Diurnal Temperature Range Trends in the CCCma Coupled Model

The observed warming trend over land during the second half of the 20th century has been characterised by a faster warming at night. This has lead to a considerable decrease in the diurnal temperature range (DTR), the magnitude of which is comparable to the mean warming itself. Here we present results of a direct comparison of observed DTR trends with those predicted in global warming simulations of the Canadian Centre for Climate Modelling and Analysis coupled general circulation models. The models predict a DTR decrease, albeit of smaller magnitude than observed. A detailed examination of the spatial and temporal nature of the projected 20th and 21st century trends is also presented, along with an investigation into their causes. In the model integrations, DTR decreases continue into the future, and arise from combined changes in clouds and soil moisture.