCMs) coupled to a single ocean GCM, which is driven by a weighted average of the air-sea fluxes. Optimal weights are determined using a machine learning algorithm to minimize sea ...

Improving the representation of cloud-radiation interaction is a major challenge for the global climate simulation. The development of cloud-resolving models (CRMs) and the extensive Atmospheric Radiation Measurements (ARMs) provide a unique opportunity for shading some lights on this problem. Current general circulation models (GCMs) predict cloud cover fractions and hydrometeor concentrations...

the present research focuses on the changes of urmia lake level. for this purpose, two timescales have been considered. the trend changes of temperature, precipitation rate and quantitative values of climate type for the observational period from 1968 to 2011 (past scale) and from 2011 to 2100 (future scale) have been analyzed. general circulation model (gcm) is considered for simulating the va...

Abstract Changes in the Southern Ocean (SO) surface wind stress influence both meridional overturning circulation (MOC) and stratification not only SO but global oceans, which can take multiple millennia to fully equilibrate. We use a hierarchy of models investigate time-dependent response MOC low-latitude pycnocline depth (which quantifies stratification) changes: two-layer analytical theory, ...

[1] Recent high-resolution radiosonde climatologies have revealed a tropopause inversion layer (TIL) in the extratropics: temperature strongly increases just above a sharp local cold point tropopause. Here, it is asked to what extent a TIL exists in current general circulation models (GCMs) and meteorological analyses. Only a weak hint of a TIL exists in NCEP/NCAR reanalysis data. In contrast, ...

Global atmospheric circulation models (GCM) typically have three primary algorithmic components: columnar physics, spectral tran-form, and semi-Lagrangian transport. In this study, several varients of a SLT method are studied in the context of test cases for the shallow water equations in spherical geometry. A grid point formulation is used with implicit, semi-implicit or explicit time integrat...